NASA/CP-2002-211735

National

Standard Experiments

and Technology

Compiled by

Edwin J. Prior

Langley Research Center, Hampton, ldrginia

James A. Jacobs

Norfolk State University, Norfolk, Hrginia

Said Jahanmir

National Institute of Standards and Technology

Gaithersburg, Maryland

Educators' Workshop:

in Engineering,

Update 2001

Materials Science,

June 2002
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NASA/CP-2002-211735

National Educators' Workshop: Update 2001

Standard Experiments in Engineering, Materials Science,

and Technology

Compiled by

Edwin J. Prior

Langley Research Center, Hampton, Virginia

James A. Jaeobs

Norfolk State University, Norfolk, Virginia

Said Jahanmir

National Institute of Standards and Technology

Gaithersburg, Maryland

Proceedings of a workshop sponsored jointly by the National Aeronautics and Space

Administration, Washington, DC; Norfolk State University, Norfolk, VA; the National

Composite Center, Kettering, OH; the National Institute of Standards and Technology,

Gaithersburg, MD; the Energy Efficiency and Renewable Energy Program, Oak Ridge

National Laboratory, Oak Ridge, TN; the United States Automotive Materials

Partnership; the Center for Lightweight Materials and Processing, University of

Michigan-Dearborn, MI; ASM International Foundation, Materials Park, OH; Gateway

Engineering Coalition, Drexel University, Philadelphia, PA; and the University of

Maryland, College Park, MD

and held in

College Park, Maryland

October 14-17, 2001

National Aeronautics and

Space Administration

Langley Research Center

Hampton, Virginia 23681-2199

June 2002
Acknowledgments

We greatly appreciate the support provided by these organizations.

National Aeronautics and Space Administration -- Langley Research Center

National Institute of Standards and Technology

American Society for Engineering Education

Columbia University

International Council for Materials Education

Johns Hopkins University

Loyola College

Northeast Center for Telecommunication Technologies

United States Naval Academy

University of Maryland -- College Park

University of Virginia

The use of trademarks or names of manufacturers in this report is for accurate reporting and does not constitute an I

official endorsement, either expressed or implied, of such products or manufacturers by the National Aeronautics and

Space Administration.

Available from:

NASA Center for AeroSpace Information (CASI)

7121 Standard Drive

Hanover, MD 21076-1320

(301) 621-0390

National Technical Information Service (NTIS)

5285 Port Royal Road

Springfield, VA 22161-2171

(703) 605-6000
PREFACE

NEW:Update 2001, scheduled to be hosted by the National Institute of Standards and Technology in

Gaithersburg, Maryland, was held October 14-17, 2001 as a part of their Centennial Celebration.

However, the September 11th terrorist attack forced the move of the workshop to the University of

Maryland, College Park. There we received the excellent coordination of Professor Isabel Lloyd and

the Department of Materials and Nuclear Engineering.

The 16th Annual NEW:Update was built on themes, activities and presentations based on extensive

evaluations from participants of previous workshops as we continued efforts to strengthen materials

education. About 150 participants witnessed demonstrations of experiments, discussed issues of

materials science and engineering (MS&E) with people from education, industry, government, and

technical societies, heard about new MS&E developments, and chose from ten mini workshops in

state-of-the-art laboratories. Faculty in attendance represented high schools, community colleges,

smaller colleges, and major universities. Undergraduate and graduate students also attended and

presented.

We were fortunate to have excellent support from our hosts. Dr. Said Jahanmir, of the Materials

Science and Engineering Laboratory, coordinated NIST researchers, and Dr. Lloyd made most of the

arrangements at the University of Maryland and coordinated the workshop schedule for the many

scientists, engineers, professors and other staff by providing funding, opening their facilities, and

developing presentations and activities.

NEW:Update 2001 participants saw the demonstration of about fifty experiments and aided in

evaluating them. We also heard updated information relating to materials science, engineering, and

technology presented at mini plenary sessions.

This publication provides experiments and demonstrations that can serve as a valuable guide to faculty

who are interested in useful activities for their students. The material was the result of years of research

aimed at better methods of teaching materials science, engineering, and technology. The experiments

developed by faculty, scientists, and engineers throughout the United States and abroad added to the

collection from past workshops. There is a blend of experiments on new materials and traditional

materials.

Experiments underwent an extensive peer review process. After submission of abstracts, selected

authors were notified of their acceptance and given the format for submission of experiments.

Experiments were reviewed by a panel of specialists through the cooperation of the International

Council for Materials Education (ICME). Comments from workshop participants provided additional

feedback that authors used to make final revisions, which were then submitted to the NASA editorial

group for this publication.

Dr. Robert B. Pond, Sr., Professor Emeritus of Johns Hopkins University, was honored by Dr. Lyle

Schwartz, President of the Federation of Materials Society, as "Outstanding Materials Educator" for

his decades of service to strengthen materials education.

The ICME encourages authors of experiments to submit their work to the Journal of Materials

Education (JME). The JME offers valuable teaching and curriculum aids, including instructional

modules on emerging materials technology, experiments, book reviews, and editorials, to materials

educators.

iii
Critiquesweremadeof theworkshopto providecontinuingimprovementof this activity. The

evaluationsandrecommendationsmadebyparticipantsprovidevaluablefeedbackfortheplanningof

subsequent NEW:Updates.NEW:Update2002will beheldin SanJose,Califomia.

NEW:Update2001andtheseriesof workshopsthatgobackto 1986are,toourknowledge,theonly

nationalworkshopsorgatheringsfor materialseducatorsthathaveafocusonthefull rangeof issues

onstrategiesfor betterteachingabouthefull complementof materials.

We demonstratedthe secondeditionof Experimentsin MaterialsScience,Engineering,and

Technology,(EMSET2)CD-ROMwithover350experimentsfromNEW:Updates.ThisCD-ROM

is anotherexampleof cooperativeffortsto supportmaterialseducation.Theprimarycontributions

camefromthemanyauthorsof thedemonstrationsandexperimentsfor NEW:Updates.Fundingfor

theCDcamefrombothprivateindustryandfederalagencies.Please see the information on page vi

for obtaining the CD.

Special thanks go to our national organizing committee, management team, hosts, sponsors, and

especially to those of you who developed and shared your ideas for experiments, demonstrations, and

innovative approaches to teaching.

The Organizing Committee hopes that the experiments and technical material updated in this

publication will assist you in teaching about materials science, engineering, and technology. We would

like to have your comments on their value and your suggestions for improving them. Please send

comments to Jim Jacobs, School of Science and Technology, Norfolk State University, Norfolk,

Virginia 23504.

The use of trademarks or manufacturers' names in this publication does not constitute an

endorsement, either expressed or implied, by the National Aeronautics and Space Administration.

iv
MANAGEMENT TEAM

James A. Jacobs

Workshop Co-chairperson

Norfolk State University

Said Jahanmir

Workshop Co-Chairperson

National Institute of Standards and

Technology

Isabel K. Lloyd

Workshop Co-Chairperson

University of Maryland

Diana P. LaClaire

Assistant Director

Norfolk State University

Robert Berrettini

International Council on Materials

Education

Paul J. Coyne

Loyola College

Jeane Deatherage

ASM International Foundation

Wayne L. Elban

Loyola College

Leonard W. Fine

Columbia University

James Fitz-Gerald

University of Virginia

Gale A. Holmes

National Institute of Standards and

Technology

Todd C. Hufnagel

Johns Hopkins University

Kenneth L. Jewett

Materials Science & Engineering

Laboratory-NIST

Peter J. Joyce

U. S. Naval Academy

Thomas F. Kilduff

Thomas Nelson Community College

P. K. Mallick

University of Michigan-Dearborn

James V. Masi

Western New England College

Alfred E. McKenney

IBM Corporation, Retired

Angela Moran

U. S. Naval Academy

Edwin Prior

National Aeronautics and Space

Administration

Mark Palmer

American Society for Engineering

Education

Philip Sklad

Oak Ridge National Laboratory

Fred Wellstood

University of Maryland
TheNewEMSET2 CDROMfrom

JimJacobs, AIMcKenney and

Prentice Hall Publishing

The CD ROM Experiments in Materials Science, Engineering and Technology 2 (EMSET2) will be

available soon!

For more than a decade, the National Educators' Workshops have enabled educators to participate in

seminars of peer-reviewed experiments and demonstrations in materials science, engineering and

technology. Following each workshop, these papers were published in an annual compendium, with the

§enerous support of NASA.

Now, with the assistance from NASA and many other governmental, educational and industrial

organizations, we have been able to publish thirteen yearly volumes of these papers in an easily used

format, the EMSET2 CD ROM. This is an expanded and updated version of the original EMSET CD ROM.

This new version runs on all platforms and uses the universally-accepted Adobe Acrobat format for

retrieval, display and printing.

To help the user, the nearly 350 experiments and demonstrations are indexed under the following seven

categories: 1)Structure, Testing and Evaluation, 2)Metals, 3)Polymers, 4)Ceramics, 5)Composites,

6)Electronic and Optical Materials, and 7)Materials Curriculum. The user can find the material he or she

wants by browsing the tables of contents or by searching for author, title, institution, or key word. Then

the documents can be reviewed and used by displaying an exact image of the paper(s), including text,

graphs, pictures, formulae, etc. or by printing the paper as written or even by copying the text and/or

graphics into a word processor for editing.

To preview an individual demo version please reference ISBN 0130194751 and

contact:

Melissa Orsborn

Marketing Assistant

445 Hutchinson Ave. Fourth Floor

Columbus, Ohio 43235

1-614-841-3622

Melissa_Orsbom@prenhall.com

Or

To purchase the complete EMSET2 CD ROM (available Summer 2000) please reference ISBN 0130305340

and contact:

Prentice Hall Customer Service

1-800-922-0579

vi
CONTENTS

Acknowledgments ........................................................................... ii

Preface ....................................................................................... iii

Management Team ............................................................................. v

EMSET2 CD ROM ........................................................................... vi

Reviewers ................................................................................. ,. xiii

Group Picture ............................................................................... xiv

Participants .................................................................................. xv

Sponsors .................................................................................. xxiii

Meeting Places and Sessions ................................................................. xxiv

Sunday Program .......................................................................... xxxvii

Mini Workshops ............................................................................. xliii

Ceramic Fraetography: Broken Pieces Tell the Story ....................................... Ivii

George Quinn, NIST

Special Presentation - Robert B. Pond, Sr ................................................... lxxxv

Martha Goodway ........................................................................ lxxxvii

Justin Hanes ............................................................................ lxxxviii

Duane Bushey and Merrill Rudes .......................................................... Ixxxix

MATERIALS RESEARCH AT NIST - CENTURY OF PROGRESS ......................... 1

Dale Hall - National Institute of Standards and Technology

ELECTROLYSIS OF WATER IN THE K-12 CLASSROOM .............................. 27

H. Alan Rowe - Norfolk State University

TEACHING UNDERGRADUATES RESULTS FROM RECENT

RESEARCH AS PART OF A LABORATORY CLASS:

X-RAY DIFFRACTION EXPERIMENT ................................................... 33

L. J. Martinez-Miranda - University of Maryland

THE DISTRIBUTION OF ELECTROMAGNETIC ENERGY

IN A MICROWAVE OVEN ................................................................ 41

Jai N. Dahiya, Wendy Decker, and Aman Anand

Southeast Missouri State University

ACTIVE AND INTELLIGENT MATERIALS .............................................. 63

John Marshall - University of Southern Maine

UNIVERSITY OF MARYLAND MRSEC RESEARCH

EXPERIENCE FOR UNDERGRADUATES: CULTIVATING

TOMORROW'S RESEARCHER ........................................................... 69

Jennifer Stott, Donna Hammer, E. D. Williams, and

L. J. Martinez-Miranda - University of Maryland

ROOM TEMPERATURE CREEP OF Pb-Sn AND

Sn-Ag-Cu EUTECTIC SOLDERS .......................................................... 75

Matthew C. Osborne, Monica Hurley, and Angela L. Moran

U. S. Naval Academy

vii
WINDMILL-POWERED, PROPELLER-DRIVEN BOAT

DESIGN-BUILD ENGINEERING PROJECT .............................................. 87

Matthew A. Carr - U. S. Naval Academy

EXPERIMENTS FOR FIRST YEAR ENGINEERING

STUDENTS USING Sn-Bi ALLOYS ........................................................ 95

Mark A. Palmer, Kurt Wainwright, Lung C. Fok, and

Benjamin Jones - Virginia Commonwealth University

FORMATION AND CONVERSION OF CALCIUM

PHOSPHATES - A NOVEL APPROACH TO PREVENT

CAVITIES AND DENTIN SENSITIVITY ................................................. 105

Ming S. Tung - National Institute of Standards and Technology

LIGHTWEIGHT AUTOMOTIVE MATERIALS RESEARCH

AT THE CENTER FOR LIGHTWEIGHTING AUTOMOTIVE

MATERIALS AND PROCESSING (CLAMP) ............................................. 111

P. K. Mallick -University of Michigan-Dearborn

MEMS AND NANOTECHNOLOGY IN THE 21 sT

CENTURY ................................................................................ 125

Luc G. Fr6chette - Columbia University

FISHING LINE KNOT TYING CONTEST:

A FRESHMEN EXPERIENCE ............................................................ 149

Wayne L. Elban - Loyola College and

Douglas L. Frantz - Community College of Baltimore County

DETERMINATION OF REDUNDANT WORK IN

EXTRUSION USING VISIO-PLASTICITY .............................................. 171

Neda S. Fabris - California State University, Los Angeles

MAGNETIC FIELD SENSING EXPERIMENTS BASED

ON A COMMERCIALLY AVAILABLE GIANT

MAGNETORESISTIVE (GMR) SENSOR ................................................. 181

Amy Payne, Kara A. Schnell, Franz J. Himpsel, and

Arthur B. Ellis - University of Wisconsin - Madison

GATEWAY ENGINEERING COALITION ............................................... 193

Eli Fromm - Gateway Engineering Coalition and

Morton Friedman - Columbia University

COMBINATORIAL APPROACH TO MATERIALS

DISCOVERY .............................................................................. 217

Ichiro Takeuchi - University of Maryland

viii
EXPERIMENTS IN ELECTRICALLY AND

MAGNETICALLY ACTIVE POLYMERS: NOT

JUST INSULATING PLASTICS .......................................................... 241

James V. Masi - Western New England College (emeritus)

LOW-BUDGET EPITAXY: COPPER ON SILICON ...................................... 257

John N. Kidder, Jr., and Luz Martinez-Miranda - University of Maryland

MAGNETOIMPEDANCE: A USEFUL PHENOMENON

FOR MAGNETIC, ELECTRIC AND STRESS SENSORS ................................. 265

Raul Valenzuela - National University of Mexico

CHARACTERIZING ALLOY MICROSTRUCTURES FOR

SEMI-SOLID FORMING ................................................................. 277

Robert B. Pond, Jr. - Loyola College and Scott N. Hornung - Lucent Technologies

P4 PREFORMING TECHNOLOGY: PROCESS

DEVELOPMENT UTILIZING CARBON FIBER ROVINGS ............................. 287

Norman G. Chavka and Jeffrey S. Dahl - Automotive Composites

Consortium/Ford Motor Company

THE MAGSET K-12 CURRICULUM PROJECT ......................................... 309

Don L. Evans - Arizona State University

LECTURE ACTIVITY WORK KITS FOR INTRODUCTORY

MATERIALS ENGINEERING CLASSES ................................................. 325

Stephen Krause and Shahriar Anwar - Arizona State University

LUDER'S BAND FORMATION IN STEEL ............................................... 333

Mike L. Meier and Aaron Broumas - University of California, Davis

TRANSMISSION ELECTRON MICROSCOPY OF SELFORGANIZED MAGNETIC STRUCTURES IN

La0.67Sr0.33Mn FILMS ...................................................................... 343

Lourdes Salamanca-Riba, and L. J. Martinez-Miranda - University of Maryland

THE ATOMIC MASS UNIT AND THE AVOGADRO

CONSTANT: AN APPROACH TO INTRODUCE THESE

CONCEPTS ............................................................................... 351

Carlos E. Umafia - University of Costa Rica

THE ONSET OF TENSILE INSTABILITY ............................................... 361

Mike L. Meier and Amiya K. Mukherjee - University of California, Davis

FIRST ROBOTICS COMPETITION ...................................................... 379

Lori Aldridge - Northwestern High School

ix
THE CENTER FOR THEORETICAL AND COMPUTATIONAL

MATERIALS SCIENCE ................................................................... 407

James Warren - National Institute of Standards and Technology

LOAD TESTING OF TEMPORARY STRUCTURAL

PLATFORMS ............................................................................. 413

Harvey Abramowitz, Ralph E. Bennett III, John Bennett,

Rick J. Hendrickson, Caris Koultourides, Brandon W. Tredway,

and Walter Kuchariski - Purdue University at Calumet

NON-LINEAR ACOUSTIC SYSTEM FOR DAMAGE

ASSESSMENT ............................................................................ 435

Yulian Kin, Alexander Sutin, Eric Roades, Karen Dalton, and Kimberly Bateman

Purdue University Calumet

MOTORLESS MOTION WITH NiTi: A SENIOR

DESIGN PROJECT ....................................................................... 441

Suzanne Keilson, Robert Redfield, and

Michael Guarraia - Lockheed Martin Corporation

AN INSTRUCTIONAL SOFTWARE PACKAGE ON

FTIR SPECTROMETRY .................................................................. 451

Leonard W. Fine, L. Avila, and B. Venkataraman - Columbia University

SUBSTRATE ANALYSIS GRIT BLASTING .............................................. 455

Rodney D. Jiggetts, F. Biancaniello, S. Ridder, S. Mates, M. Stoudt,

R. Schaefer, and P. Boyer - National Institute of Standards and Technology

THE DYNAMIC YOUNG'S MODULUS .................................................. 471

Ron E. Smelser, E. M. Odom, and K. V. Organ - University of Idaho

CASE STUDY: USING A NEURAL NETWORK TO

IDENTIFY FLAWS DURING ULTRASONIC TESTING ................................. 481

A. Kayabasi, Glenn S. Kohne, and P. J. Coyne, Jr. - Loyola College

DEMONSTRATIONS OF SOME FUNDAMENTAL CONCEPTS

CONCERNING FUELS AND ENGINES .................................................. 495

John J. Fortman - Wright State University

HARDNESS INDENTATION ANALYSIS ................................................. 505

Richard J. Fields - National Institute of Standards and Technology,

and Thomas A. Pierce - Norfolk State University

OVERVIEW OF NEW:UPDATE 2002 .................................................... 509

W. Richard Chung - San Jose State University

CARBON FIBER: THE MATERIAL OF THE FUTURE ................................. 525

C. David Warren - Oak Ridge National Laboratory

X
SMART MATERIAL ACTUATORS ...................................................... 579

Charlie E. Woodall, Walter T. Golembiewski, and Kyo D. Song - Norfolk State University,

and Won J. Yi - ICASE, NASA Langley Research Center

COLLOIDAL SELF-ASSEMBLY PHENOMENA ......................................... 587

O. C. Wilson, Jr. and L. J. Martinez-Miranda - University of Maryland

THE MAGIC OF CRYOGENICS ......................................................... 593

Daniel P. Vigliotti, James B. Alcorn, Brian P. Marsh, and Nicole A. Neumeyer

National Institute of Standards and Technology

MOLECULAR DYNAMICS SIMULATIONS OF CRACKING

PHENOMENA IN POLYMER LIQUID CRYSTALS (PLCs) .............................. 609

Witold Brostow and Ricardo Sim6es - University of North Texas

Ant6nio M. Cunha - University of Minho

DEVELOPMENT OF A DEFORMATION PROCESSING

LABORATORY ........................................................................... 617

Richard B. Griffin, K. Ted Hartwig, Robert Barber, Tiffany New, and

Ibrahim Karaman - Texas A&M University

BIMAP (BINARY ISOMORPHOUS PHASE MAP) -- AN

INTERACTIVE COMPUTER TOOL FOR PHASE DIAGRAM

INSTRUCTION ........................................................................... 627

Jeffrey Csemica, J. Stolk, M. E. Hanyak, and V. Subramanian - Bucknell University

TEAPOT DRIBBLES AND LADLE POURS .............................................. 637

Edward L. Widener - Purdue University

NATIONAL COMPOSITE CENTER AND DIRECTED FIBER

PREFORMING ............................................................................ 641

Tobey Cordell - National Composite Center

xi

REVIEWERS

Harvey Abramowitz

Department of Engineering

Purdue University - Calumet

Else Breval

Professor of Materials Science

Center for Materials Characterization

University of North Texas

L. Roy Bunnell

Material Science Department

Southridge High School

William Callister

Adjunct Professor of Metallurgy

University of Utah

K. C. Chan

Physics Department of Natural Sciences

Albany State University

Wayne L. Elban

Professor of Engineering

Loyola College, Maryland

Leonard W. Fine

Department of Chemistry

Columbia University in the City

of New York

Richard Griffin

MEEN Department

Texas A&M University

L. J. Martinez-Miranda

Dept. of Materials and Nuclear

Engineering

University of Maryland

James V. Masi

Western New England College

(Emeritus)

Mike Meier

Dept. of Chemical Engineering and

Materials Science

University of California, Davis

Robert Newnham

Solid State Science

The Pennsylvania State University

Edward L. Widener

Department of Mechanical Engineering

Purdue University

Technical Notebooks were provided by

NASA LANGLEY RESEARCH CENTER

Announcements of the workshop were provided by

THE ASM INTERNATIONAL FOUNDATION

xiii
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xiv
Participants - National Educators' Workshop 2001

Harvey Abramowitz

Department of Engineering

Purdue University B Calumet

2200 169th Street

Hammond, IN 46323

219-989-2473

harveya@ calumet.purdue.edu

Sean Agnew

MSE Faculty Member

University of Virginia

Loft Aldridge

Northwestern High School

2503 W. Main Street

Rockhill, SC 29732

803-417-0863

laldridg@rock-hill.K 12.sc.us

Eric J. Amis

Polymers Division (854)

Polymers Building (224), Room A303

National Institute of Standards and Technology

100 Bureau Drive, Stop 8540

Gaithersburg, MD 20899-8540

301-975-6681

eric.amis @nist.gov

Aman Anand

1000 Towers Circle

Apartment South 718

Cape Girardeau, MO 63701

573-339-4376

amanfromcs @hotmail.com

Shahriar Anwar

Arizona State University

1171 N. Tercera Court

Chandler, AZ 85226

480-965-5696

anwar@asu.edu

Luis Avila

Columbia University

Dept. Of Chemistry

116th Broadway

New York, NY 10027

212-854-2587

avila@ chem.columbia.edu

Michael B agby

West Virginia University

School of Dentistry

HSC North

Box 9403

Morgantown, WV 26506-9403

304-293-3370

mbagby@hsc.wvu.edu

Raj Bansal

University of Virginia

2021 Ivy Road, #C-5

Charlottesville, VA 22903

434-923-8794

rajbansal@ virginia.edu

Laura M. Bartolo

Associate Professor

Libraries & Media Services

Kent State University

Kent, OH 44141-0001

330 -672-1691

lbartolo @kent.edu

Robert Berrettini

209 Kenmar Drive

Monroeville, PA 15146-1717

412-373-7975

e-mail berrettini@stargate.net

John Blendell

National Institute of Standards and Technology

Ceramics Division 223/B324

110 Bureau Drive, STOP 8522

Gaithersburg, MD 20899-8522

301-975-5796

John.Blendell@ nist.gov

Duane Bushey

Maury High School

322 Shirley Avenue

Norfolk, VA23517

757-628-3348

dbushey@infi.net

William D. Callister

University of Utah

2419 East 3510 South

Salt Lake City, UT 84109

801-278-8611

bill.callister @m.cc.utah.edu

XV
Joseph C. Carpenter

EE 32

U. S. Department of Energy

100 Independence Avenue SW

Washington, DC 20585

202-586-1022

joseph.carpenter@ ee.doe.gov

G. Slade Cargill III

Department MS &E

Lehigh University

5 E. Packer Avenue

Bethlehem, PA 18015

610-758-4207

gsc3 @lehigh.edu

John Cassidy

jacassil @kent.edu

K. C. Chan

Albany State University

Natural Sciences Dept.

504 College Drive

Albany, GA 31705

229-430-1728

kcchan@ asurams.edu

Kaushik Chatterjee

University of Virginia

Kc5v@virginia.edu

W. Richard Chung

Department of Chemical and Materials Engineering

San Jose State University

San Jose, CA 95192-0082

408-924-3927

wrchung@sjsu.edu

Michelle Churma

Prentice Hall

445 Hutchinson Avenue

Columbus, OH 43235

614-841-3636

Michelle_Churma@prenhall.com

Toby Cordell

National Composite Center

2000 Composite Drive

Kettering, OH 45420

937-369-1174

tcordell@compositecenter.org

Paul J. Coyne, Jr.

Loyola College

Dept. of Electrical Engineering

and Engineering Science

Baltimore, MD 21210-2699

pcoyne@loyola.com

Roger Crider

2100 Concert Drive

Virginia Beach, VA 23456

757-468-3800

rlcrider@vbcps.kl 2.va.us

Jeffrey Csemica

Department of Chemical Engineering

Bucknell University

Lewisburg, PA 17837

570-577-1257

csemica@bucknell.edu

Jai N. Dahiya

Professor of Physics & Associate Dean

College of Science & Mathematics

Southeast Missouri State University

One University Plaza, MS 6000

Cape Girardeau, MO 63701

573-651-2163

dahiya@physics.semo.edu

Jeff Dahl

Ford Research Lab

SRL, MD3135

2101 Village Road

Dearborn, MI 48124

313-322-7814

jdahl@ ford.com

Sabine Dickens

National Institute of Standards and Technology

Avinash M. Dongare

Materials Science and Engineering

University of Virginia

2021 Ivy Road

University Forum, Apt. #C-5

Charlottesville, VA 22903

434-923-8794

davinash @virginia.edu

Frederick C. Eichmiller

Polymers Division (854)

Polymers Building (224), Room A155

National Institute of Standards and Technology

100 Bureau Drive, Stop 8546

Gaithersburg, MD 20899-8546

301-975-6813

frederick.eichmiller @nist.gov

Efremfon Frank Ekpo

Bethune-Cookman College

640 Dr. M. M. Bethune Blvd.

Daytona Beach, FL 32114

386-255-1401 xd 532

ekpoe@cookman.edu

xvi
WayneL.Elban

Dept.ofElectrical Engineering andEngineering

Science

LoyolaCollege

Baltimore, MD21210

410-617-2853

welban@loyola.edu

DonEvans, Director

CenterforResearchonEducationinScience

ArizonaStateUniversity

Tempe, AZ85287-5006

480-965-5350

devans@asu.edu

NedaFabris

Department ofMechanical Engineering

CaliforniaStateUniversity, LosAngeles

5151StateUniversity

LosAngeles, CA 90032-8153

323 -343-5218

nfabris@exchange.calstatela.edu

Louis Feng

lfeng @kent.edu

R. J. Fields

National Institute of Standards and Technology

MATLS B252

100 Bureau Drive, Stop 8553

Gaithersburg, MD 20899-8533

301-975-5712

rjf@nist.gov

Leonard W. Fine

Department of Chemisa-y

Columbia University in the City of New York

Havemeyer Hall

New York, NY 10027

212-854-2017

fme @chem.columbia.edu

James M. Fitz-Gerald

Department of Materials Science & Engineering

Advanced Laser Processing

School of Engineering and Applied Science

University of Virginia

116 Engineer=s Way

Charlottesville, VA 22904-4745

804-243-8830

jmfSh@virginia.edu

John J. Fortman

Department of Chemistry

Wright State University

Dayton, OH 45435

937-775-2188

john.fortman@wright.edu

Douglas Frantz

Community College of Baltimore County

800 S. Rolling Road

Baltimore, MD 21228

410-455-4317

dflantz@ccbc.cc.md.us

Morton Friedman

Columbia University .

500 West 120th Street

Room 510 Mudd

New York, NY 10027

212-854-2986

fiiedman@columbia.edu

Eli Fromm

Director and P.I. of Gateway Engineering

Education Coalition

fromm@drexel,edu

Edwin Fuller

Ceramics Division (852)

Materials (223), Room A325

National Institute of Standards and Technology

100 Bureau Drive, Stop 8521

Gaithersburg, MD 20899-8521

301-975-5795

edwin.fuller @ nist.gov

James Gardner

Technology Commercialization Center

12050 Jefferson Avenue, Suite 350

Newport News, VA 23601

757-269-0025

jgardner@teccenter.org

Kathryn Gargurevich

4920 Strathmore Avenue

Kensington, MD 20895

3/469-6034

garg4@msn.com

Ronald R. Garrison

4653 Priscilla Lane

Virginia Beach, VA 23455

757-460-6052

rrgarris @vbcps.kl 2.va.us

Charles J. Glia_ka

National Institute of Standards and Technology

Center for Neutron Research

100 Bureau Drive, STOP 8652

Gaithersburg, MD 20899-8562

301-975-6242

cglinka@nist.gov

xvii
RichardB.Griffin

MahanHall,C&ME(2001-2002)

UnitedStatesMilitaryAcademy

WestPoint,NY10996-1972

845-938-4093

rgriffm@mengr.tamu.edu

Richard.Griffin @usma.edu

MarthaGoodway

Archaeometallurgist

Smithsonian CenterforMaterials

ResearchandEducation

Washington, DC20560

301-238-3700 x 164

GoodwayM@ SCMRE.SI.EDU

Michael Guatmia

Loyola College

Dale Hall, Deputy Director

Materials Science & Engineering Laboratory

National Institute of Standards and Technology

Bldg. 310, Room B309, MS 8500

Gaithersburg, MD 20899-8500

301-975-5658

dale.hall@nist.gov

Justin Hanes

Department of Chemical Engineering

Johns Hopkins University

221 Maryland Hall

3400 North Charles Street

Baltimore, MD 21218

410-516-3484

hanes@jhu.edu

Luke H. Huang

Assistant Professor

Industrial Technology

University of North Dakota

Grand Forks, ND 58202

701-777-2202

luke_huang @und.edu

Yolanda L. Hinton

Department of Engineering

Norfolk State University

700 Park Avenue

Norfolk, VA 23504

757-823-2697

ylhinton@nsu.edu

y.l.hinton@larc.nasa.gov

Todd C. Hufnagel

Dept. Of Materials Science and Engineering

Johns Hopkins University

102 Maryland Hall

3400 North Charles Street

Baltimore, MD 21218

410-516-6277

hufnagel@jhu.edu

Monica Hurley

U. S. Naval Academy

590 Holloway Road

Annapolis, MD 21402

410-293-6534

amoran@usna.edu

James A. Jacobs

School of Science and Technology

Norfolk State Univesity

700 Park Avenue

Norfolk, VA 23504

757-823-8109

jajacobs@nsu.edu

Said Jahanmir

Ceramics Division

Materials, Room B 360

National Institute of Standards and Technology

100 Bureau Drive, MS 8520

Gaithersburg, MD 20899-8520

301-975-3671

said.jahanmir @nist.gov

Greg Jennings

University of Virginia student

258-11 Colonnade Drive

Charlottesville, VA 22903

434-297-3406

gmj 3t @cms.mail.virginia.edu

Rodney D. Jiggetts

Metallurgy Division (855)

National Institute of Standards and Technology

100 Bureau Drive, Stop 8555

Gaithersburg, MD 20899-8555

301-975-5122

rodney.jiggetts @ nist.gov

Ajit Jillavenkatesa

Ceramics Division (852)

Materials (223), Room A215

National Institute of Standards and Technology

100 Bureau Drive, Stop 8520

Gaithersburg, MD 20899-8520

301-975-5089

ajit.jilla@nist.gov

..°

XVlll
Peter Joyce

U. S. Naval Academy

590 Holloway Road

Annapolis, MD 21402

410-293-6533

pjoyce@usna.edu

Suzanne Keilson

Loyola College

4501 North Charles Street

Dept. of Electrical Engineering and

Engineering Science

Baltimore, MD 21210

410-617-2722

skeilson@loyola.edu

John N. Kidder, Jr.

Assistant Professor

University of Maryland

Department of Materials Science and Engineering

Bldg. 090, Room 2142

College Park, MD 20742

301-405-0499

kidder @eng.umd.edu

Yulian Kin

Purdue University Calumet

2200 169thStreet

Hammond, IN 46323

kin @calumet.purdue.edu

Glenn Kohne

Loyola College

Dept. Of Electrical Engineering

& Engineering Science

Baltimore, MD 21210-2699

410-617-2249

kohne@loyola.edu

Diana P. LaClaire

School of Science and Technology

Norfolk State University

700 Park Avenue

Norfolk, VA 23504

757-823-9072

dplaclaire@nsu.edu

Elodie Leveugle

2728 McElroy Drive

Charlottesville, VA 22903

434-243 -7754

el8d@ virginia.edu

Isabel Lloyd

Department of Materials and

Nuclear Engineering

Room 2138, Building 090

University of Maryland

College Park, MD 20742-2115

301-405-5221

illoyd@eng.umd.edu

P. K. Mallick

Department of Mechanical Engineering

University of Michigan-Dearborn

Dearborn, M148128

313-593-5119

pkm@umich.edu

John Marshall

University of Southern Maine

Mitchell Center

37 College Avenue

Gorham, ME 04038

207-780-5447

jmarshal@usm.maine.edu

L. J. Marfinez-Miranda

Dept. of Materials and Nuclear Engineering

University of Maryland

College Park, MD 20742-2115

301-405-0253

martinez@eng.umd.edu

James V. Masi

Western New England College (Emeritus)

242 Spurwink Avenue

Cape Elizabeth, ME 04107-9612

207-767-3196

masij@hotmail.com

Alfred E. McKenney

516 Fairfax Way

Williamsburg, VA 23185

757-221-0476

aem2@prodigy.net

Mike Meier

Department of Chemical Engineering and Materials Science

University of California, Davis

Davis, CA 95616

530-752-5166

mlmeier@ucdavis.edu

Andrew Mercado

313 13th Street NW Apt. 1D

Charlottesville, VA 22903

434-923-8226

alm5w @cms.mail.virginia.edu

xix
MohsenMosleh

HowardUniversity

2300SixthStreet,N.W.

Washington, DC20059

202-806-6622

mmosleh@fac.howard.edu

Angela Moran

Department of Mechanical Engineering

U. S. Naval Academy

Annapolis, MD 21402

410-293-6534

amoran @gwmail.usna.edu

Frederick W. Oliver

Morgan State University

Baltimore, MD 21251

443-885-3751

fwoliver@morgan.edu

Matthew C. Osborne, Midshipman 1/C

Assistant Professor

U. S. Naval Academy

Mechanical Engineering Dept.

Rickover Hall Room 66

590 Holloway Road M/S llC

Annapolis, MD 21402

410-293-5528

Osborne@usna.edu

Richard J. Osborne

GMNA Materials & Fastening

MC 480-205-314

Dock #17, Room 306-07

3007 Van Dyke

Warren, M148090-9065

810-575-7039

richard, osborne @GM. com

Mark A. Palmer

Kettering University

1700 West Third Avenue

Flint, MI 48504

810-762-7973

mpalmer @kettering.edu

Amy Payne

University of Wisconsin: MRSEC

1101 University Avenue

Department of Chemistry

Madison, W153706

608-262-6711

payne@chem.wisc.edu

Thomas Pierce

Norfolk State University

700 Park Avenue

Norfolk, VA 23504

757-823-8109

tapnsu@yahoo.com

Robert B. Pond, Jr.

913 Ellendale Drive

Towson, MD 21286

410-617-5563

rpond@loyola.edu

Merredith Portsmore

Tufts University

Department of Mechanical Engineering

200 College Avenue

Anderson Hall

Medford, MA 02155

617-627-5888

mportsmo@tufts.edu

Adam C. Powell IV

hazelsct@mit.edu

George D. Quinn

Ceramics Division (852)

Materials (223), Room A359

National Institute of Standards and Technology

100 Bureau Drive, Stop 8521

Gaithersburg, MD 20899-8521

301-975-5765

george.quinn@nist.gov

Robert Redfield

Loyola College

Chris Rogers

Associate Professor

Department of Mechanical Engineering

Tufts University

Medford, MA 02155

617-627-2882

crogers@tufts.edu

William Ross

Muskegon Community College

221 S. Quartweline Road

Muskegon, MI 49442

231-777-0367

RossB @muskegon.cc.mi.us

XX
H. Alan Rowe

Professor of Chemistry

Norfolk State University

Chemistry/Center for Materials Research

Norfolk, VA 23504

757-823-2248

harowe@nsu.edu

J. Michael Rowe

NIST Center for Neutron Research (856)

Reactor Building (235), Room A104

National Institute of Standards and Technology

100 Bureau Drive, Stop 8560

Gaithersburg, MD 20899-8560

301-975-6210

j.rowe@nist.gov

Merrill Rudes

Energy Concepts, Inc.

404 Washington Blvd.

Mundelein, IL 50050

847-837-8191

ecisales 1@ aol.com

mrudes@ aol.com

Lourdes Salamanca-Riba

Materials and Nuclear Engineering Department

University of Maryland

College Park, MD 20742-2115

riba@eng.umd.edu

Robert D. Shull

Metallurgy Division (855)

Materials (223), Room B150

National Institute of Standards and Technology

100 Bureau Drive, Stop 8552

Gaithersburg, MD 20899-8552

301-975-6035

robert.shull@nist.gov

Ricardo Simoes

Laboratory of Polymers

Department of Materials Science

University of North Texas

Denton, TX 76203-5310

940-565-3262

rsimoes@unt.edu

Philip Sklad

Grant Tech Monitor

Oak Ridge National Laboratory

skladps@ornl.gov

Ron E. Smelser

University of Idaho

Sixth and Ash

P. O. Box 440902

Moscow, ID 83844-0902

208-885-4049

rsmelser@uidaho.edu

Jonathan D. Stolk

Asst. Professor of Mechanical Engineering

And Materials Science

Franklin W. Olin College of Engineering

1735 Great Plain Avenue

Needham, MA 02492

jonathan.stolk@olin.edu

Kyo D. Song

Norfolk State University

700 Park Avenue

Norfolk, VA 23504

757-823-8105

ksong@nsu.edu

Ichiro Takeuchi

Assistant Professor

Dept. of Materials and Nuclear Engineering

and Center for Superconductivity Research

University of Maryland

College Park, MD 20742

301-405-6809

takeuchi@ squid.umd.edu

Vinot Tewary

tewary@boulder.nist.gov

Ming Tung

National Institute of Standards and Technology

100 Bureau Drive,Stop 8546

Gaithersburg, MD 20899-8546

301-975-6823

Ming.tung@nist.gov

Carlos E. Umana

School of Mechmtical Engineering

University of Costa Rica

San Pedro, Costa Rica

506-207-4548

caruma@ terrab a.fmg.ucr .ac.cr

Raul Valenzuela

Institute for Materials Research

National University of Mexico

P. O. Box 70-360

Mexico 04510 Mexico

525-622-4653

monjaras@ servidor.unam.mx

xxi
Bhawani Venkataraman

340ColumbiaUniversity

MC3142Havemeyer Hall

NewYork,NY10027

212-854-4598

bhawani@chem.columbia.edu

DanielP.Vigliotti

National InstituteofStandards andTesting

Division853

325Broadway

Boulder, CO80303-3328

303-497-3351

vigliotti@boulder.nist.gov

CurtissE.Wall

SchoolfScienceandTechnology

NorfolkStateUniversity

700ParkAvenue

Norfolk,VA23504

757-823-9571

cewall@nsu.edu

C.DavidWarren

Bldg.9204

Oak Ridge National Laboratory

P. O. Box 2099, MS 8050

Oak Ridge, TN 37831-8050

W95 @ornl.gov

James Warren

Metallurgy Division (855)

Materials (223), Room A311

National Institute of Standards and Technology

100 Bureau Drive, Stop 8554

Gaithersburg, MD 20899-8554

301-975-5708

jwarren@nist.gov

Edward L. Widener

Purdue University

Knoy Hall 119

West Lafayette, IN 47907-1317

elwidener @tech.purdue.edu

O. C. Wilson, Jr.

Department of Materials and Nuclear Engineering

University of Maryland

College Park, MD 20742-2115

Amy Wilkerson

Applied Research Center

12050 Jefferson Avenue, Suite 713

Newl_rt News, VA 23606

757-269-5760

alwilker@ AS.WM.EDU

Charlie Woodall

Norfolk State University

700 Park Avenue

Norfolk, VA 23504

brickcha@hotmail.com

xxii
NATIONAL EDUCATORS' WORKSHOP

Update 2001: Standard Experiments

in Engineering Materials, Science,

and Technology

October 14 - October 17, 2001 - Gaithersburg, Maryland

Sponsored by

Materials Science & Engineering Laboratories

National Institute of Standards and

Technology

Department of Energy

Office of Energy Efficiency and

Renewable Energy

School of Science and Technology

Norfolk State University

Center for@Lightweight Materials

and Processing

University of Michigan - Dearborn

Energy Efficiency and Renewable

Energy Program

Oak Ridge National Laboratory

_ TheASM

International

FOUrK_On

The ASM International Foundation

Gateway Engineering Coalition

National Aeronautics & Space

Administration

Langley Research Center

USAMP

United States Automotive

Materials Partnership

N C C

National Composite Center

With the support of

American Society for Engineering Education

International Council for Materials Education

Loyola College

United States Naval Academy

University of Virginia

Columbia University

Johns Hopkins University

Northeast Center for Telecommunications Technologies

University of Maryland - College Park

xxiii
MEETING PLACES AND SESSIONS

i=i_iiii i

Said Jahanmir

Workshop Co-Chairperson

NIST

xxiv
XXV
SESSIONS

-_=_-I-i _i 111 I ̧ ii ' i...... ii i  ̧ i

xxvi
SESSIONS (continued)

xxvii
SESSIONS (continued)

°°°

XXVlll
SESSIONS (continued)

xxix
SESSIONS (continued)

XXX
SESSIONS (concluded)

xxxi
Diana La Claire and Amy Wilkerson

ii!!!!i!i!iiii!_!i!i!i!!!!i!iiiiii!i!i!iiiiii!i!i!iiiiii_  ̧ii!_iii!_i!i!?i!i!!?i!iii!  ̧'i!i!i!  ̧i_i!!?_i!i!i!i_i_iii!i!!!!i!i!i!_!_!ii!i!i!!i_i!i!i!_!_!i!i!i!_!

Michelle Churma - Prentice Hall Merrill Rudes - Energy Concepts

xxxii
BREAKS

ili_!ililililililililili_!iiii_i_!iiiiiliiiiiilililililil,

!!!!i!!!!!!!!!!i!i!!!!!!!i!i!!!!!!!!i!i!!!!!!!!i!i!!!!!!!!i!i_

xxxiii
lsobel Lloyd

xxxiv
AI McKenney

XXXV
NATIONAL EDUCATORS' WORKSHOP

NEW:UPDATE 2001

SUNDAY PROGRAM

SUNDAY AFTERNOON_ October 14, 2001

Welcome and Introduction to the University of Maryland

Materials Science and Engineering at the University of Maryland (Research and UG

Program)

Lab tours and Demonstrations

Registration at Conference Center

xxxvi:
SUNDAY PROGRAM

xxxvii
SUNDAY PROGRAM (Continued)

iiiii_@_iiii?_i!!!!i?!i_i_i_i!iiiiiiiiiiiiiiiiiii_i_i_iiiiii!iii_iiiiii_ii!iiiiii!i!i!iiiiii!!!i!iiiiii!!!!!iiiiii!!!!!iiiiii!!!!!iiii!!!!!iiii!!!!!_i!!!!!

...

XXXV111
SUNDAY PROGRAM (Continued)

xxxix
SUNDAYPROGRAM(Continued)

xl
SUNDAYPROGRAM (Continued)

xli
SUNDAYPROGRAM (Concluded)

xlii
MINI WORKSHOPS

MONDAY AFTERNOON

WONDERFUL WORLD OF POLYMERS

Presented by Eric J. Amix

National Institute of Standards and Technology

CERAMIC FRACTOGRAPHY

Presented by George Quinn

National Institute of Standards and Technology

LIGHTWEIGHT AUTOMOTIVE MATERIALS DATABASE

Presented by P. K. Mallick

University of Michigan-Dearborn

LINEAR ACCELERATOR

Chemical and Nuclear Engineering Building

GREEN'S FUNCTION LIBRARY

Presented by Laura M. Bartolo

Kent State University

TUESDAY AFTERNOON

MICROSTRUCTURAL-BASED FEM MODELING

Presented by Mark R. Locatelli

National Institute of Standards and Technology

NEUTRON RESEARCH FACILITY

Presented by Charles Glinka and Michael Rowe

National Institute of Standards and Technology

CERAMICS AROUND US

Presented by John Blendell and Ajit Jillavenkatesa

National Institute of Standards and Technology

METALS

Presented by Robert Shull

National Institute of Standards and Technology

K-COLLEGE ENGINEERING EDUCATION WITH LEGO BRICKS

Presented by Chris Rogers and Merredith Portsmore

Tufts University

xliii
Chris Rogers

Robert Shull

xliv
MINI WORKSHOPS

xlv
MINI WORKSHOPS (Continued)

xlvi
MINI WORKSHOPS (Continued)

xlvii
MINI WORKSHOPS (Continued)

xlviii
MINI WORKSHOPS (Continued)

xlix
MINI WORKSHOPS (Continued)
MINI WORKSHOPS (Continued)
MINI WORKSHOPS (Continued)

lii
MINI WORKSHOPS (Continued)

lift
MINI WORKSHOPS (Continued)

liv
MINI WORKSHOPS (Continued)

|V
MINI WORKSHOPS (Concluded)

lvJ
Ceramic Fractography: Broken Pieces Tell the Story

Mr. George Quinn

Ceramics Division,

NIST

Materials Science and Engineering Laboratory

A demonstration of the fractographic analysis of fractured ceramic pieces will be presented.

Fractographic analysis is a valuable tool for interpreting laboratory tests wherein ceramics and

glasses are broken under controlled conditions. Fractographic analysis also is a powerful tool for

forensic investigations of ceramics and glasses that have broken in service. A surprising amount

of information may be gleaned from the fractured pieces including the stress in the part at

fracture, the:mode of loading, and the exact source or cause of fracture. Several case studies

will be demonstrated ranging from advanced ceramic laboratory fractures to domestic glass or

kitchenware fractures.

The demonstration will feature a "discussion stereo binocular microscope" 'which enables

multiple viewers to simultaneously view the fractured object, either by direct viewing or by

projection on television monitors.

%

Fractographers are detectives!

\

lvii
• Ceramics and Glasses: Examples

Tools of the Fractographers Trade

Mark l eyeball

Hand lens

Stereo binocular microscope (3x- 200x, extraordinary depth of field)

Scanning Electron Microscope (50X-5,000+x)

Other (microscopes, cameras, computers ........... )

Some Fractographic Markings.

Much of fractography is pattern recognition.

3 Examples of markings:

Twist Hackle ("River lines", "delta patterns")

Wallner Lines (curved cracks, direction of crack propagation,

"impact ringing")

Fracture mirrors (The origin of fracture, Flaws)

Quantitative Analysis

The stress in the part at fracture may be determined.

Examples:

Fragmentation extent

Mirror Sizes

• Demos

• Case Studies

For further information:

Book:

Web Site:

ASTM standards:

Failure Analysis of Brittle Materials, V. D. Frechette, American

Ceramic Society, Westerville, OH, 1990.

www.ceramics, nist.gov

www.ceramics.nist.gov/webbook/fracturelfracture.htm

C 1322 Standard Practice for Fractography and Characterization of

Fracture Origins in Advanced Ceramics

C 1256 Standard Practice for Interpreting Glass Fracture Surface

Features

lviii
The following fractured parts were available for demonstration:

• Broken drinking glass•

Impact origin on inside bottom where knives or forks impacted the surface.

Subsequent heating and cooling in the dishwasher propagated the crack.

. Broken (4 point bending) glass rod

Classic fracture mirror• One example demonstrated on stereo scope and

second one passed around with 10X jeweler's Ioupe.

. Automobile side mirrors•

Examples of Wallner lines and twist hackle• Origin was edge damage on

beveled outer rim. Cra'cks were propagated by thermal heating and contraction,

or alternatively, by mechanical bending from mounting stresses.

, Ceramic rectangular bend bar. 4-point flexure, alumina

The white ceramic appeared washed out when viewed in the stereo scope, but

staining the surface with a green felt tip pen helped the fracture markings come

out. Origin was a large pore near the surface•

. Glass disk specimens tested in biaxial (ring on ring) flexure.

Demonstrated the extent of fragmentation is proportional to the stress or energy

in the part at fracture.

. Tempered automobile side window.

Destroyed by tornado impact• Pattern of fracture demonstrated along with actual

fracture origin, which was a severe impact site on the outer surface.

Case Studies discussed at end of lecture:

a.

b.

Auto windshield (see #6 above)

Glass windows ("lights") in a tall office building in Boston.

sequence event.

Failure was a multi

lix
Stereo Binocular Microscope

Wild (Leica)M-3Z or M-IO

with fiberoptic light source.

Stepless magnification changes

Continuous focus

_l-)e

Zoom 6X or IOX 7_/J/'//,iCmq,;l_//,;,

"¢,"'!,. x./

Good working distance (distance between objective lens an_t object being

examined!)

Superb depth of field

1x
Conventional Materials Science Microscope

Reflected light Two eyepieces but not stereo viewing

Very limited depth of field

Very small working distance

No stereo effect

Up to IO00X

lxi
b

t5

L_

a

b

I

¢ j_ I

d

Fig. 2-14. Stages in the formation of twist hackle: (a) Cross-sectional view of the

crack surface, forming perpendicular to the axis of principal tension and running

away from the observer; (b) a lateral twist in the tension axis causes the crack

surface to split into unconnected segments, each perpendicular to the new axis of

tension, the average crack surface coinciding with the original; (c) breakthrough

between the segments completes the separation of the specimen into two

fragments, forming shallow "risers" in the stairway in which the initial cracks

segments are the "treads"; and (d) isometric view of the resulting surface.

lxfi
_E

__×

4.

3

_ci

/

/

¢_3 -d

lxiii
3 PHOTOS

1. Whole Fracture Surface

2. Fracture Mirror

I \ ,_\_\.- ' '

, _,_,_ ,_.,. ":_ "._--I

\_.;__-__. _., :."___

3. Fracture Origin

(1-5x)

(10-50x)

(100-1000x)

QUINN/A1

lxiv
64x

note

flaw

mirror

hackle

flaw is a 9/lm deep

crack

from polishing

Mirrors

(Glass)

identical

specimen

different lighting

\

|xv
bv_,,- _ .

|xvi
CI A l e.l.

__ <\

I

I

$o _J Fi,_

, . .i':

/ . o_,_ , . +f

lxvii
!

?

l

TENSION

\

\ COMPRESSION CURL

COMPRESSION "_ ,i

(

ORIGIN

LOW ENERGY FAILURE

FRACTURE SURFACE IS PERPENDICULAR TO

TENSILE SURFACE

CRACK BRANCH AND DOUBLE

COMPRESSION CURL CAUSES A

"Y" SHAPED PATrERN

I T I

ORIGIN 7

MEDIUM - HIGH ENERGY FAILURE

UPPER FRAGMENT iS NOT IMPORTANT AND

CAN BE DISCARDED

A SECONDARY FRACrURE CAUSED BY THE

ELASTICRELEASEWAVE - REFLECTION

OFF OFTHE END FACES.

NOTE THIS OFTEN OCCURS AT

LOAD PINS.

NOTETHE MIRROR IS ON WHAT f'/

ORIGINALLYWAS THE /

COMPRESSIONSIDE, /

/

1 ,J

SECONDARY BREAK

OFTEN AT AN ANGLE

_PRIMARY FRACTURE - ORIGIN

MEDIUM - HIGH ENERGY FAILURE

CRACK BRANCHES AND CURVES

BACK TO TENSILE FACE=/

¥

J /'-'¢'x

/

ORIGIN

HIGH ENERGY FAILURE

p/. SECONDARY BREAK

\ I

1

SECONDARY FRACTURE AT A PRIMARY - ORIGIN NEAR, BUT

LOAD PiN NOT DIRECTLY AT A LOAD PiN

MEDIUM - HIGH ENERGY FAILURE

© I t

/

BREAK AT OR NEAR LOAD PiN.

BEWARE OF MISALIGNMENTS

OR TWISTING ERRORS

NOTE ANGLE TO TENSILE SURFACE

PRIMARY FRACTURE OUTSIDE GAGE LENGTH

Lff. _.GITIMATE DUE TO SEVERE FLAW

tCJ

L__ ( I

LOW ENERGY FAILURE

lxviii
Comparison: Optical versus SEM views of the same origin

Reaction Bonded

Silicon Nitride

Norton NC 350 grade

Cr-=,31 ¢o _ oo_

Optical Photo

-25X

_rv_

SEM

Closeup

500X

lxix
Sometimes microcracks induced by machining (surface grinding)

the part can become the strength limiting flaws!

The work piece is

moved back and forth

while the wheel grinds

its surface

Diamond grit impregnated

grinding wheel

[_-J'_Ceramic Part or Test Piece

The diamond particles impact the surface and cause

microcracks to form.

Straight

PARALLEL

CRACKS

ORTHOGONAL

CRACKS

Bowed

Crack

Offset

Cracks

ABRAStVE

PARTICLE

]xx
/

_,°_._'"_. Z_ t,,.,

r /pc_ t'z" 4

ck,,_

3_

T__

,2,<.//

"" " :7

lxxi
Ceramics Division Characterization of Fracture Origins http://www.ceramics.nist.gov/webbook/fracture/frac0005.htrn

/Erie

_/_,s

d;_;r

Mtt7--

h/e_

lxii
Biaxial Disk Strength Testing

Ring on Ring

As_.÷

HIGH STRENGTH - HIGH ENERGY

HIGH STRENGTH - HIGH ENERGY LOW ENERGY

lxxiii
-4

%",

4

lxxiv
Fracture Mirrors

_,'_,..,-,._. ,o.- .... t ..'..-,, /

,.:T?::

R_. "1 _ I l--2_,-q I I

Rg, 1. _hematic of"f_ctu_ surface of a bfiu]c matena| subjected to a constant subcfitica] load, o'. The solid

semielliptical line at the center _presents the initial flaw size. and the dashed line outlines the critical flaw before

catastrophic failure. The inner (r,), outer (rs). and crack br_nehing (r,-b) mirror radii are shown withsubscripts I and 2 to

indicate that mirrors may be unsymmetric.

Ref. Mecholsky, Gonzalez, Freiman, "Fractographic Analysis of Delayed Failure in Soda-Lime Glass," J. Amer. Ceram.

Soc. 1979, Vol. 62, #11-12 p 577 - 580.

Inner Mirror (mirror/mist)

Outer Mirror (mist/hackle)

Branch Point

A's have units of Force /length 1_

A i = Ainne r = o--_f"Ri

A o = Aoute r = O"_o

A_ = A_aoc. = cH-R_

ie. MN/m _'_ or MPa'_ or ksi_-n

Note the Hierarchy:

K_c

Ainner

Aouter

Abranch

at the flaw

at the mirror/mist boundary

at the mist/hackle boundary

at the branching distance

Theories:

Velocity

Energy

Stress

Stress Intensity

Strain Intensity

Yoffe, 1951

Johnson and Holloway, 1966

Orr, 1972

Clark, Irwin, 1966;

Kirchner, 1987

Kirchner, 1986

Phil Mag, 42, 1951, p 739.

Phil Mag, 14 (1966) p 731.

"Practical Analysis of Fractures in Glass Windows, Mater.

Res. and Stand., Jan. 1972, pp 21-23, 47

Expl. Mech., 23 1966, p 321.

H. K-Jrchner and J. Conway, "Chteda for Crack Branching in

Cylindrical Rods: Part I, Tension, and part II, Flexure, J. Amar.

Ceram. 8o¢. 70#6 1987 lop 413-425.

H. Kirchner, "Brittleness Dependence of Crack Branching in

Ceramics," J. Amer. Ceram. Soo., 69 #4 1986, pp 339-342.

lxxv
F_ue_y 10, 20OO

usesCerm-aB.xtsandce.'m.al2_ls _leswhich hav_ldatl

then uses FiT funcUon

corrected 2/10t2000

Indude= NtST 600

Fracture Mirror Size Analysis

stress = A o/4 R

0O

n

V

or)

u)

e

00

Stress is corrected for location for the rod origins.

* Residual stress assumed to be zero.

* Mirror radius is the average of deepest R,

and 2R along surface, or

average of two diameters if origin in interior.

" Wild stereo M-I0 microscope at 32-63X only!

* Mirror boundary is onset of hackJe and

major roughness change relative to the

"bumpy" mirror characteristic of this materiai.

Mirror Radius,

1000 600 400 300 200

lOOO I l I I !

Ceradyne

,u_,,jj.,_ c,,_,_I,, #

R (_m)

150 100

I l

140

800 --

600 --

400 --

200 --

0

SRBSN

A = 8.47 MPa _/rn

o

/

//

//

,/

/

/

/

80 60

I I

/

/© /

147 - 31N , "o,

%_O,o

oo° 2/oo

for RODS A_ _

_ " A o = 7.79 MPa 4m foraAaS

i

o " / "_" _ -.,.,_-c_,r_ //

/,

//

,/

/

/

I I I I I I

120

100

80

- 6O

- 4O

- 2O

0

U)

V

U)

U)

Or)

0 20 40 60 80 100

1./,/(Radius) (m -1/2)

120 140

lxxvi
lxxvii
c"

e,i o_ _

C_O ¢-" =

Y_

t-"

I---

lxxviii
Ixxix
The car was totaled, based on the glass and body paint damage.

The rear hatch, driver's door, two side panels, and one side mirror were destroyed.

lxxx
lxxxi
lxxxii
L'erarmcs Division Characterization of Fracture Origins __v.ceramicsmist.gov/webbooW_acture/fi'_

The strength of many advanced ceramics reflects the flaws present in the material and the material's intrinsic

fracture toughness. Monolithic ceramics and some composite ceramics (i.e., particulate- or whisker-reinforced)

wit_ fail in a brittle fashion when stressed due to unstable propagation of cracks from preexisting flaws.

The terms "flaw" and "fracture origin" are used interchangeably in this context. Scientists and engineers in the

ceramics community/traditionally have used these terms to describe the fracture initiation site in ceramics and

other brittle materials• These terms are used in the context of fracture mechanics whereby a singularity or

microstructural irregularity acts as a stress raiser from which fracture commences. It should be understood that

the use of the term "flaw" does not imply that a ceramic product has been prepared improperly or is somehow

defective.

Strength-test results must be interpreted in the context of these flaws whether the strength testing has been

done for quality control, materials development, or design purposes• Fractographic observations should be

coupled directly to strength results. Fractoqraphic montaqes and labelled Weibull graphs are an exceptionally

versatile means of accomplishing this. See ASTM C1239 for more details on Weibull analysis of strength data,

American Society for Testin,q of Materials (ASTM) developed C1322 "Standard Practice for Fractography and

Characterization of Fracture Origins in Advanced Ceramics", This practice provides an efficient and consistent

methodology to locate and characterize fracture origins in advanced ceramics. The table below outlines the

fracture origin characterization scheme and the linked figures show examples of the most common types of

flaws observed in advanced ceramic materials. (See Fracture Origin Characterization and the Flaw Catalog.)

Any questions or comments about ASTM C1322 the fracture origin examples given here. or fractography of

ceramics can be addressed to Jeffrey Swab (iswab@arl.mii) or George Quinn (cleoq@nist.qov).

® Back qrouna and General Information

Fractoaraphic Montaqes

Labelled Weibull Graphs

Photoqraphic Recordkeepln_q

Fracture Origin Characterization and the Flaw Catalog

The fracture odgin in each specimen/component shall be characterized by the following three attributes:

identity location, and size as summarized in the table below.

Please note that the descriptive terms 'volume" and "surface" may have two distinctly different uses.

lxxxiii

Lyle Schwartz, President of Federation of Materials Society

Recognizes Robert B. Pond, Sr.

for his contribution to materials education

1XXXV
Robert B. Pond, Sr.

Jim Jacobs and Robert B. Pond, Sr.

lxxxvi
Martha Goodway

Archeometallurgist

Smithsonian Center

For

Materials Research and Education

lxxxvii
MATERIALS SOLUTIONS TO

MEDICAL PROBLEMS

Justin Hanes

Johns Hopkins University

lxxxviii
ENERGY CONCEPTS MATERIALS SCIENCE

AT MAURY HIGH SCHOOL

i_iiiiiiiiii_iiiiiiiiiiiiii!iiiiiiiiiiiiiiiiiiiiiiiiiii!i!iiiiiiiiiiiiiii!iiiiiiiii!iiiiii!i!iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii!iiiiiiii_i

Duane Bushey and Merrill Rudes

Maury High School and Energy Concepts, Inc.

lxxxix

MATERIALS RESEARCH AT NIST -

CENTURY OF PROGRESS

Dale Hall

Deputy Director

Materials Science & Engineering Laboratory

National Institute of Standards and Technology

Bldg. 310, Room B309, MS 8500

Gaithersburg, Maryland 20899-8500

Telephone: 301-975-5658

e-mail dale.hall@nist.gov
Dale Hall


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26
ELECTROLYSIS OF WATER IN THE

K-12 CLASSROOM

H. Alan Rowe

Chemistry/Center for Materials Research

Norfolk State University

700 Park Avenue

Norfolk, Virginia 23504

Telephone: 757-823-2531

e-mail harowe@nsu.edu

27
Dr. Rowe is currently a Professor and Chair of the Chemistry Department at Norfolk

State University. He is a graduate of UNC-Chapel Hill, North Carolina State University,

and was a postdoctoral fellow at Wake Forest University. Dr. Rowe was honored as a

Research/Lecturing Fulbright Scholar in South Asia and has been awarded the Teacher of

the Year at Norfolk State University. He is the author of numerous research publications

as well as several articles on chemical education.

28
Electrolysis of Water in the K-12 Classroom

Dr. H. Alan Rowe

Professor of Chemistry

Norfolk State University

Norfolk, Virginia 23504

Key Words

Electrolysis, oxygen, hydrogen, electrodes

Pre-requisite knowledge

From none to a general theory of electrolysis depending on the level of the student to

which the experiment is presented

Objective

To understand the reactions that occur when water molecules are subjected to an

electrical current

Equipment and Materials

3" x 3" piece of cardboard, two pencils sharpened on each end, 100 ml beaker, two

wires with alligator clips on each end, salt, 9volt battery, optional materials -other

metals and salts

Introduction

When an electrical current is passed through water, hydrogen and oxygen gas is

produced. Since distilled water is a non-electrolyte, a source of ions must be added to

conduct the current. Optionally, bromothymol blue or other appropriate pH indicators

can be added to test for the acid/base changes at each electrode.

2H20 ............... --) 2H2 + 02

If models are available have the students make 2 water molecules and then reassemble as

per the equation above

Construct the electrolysis apparatus by placing the two sharpened pencils 1" apart

through the piece of cardboard. Use the alligator clips to attach the wire to the

sharpened pencils and the 9V battery.

29
Procedure:

1) Put distilled water in the beaker. Predict what will happen when the electrodes are

attached. Attach the electrodes to the battery (be sure the wire has a good connection

to the graphite of the pencil) and record your observations and conclusions.

DI STILLED WATER IN BEAKER WITH GRAPHITE ELECTRODES

PREDICTION(S):

OBSERVATION(S):

CONCLUSION(S):

2) Put a small mnount of sodium chloride [about 0.25g, about 1⁄4 teaspoon in a cup (250

ml ) of water and connect the apparatus. ]

DILUTE SALT IN BEAKER WITH GRAPHITE ELECTRODES

PREDICTION(S):

OBSERVATION(S)

CONCLUSION(S):

30
3) Addalargeamountof sodiumchloride( about2 g,or2 teaspoons)andconnecthe

apparatus

CONCENTRATEDSALTWITH GRAPHITEELECTRODES

PREDICTION(S):

OBSERVATIONS(S):

CONCLUSION(S):

4) Several other variables can be studied. Different objects can be used for the

electrodes [galvanized and non-galvanized nails (the formation of insoluble Zn salts

are observed), copper, steel, different coins, etc)]. Different materials can be used for

the electrolyte. In all of the above activities, after observing for a few minutes the

connections can be reversed and the results noted.

31
Comments

At the cathode (negative electrode), sodium and hydrogen ions are available for

reduction. Since hydrogen ions are reduced far more easily than sodium ions, they will

react to form hydrogen gas

2 H + (aqueous) + 2 e -........... -) H2 (gas)

At the anode (positive electrode), hydroxide and chloride ions are available for oxidation.

Hydroxide ions are oxidized more easily than chloride ions in dilute solution so they will

react to form oxygen gas.

4 OH" (aq) ................ --) 02 (g) + 2 H20 (liquid) + 4 e-

[Hydrogen and oxygen gas should be expected to be produced in what ratio ?]

While there is no net change in pH, there is a localized change. Examining the equations

above there should be a loss of hydrogen ions at the cathode and a loss of hydroxide ions

at the anode. Added bromothymol blue is blue, green, and yellow at pHs that are basic,

neutral, and acid, respectively. [Which electrode will become more acidic? Explain]

TESTS FOR GASES PRODUCED

Hydrogen and oxygen gas have low solubilities in water and will appear as bubbles.

Chlorine gas, if it forms, is more soluble and will not form bubbles until the water is

saturated. [Give the balanced equation for the production of chlorine gas at the anode]

If the gases are collected, oxygen gas will cause a glowing splint to flare, hydrogen gas

will cause a glowing splint to pop, and chlorine will cause a solution of KI to turn brown.

Both Hy&ogen and oxygen gas are colorless and odorless, chlorine gas is greenishyellow and has a strong tmpleasant odor (Take care to provide adequate ventilation).

References

Brown, LeMay, and Bursten0 Chemistry, The Central Science, 8th Edition, Prentice-Hall

(2000)

32
TEACHING UNDERGRADUATES

RESULTS FROM RECENT RESEARCH

AS PART OF A LABORATORY CLASS:

X-RAY DIFFRACTION EXPERIMENT

L. J. Martinez-Miranda

Department of Materials and Nuclear Engineering

University of Maryland

College Park, Maryland 20742-2115

Telephone 301-405-0253

e-mail martinez@eng.umd.edu

33
t

L. J. Martinez-Miranda

Biography:

L. J. Martfnez-Miranda is Associate Prof. of Materials in the Dept. of Materials and

Nuclear Eng at the University of Maryland - College Park. She received her bachelor's

and master's degree in Physics from the Universidad de Puerto Rico in Rio Piedras, a

bachelor's in Music degree from the Conservatory of Music of Puerto Rico and her

doctoral degree in Physics from Massachusetts Institute of Technology. At Maryland she

has been responsible for designing the junior level laboratory undergraduate course with

the help of her colleagues, and has taught the introductory design course and the physics

of materials course. She is the faculty coordinator for the NSF-MRSEC Research

Experiences for Undergradautes and is a co-PI in the University's G K-12 program. Her

interest is in X-ray scattering from liquid crystals and related nanomaterials and solid

films.

34
Teaching Undergraduates Results From Recent

Research As Part of a Laboratory Class: An

X-ray Diffraction Experiment

L. J. Martinez-Miranda

University of Maryland, Dept. of Materials and Nuclear Eng., College Park, MD, 20742-

2115

Key Words: X-ray diffraction, powder, texture, nanocrystalline and nanometer size

sample, time-dependent structure

Prerequisite Knowledge:

What is X-ray diffraction?

What characteristics of a material can X-ray diffraction measure?

In what size range does it measure these (angstroms, microns)?

What is a powder sample?

What is a textured sample?

Objective:

How can X-rays be used to distinguish between samples prepared using different

methods, i.e., different times? How can X-rays be used to distinguish between samples of

different thickness?

Equipment:

1. An X-ray diffractometer

2. Two samples prepared at different times

3. A computer with any plotting program

Introduction:

Copper samples prepared using electrodeless deposition on Aluminum Nitrade

(A1N) substrates have been studied for interconnections. The method of deposition is less

intrusive than other methods, which require the use of catalysts on an electrically

insulated surface. The quality of the samples depends both on the direction of coating

and the time the solution is refluxed. The samples which were prepared horizontally

(parallel to the bottom of the flask) seemed to contain more Cu20 than the samples

prepared vertically (perpendicular to the bottom of the flask) 1'2. In both samples, the

structural evolution was that Cu was more textured for lesser times and more

polycrystalline for longer times in the reflux. The students will look at the effect of time

on the structure of the films 3.

35
polycrystallineforlongertimesin thereflux. Thestudentswill look attheeffectof time

onthestructureof thefilms3.

Samplesof lead-zirconium-titanium(PZT)oxidehavebeenpreparedusingpulsed

laserdeposition(PLDto differentthicknessonlanthanumaluminate(LAP). LAP is

chosenbecauseits latticeconstantis almostmatchedto thatof thea-latticeconstantof

tetragonalPZT.Becauseit isnotexactlymatched,variationonthec-latticeofPZTcan

beobservedwhichinturnreflectsthevariationof thea-latticeparameterasafunctionof

thickness4.Thishasconsequencesonthepropertiesof thePZT,in particularthe

ferroelectricproperties.Althoughthestudentsdonotlook attheferroelectricproperties,

thereis adiscussiononhowthestructureisrelatedto themandhowalteringthelattice

parameters(aandc) will affectthepolarizationof thefilm. Theneedfor thisfilm to be

grownin singlecrystalform(epitaxy)is alsodiscussed.

Procedure:

The students begin by looking at a standard silicon sample to become familiar

|m

c

xi

(111) I -- Si peaks

(220)

I I ' I "

20 30 40 50

1311)

(400) (3311

60 70 80

2th (deg)

Figure 1. Results of the scan in a standard silicon sample.

with the structural analysis of powders. They do a 0 - 20 scan, illustrated in Figure 1.

Students are asked to compare the peaks observed with those given in the X-ray cards

(which they are asked to bring) and to see how the intensities compare.

Two films of cupper prepared at 20 minutes and 30 minutes are analyzed, using

0-20 scans. Depending on class size, one group does the analysis for the 20 minute film

and the other the 30 minutes. They have gone to the library to find the card for Cu. We

36
alsoaskthemto getthecardsfor Cu20andforA1N.Theyhaveusedthecardsto

comparethescansobtainedforthecrystallinesampleandto seethattherelative

intensitiescomparewiththeonescitedonthecards.

Afterobtainingthe0-20 scans,theycompareit tothecardsandidentifyeach

peakobserved.Theytaketherelativeintensityof thex-raypeaks,especiallythestronger

ones,andcommentontheresults,ff twogroupsaredoingdifferentsamples,theyget

togetherandcompareandexchangeresults.Theycommentonthedifferenttimesthe

samplespentonthereflux. TheirresultsaresimilartothosepresentedinFigure2.

(111)

Cu20

-i .......... 20 mins

"2= _ --30 mins

=5

AIN AIN(22 )

_ oo)

' I I

7o 7s 8o

2th (deg)

Figure 2. Results of the scan obtained from the Cu samples prepared at 30 minutes and 20

minutes.

The students proceed to look at a single crystalline sample. We chose LAO,

because that is the crystal on which the films of PZT are deposited. They are taught how

to center the sample such that the peak is maximized. The students go to a known peak,

at 23.4 °. They proceed to rock the sample about 0, until the maximum 0 is obtained. The

value of 0 maximum is defined as one-half of 23.4 °. Then they take a 0-20 to make sure

the centering has been done correctly and to check the maximum. The process is

illustrated in Figures 3 and 4.

The students then study the PZT films as a function of thickness. One group

receives the 500A sample and the other receives the 2500_. The sample is centered

according to the previous paragraph, at the same 20 as before, since the films have been

37
e-

-I

>,

ee-

-- theta centering

11'.4' 11'.6"11'.8' 12.0' 12.2' 12.4' 1:2.6' 1:2.8'1:3.0' 1:3.2

th

Figure 3. Theta centering at 2theta equal 23.4 °. The maximum theta at 12.25 ° is set to

11.7 ° , or half of 23.4 °.

t_

ul

ee"

m

-- LAO (100) peak ]

2th (deg)

Figure 4. 0-20 scan of the 23.4 ° peak of LAO, after 0 was reset as explained in Figure 3.

38
A

"10

N|l

l

t_

E

!__

O

e"

|m

exi

t_

e- l

0.1

0.01

LAO

5ooA7,,

20

o \

I

18 22 24 2'6

2tth

Figure 5. Superposition of the 500,_ and 2500A films, showing that for 500A film has a

larger c-axis parameter (a smaller 20). The 500,_ was a larger sample: that's why it has a

stronger signal.

grown on LAO. A 0-20 is then taken to look at the peak from the film plus the peak at

23.4 ° from LAO. This last peak is recentered such that it coincides in both scans, the one

on the 500A and the one on the 2500A. The students compare the positions of the peak

to those presented in reference 4. The students discuss the evolution of the c-peak as the

films get thicker. A discussion on the effect of the substrate on the lattice parameters of

the epitaxial film follows. Results are shown in Figure 5.

Comments:

This experiment aids in introducing the students to the effects of materials

processing on sample structure. The experiment serves as a study of textured samples

alone. Any kind of processing that leads to a different structure can be used, as well as

any kind of material. The aim is for the students to realize how useful X-ray diffraction

can be.

The students are asked what is different about each sample, and how do they think

the structure comes about. The purpose is to get them to think about how processing

affects the structure and also the properties. The instructor can mention how properties

are affected by the orientation of the crystal. This discussion is very basic; the students

39
haveseenthisinelementarytermsintheirintroductionto materialsclass,andwill seeit

laterin thephysicsof solidsclass.

In thepartthatconcernstheCumaterialsin thereport,thestudentsareaskedto:

a.Plotbothgraphs;b.Write downtherelativeintensitiesof thedifferentpeaks;c.

Identify,if possibletheotherpeaks,basedonthecards;d. Commentonhowthe

preparationtimeaffectsthestructureof thesample.Theyarenotaskedto calculatethe

textureof thesamples:theexperiment,dueto limitationsin equipmentisdoneona

machinewhichcannotakeangleshigherthan90° . More angles are needed to measure

the texture. For the PZT films on LAO, the students are asked to: a. plot both graphs; b.

explain how they go about centering a single crystal and epitaxial film in the

diffractometer; c. compare the position of the c-axis peak to the one obtained from

reference 4 and given by the instructor.

When time allows, the instructor gives the students more details on the research.

For example, the instructor tells the student that studies on the samples were done with

different X-ray energies, and that these energies and the absorption properties of the

sample can limit the depth the X-rays can penetrate, into the sample which allows for a

study of the structure as a function of depth.

All of the results presented were taken as part of the class in the Fall of 2001.

References

1. G. M. Chow, L. K. Kurihara, D. Ma, C. R. Feng, P. E. Shoen, and L. J. MartfnezMiranda, Appl. Phys. Lett., 70, 2315 (1997).

2. L. J. Martfnez-Miranda, Yiqun Li, G. M. Chow and L. K. Kurihara, NanoStructured

Materials, 12, 653 (1999).

3. Samples donated by Lynn K. Kurihara (NRL).

4. V. Nagarajan, I. G. Jenkins, S. P Alpay, H. Li, S. Aggarwal, L. Salamanca-Riba and R.

Ramesh, JAP, 86, 595 (1999).

40
THE DISTRIBUTION OF ELECTROMAGNETIC

ENERGY IN A MICROWAVE OVEN

J. N. Dahiya

and

Wendy Decker

Physics Department

Southeast Missouri State University

One University Plaza

MS 6600

Cape Girardeau, Missouri 63701

Telephone: 573-651-2390

e-mail dahiya@physics.semo.edu

and

Aman Anand

Computer Science Department

Southeast Missouri State University

One University Plaza

Cape Girardeau, Missouri 63701

e-mail amanfromcs@hotmail.com

41
AmanAnand

J.N. Dahiya

42
The Distribution Of Electromagnetic Energy

In A Microwave Oven

Jai N. Dahiya & Wendy Decker

Physics Department

dahiya(_physics.semo.edu

And

Aman Anand

Computer Science Department

amanfromcs@hotmail.com

Southeast Missouri State University

One University Plaza,Cape Girardeau, Mo-63701

KEY WORDS

Microwaves, Temperature, Heat Distribution, Frequency

OBJECTIVES

The main Objective of this experiment is to study the distribution of temperature in a

food sample placed inside the microwave oven.

SUMMARY

Electromagnetic Distribution of the microwave field is studied by placing the food

sample inside a microwave oven. This distribution is studied in terms of change of

temperature as the microwaves are absorbed by a particular food sample. A series of

thermometers are probed in a circular fashion in the food sample. The penetration depth

of these thermometers are kept constant. The microwave oven is turned on for a certain

time and the thermometers are read as quickly as possible as discussed in the procedure

section of this paper. The distribution of temperature is related to the microwave field

pattern inside the microwave oven.

43
Introduction And Theory

This paper is being written for the scientific investigators who wish to understand

in detail the concept of microwave spectroscopy and use in their research laboratories the

techniques of microwave heating. A mental or a physical picture of complete

electromagnetic spectrum as a classified array of energy sources is a valuable aid to the

scientists. In this experiment over microwave heating certain tests are performed and

conclusions are drawn about the spectrum developed within a microwave oven.

__Vlstbie

Spectrum ,,_

-o

; i il

rav_ol_t !n_a_ed

Figure A. Electromagnetic Spectrum from radio waves to gamma rays

The picture in figure A above, is an electromagnetic spectrum and the frequency

ranges between 300 MHz to 300 GHz for the microwaves. The microwaves within the

microwave oven is 2.4 GHz. We know that in general, the food placed within the

microwave oven has water contents. The water is a polar compound and has a permanent

44
dipole. Within the microwave oven these water molecules develop a dipole moment and

experience a force ( torque between the two charges separated by a distance ) and in turn

these dipoles then start oscillating with the same frequency as those of the microwaves.

With these oscillations the water molecules follow the frequency of the microwaves and

then transfer the heat content to the material. In the process of Free Induction Decay the

water particles in food sample placed inside the microwave oven get converted into vapor

phase and get induced dipole charges which promotes heating.

microseconds

Figure B. Free Induction Decay

Depending on how many spectral lines are in the region being scanned these FID's can

be simply, a singly oscillating (sinusoidal or cosinusoidal) function with a superimposed

exponential decay. However when more than one line is present in the region being

45
scannedweoftenseetwo ormoredifferentfrequenciesintheFID pattern(suchasthe

oneabove).Thesefrequenciescorrespondto differencesbetweenthenaturalabsorbance

frequencyof themoleculeandthefrequencyof thelightinthecavity. Wecanaccurately

determinethenaturalfrequencyof themoleculebydoingaFourierTransformof theFID

andadding(or subtracting)thedifferencefrequencyfromthefrequencyof thelightinthe

cavity. TheFourierTransformof thisFID is showninfigureC.

6968.145 6968.345 6968.545

Frequency (MH z)

Figure C. Fourier Transform

PROCEDURE

Following procedure was used in conducting this experiment:

46
°

2.

3.

Figure D. The Microwave Oven used in this experiment

The sample taken into consideration was frozen New York Style Cheese Pie.

Then the dimensions(diameter, depth of the sample were recorded. )

Using a protractor and compass 9 different plots were made in an octagonal

form for placing the thermometers dipped in water initially at room

temperature as shown in the figure below:

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_S__ iiii ii_iiiiiiiiiiiiiiiiiiiiiiiiiiiiiii!I .......... ___

i ::

Figure E. Distribution of Thermometer probes inside the food sample

4. The initial temperature of thermometer was recorded.

47
5. Thermometers were inserted and they were marked 1 - 9 clockwise as shown

in figure E.

6. The initial temperature of the cheese pie was recorded for all the 9 plots.

7. The sample was placed with thermometers into a microwave oven as shown

in figure D, and experiment was performed in two different parts

PART A:

.

PART B:

1.

1. The frequency of the thermometers was kept 50 % and the time was 30

seconds and the turntable of the oven was also off.

2. The microwave oven was switched on and after 30 seconds of heating

the final temperature was recorded for all the 9 plots. It was made sure

that the temperature recording was done most efficiently.

3. The sample was kept in deep freezer for cooling for 5 hours. This was

done just to make sure that next time the experiment was performed

the sample reaches the same temperature as for the first reading.

The whole procedure ( step 1-3 ) was repeated for 5 different times.

Now this time the frequency of the microwave oven was increased to

100 % and the time was 30 seconds, but the turntable was left on.

2. Then the microwave oven was switched on and after 30 seconds of

heating the final temperature was recorded for all the 9 plots. It was

made sure that the temperature recording was done most efficiently.

3. Then the sample was kept in deep freezer for cooling for 5 hours. This

was done just to make sure that next time the experiment was

48
performedthesamplereachesthesametemperatureasforthefirst

reading.

4. Thewholeprocedure( step1-3) wasrepeatedfor 5 differenttimes.

Fromboththestylesof observationswedeterminedthetemperatureshiftandtriedto

determinetherelationbetweenthefrequencyandtemperaturechangewithina

microwaveoven.Experimentwasconductedanumberof timesbychangingthevariables

suchasthediameterof theplots,turntable,frequencyandthetimeintervalof heating.

Thedataof theexperimentperformedhasbeenshownastablesunderneathwiththeir

supportinggraphs.

ANALYSIS:

From the experiment conducted above there are certain inferences that were drawn.

1. The temperature efficiency depended upon the probes distribution(circular,linear)

2. The thermometers labeled 8thand 9 th showed the maximum temperature change.

3. The efficiency of heating was more when the turntable was left on.

4. There were certain regions that was close to the magnetron that received

maximum heat waves.

5. During the experiment between two readings food sample was placed in deep

freezer for 5 hours, so that the initial temperature was always the same.

6. When the frequency of the microwave oven was kept 100% maximum efficiency

was obtained.

49
, The data taken for various runs is shown in data tables 1 - 8 and the final results

are shown in graphs 1 - 8.

References

1. Cutnell & Johnson, Physics, 5th Edition, Wiley Publishing Co, 2000

1 Watson ,"Microwave Semiconductor Devices And Their Circuit

Applications", McGraw Hill Company 1969

3. V. L. Granatstein, "Applications Of High Power Microwaves", Archtech

House Inc, 1994

4. David A. Copson, "Microwave Heating", The Avi Publication, 1975

5. Przybylinska przyby@ifpan.edu.pl

6. J. Van Bladel, Electromagnetic Fields, McGraw Hill, New York, Ch.10,1964

7. C.H. Townes and A.L. Schawlow, Microwave Spectroscopy, McGraw-Hill,

New York, 1961

5o
Trial 1/Table 1

Eight thermometers were placed in a circle of radius 4 cm.

The ninth thermometer was placed in the center.

The depth of each thermometer was set at 2.3 cm.

The microwave was on for 30 seconds at full power.

The turntable was ON.

Location of thermometer Location of thermometer Change in temperature (°C)

probe (x axis) probe (y axis)

0 -4 5.125

2.828 -2.828 4.5

4 0 4.9

2.828 2.828 5.83333

0 4 6.89286

-2.828 2.828 6.85714

-4 0 6.39286

-2.828 -2.828 6.85714

0 0 5.66667

Trial 2/Table 2

Eight thermometers were placed in a circle of radius 4 cm.

The ninth thermometer was placed in the center.

The depth of each thermometer was set at 2.3 cm.

The microwave was on for 30 seconds at full power.

The turntable was OFF.

Location of thermometer Location of thermometer

probe (x axis) probe (y axis)

0 -4

2.828 -2.828

4 0

2.828 2.828

0 4

-2.828 2.828

-4 0

-2.828 -2.828

0 0

Changeintemperature(°C)

4.16667

5.8

5.25

3.92857

5.61111

4.5

4.625

3.5

4.27778

51
Trial 3/Table 3

Eight thermometers were placed in a circle of radius 4 cm.

The ninth thermometer was placed in the center.

The depth of each thermometer was set at 2.6 cm.

The microwave was on for 30 seconds at full power.

The turntable was ON.

Location of thermometer Location of thermometer Change in temperature (°C)

probe (x axis) probe (y axis)

0 -4 3.4375

2.828 -2.828 4.125

4 0 5

2.828 2.828 5.25

0 4 6.3125

-2.828 2.828 6.5

-4 0 6

-2.828 -2.828 5.0625

0 0 4.07143

Trial 4/Table 4

Eight thermometers were placed in a circle of radius 4 cm.

The ninth thermometer was placed in the center.

The depth of each thermometer was set at 2.6 cm.

The microwave was on for 30 seconds at full power.

The turntable was OFF.

Location of thermometer Location of thermometer Change in temperature (°C)

probe (x axis) probe (y axis)

0 -4 3.83333

2.828 -2.828 4.91667

4 0 3.14286

2.828 2.828 4.64286

0 4 4.85714

-2.828 2.828 5.08333

-4 0 3.83333

-2.828 -2.828 4

0 0 4.85714

52
Trial 5/Table 5

Eight thermometers were placed in a circle of radius 5 cm.

The ninth thermometer was placed in the center.

The depth of each thermometer was set at 2.3 cm.

The microwave was on for 30 seconds at full power.

The turntable was ON.

Loc_ion ofthermometer Loc_ion ofthermom_er Changeintemperature(°C)

probe(xaxis) probe(yaxis)

0 -5 4.08333

3.535 -3.535 4.6875

5 0 5.5

3.535 3.535 6.8125

0 5 7.21429

-3.535 3.535 6.88889

-5 0 6.42857

-3.535 -3.535 5.35714

0 0 5.1875

Trial 6/Table 6

Eight thermometers were placed in a circle of radius 5 cm.

The ninth thermometer was placed in the center.

The depth of each thermometer was set at 2.3 cm.

The microwave was on for 30 seconds at full power.

The turntable was OFF.

Location ofthermom_er Locmion ofthermometer Change in temperature (°C)

probe(xaxis) probe(yaxis)

0 -5 5.83333

3.535 -3.535 5.57143

5 0 6

3.535 3.535 3.83333

0 5 4.0625

-3.535 3.535 5.42857

-5 0 4.57143

-3.535 -3.535 5.5

0 0 4

53
Trial 7/Table 7

Eight thermometers were placed in a circle of radius 5 cm.

The ninth thermometer was placed in the center.

The depth of each thermometer was set at 2.0 cm.

The microwave was on for 30 seconds at full power.

The turntable was ON.

Location of thermometer Location of thermometer Change in temperature (°C)

probe (x axis) probe (y axis)

0 -5 4.92857

3.535 -3.535 5.14286

5 0 6.5

3.535 3.535 6.375

0 5 5.91667

-3.535 3.535 6.16667

-5 0 5.85714

-3.535 -3.535 6

0 0 4.71429

Trial 8/Table 8

Eight thermometers were placed in a circle of radius 5 cm.

The ninth thermometer was placed in the center.

The depth of each thermometer was set at 2.0 cm.

The microwave was on for 30 seconds at full power.

The turntable was OFF.

Locmion ofthermometer Loc_ion ofthermometer Changeintemperature(°C)

probe(xaxis) probe(yaxis)

0 -5 4.58333

3.535 -3.535 7.4375

5 0 7.57143

3.535 3.535 5.64286

0 5 4.21429

-3.535 3.535 6.66667

-5 0 4.2

-3.535 -3.535 6.25

0 0 4.25

54
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62
ACTIVE AND INTELLIGENT MATERIALS

John A. Marshall

School of Applied Science

University of Southern Maine

Gorham, Maine 04038

Telephone 207-780-5447

e-mail jmarshal@usm.maine.edu

63
Biographical Information:

Dr. JOHN ALLEN MARSHALL taught senior high school prior to receiving

his Ph.D. from Texas A&M University. He has eighteen years.of university

teaching experience, and is currently the Coordinator of the Industrial

Power and Control curriculum and laboratories as well as the Internship

Coordinator for the University of Southern Maine's Department of

Technology.

64
Active and Intelligent Materials

John A. Marshall, PHD

University of Southern Maine

Key Words:

Hydraulics, mechanical power transmission, and rheology.

Perquisite Knowledge:

Elementary concepts of power transmission.

Objective:

To observe the tunable characteristics of one of the most active and

intelligent materials, magneto-rheological fluids. To understand the

potential power transmission advantages of these fluids.

Equipment and Supplies:

Magneto-rheological clutch assembly and power supply.

Introduction:

Magneto-rheological fluid is an active and intelligent material that changes

its flow characteristics when subjected to an electrical field. Response,

which takes only milliseconds, is in the form of a progressive gelling that is

proportional to field strength. With no field present, the fluid flows as

freely as hydraulic oil (Korane, 1991).

Magneto-rheological fluids represent a technology that has the potential to

widen the performance range of automated electromechanical and

electrohydraulic equipment. Research and ongoing developments are

refining this active material and experts predict an important future for

these fluids.

65
Importance of Magneto-rheological Fluids:

Current automation capabilities are not advanced enough to build a robot

that could play tennis. Even though cameras and computers could direct

the robot towards a ball, robot's move in an awkward, lumbering fashion

because conventional hydraulic valves cannot keep pace with the

commands of the computerized controllers.

With an active material such as magneto-rheological fluid, this type of

response time is possible. This technology will allow devices that can

operate instantly and without mechanical valves. Increased productivity

and better product quality through more dependable and responsive

automated equipment is just a small part of what this maturing technology

can deliver.

How This Active and Intelligent Material Functions:

Magneto-rheological fluids are composed of two primary components.

They are the carrier fluid and the suspended particles. The carrier fluid

needs to be a good insulator, compatible with the materials they contact.

Typical particle materials include polymers, minerals, and ceramics (Scott,

1984).

When a magnetic field is applied to the active fluid, positive and negative

charges on the particles respond by separating, so each particle then has

a positive end and a negative end. Particles of the magneto-rheological

fluid then link together in the same manner that the north pole of one

magnet is attracted to the south pole of another magnet (Duclos, 1988).

Potential Applications:

Magneto-rheological fluids can activate from solids to liquids so fast, they

will work well with fast-acting computers. These characteristics suggest a

number of unusual engineering applications such as fluid clutches and

vibration isolators (Duclos, 1988).

According to Hans Conrad, professor of materials science and

engineering at North Carolina State University, magneto-rheological fluids

will lead to a whole new generation of brakes, automatic transmissions,

actuator devices, hydraulic valves, pump parts, and motors (Conrad,

1992).

66
Procedure:

Safety Considerations:

1. Protective eye wear is mandatory for all those in the lab area.

2. Read the operating instructions that accompany the active

magneto-rheological clutch assembly and power supply.

3. Obtain a "Material Data Safety Sheet" on the fluid from the

supplier. Read the sheet completely and ask questions to any

information you do not understand.

Observing the tunable clutch assembly:

1. With the power supply off, notice how easily the shafts can be

rotated by hand.

2. Increase the power output through the range of 4, 8, 16, 32, 60,

and 80 % and record your findings on the data sheet.

3. Vary the cycling frequency through the range of 4, 8, 16, and 32 Hz

and notice the pulsating sensation while rotating the shafts.

Record your findings on the data sheet.

Sample Data Sheet:

Record below the characteristics of the clutch when varying the power

output.

Record below the characteristics of the clutch when varying the cycling

frequency.

Instructor Notes:

1. The power being transmitted through the clutch increases

proportionally when the power output is increased.

2. The impulses of power transmission increase as the cycling

frequency is increased.

67
References:

Korane, K.: Putting ER Fluids To Work. Machine Design, May 9,1991,

pp. 52-57.

Scott, D.: Amazing Hardening Fluids Open a New World of Hydraulic

Drives. Popular Science, April 1984, pp. 42-46.

Duclos, T.G.: Electrorheological Fluids and Devices. Automotive

Engineering, December 1988, pp.45-48.

Conrad, H.: The Impact of ER Fluids. Compressed Air Magazine,

March 1992, pp.14-17.

"Procedure Demonstration Power Supply Controller" directions which

accompany the tunable clutch.

Source of Supplies:

Internet resource to supplies and additional information:

http://www.rmit.edu.au/departments/ch/rmpc/

68
UNIVERSITY OF MARYLAND MRSEC RESEARCH

EXPERIENCE FOR UNDERGRADUATES:

CULTIVATING TOMORROW'S RESEARCHER

Jennifer Stott (a)

Donna Hammer (a)

E. D. Williams <_b)

and

L. J. Martinez-Miranda c_c)

a. Materials Research Science and Engineering Center

b. Department of Physics

c. Department of Materials and Nuclear Engineering

University of Maryland

College Park, Maryland 20742-2115

Telephone 301-405-0253

e-mail martinez@eng.umd.edu

69
70
University of Maryland MRSEC Research Experience

for Undergraduates: Cultivating Tomorrow's

Researcher

Jennifer Stott (a), Donna Hammer (a), E. D. Williams (a'b)and L. J. Martinez-Miranda (a'c)

a. Materials Research Science and Engineering Center

b. Dept. of Physics

c. Dept. of Materials and Nuclear Engineering

University of Maryland, College Park, MD 20742

Key Words: Scientific research, engineering research, undergraduate program

Prerequisite knowledge:

None, specifically.

Freshman chemistry, physics, first year materials

Objective:

What is involved in doing a research project?

What other aspects we must consider when doing research: communication, awareness of

what other people are doing, how research is done in other environments.

Equipment:

Varies with the project.

Introduction:

The University of Maryland MRSEC Summer Research Experience for

Undergraduates provides the students with a well rounded educational experience doing

materials research. Supplemental activities enhance the laboratory experience and

provide students with opportunities to advance into graduate school and careers in

science. Approximately 6 - 8 sophomores and juniors with science and engineering

backgrounds participate in the 10-week program. The REU offers a diverse range of

research topics and includes a weekly seminar series, industrial tours of several

neighboring facilities, and a tutorial on how to conduct oral and poster presentations.

Research programs are available in Physics, Chemistry, Materials Science, and Electrical

Engineering. The students get to present their research results twice during the course of

the program.

71
Procedure:

The 6 - 8 students are selected by national competition. This competition is not

limited to large universities, with graduate programs. People from small colleges which

do not necessarily have a research program in place are especially encouraged to apply.

They choose three projects in order of preference, from which one is chosen by the

faculty in charge. If there are many students who ask for the same project as their first

choice, the advisors are consulted. The students come to the University with their

projects already assigned. In their orientation, they meet with their advisors, who

summarize the project. They begin to work the next day.

The advisors are informed ahead of time that there are certain activities which the

students need to attend. These are the seminar series and the tour series. The seminar

series is presented by faculty in the MRSEC, some of whom are not advisors and work in

projects different than what the students are working. The faculty are advised that the

audience will be mostly undergraduates and that they must prepare the talk such that

people with only basic knowledge in the field will be able to understand it. Occasionally,

the talk may be accompanied by a mini-tour of the faculty's laboratory. The purpose of

the tours is to introduce the students to how research is done at different laboratories and

how experiments with a small amount of sample are taken to industrial quantities.

The students have the opportunity to present their work twice as part of the

seminar series. They are given a seminar on how to present their results considering time

limitation. Many of the students have presented work before, but many have not

presented it under the strict time limitations required here or in any professional meeting.

Others have not presented at all. Generally, they have a poster and an oral presentation,

so they get to practice for both. In addition, they must present a final written report.

They are provided with a set of instructions on how to prepare the report, and in addition

are told to look into the articles they have read as references for additional style and

language requirements in their field. This helps not only the students, but also the

advisors, who get a write-up on the Summer research that can serve a student coming in

the fall to continue the work or to do related research.

Comments

At the end of the 10-week period, the students are given a series of questions

aimed at evaluating how successful the program has been. The purpose of this is to find

ways to improve on the offerings and if they have served the purpose we intended them

to serve. They are also encouraged to write telling us about their progress. Some

comments we have received during the years include (not exact citation):

"I don't know if I will go to graduate school or do research, but now I know what it

involves and will be able to make an informed decision."

72
"Beforecomingto theprogram,I wasin aprogramthatreallydid notencouragemeto

continue.Aftertheprogram,I mademy ownprogram(approvedbythedean),andfeelI

cancontinuenow."

"Thetour(ofNASA) inspiredmeto applytoNASAwhenI finished."

"Thetourof (Grace)industriallaboratoryhelpedto seehowthingsarescaledup. I

thoughtthatwas'reallycool'."

"I hadneverpresentedanythingin class.I amsonervous."Thisstudentdid agreat

presentation.Sheappreciatedtheopportunityto doit.

Otherstudentshavetoldtheirfriendsabouttheprogram,andthesehavein turn

applied.In thislastapplicationpool,wereceivedapplicationsthatreferredto our

specificactivities(thepresentationof areport,thetours)asareasonfor applyingto

Maryland.

Acknowledgements:

This work was supported by NSF Grant No. DMR-0080008.

73
74
ROOM TEMPERATURE CREEP OF

Pb-Sn and Sn-Ag-Cu EUTECTIC SOLDERS

Matthew C. Osborne

Monica Hurley

and

Angela L. Moran

Department of Mechanical Engineering

U. S. Naval Academy

590 Holloway Road

Annapolis, Maryland 21402-5042

Telephone: 410-293-5528

e-mail osborne@usna.edu

Telephone: 410-293-6534

amoran@usna.edu

75
Angela Moran

76
Room Temperature Creep

of Pb-Sn and Sn-Ag-Cu Eutectic Solders

Assistant Prof. Matthew C. Osborne

MIDN1/C Monica Hurley

Associate Prof. Angela L. Moran

Department of Mechanical Engineering

U.S. Naval Academy

Annapolis, MD 21402-5042

Key Words: Lead (Pb), Tin (Sn), Copper (Cu), Silver (Ag), Creep

Prerequsite Knowledge:

Objective: To provide the students with a fundamental understanding of time-temperature-load

behavior of materials and the creep behavior of two similar metal alloys.

Equipment: Wood and nails to build a frame, Solder, Dial Indicator, U-joint

Introduction:

When a metal or an alloy is under a constant load or stress, it may undergo a

progressive plastic deformation over a period of time. This time-dependent strain is called creep.

Creep occurs at different rates, the rate being dependent on the stress level, material properties,

and the application temperature. Ifa constant stress level is applied to a material, an increase in

temperature can increase the creep rate. This characteristic is termed as a thermally activated

process. Creep rate is also affected by the microstrueture of the material, its prior processing and

mechanical history, and its composition. When considering long term applications such as steam

plants, nuclear power plants or gas turbine engines, it can be seen that creep rate is an extremely

important property of a material to understand, for it can be regulated and controlled by the

materials processing, environment, and application.

Creep tests are run to determine the creep rate of a material. These tests are either

run at a constant temperature with varying stresses, or at a constant stress with varying

temperatures. The change in length of the specimen over a period of time is plotted against time

increments, which is termed a creep curve (see Fig. 1). The slope of the creep curve is creep rate

of the material (de/&). During primary creep, the metal strain-hardens to support the applied

load and the creep rate decrease with time as further strain hardening becomes more difficult.

During secondary creep, processes involving highly mobile dislocations counteract the strain

hardening so that the metal continues to elongate at a steady rate. During this stage the creep

resistance of the metal or alloy is the highest. Then for a constant-loaded specimen, the creep

rate accelerates in the tertiary stage of creep due to necking of the specimen and also to the

77
formationof voids,particularly along grain boundaries. The complete time it takes for the

specimen to fracture is termed the rupture time. Either a higher stress of a higher temperature

reduces the rupture time and increases the creep rate. In essenee, the creep test measures the

resistance of a material to deformation and failure when subjected to a static load below the yield

strength at an elevated temperature, or to a constant temperature at a varying stress. The

temperature at which creep becomes significant is generally considered to be approximately 0.4

Tm where rim is the absolute temperature so for lower melting point materials such as lead -tin

solders, creep can become an issue at room temperature.

The experimental tests described in this paper were designed to give quantitative results

which allow students to see room temperature changes in a commonly used material. This

experiment compares common solder materials with a new solder alternative, a mixture (alloy)

of tin, silver and copper. Figure 1 gives a typical creep curve of strain vs time.

Common lead (Pb)- tin (Sn) solder can be found in a range of mass fractions of Pb and

Sn. This study used 38% Pb by mass and 62% Sn by mass which results in a single melting

point of 183°C. The lead free alloy tin (Sn)-silver (Ag)-eopper (Cu) is a combination of 95% Sn

by mass, 4% Ag by mass and the remainder is Cu. The Sn-Ag-Cu alloy has a melting point of

219°C.

0.8

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Figurel. Example Creep Curve with Labeled Regions

Experimental Methods:

78
The Sn-Ag-Cu alloy was provided by OMG. The Pb-Sn was manufactured at USNA by

melting Pb and Sn pellets mixed in the appropriate mass fractions. Melting was done in a small

crucible in a furnace at 400°C to produce ingots which were subsequently cut into 1⁄2" thick

blocks measuring l"x 2" in size. The cut blocks were rolled (or pressed) to a 1/16" thick 3' long

strip approximately 1 1⁄2" wide. These were then punch cut according ASTM D 1708 to form the

specimens shown in Figure 2.

Figure 2. Cut Sn-Ag-Cu Tensile Specimens

The specimen is hung from a frame using special fixtures to allow for application of the

load and to prevent the specimen from slipping as shown in Figure 3. The grip is made of

aluminum, the pins are made of brass which prevent the specimen from sliding out of the grips.

The thumb screws and steel strip inserts apply pressure to the wide fiat face of the specimen so

that the sot_ solder is not pulled by the brass pins.

79
Figure3. SpecimenMounting in Grip Fixture.

The complete experimental set-up, with grip fixtures at both ends of the specimen, is

shown in Figure 4. The upper grip fixture is connected to a small U-joint to prevent specimen

bending. The entire load is aligned parallel to the long axis ofthe specimen. The lower grip

fiX_Ur_ is attached to an aluminum hangar for the weights. The hangar is composed of a threaded

rod_ti a disc with a threaded hole in its center. The hangar hangs free in space. The weight of

tl_e l_tt0m grip _fixture and hangar is 1.8 lbs.

80
Figure 4. Creep Experiment in Test Frame

To measure deflection, a dial indicator is mounted next to the hanging specimen as seen

in Figure 3 or directly above the weight as seen in Figure 4. Rigorous experimentation would

not measure deflection in such a manner since errors are inherent when not measuring directly

from a gage section. For demonstration purposes, the errors are considered unimportant but can

be discussed as follows. These errors are minimized for this type of material since creep is

essentially non-existent in the A1 parts as they are operating at 0.314 times the melting point

while the Sn-Ag-Cu and Pb-Sn solders are at 0.596 times and 0.643 times, respectively, their

melting points. Generally in materials, the closer one comes to the melting point the softer and

more easily a material will deform. The only true error will be the deflection measured from the

fillet section as the gage section transitions to the clamping section. This error is expected to be

small since the gage section is much larger than the filleted sections.

Procedure and Results:

The specimens were mounted as described above and data was recorded at different

intervals depending upon the time to failure. The specimen loadings were 30 and 20 lbs. for the

Sn-Ag-Cu solder and 20, 10 and 5 lbs. for the Pb-Sn solder. All tests were performed at room

temperature. 1 Typical results are presented in Figure 5 thru 7. Figure 8 has images of the failed

specimens.

1 A walk in freezer can provide low temperature effects and a Plexiglas enclosure with a small heater can provide a

higher temperatureeffect.

81
1.4

1.2

1

0.8

0.6

0.4

0.2

0

0 100 200 300 400 500 600

Time (mi_)

Figure 5. Creep Strain vs. Time for Pb-Sn solder at Room Temperature (20°C)

:3• ,: .7;

s:55::'_-7!

N

Figure 6. Creep Strain vs. Time for Pb-.Sn solder at Room Temperature (20°C) (Expanded view

of Figure 5)

82
Figure 7. Creep Strain vs. Time for Sn.Ag-Cu solder at Room Temperate (20°C)

..o_

5"::?: -_ Z: "

Figure 8. Creep Strahn vs. Time for Sn-Ag.Cu solder at Room Temperature (20°C)

83
As can be seen in these figures, two different solders with close melting points have -very

different creep behaviors. Also by examining Figures 5-8, one can see that the steady state creep

rate increases as loading increases, the slope is higher. The Pb-Sn failed the quicker than the SnAg-Cu solder but it had much greater deformation. This effect can also be seen by examining

the failed specimens in Figure 9.

Figure 9. Creep Specimens after failure at 20 lb. loading and at Room Temperature (20°C)

Summary:

This experiment was designed to provide the students with a fundamental understanding

of the time-temperature-load behavior of materials and the creep behavior of two similar metal

alloys. It is hoped that the students will take note of the following:

When a metal or an alloy is under a constant load or stress, it may undergo a

progressive plastic deformation (creep) over a period of time.

Creep occurs at different rates, the rate being dependent on the stress level, the

material properties, and the application temperature.

For constant - stress tests, alloys having different melting temperatures will exhibit

different strain - time behavior.

84
References:

1. W. Callister, Materials Science and Engineering: An Introduction, John Wiley & Sons

(2000).

2. American Society for Testing and Materials, Annual Book of ASTM Standards, Philadelphia

PA.

85
86
WINDMILL-POWERED, PROPELLER-DRIVEN

BOAT DESIGN-BUILD ENGINEERING PROJECT

Matthew A. Carr

Mechanical Engineering Department

U. S. Naval Academy

590 Holloway Road, MS 11C

Annapolis, Maryland 21402

Telephone: 410-293-6504

e-mail macarr@usna.edu

87
Matthew A. Carr

88
Windmill-Powered, Propeller-Driven Boat Design-Build Engineering Project

CDR Matthew A. CarT, USNR

Mechanical Engineering Department, United States Naval Academy, Annapolis, MD 21402

Abstract: This engineering project answers the question: "Can a boat use wind power to

propel itself directly into the wind?" The solution is a model boat with a windmill mounted on it

that is connected to a propeller that, in turn, propels the boat. This project is designed as a

team competition and is suitable for students ranging from high school physics through collegelevel engineering students. Concepts taught and/or reinforced by this design-build experience

include: fluid statics, buoyancy and stability; strength of materials; machinery design, friction,

and power transmission; and fluid drag resistance of various shapes. This article is structured to

provide a general overview of the supporting theory and key terminology, resources for

additional information, project rules for the student teams, and a supplies list for executing this

project. Where possible, the references cited are commonly available at public or larger high

school libraries.

Introduction: Anyone with sailing experience knows that a sailboat cannot sail directly into the

wind. However, can a boat use wind power to propel itself directly into the wind? The answer is

"yes," if properly designed and constructed, and can be done on a model scale with the skills of

most college-track high school students.

Project Considerations:

Facilities. This project requires access to a body of water of sufficient depth to allow the boat

propellers to clear the bottom and of sufficient length to allow a reasonable run. This is easily

met by an in-ground swimming pool, but can also be conducted in self-supporting, shallow,

89
plastic pools with a recommended length of at least six feet and a depth of at least six inches. A

m ulti-speed fan (large desk-top, box, or pedestal fan) provides the "wind." Electric power for the

fan is necessary. Students need to be informed of the dimensions of the pool for consideration

in their design. The length of the required run must be adjusted for the available facility, but a

run of at least three feet is recommended for scoring purposes.

Materials. Materials for the boat hulls may either be provided in a kit form or left to the students'

resourcefulness. Suitable materials for the hulls may be wood (balsa or construction lumber),

plastic (soft drink bottles or PVC pipe sections from a plumbing supply store), or foam

(Styrofoam or other insulation boards from a building supply store). Materials for the rest of the

boat structure typically include wood dowels, coat hanger wire, and cardboard. The windmill and

propeller are typically made from soft drink cans, balsa wood sheets, Venetian blind slats, and

pre-molded plastic fan blades and model airplane or boat propellers. Power transmission is

typically via a straight steel rod, with threaded ends, mounted on an angle such that the windmill

is on one end and the propeller is on the other. The rod may include small bearings or plastic or

Teflon tubing bushings to reduce friction. Other useful materials include graphite powder, duct

tape, super glue, and a plumber's epoxy stick. (Plumber's epoxy is clay-like and is hand-molded

into the desired shape. The action of kneading the clay sets off a rapid curing process.) The

material cost to build each boat should be less than $15 to $20, if materials such as foam are

purchased in sheets and cut down to blocks and provided, recycled materials such as wire coat

hangers or soft ddnk containers are used, and excluding tools.

Tools. This project may be constructed with hobby craft hand tools that include a small hammer

and various punches (nails are a suitable substitute), tin snips, coping saw, razor knife, wire

cutters/pliers, sand paper and a sanding block. A hand-held power drill and various small drill

bits are helpful, but not necessary if foam is used for the hulls. If construction lumber were used,

then access to a band saw or scroll saw would be helpful.

Safety. The fan must be located adjacent to the pool. The fan must be restrained from falling

into the water. Electric power for the fan should be provided via a ground-fault interrupting

circuit breaker or extension cord. The extension cord should be kept dry.

Terminology and Definitions:

Boat. Also known as a "vessel."

Hull - The "body" of a boat.

Catamaran - A boat with two parallel hulls aligned in the direction of motion. Note that most

of the designs will probably be catamarans.

Trim aran - A boat with three parallel hulls aligned in the direction of motion; the center hull

typically being longer than the other two.

Bow - The front of the hull.

Stem - The rear end of the hull.

Aft - Toward the stem of the vessel.

Displacement - The weight of the entire vessel. Archimede's Principle states that a floating

object displaces a volume of fluid that will weigh the same as the floating object.

Propeller. Good visual aids for a boat propeller are either a set of fan blades from a desk fan or

a small boat propeller from a marine parts store.

Propeller- A propeller is analogous to a screw and "advances" through the fluid in much the

same way as a screw advances through wood. The typical propeller used on boats is a

multi-blade screw propeller with two, three, or (sometimes) four or more blades (Naval

vessels typically have five or more blades on their propellers). The blades attach to the

9o
"hub"of the propeller. The hub is connected to the propeller "shaft."

Blade - Each blade attaches to the hub at its "root." The opposite end is called the "tip." The

"face" is the blade surface generating pressure. The "back" is the surface opposite the

face. Suction is generated on the back of the blade.

Blade Angle - Also known as the "pitch angle." The angle measured between the blade, at

some radius from the hub, and a line perpendicular to the shaft. If the blade angle is zero

degrees, then no pressure is generated on the blade face and no thrust is produced as

the propeller rotates. If the blade angle is 90 degrees, then all the pressure is directed

sideways and not aft.

Pitch - The axial distance that the propeller theoretically advances in one revolution. The

pitch of a "fixed pitch" propeller can not be changed during operation. A "controllable

pitch" propeller can be changed during operation, such as with a turboprop airplane. A

solid propeller (one piece) may also be classified as "constant pitch" or "variable pitch." A

constant pitch propeller has the same blade angle at each radius away from the hub.

The blade angle is different at each radius for a variable pitch propeller.

Slip - The difference between the theoretical and actual advance per propeller revolution.

(This effect will be addressed in the actuator disc theory discussion.)

Design Rules: (Instructor to adapt as necessary) Each team shall design and build its own

boat. Total length shall not exceed XX inches (instructor specify; recommend 30). Width and

height limitations are XX and XX (instructor specify; USNA chose the dimensions to fit inside an

available display cabinet). Power transmission from the windmill to the propeller may

incorporate direct-drive, gears or belt drives, with or without speed reduction. There is no limit

on the choice of materials, but the total material expenditure, including sales tax paid, shall not

exceed SXX (instructor specify) for the team. Note - if larger quantities are procured and only a

portion used, the total cost of the item shall be counted. Free or scrap materials may be

obtained from XX (instructor suggest sources such as local technical support shop or other

sources), but the owner's permission is required to use any free materials not retrieved from

scrap or recycling containers. Remember that the top finishing boats will be placed on display,

so that the boats and their component parts will not be returned. Expenses shall be shown on a

spreadsheet and included as an enclosure to the design report. Receipts shall be maintained

and copies turned in as an enclosure to the design report.

Competition Rules: (Instructor to adapt as necessary) A static tank (describe the tank) will be

used for the competition and will be available (instructor's judgment) for preliminary testing. A

multiple speed fan (instructor describe the fan) will be provided and placed adjacent to the tank.

Each team may set the speed of the fan for their run. The speed and direction of the fan many

not be changed during the run. The team may add a nozzle to the fan (typically duct-taped

cardboard), but once placed the nozzle may not be removed during the run. The boat may be

placed at any location, s_,not touching the walls. The run time will start when the boat is

released at s_.The time will stop when the boat crosses sf, as measured by a string stretched

perpendicularly across the tank (or contact with the tank wall or as viewed by a judge, at the

instructor's option). Two runs may be made on the day of the competition. The boat may be

modified between runs, but all modifications must be accomplished and subsequent run

completed within the class period. The best score of the two runs will be the score for the

competition. If As < 3 ft, the grade is a D. If t < 5 sec, the grade is a D. If the boat capsizes

twice, the grade is a D.

9]
ContestScoring: Theteam'sscoreisbasedprimarilyuponthe performancefactor,G. The

valueof G isdeterminedfromthefollowing equation.

G = 100 * (s= - sf) / t = 100 * As / t

Where, t = time of travel (seconds); must be greater than 5

s_ = initial distance from the reference point (ft)

sf = final distance from the reference point (ft)

As = s_- s_(ft); must be > 3 ft

Each team shall submit a design report and their lessons learned in memorandum format for the

balance of the grade on this project (See Reporting Requirements section, below).

Construction Pointers to Students: Hulls have been made from foam blocks, plastic bottles,

PVC pipe, and balsa wood. Propeller shapes have been purchased, or fabricated from scrap

aluminum or tin can lids. This project can be built with common hand tools. Students may find

tin snips useful in fabricating propeller shapes. Good local sources of materials for this project

include hardware stores, arts and crafts/hobby stores, and marine parts stores. Students may

find it advantageous to tour these types of stores with a concept in mind in order to get ideas on

materials and shapes available to facilitate boat construction. Bearings, should they be desired,

are available on-line from model parts companies (Small Parts Inc., Boca Bearings, et. al.).

Key concepts to consider in your plan include drag of both the air and the water on your boat

and friction in the machinery components. Also consider what happens to the drag and

propeller/windmill forces when the boat starts to turn.

Preliminary testing, well in advance of the competition, is vital to achieving the optimum

performance from your vessel. Plan on adjusting or even rebuilding your team's vessel from

what you will learn from a properly conducted series of tests.

Reporting Requirements: (Instructor adapt) (1) Four weeks prior to the competition, submit a

concept sketch of what your team intends to build. (2) Two weeks prior to the competition, each

team provide a written progress report of what you have done and describe your plan to

complete and test your entry prior to the day of the competition. (3) On the day of the

competition, each team is to submit a design report in memorandum format describing your

vessel, how it is constructed, and how it was tested. Include the financial spreadsheet as an

enclosure. (4) Within the week following the competition, provide lessons learned from this

experience by each person on the team and specifically answer what you would do differently

given the opportunity to do it over again.

Prizes and Awards: (Instructor adapt) The total score of this competition is worth XX. (Also

suggested) The instructor will treat the top place team to dinner. The top team from each class

will have their boat and team photograph placed on display.

Theory and Derivation:

W. J. M. Rankine (1869) and R. E. Froude (1889) applied momentum theory to

conceptualize the ideal propeller. The propeller was modeled as an actuator disk or mechanism

that imparted an increase in pressure to the fluid passing through its cross-sectional area. The

theory ignores how this increase in pressure is achieved. We know that fluid flows in response

to a pressure gradient, thus the propeller and windmill terms can also be looked at using

upstream and downstream velocities. Applying actuator disc theory for both the propeller and

the windmill, the propeller equations are written in terms of the axial "interference factor," a,

a = 1⁄2 [V2N1 - 1) (1)

where, Vl is the water entry speed relative to the propeller's plane, and

V2 is the water exit (wake) speed relative to the propeller's plane.

In other words, the change in velocity of the water entering and exiting the propeller's control

92
volumeis directly related to the interference factor.

The thrust, T, is

T = 2A pV 2 (l+a) a (2)

where, A is the propeller circumscribed area,

D is the water density, and

V is the velocity of the vessel (Note that V1 = V, see Equation 1).

The power absorbed, P, is

P = 2 A p V 3 (l+a) 2a (3)

The efficiency is the ratio of useful work obtained to the work expended.

11=TV/P= 1 / (l+a) (4)

Similar relations can be set up for the windmill. The power generated is

P. = 2 Aw pw(U+V) 3 (1-aw)2 aw (5)

where, U is the wind velocity,

(U+V) is the relative velocity of the wind to the vessel (and to the windmill),

Aw is the windmill area,

Dw is the air density.

and the windmill's drag, Dw is

Dw = 2 Aw Pw (U+V) 2 (1-aw) aw (6)

and the windmill interference factor is

aw = 1⁄2 [1- (U2+V)/(U+V)] (7)

where, U2 +V is the relative leaving velocity.

If the boat is in steady motion, the forces must balance, so that

Propeller Thrust = Windmill Drag + Air Drag on Hull + Water Drag on Hull (8)

Assuming that the hull is low riding so that the air drag is negligible as compared to the windmill

drag (this is really important to the success of the boat), we can now consider whether the boat

can travel against the wind, i.e., whether V>0 is possible. For the limiting case, V=0, there is

also no water drag and the combination of (2) and (6) then yields the force balance.

2 A p V2 (l+a) a = 2 Aw LOw(U+V) 2 (1-aw) aw (9)

Furthermore, if the power generated is fed into the propeller neglecting friction and actual

inefficiencies, then equations (3) and (5) may be equated to yield

2 A p V3 (l+a) 2 a = 2 Av pw (U+V) 3 (1-aw)2 aw (10)

Dividing (10) by (9) results in

or

V (1 +a) = (U+V) (1-aw)

V = (U+V) [(1-aw) / (l+a)]

Since the ranges of the interference ratios are

0 <a._< 1⁄2 and 0_< a <oo

V>0 is possible,

(11)

(12)

(13)

93
For the theoretical optimum windmill condition, a = 1/3, so that

V = 2U / (3a+1) (14)

in the absence of drag or inefficiencies. The necessary propeller/windmill area ratio can be

estimated from

NA. = [Pw/p][(l+a)/a] [a/(1-a.)] (15)

where, for aw = 113 and pw/p = 1833, then the area ratio is

A/Aw = [1/1700] [p(l*a)/a] (16)

Since reasonable values of "a" are on the order of a = 1⁄2, a fairly large area ratio is indicated.

This reduces to a diameter ratio of about 23.8.

Now, we know that there are a variety of windmill designs and not all of them will posses the

same efficiency. For windmills, the efficiency term is called the power coefficient, Cp

Cp = Pactual/Pideal = 4aw (1-a.) 2 (17)

The power coefficient of an ideal wind machine rotor varies with the ratio of blade tip speed to

free-flow wind-stream speed and approaches the maximum of 0.593 when this ratio reaches a

value of 5 or 6 and coincides with a. = 1/3.

Supplementary Reading:

The following references apply to this specific project.

Experiment #37, Experiments in Fluid Mechanics, R. A. Granger, 1988.

Engineering Applications of Fluid Mechanics, Hunsaker & Rightmire, McGraw Hill, 1947, pp.

382-383.

The following reference provides useful background information for various aspects of this

project. Annotations describe the content used in this project.

Marks Standard Handbook for Mechanical Engineers, 10thEd, Avallone & Baumeister, 1996,

Section 3.2 - discusses friction.

Section 3.3 - discusses vessel stability.

Section 9.1 - discusses wind power.

Section 11.3 - provides ship and propeller taxonomy.

Section 11.5 - discusses actuator disc theory and airplane propellers,

Students may also find useful books on wind-powered machines under the wind energy,

alternative energy, or renewable energy key words.

94
EXPERIMENTS FOR FIRST YEAR

ENGINEERING STUDENTS USING Sn-Bi ALLOYS

Mark A. Palmer

Manufacturing Engineering

Kettering University

1700 West Third Avenue

Flint, Michigan 48504-4898

Telephone: 810-762-7973

e-mail mpalmer@kettering.edu

and

Kurt Wainwright

Lung C. Fok

and

Benj amin Jones

Virginia Commonwealth University

95
Mark A. Palmer

96
Experiments for First Year Engineering Students Using Sn-Bi Alloys

Mark A. Palmer 1, Kurt Wainwright, Lung C. Fok, Benjamin Jones

Virginia Commonwealth University

Abstract

An introductory course, the completion of which will enable first year students to make design

decisions based on experimental data and using their knowledge of structure and processing

identify possible alternative materials has been developed at VCU and RPI. The order of topics

selected for this course is based on the paradigm that Processing effects Structure which effects

Properties which in turn determines Performance and is the basis for design. To make this course

successful laboratory experiments and hands-on exercises have been incorporated into the studiobased recitation which is the key learning experience. Alloys based on Sn and Bi have been used to

demonstrate eutectic melting and diffusion in the solid and liquid states

• validate the Sn-Bi phase diagram through determination of the amount of proeutectic

constituent,

• demonstrate coarsening of second phase particles,

• demonstrate sintering using Sn-Bi solder paste,

• and demonstrate grain growth using Sn.

The success of these experiments]demonstrations and how they were integrated into a course

without a separate lab or lab grade will be discussed.

This was funded by the National Science Foundation_ CCLI Program

Introduction

A second semester first, year course, Applied Materials Science (or Materials Chemistry II) was

taught at Virginia Commonwealth University. This course evolved out of a course originally

developed at Rensselaer Polythechnic Institute. The course seeks to respond to several of the

criticisms regarding freshman engineering education specifically, that much of the dissatisfaction

and disinterest in engineering occurs during the first two years of an enginee$ education when

they are exposed to the scientific concepts they will apply during their careers _. These criticisms

include,

o

*

,

4.

A vast majority of engineering students who described the quality of teaching as

poor overall, and that the focus on weed-out objectives and use of poor teaching

practices in the first two years had given them a shaky foundation for higher level

work.

A lack of student-teacher dialogue, which was perceived to reflect faculty

indifference. Large classes which are mainly one-way lectures, compared

unfavorably to the high school experiences of many students. Recitations taught by

non-faculty did not adequately address this.

A disjointed laboratory experience frequently annoyed students as did cook-book

laboratory exercises which were perceived as busy work _.

An ineffective use of instructional technology.

The typical experience therefore is inappropriate for beginning engineering students. Bloom, a

noted educational specialist identified a hierarchy of educational levels, each one required to the

next, and each higher level being more rewarding z. The first four of these of these are

1Now at Kettering University

97
1.

2.

3.

4.

Knowledge (memorization of facts),

Comprehension (restating learned facts),

Application (simple one-step application of abstract concepts),

Analysis (breaking down a problem into parts and solving it),

The large introductory courses characterized by the criticisms mentioned earlier focus on the first

three levels. Consider however, that first graders learn at the knowledge level, fourth graders at the

comprehension level, junior high school students at the application level and high schoolers at the

analysis level in English and social studies courses. One cannot be surprised that college students

do not respond well to being treated like children.

The course description for our course is: The students will learn how to specify materials for a given

performance criterion based on experimental data. Mechanical, chemical (corrosion) and electrical

property-performance issues will be discussed, as will the fundamental scientific principles needed

to understand how structure and processing effects these properties _. In order to do this students

need to be exposed to the interplay between processing, structure, properties and performance.

There are two approaches to presenting this material, the tetrahedral 5 and the chain 6 approaches as

shown below.

Performance

/

Properties

Figure 1: Tetrahedral approach where the

constant interplay of performance, properties,

structure and processing are emphasized.

Figure 2: The chain approach where it is

presented that processing affects structure,

structure affects properties and ultimately

performance.

We feel that the chain approach is the most pedagogically sound and therefore present the material

in the following order: Structure -> Processing -> Property-Performance Relationships. One cannot

tell students how structure is changed without first describing structure and therefore a discussion

of structure must precede processing. Once these two issues are covered the students can spend the

last one-half of the course applying the theory.

To successfully do this we integrated the laboratory into the course, expanding upon earlier work 7,

and identified a set of experiments and demonstrations to enhance the discussion of phase diagrams

(structure), coarsening, sintering and grain growth (processing). Because Sn and Bi are low melting

temperature metals all of the experiments could be performed on a hot plate s.

Experiments and Demonstrations

98
Thefollowingexperimentsanddemonstrationsweredevelopedandfully integrated into the course.

Structure

Phase Diagrams

Demonstration of Melting Point Depression

Estimation of Relative Amount of ProEutectic Constituent

Processing

Grain Growth of Sn

Coarsening of ProEutectic Constituent

Sintering of Eutectic Sn-Bi Solder Paste

Melting Point Depression

As shown in the phase diagram on the right Sn and Bi both have melting temperatures above 200°C

and a eutectic at 58Sn-42Bi and 138°C s. Thus when placed on a hot-plate at 200°C chunks of Sn and

Bi will not melt. However, when placed in contact diffusion occurs and a liquid forms at the

interface. Then melting occurs quickly. Once the alloy is completely mixed, it readily melts at 200°C.

Because Sn and Bi have comparable densities equal size chunks can be used.

Following the demonstration the students were asked the following question on the second test.

When two different (oxide.free) metals are placed on a hot-plate at a temperature below the melting

point of either material they will not melt. Yet when placed in contact with each other a liquid forms

at the point of contact, and then the metals melt more rapidly. Explain both observations. At least

80% of the students were able to explain that the mixing of atoms caused melting point depression,

and about 35% of the students were able to explain that once liquid formed diffusion occurred more

rapidly.

Estimation of Relative Amount of ProEutectic Constituent

Determining the amount of proeutectic constituent is a challenge to most students, however during

solidification the proeutectic constituent is the most recoguizeable. Students were told to prepare a

Sn-Bi alloy, measure the amount of proeutectic and compare it to that predicted by the phase

diagram as part of the homework assignment. An internet tip was written to guide them through

the process should they have trouble. In addition in class they were assigned a team problem to

estimate the proeutectic.

Representative Micrographs Showing Proeutectic Constituent in Sn-Bi Alloys

Note the proeutectic is fairly easy to spot.

99
Grain Growth of Sn

Since Sn melts at 232°C grain growth will occur quite rapidly at 200°C which is 94% of the melting

point. Sn can be melted readily on the hot-plate, cooled quickly and the grain boundaries can be

exposed using very dilute nitric acid. The Sn was placed in a furnace, although a conventional

toaster oven could have been used, for periods between 1 and 4 hours. Results of one experiment are

shown below.

Grain Growth of Sn at 200°C for 4 Hours

Appreciable grain growth is evident after a short time period.

Coarsening of ProEutectic Constituent

The proeutectic constituent will coarsen at 100°C, students took an initial micrograph and processed

the material for up to two hours. Results of one experiment are shown below.

Coarsening of Proeutectic After 90 Minutes at 100°C

It is evident that the size of the particles has increased.

100
Sintering of Solder Paste

Eutectic Sn-Bi solder paste is readily available from a number of commercial sources. Prior work

has demonstrated that it is possible to sinter solder pastes at low temperatures 9,1o.It is important

that to use paste and not powder as the flux will prevent the material from oxidizing. Students took

an initial micrograph and then placed the solder paste on the hot plate for up to 3 hours. Results of

one experiment are shown below.

Sintering of Sn-Bi Solder Paste at 100°C for 90 Minutes

Note that after 90 minutes it is evident that extensive necking has occurred and pores have begun

to form.

Discussion

Students were required to answer questions about the laboratory experiments on homework,

quizzes, tests and the final examination. To assist them on homework a series of internet tips was

provided so that they could work outside of class _1.

Structure Experiments

Graded performance records demonstrate that the students mastered the reading of phase diagrams

with roughly one-half of the students being able to calculate the amount of proeutectic. 50% of the

students were able to explain why a 1040 steel would be more fatigue resistant than a 1077 because

of the presence of proeutectoid ferrite when asked on the fma] examination. When asked to rate

how well the following learning objective was satisfied, To understand how multiphase systems are

formed, and predict the material properties of such systems the students rating was: (3.8+0.8)/5.0.

Processing Experiments

Students chose to complete one of the three processing experiments described and were required to

analyze their data as part of the following homework assignment. However, nothing can quantify

the excitement expressed by the students when they realized that solid state motion had occurred.

This confirmed to them that surface energy does exist and that once sufficient energy is provided

for atomic motion the microstructure will evolve to minimize surface area.

101
Graded performance records demonstrate that on the following test over 50% of the students could

explain coarsening, grain growth, and annealing and the effect on mechanical properties. On the

final examination students were able to explain sintering, but did not make the connection to small

grain size. When asked to rate how well the following learning objective was satisfied, To

understand, the principles of material processing and how processing effects structure the students

rating was: (4.2±0.8)/5.0.

Conclusion

This set of simple and inexpensive experiments can be used to teach students two of the most

difficult topics in introductory materials science courses. Following a suggestion by reviewers of the

assessment package, student teams will present their results to the class at the end of the term.

This will allow them to demonstrate their communication skills and help them prepare for the final

examination.

Acknowledgment

This was funded by the National Science Foundation_ CCLI Program DUE 9980982. The support

and encouragement of NSF is appreciated.

References

° Shaping the Future: New Expectations for Undergraduate Education in Science,

Mathematics, Engineering, and Technology: National Science Foundation Document NSF

96-139, © 1996.

.

.

Kenny S. S.: The Boyer Commission on Educating Undergraduates in the Research

University Reinventing Undergraduate Education: A Blueprint for America's Research

Universities; Carnegie Foundation for the Advancement of Teaching,

Bloom B. S. and Krathwohl D. R.:Taxonomy of Educational Objectives: the Classification of

Educational Goals, by a Committee of College and University Examiners. Handbook I:

Cognitive Domain: Longmans, Green New York, © 1956.

. Palmer M. A., Wnek G. E., Hudson J. B.: New Approaches for an Introductory Materials

Science Course; ASEE Materials Division 1998 Conference

1 Flemings M. C., Sadoway D. R.: Frontiers of Materials Education; MRS Proceedings v66,

©1985.

. Linden B., Vanasuppa L., Heidersbach R.: The Structure of Materials Engineering: A New

Model for Materials Engineering Curricula; TMS Annual Meeting, Education Symposium

(1996).

.

8.

Hudson J. B and Palmer M. ,_: Interactive Learning in a Multidisciplinary First-Year

Course; ASEE Educational Research and Methods Division 1996 Conference Proceedings.

Baker H. (ed): ASM handbook - Volume 3 Alloy Phase Diagrams; ASM International,

Materials Park, ©1992

, Palmer M. A., Alexander C. N., and Nguyen B.: Forming Solder Joints by Sintering Eutectic

Tin-Lead Solder Paste; Journal of Electronic Materials, 7/99 pp. 922-925.

102
10.

11.

PalmerM.A.,ErdmanN., McCall D.: Sintering of High Temperature Solder Materials;

Journal of Electronic Materials, 11/99 pp. 1189-93.

Palmer M. A., Hudson J. B., Moynihan C. T., Wnek G. E.: Using the Internet in a Freshman

Engineering Course; Journal of Materials Education v18, pg. 35, (1996).

103
104
FORMATION AND CONVERSION OF

CALCIUM PHOSPHATES -

A NOVEL APPROACH TO PREVENT

CAVITIES AND DENTIN SENSITIVITY

Ming S. Tung

American Dental Association Health Foundation

Paffenbarger Research Center

National Institute of Standards and Technology

100 Bureau Drive, Stop 8546

Gaithersburg, Maryland 20899-8546

Telephone: 301-975-6823

e-mail Ming.tung@nist.gov

105
Biography:

Ming S. Tung is a Senior Project Leader at

American Dental Association Health Foundation,

Paffenbarger Research Center, National Institute

of Standards and Technology. He has a B. S.

degree in Chemical Engineering from ChengKung University in Taiwan and a Ph.D. in

Chemistry from Brown University. His research

includes calcium phosphate chemistry and

remineralization of the tooth.

106
Formation and Conversion of Calcium PhosphatesA Novel Approach to Prevent Cavities and Dentin Sensitivity

Ming S. Tung

American Dental Association Health Foundation

Paffenbarger Research Center

National Institute of Standards and Technology

Gaithersburg, MD 20899

Key Words: Amorphous calcium phosphate, Apatite, Cavities, Dentin sensitivity, Gel,

Carbonate.

Prerequisite Knowledge: General Chemistry.

Objective: To demonstrate the chemical principle of a novel approach to prevent cavities and

dentin sensitivity.

Materials:

1. One mL of calcium chloride solution (1.5 mol/L) and one mL of dipotassium hydrogen

phosphate solution (1 mol/L).

2. One mL of 33 mmol/L of calcium chloride and 50.6 mmol/L of acetic acid at pH of 2.5

and one mL of 50.6 mmol/L of potassium carbonate, 7.4 mmol/L of potassium dihydrogen

phosphate and 12.6 mmol/L of phosphoric acid at pH of 9.7.

Introduction:

About 95 percent of the tooth enamel is inorganic calcium phosphate crystal,

known as apatite. Dental cavities and dentin sensitivity are due to the dissolution or loss of the

apatite crystal, demineralization. To prevent and heal these problems, the tooth mineral is

deposited back to where it is lost by a novel process of rapid remineralization, the

recrystallization of apatite. This is accomplished with a new, clinically feasible method: rapid

formation on and in the tooth of amorphous calcium phosphates, which then crystallize to

apatite slowly after application. 1 The highly concentrated calcium phosphate solutions are

applied in two ways: two-step gel and one-step carbonated mouth rinse. Two-step application

forms the calcium phosphate gel on the tooth by applying a calcium solution on the tooth

followed by applying a phosphate solution. The one-step application rinses a carbonated

calcium phosphate which is mixed before application.

107
Chemical Reactions: 2

1. Two-step gel application.

When a highly concentrated calcium chloride solution (1.5 mol/L) is mixed with a highly

concentrated potassium phosphate solution (1 mol/L) at high pH (pH = 9.5), the initial phase

formed is a gel of calcium phosphate, which then converts to the apatite through an

intermediary of amorphous calcium phosphate.

3 CaC12 + 2 K3PO4 + y H20 _ (Ca3 (PO4)2)xeyH20 (gel) + 6 KC1

(Ca3 (PO4)z)xoyH20 (gel) _ Ca3 (PO4)z*3H20 (ACP),I, + (y-3) H20

5 Ca3 (PO4)zo3HzO(ACP) --+ 3 Ca5 (PO4)3(OH)(apatite) + H3PO4+l 2H20

2. One-step carbonated calcium phosphate solution application.

Two solutions are mixed and then used as mouth rinse. One contains 33 mmol/L of calcium

chloride and 50.6 mmol/L of acetic acid at pH of 2.5, and the other contains 50.6 mmol/L of

potassium carbonate, 7.4 mmol/L of potassium dihydrogen phosphate and 12.6 mmol/L of

phosphoric acid at pH of 9.7. Both solutions are stable under atmospheric pressure. Upon

mixing, a carbonated calcium phosphate solution is formed; this solution is highly

supersaturated with respect to the carbon dioxide and the calcium phosphate. As carbon

dioxide evaporates, which is the same as removal of carbonic acid, the pH of the applied

solution increases and the amorphous calcium phosphates precipitate rapidly, and then converts

to tooth mineral. The reaction can be observed visually in one minute.

3CaClz+2KH2PO4+2K2CO3+ H20 _ Ca3(PO4)2o3HzO(ACP),I, + C02"_

5Ca3(PO4)2o3H20(ACP)---_3Ca5 (PO4)3(OH) (apatite) +H3PO4+ 12H20

Demonstration:

1. Two-step gel application.

Two solutions will be mixed: one contains calcium, and the other contains phosphate. The

mixing of the two solutions initially induces the formation of calcium phosphate gel within

seconds. The gel will precipitate as amorphous calcium phosphate, which then converts to

apatite, the tooth mineral. The reaction can be observed visually in one minute.

2. One-step carbonated calcium phosphate solution application.

Two solutions will be mixed: one contains calcium and the other contains phosphate and

carbonate. Upon mixing, a highly saturated carbonated mouth rinse is formed. As carbon

dioxide evaporates (as in carbonated beverages and beers), the pH of the applied solution

increases and the amorphous calcium phosphate precipitates rapidly and then converts to

apatite. The reaction can be observed visually in one minute. The evaporation and the pressure

of carbon dioxide can be observed and felt.

108
Comments:

The dissolutionof tooth mineral by acids produced by bacteria fermentation in the mouth

causes destruction of the dental enamel and dentin. The calcium and phosphate ions in saliva

continuously remineralize the tooth, thus repairing this demineralization. When

demineralization is faster than remineralization, cavities occur. In vitro studies 3 show that

increases in remineralization can reverse the cavities. Unfortunately, this repair takes months

since the direct crystal growth of tooth mineral is a very slow process. The clinically feasible

remineralization is accomplished by rapid deposition of amorphous calcium phosphate on and

in the tooth which then converts to the tooth mineral after application.

References:

1. Tung, M.S. and Eichmiller, F.C. (1999): Dental Applications of Amorphous Calcium

Phosphates, J of Clinical dentistry 10:1-6.

2. Dorozhkin, S.V. (2001): Systems of Chemical Equations as Reasonable Reaction

Mechanisms, J Chemical Education 78:917-920.

3. ten Cate, J.M. (2001): Remineralization of Caries Lesion Extending into Dentin, JDental

Research 80:1407-1411.

109
110
LIGHTWEIGHT AUTOMOTIVE MATERIALS

RESEARCH AT THE CENTER FOR

LIGHTWEIGHTING AUTOMOTIVE

MATERIALS AND PROCESSING

(CLAMP)

P. K. Mallick

Department of Mechanical Engineering

University of Michigan-Dearborn

Dearborn, Michigan 48128

Telephone 313-593-5119

e-mail pkm@umich.edu

111
P. K. Mallick

112
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MEMS AND NANOTECHNOLOGY

IN THE 21ST CENTURY

Luc G. Fr_chette

Department of Mechanical Engineering

Columbia University in the City of New York

220 S. W. Mudd Building

Mail Code 4703

500 West 120th Street

New York, New York 10027

Telephone: 212-854-2962

e-mail lf307@columbia.edu

125
Luc G. Fr_chette

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148
FISHING LINE KNOT TYING CONTEST:

A FRESHMEN EXPERIENCE

Wayne L. Elban

Department of Electrical Engineering and

Engineering Science

Loyola College

4501 North Charles Street

Baltimore, Maryland 21210

Telephone: 410-617-2853

e-mail welban@loyola.edu

and

Douglas L. Frantz

Department of Physics

Earth Science, and Geography

Community College of Baltimore County

Baltimore, Maryland 21228

Telephone: 410-455-4317

e-mail dfrantz@ccbc.cc.md.us

149
Wayne L. Elban

Wayne L. Elban Douglas L. Frantz

Since 1985, Professor Elban has

taught engineering science courses at

Loyola College, including introductory

materials science, materials science lab,

mechanical properties of materials, and

transformations in solids. He received a

BChE with distinction ('69) and a PhD in

Applied Sciences: Metallurgy ('77) from

the University of Delaware and a MS in

Engineering Materials ('72) from the

University of Maryland, College Park.

From 1969-1985, he was a research

engineer at the Naval Surface Warfare

Center, White Oak Laboratory, Silver

Spring, Maryland. He is a member of

ASM International.

Doug Frantz has been an adjunct

faculty member for the Physics Laboratory

at the Community College of Baltimore

County (CCBC), Catonsville Campus since

1980. He received his BS in Chemistry

('70) from Towson State College (now

Towson University). He serves primarily

as Network Administrator for the

Mathematics, Science, and Engineering

Division at CCBC. His focus as adjunct

faculty member is first-year physics

laboratory experiences.

150
FISHING LINE KNOT TYING CONTEST:

A FRESHMEN EXPERIENCE

Wayne L. Elban

Dept. of Electrical Engineering and Engineering Science

Loyola College

Baltimore, Mar-yland 21210

and

Douglas L. Frantz

Dept. of Physics, Earth Science, and Geography

Community College of Baltimore County, Catonsville Campus

Baltimore, Maryland 21228

ABSTRACT: A procedure is described for conducting a knot tying contest for freshmen

engineering/physics students using commercial 6 (and 4) lb-test nylon monofilament fishing lines.

A bench-top universal testing machine is used to obtain room temperature determinations of

tensile breaking load for knots tied to a swivel or hook. Emphasis is given to exposing students

to materials testing methodology, modifying a standard test fixture configuration to accommodate

the knotted samples, and (optional activity) using elementary statistical analysis to assess knot

quality. Results from testing samples with a variety of knots, including double overhand, modified

double overhand, Palomar, Improved Clinch, Perfection, and Harvey are presented. Experimental

determinations of knot efficiencies are compared to values appearing in the literature.

KEY WORDS: Uniaxial tensile testing, fracture, stress concentration, thermoplastic polymers,

nylon, monofilament fishing line.

PREREQUISITE KNOWLEDGE: High school mathematics and physics.

OBJECTIVES:

(a) Experimental Goals:

o to design and tie fishing line knots in order to enter contest for freshmen

engineering/physics students;

.

to measure the breaking load (i.e., fracture force) of various fishing line knots

tested in uniaxial tension; and

3. to improve on the design of fishing line knots.

151
(b)LearningGoals:

.

to become familiar with uniaxial tensile testing, a prominent technique for

characterizing the mechanical response of materials;

2. to become familiar with measuring dimensions using a dial caliper;

3. to become familiar with the strength properties of common engineering materials;

.

to become exposed to stress concentration and its effect on material

deformation/fracture behaviors; and

. (optional activity) to become exposed to rudimentary statistical analysis of

experimental data (Instructor Note 1).

EQUIPMENT AND MATERIALS: (1) Chatillon model LRX universal testing machine (bench

top model with 500-1b capacity); (2) Wedge-action grip (Chatillon model TG15N); (3) Bollard

wire, yarn, and thread grips (Chatillon model TG12N); (4) Metric universal dial caliper (Brown

and Sharpe 559-579-13); (5) Ruler; (6) Extruded nylon monofilament fishing line [Berkley Trflene

XL 6- (and 4-) lb test (or equivalent)] (Instructor Note 2); (7) 1" x 1-3/4" x 1/4" oak lath with

eyehook screwed into the center of the thin dimension (Instructor Note 3); (8) Interlock swivels

[Berkley size 7 (or equivalent)]; (9) Fishing hooks [Mustad 9672 3X-8 (or equivalent)]

(Instructor Note 4).

SAFETY PRECAUTIONS: Care must be taken to avoid being stuck if fishing hooks are

used instead of interlock swivels when tying knots. (Instructor Note 4)

INTRODUCTION:

A. CONTEST RULES (Instructor Note 5)

The objective of this competition is to obtain the knot with the highest fracture force using

commercial nylon monofilament fishing line tied to an interlock swivel or fishing hook. It is

expected that participation will result in an improved understanding of the important engineering

concept of stress concentration and its effect on the strength of polymers and its use in designing

with these materials. Listed below are the various constraints and rules that must be adhered to

with your entries.

Materials:

° All knots must be tied using only the fishing line and swivels/hooks supplied in

your kit.

2. Each kit consists of:

152
(a)Five(5)two-footlongpiecesof fishingline;

(b)Three(3)No. 7interlockswivelsor 3X-8fishinghooks;and

(c) Bookletentitled"A Guideto KnotsandLines:Angler's Reference" [1]

describing several popular knots used for the type of line provided.

Physical Constraints:

° An entry (one per individual) shall consist of no more than three (3) knots. These

may be of any type -- all the same or a variety. Two (2) additional lengths of line

have been provided so practice knots can be prepared.

, Each knot must be tied to a single swivel/hook with at least 18 in. of line available,

so that the knot can be tested as described below.

3. No foreign substance, such as adhesive or glue, may be added to the knot or line.

4. It is expected that each contestant will tie his/her own knots.

Loading:

. Each knot will be tested in tension using the department's universal testing machine

(Chatillon model LRX) operating at a crosshead speed of 1 in./min. Equipped

with a couple of different types of grips, the tester is computer controlled and has

computer data acquisition capability.

2. The line is elongated at constant rate until one of three events occurs:

(1) knot fails;

(2) line fails, leaving knot intact; or

(3) line fails at the gripping fixture, again leaving knot intact.

Generally, a grip failure occurs at a load significantly below the test rating of the

line as specified by the manufacturer and is considered to be a test artifact.

° Regardless of failure location, the maximum tensile force is recorded for each of

three knots maximum per entry. Only the highest force per entry is used to rank

order the entries and for the awarding of prizes. This allows for a maximum

number of contest winners.

Qualifications:

° All knots are subject to the above constraints, and any knot failing to meet any of

the constraints will be disqualified by the judges.

2. All decisions of the judges are final.

153
B. BACKGROUND TOPICS

Nylon is a prominent example of a large class of industrially important materials known as

thermoplastic polymers, which usually have a linear structure. Typical uses for nylon include

outdoor fabrics, carpet fibers, and monofilament fishing lines (introduced by Berkley in 1957 [2]).

The continuous extrusion/drawing process used to manufacture fishing line has been briefly

described [3] previously. The most significant feature of the drawing operation is the resultant

alignmem of molecules along the filament longitudinal axis. Consequently, the highest tensile

strength is realized in this direction as desired, for example, in nylon monofilament fishing line.

Stress concentration [4] arises in a material sample experiencing a point applied force or in

one of varying cross-sectional area subjected to a uniform applied force. For example in the latter

case, a tensile specimen consisting of a bar with reduced cross section in the center has the highest

normal stress where the area is smallest. This effect is assessed using a stress-concentration

factor, 1%which is given as

1%= Om_x/%w (1)

where Omax = maximum normal stress, and

Oavg= average normal stress at the smallest cross-sectional area.

This ratio provides a quantitative measure of the effect of sample geometry on the local stress at

the smallest cross-sectional region. As a result of the stress concemration that occurs at a preexisting surface flaw (e.g., nick) or a knot, nylon monofilamem fishing line exhibits a notch

weakening effect. [3]

It is useful to gage the performance of a knot in fishing line, say, by comparing its fracture

force with that of the same line without a knot. These two forces allow the calculation of a knot

efficiency, l]_ot, which is defined as

_ot = F_ot/Fo, (2)

where Fk, ot = fracture force of knot, and

Fo = fracture force of line without knot.

For 6-1b test Berkley Trilene XL fishing line tested [3] previously, a single in-line overhand knot

had an average efficiency of 54.9%. From analogous sets of measurements obtained by other

researchers [5] for a variety of 30- and 50-1b test nylon monofilament lines, knot efficiencies were

somewhat higher, typically in the 60-70% range. In kernmantle climbing rope, a differem class of

structural material, efficiencies ranged [6] from 60 to 80% depending on the knot, all of which

were more complicated than a single overhand knot.

For repeated experimental measurements of a given quantity, such as knot fracture force,

the arithmetic mean or average [7] is generally considered to be the best estimate of the so-called

"true" value for a particular set of experimental conditions. However, calculating just the average

154
conveysnoknowledgeaboutthedistributionor spreadinthedataset.To assessthis

characteristic,statisticiansrelyonacalculationofroot meansquaredeviationor standard

deviation[7]. Thisparameterprovidesameasureof theuncertaintydueto fluctuationsinthe

measurements.

Thepurposeof this activity is to provide a "hands-on" experiment designing, preparing,

and evaluating various knots tied using nylon monofilament fishing line. To this end, a

quantitative evaluation of knot fracture force will be made from uniaxial tensile testing. The

current experiment follows on from last year's National Educators' Workshop (NEW) paper [3]

describing a procedure for characterizing the fracture behavior of commercial nylon monofilament

fishing line. Further, it relates to a previous year's NEW paper [8] that provides a very nice

description for evaluating the load reducing (stress concentrating) effect of knots in various lines

and threads.

PROCEDURE:

A. INTRODUCTORY TENSILE TESTING OF AS-MANUFACTURED LINE (Instructor Note

6)

1. Measure the diameter of each specimen using a dial caliper prior to tensile testing.

. Perform tensile testing (specimen gage length = 43⁄4 in.; crosshead speed (CHS) = 1 in./min

-- Instructor Note 7) on five (5) specimens minimum of line (without knot) using bollard

grips.

. For each specimen, note whether failure occurred in the line as desired or where it was

clamped corresponding to a testing artifact. In this case, the data should be discarded.

B. KNOT DESIGN

° Recognizing that knots inherently degrade the strength of nylon monofdament fishing line

[3,5] and other materials [8], attempt to identify desirable features of a knot that can serve

as a basis for designing a strong, high performance knot.

o Review various widely used knots appearing in the literature [1,9,10] and on Web sites

[11-13] to determine whether and how these design features have been used.

° To commence designing knots and to become familiar with handling/tying fishing line,

prepare several double overhand knots for initial testing.

. Once the double overhand knot is tested, consider ways to improve it's performance and

prepare several modified double overhand knots for testing. (Instructor Note 8)

5. Tie knots of your own design or select knots to tie from the literature to enter the contest.

155
C.TENSILETESTINGOFKNOTS

1. Performtensiletesting(samespecimengagelengthandCHSemployedpreviously)using

atop bollardgripandabottomwedge-actiongripwitheyehook/lathassemblyto provide

thenecessarysamplefixtures(Figure1)fortheknotsprovided.

2. For eachspecimen,notewhetherfailureoccurredattheknotasdesiredto evaluateits

fractureforceor elsewhere(whereit wasclampedor inthelineawayfromtheknot). In

thelattercases,thedatashouldbediscardedintheanalysisthatfollows.

D.ANALYSIS

Performthe followinganalyses.

1. Tensiletestingmeasurements:

a. Tabulatethemeasuredvaluesof fractureforce.

b. Calculate[7] theaverageand(optional activity) standarddeviation,e, forthis

valueifa minimumof five(5) specimensof thesametypeweretested.

2. Fracturestrengthof as-manufacturedline:

a. Calculatefracturestrength,of,for eachlinespecimenwithoutknotusingthe

engineeringstressrelationship(e.g.,Eqn.(2-1),Ref.[14]):

of= Fe/(xd2/4), (3)

where Ff = fracture force in force-displacement curve, lbf, and

do = initial diameter of specimen, in.

b. Calculate [7] the average and (optional activity) standard deviation, o, of this

determination.

3. Knot efficiencies:

a. Calculate the efficiency of a given knot using EqrL (2), where both forces have

units of lbf.

b. Calculate [7] the average of this determination.

COMMENTS with Data Sheets and Plots:

All of the experimental steps were repeated to verify that the results are reproducible. The

greatest uncertainty is associated with the quality of knots that were tested and not in the

156
Boll_d Grip TG12N

Knot

Fishing Line

Woo La ConnectoWo°d'OaLath De'a"

Wedge-Action Grip TG15N_ _ 1/8" Eyehook

1/4"- _ rl _ 7

_ II _ _ 3/4"

Equipment Base . It

Figure 1, Sample fixture arrangement used in uniaxial tensile testing of

fishing line knots.

157
measurements themselves. The data sets appearing in this section are considered to be

representative for Berldey 6-1b test line and the various knots that were evaluated. A complete set

of measurements obtained for Berkley 4-1b test line appears in the Appendix. (Instructor Note 2)

Tensile Testing of As-Manufactured Line: Force measurements taken from experimental curves

(e.g., Figure 2) are given in the first data set of Table I for Berkley 6-1b test line without knots.

The average fracture force was 7.96 lbr (35.4 N), corresponding to 133% of the line's rating.

Four of the six specimens broke in the middle, while fracture in the remaining two occurred at a

bollard but away from the clamp. As such, the bollard that takes up the filament before it is

clamped in each grip successfully isolates the specimen from the deleterious effect of clamping.

Thus, all of these measurements are valid.

Fracture Strength of As-Manufactured Line: The average fracture strength was computed to be

141,000 psi (972 MPa). For comparison purposes, this value appears in Table II along with

(ultimate) tensile strengths for several other materials [15-19] that have familiar applications. The

relatively (and surprisingly) high fracture strength of the fishing line is attributed to the polymer

molecules becoming aligned during the drawing operation along what is to become the tensile

axis. As such, a relatively high percentage of strong intramolecular bonds oppose the applied

force.

Tensile Testing of Knots and Their Efficiencies: Force measurements taken from experimental

curves (e.g., Figure 3) are given in the remaining data sets of Table I for various knots in the 6-1b

test line. The double overhand knot yielded an average maximum force of 3.10 lbf (13.8 N),

corresponding to an efficiency of 39.0%. For this knot, failure occurred by filament pull through

rather than by breaking. Modifying this knot by providing an additional loop in the swivel to

decrease line slippage increased the average maximum/fracture force to 4.77 lbf (21.2 N),

corresponding to an improved knot efficiency of 59.9%.

All of the standard knots except the Perfection failed at loads that exceeded the line's rating. The

average fracture force for the Palomar, Improved Clinch, and Harvey knots were 6.58 lbf (29.3

N), 6.76 lbf (30.1 N), and 6.66 lbf (29.6 N), respectively, corresponding to very similar knot

efficiencies (82.6, 84.9, and 83.6%). The Perfection knot exhibited poorer performance on the

order of the modified double overhand knot; the average fracture force was 4.82 lbf (21.4 N),

resulting in an efficiency of 60.6%.

With the exception of the double overhand knot which did not actually break, all of the knots had

higher average efficiencies than the in-line single overhand knot evaluated [3] previously. Thus,

these current knots have improved designs that lessen the deleterious effect of stress

concentration.

(Optional activity) Insights from Standard Deviation: Referring to the standard deviation values

appearing in Table I, the only knot whose standard deviation approached that of line without a

knot was the double overhand. The greatest fluctuation from the average value occurred for the

modified double overhand knot and is attributed to the two distinct failure modes that occurred as

denoted under Comments in the Table. Of the standard knots, the Improved Clinch had the

158
Load (Ibf)

10.00 1 ........................................................................................

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0.0000

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Figure 2. Force-displacement curve for Berkley Trilene XL six-pound test

nylon monofilament fishing line (specimen T6XL0401).

159
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six-pound test nylon monofilament fishing line (specimen T6XL2201).

164
higheststandarddeviation,indicatingthatits levelof complexitymakesit moredifficultto achieve

highlyreproducibleperformance.

INSTRUCTOR NOTES:

1. To conduct meaningful statistical analysis requires a greater number of specimens than what is

called for in the Contest Rules. An ASTM standard for tensile testing of plastics indicates [20]

that a minimum of five (5) specimens are to be evaluated.

2. The particular nylon monofilament fishing line selected for this activity was purchased only

weeks before it was tested. To relate to last year's experiment [3], 6-1b test Berkley Trilene XL

line was chosen as well as analogous 4-1b line. A complete set of data was obtained for both lines.

It is recommended that beginners use a larger diameter line since this facilitates knot tying.

3. In order for fishing line tied to a swivel/hook to be tested using a universal testing machine, it is

necessary to alter the standard sample fixture by providing some means to attach the swivel/hook.

This was accomplished (See Figure 1.) using a eyehook screwed into the center of the

longitudinal surface of an oak lath that was cut to the proper length to fit in a wedge-action grip.

Here, it is suggested that students be exposed to this sample fixture modification issue. Student

designs to solve this problem can be sought, and a group discussion to evaluate them can ensue.

It is possible that one or more of the better student designs can even be implemented.

4. While the majority of knots can be tied to swivels, which are much safer for students to handle,

some commonly used knots are tied to hooks, particularly involving their shanks. To avoid

getting stuck while a knot is being tied, the head of the hook can be embedded into a small cork

or piece of rubber.

5. The contest rules were originally specified to be followed by engineering students as part of the

1996 National Engineers Week activities at Loyola College. The procedure has now been

expanded with the aim of providing freshmen engineering and physics students with a hands-on

laboratory experience. It is envisioned that this would involve preparing student-designed

samples for characterization and subsequent data analysis and review that allows development of

analytical and critical thinking skills.

6. Students should be shown how to operate the universal testing machine and to position

specimens in the machine prior to actual testing.

7. It came [3] to one of the author's (W-LE) attention last year that nylon monofilament fishing line

is typically tested wet (after soaking in tap water for two hours) using a gage length = 12 in. and a

CHS = 10 in./min. Nylon is water conditioned because its mechanical properties decrease when

exposed to water, and hence the attempt to simulate service life conditions. While water degrades

mechanical properties, the slower CHS used in the current experiment should result in a lower

strength because of nylon's strain rate sensitivity. Further, retaining the current experimental

conditions allows results to be related to those in last year's workshop paper [3].

165
8.By performingthisstep,studentsareintroducedto theiterativeprocess(conception,prototype

preparation,testing/evaluation, andimprovednewergenerationprototype)thatdesign

methodologyoftenfollows.

REFERENCES:

[1] "A Guide to Knots and Lines: Angler's Reference," Form No. L00587, Stren Fishing

Lines, Remington Arms Company, Inc., 870 Remington Drive, Madison, North Carolina,

27025.

[2] Evans, S. (Ed.): "Trout Fishing History and Lore," in Sports Afield Trout Fisher's

Almanac: Expert Advice from America's Greatest Anglers, The Atlantic Monthly Press,

1997, pp. 1-29.

[3] Elban, W.L.: Fracture Behavior of Nylon Monofilament Fishing Line, in National

Educators' Workshop: Update 2000, NASA/CP-2001-211029, 2001, pp. 81-112.

[4] Hibbeler, R.C.: Mechanics of Materials, 4th Edn., Prentice Hall, 2000, pp. 156-161.

[5] Dugger, A.: "Break Point: We Test 50- and 30-Pound Lines," Sport Fishing, Volume 12,

April 1997, pp. 48-54.

[6] Gregory, J.F.: Rock Sport: Tools, Training, and Techniques for Climbers, Stackpole

Books, 1989, p. 54.

[71 Holman, J.P.: Experimental Methods for Engineers, 7th Edn., McGraw-Hill Book Co.,

2001, pp. 62-63.

[8] Karplus, A.K.: Knotty Knots, in National Educators' Workshop: Update 93, NASA

Conference Publication 3259, 1994, pp. 369-372.

[91 McClane, A.J.: McClane's Secrets of Successful Fishing: A Complete Guide to the

Techniques, Tackle, and Know-How of Sport Fishing, Holt, Rinehart, and Winston, Inc.,

1979, pp. 191-210.

[10] Sosin, M; and Kreh, L.: Practical Fishing Knots II, The Lyons Press, 1991.

[11] URL Address (www.fieldandstream.com/fishing/fsgoodties.html).

[ 12] URL Address (www.fishinglife. corn).

[ 13] URL Address (www.jacksonholeflyfishing. com).

[14] Hertzberg, R.W.: Deformation and Fracture Mechanics of Engineering Material._, 4th

Edn., John Wiley and Sons, Inc., 1996, p. 3.

166
[15] Flinn,R.A.;andTrojan,P.K.:Engineering Materials and Their Applications, 4th Edn.,

Houghton Mifflin Co. (now John Wiley and Sons, Inc.), 1990, pp. 334-335.

[16] Flinn, R.A.; and Trojan, P.K.: _, p. 346.

[17] Flinn, R.A.; and Trojan, P.K.: oo. cit., p. 376.

[18] Flinn, R.A.; and Trojan, P.K.: _, p. 424.

[19] Flinn, R.A.; and Trojan, P.K.: _, pp. 560-561.

[20] "Standard Test Method for Tensile Properties of Plastics," ASTM Designation D638-89 in

1989 Annual Book of ASTM Standards, Section 8: Plastics, Volume 08.01, American

Society for Testing and Materials, pp. 156-167.

SOURCES OF SUPPLIES: Commercial-grade nylon monofilament fishing line, swivels and

hooks are inexpensive and readily available at numerous retail stores from a variety of vendors. It

is also possible that some fishing line manufacturers will supply complimentary small spools of test

material and accompanying information. One such example is Pure Fishing Angler Service, 1900

18th Street, Spirit Lake, Iowa 51360. [3]

ACKNOWLEDGEMENTS: Special thanks to Mark A. Elban for analyzing all of the

experimental data leading to preparation of Tables I and A-I. Calling on his vast experience tying

and using a variety of fishing knots, Jonathan Thompson, Department of Electrical Engineering

and Engineering Science, Loyola College, provided helpful discussion regarding the contest rules.

Dr. David S. Richards, formerly in the Department of Electrical Engineering and Engineering

Science, helped draft the rules and administer the original National Engineers Week contest. The

identification of any manufacturer and/or product in this report does not imply endorsement or

criticism by the authors or Loyola College and the Community College of Baltimore County.

APPENDIX: A complete set of test data/results for Berldey Trilene XL 4-1b test line appears in

Table A-I that follows. (Instructor Note 2)

167
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170
DETERMINATION OF REDUNDANT

WORK IN EXTRUSION USING

VISIO-PLASTICITY

Neda S. Fabris

Mechanical Engineering Department

California State University, Los Angeles

5151 State University

Los Angeles, California 90032

Telephone 323-343-5218

e-mail nfabris@exchange.calstatela.edu

171
Biography:

Neda Saravanja-Fabris is a Professor of Mechanical Engineering Department at

California State University (CSLA) in Los Angeles. She holds Diploma Engineer degree

in Manufacturing from University of Sarajevo Bosnia and Herzegovina, M.S. and Ph.D.

in mechanical engineering at Illinois Institute of Technology, Chicago Illinois. Her work

experience includes teaching at University of Sarajevo and University of Illinois, research

position at Technical University in Aachen Germany and at Bell Telephone Laboratory in

Napperville Ill. At Cal State University she has taught 27 different courses mostly in the

area of materials, design, manufacturing and engineering mechanics. She is a member of

SME, ASEE, and SWE. In 2001 she has received Society of Women Engineers highest

honor, "Distinguished Educator Award", given to one engineering faculty a year.

172
Determination of Redundant Work in Extrusion

Using Visio-Plasticity

Neda S. Fabris,

Professor, Mechanical Engineering

California State University,

Los Angeles, California

Key Words: Exmasion, ideal work, redundant work, frictional work, optimum die angle,

Visio plasticity

Prerequisite Knowledge: Basic knowledge of material flow in extrusion process,

tmderstanding the difference between ideal, friction and redundant work.

Objective: Visualization ofthe material flow in extrusion process and influence of the

die angle on the homogeneity of deformation. Basic demonstration of the experimental

method known as visio-plasticity. Experimental demonstration of the difference between

ideal and actual work performed.

Equipment:

Self-manufactured extrusion set up with die inserts with different extrusion angles and

glass upper plate allowing students to observe the material flow in extrusion process

(machining time one hour, piece of the steel and glass). Extrusion set machined out of

steel plate, glass upper, pressure gage (appr. $10), Ply-Doh, different color, for the

extrusion media, cost app. $9.

Introduction

In the extrusion process thebillet is forced through a die with a substantial reduction, the

friction between the billet and the die causes the retardation of the material close to the

die and surface of the cylinder, causing non-uniform material flow pattern. That pattern is

highly influenced by the die angle, friction coefficient between die and material extruded

and temperature of the material.

Ideal Deformation

The total work Ut required to extrude the part in direct extrusion from original area ?to to

final area A f (or from the original length L0 to final length Le), is considered to be the

sum of ideal work Ui, frictional work Ufand redundant work Ur., i.e.,

Ut= Ui + Uf+ Ur (1)

Ui is computed from the properties of material and extrusion ratio R, where R= A0/Af

Also, R can be related to the absolute value of the true strain e as

8 = In (Ao/Af) = 111 (Lt/Lo) = In R (2)

173
For the perfectly plastic material with a yield strength Y, the energy dissipated in plastic

deformation per unit volume, u, is:

u = Y a (3)

The ideal work Ui done to deform the billet is:

Ui = u Ao L0 (4)

This work is supplied by the ram force F that travels a distance Lo as seen in the Fig. 1

Work = F 12o= p Ao Lo (5)

where p is the extrusion pressure at the ram

P

Fig. 1. Variables in Direct Extn_ion Process

Equating the work of plastic deformation to the external work done, we find that

u = p =Y In (Ao / Af) (6)

Ideal Deformation and Friction

Equation (6) pertains to ideal deformation without any friction. It could be shown

[1] * that based on the slab method of analysis, the extrusion pressure p for the small die

angle cz and coefficient of friction g can be expressed as:

p = Y [1 + (tan cz) / g ] [(R) _ot _ -1 ] (7)

An estimate of pressure can be obtained from the total power P provided by the piston,

moving with the velocity Vo and exerting pressure p on the material billet as:

P = pV0 (Tt Do2/4) (8)

The power due to the plastic work of deformation is the product of volume rate of flow

and the energy per unit volume. If we assume that, because of the dead zone, material

flow in the die region takes place along a 45 o "die angle" and that the frictional stress is

"Numbers in [ ] represent references at the end of the article.

174
equal to the shear stress k = Y/2 of the material by equation of the power input to the sum

of the plastic deformation and frictional powers, we obtain that [1] •

p= 1.7YlnR (9)

where R is the extrusion ratio R = A 0/Af

If we include in this analysis the force required to overcome the friction at the billet

container interface, Eq.(9) becomes

p = Y (1,7 In R + 2L/D0 ) (10)

Actual Forces

Equation (10) represents a simple estimate of the pressure in extrusion without

considering redudandant work i.e. the effect of the inhomogeneous deformation on the

required pressure to extrude material. It is also assumed, as mentioned before, that

regardless of the actual die angle, material always flows under 450 angles, leaving the rest

of the material in the dead end zone. Experimental evidence has shown that the die angle

influenced the extrusion pressure and the relationship is shown schematically in Fig. 2.

• %. .,"

• g "N

Fig.2 Extrusion force as a function of die angle; (a) total force; (b) ideal force; (c) force

required for redundant deformation (d) force required to overcome friction

As can be seen from Fig. 2, the friction component of the force and work done decreases

with the increase in die angle due to the decrease in contact between the billet and die,

while redundant work (and force) increases with a decrease in the angle of die. There is

an optimum die angle for which the extrusion force is the minimum. That angle can be

found only experimentally.

Redundant Work in Extrusion

Redundant work is due to the internal distortion in excess of that needed to produce the

desired shape [2]. It is the work that goes into inhomogeneous deformation of the

175
workpiece, which can cause internal defects and non-homogeneous properties of the final

product. Because the billet is forced through a die, with a substantial reduction in its

cross-section, the metal flow pattem in extrusion is an important factor in the overall

process. It is also the amount of work "wasted" in the process, so it is naturally desirable

to decrease that work, provided that other components of the work remain constant. It has

to be emphasized that it is not the case with friction work in extrusion; therefore, it is

desirable to find an optimum angle for a minimum power consumption.

The best way to understand the concept of redundant work is to visualize the flow pattern

of the material in the process. The common practice to visualize the flow pattern is to

halve the round billet lengthwise and mark one face with the grid pattern. The two halves

are then placed together in the container and then extruded. They are taken apart and

inspected.

Our Experimental Procedure

We have modified above described approach by designing the extrusion set-up with

Plexy glass cover as seen in Fig. 1. The angle of extrusion can be changed using

exchangeable dies. The material extruded is common Play-Doh. In order to visualize the

material flow, the squares of different colors of Play-Doh are used as shown in Fig. 3

The deformation of each square during the process is easy to follow. The process is

scanned to follow subsequent deformation of the squares located in different positions of

the specimen. As seen from the figures, the flow of the material is non-uniform, and the

material undergoes a much higher deformation than the ideal deformation predicts. The

force required to push the material through the die is measured using a fluid USG, (0-

300psi) pressure gage. The set-up was scanned in frequent intervals and transformed

into image files on Dell Lap-top computer as shown on the picture in the Figure3.

Fig.3 Experimental Set-Up

Experiments have shown that the formation of dead zone in the comers of the dies is

highly dependent upon the die angle. They have also shown that the force necessary to

push the material through the dies roughly increases 30% when the die angle increases

from 30-90 degrees. Actual reading on the pressure gage for the two angles: 600 and 450

are shown on the Fig.5 and Fig.6. They are 175 psi and 150 psi respectively.

176
Fig.5 Extrusion angle 600 Fig. 6 Extrusion angle 450

Several steps of flow of the material during extrusion are shown in pictures below.

177
Fig.7. MaterialFlowinExtrusion

Conclusions

These experiments are in the development stage. Up to now we did not have a chance to

analyze the strains for each particular die angle. It will be interesting to relate the

deformation of each square of the model with the amount of force necessary to conduct

deformation.

This experimental approach will be also used to verify the validity of Equation 10. All

what is needed is the yield strength of the Play-Doh. Also, using this relatively simple

experimental set-up we can verify other more sophisticated models of material flow in an

extrusion-like upper-bound approach and the slip line theory presented in [2], taught by

the author of the paper in a graduate metal forming class.

Visio plasticity is a very successful method in explaining the concept of redundant work

in extrusion and the concept of redundant work in general. This powerful method is often

neglected in material and manufacturing education. The experiment is similar to flow

visualization methods used in fluid mechanics, with possibilities for even more practical

applications.

178
Theauthorof thispapergottheideafortheexperimentalset-upduringavisit to the

Universityof MichiganattheNEW 1999conference.Shewantsto acknowledgethe

facultyatthatschoolfor developingasimilarexperimentalset-up.

REFERENCES:

1. Kalpakjian S. Manufacturing Processes for Engineering Materials, Third Edition,

Addison Wesley, 1997

2. Hosford R.M.C., Caddell R.M., Metal Forming Mechanics and Metallurgy,

Second Edition, Prentice Hall, 1993

179
180
MAGNETIC FIELD SENSING EXPERIMENTS

BASED ON A COMMERCIALLY AVAILABLE

GIANT MAGNETORESISTIVE (GMR) SENSOR

Amy Payne a

Kara A. SchnelP

Franz J. Himpsel b

and

Arthur B. Ellis a

aDepartment of Chemistry

University of Wisconsin: MRSEC

1101 University Avenue

Madison, Wisconsin 53706

Telephone: 608-262-6711

e-mail payne@chem.wisc.edu

bDepartment of Physics

181
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i!i!i_i_i_i!i!i_!i_i_i_i!i_i_i_i_i!ii_ii_i_i!iii!i_i_i_!iii_i_i_i_i_iii_i_i_i_i_i_i_i_i_! _

Amy Payne

Biographies

Amy C. Payne is a Research Intern at the University

of Wisconsin-Madison. She has a bachelor's degree

from Randolph-Macon Woman's College and

performed her doctoral research at the University of

California-Davis.

Kara A. Schnell is a Program Assistant at the

University of Wisconsin-Madison with a bachelor's

degree from the University of Wisconsin-Madison.

Franz J. Himpsel is the Ednor M. Rowe Professor of

Physics at the University of Wisconsin-Madison.

He received a Diplom and a Ph.D. from the

University of Munich. He joined the IBM Research

Division at Yorktown Heights in 1997 and moved

to the UW-Madison in 1995. Currently, he is

investigating how surfaces can be structured on the

nanometer scale by self-assembly, with the goal of

producing new types of electronic materials.

Arthur B. Ellis is Meloche-Bascom Professor of

Chemistry at the University of Wisconsin-Madison.

He received a Bachelor's degree from California

Institute of Technology and a Ph.D. from M.I.T. He

teaches introductory and advanced chemistry

courses as well as a graduate course on

nanostructured materials at UW-Madison, and

coordinates the education efforts of the NSF-funded

MRSEC on Nanostructured Materials and

Interfaces.

182
Magnetic Field Sensing Experiments Based on a Commercially

Available Giant Magnetoresistance (GMR) Sensor

Amy C. Payne," Kara A. Schnell," Franz J. Himpsel, b Arthur B. Ellis a

Department of Chemistry a and Department of Physics b

University of Wisconsin - Madison

Madison, Wisconsin 53706

Key Words: Giant magnetoresistance, magnetic field sensing

Prerequisite Knowledge: magnetic north and south poles, magnetic attraction and repulsion of

poles, basic algebra skills, ferromagnetism and antiferromagnetism, electrical resistance.

Objective: The purpose of this lab is to familiarize students with the concept of giant

magnetoresistance (GMR)and its applications.

Equipment:

Individual GMR sensor, Figure 1a (Part Number: AA002-02) a

GMR Cylinder Position Sensor Assemblies, Figure lc (Part Number: AG007-07) a

Power supply (9 Volt Battery)

Set of 5 refrigerator magnets cut to create different patterns b

Multimeter with alligator clips

2 pieces of wire (26 gauge, 3" in length)

bar magnet

liquid nitrogen and styrofoam cup

_Fhese items can be obtained from NVE Corporation, (800) 467-7141, http://www.nve.com

bBulk refrigerator magnets can be obtained from office supply (e.g., Office Max) or sign stores.

Introduction:

The experiments being presented are based on a relatively inexpensive, commercially

available giant magnetoresistive (GMR) sensor. Magnetoresistance is a phenomenon in which

the resistance of a material changes in response to an applied magnetic field.1 All metals display

a small magnetoresistance; however, magnetic multilayers with nanoscale dimensions can

display a large magnetoresistance called GMR, which is based on the magnetic reversal of

individual layers in the stack. GMR has found its way into many important applications. GMR

devices are currently being used as magnetic sensors in the read heads of computer disk drives, 2

as motion sensors in automobiles, 3 and in biosensing assays. 4

Students will be introduced to GMR concepts and applications by:

1. using a GMR sensor to determine patterns of magnetic fields from a series of

refrigerator magnets;

2. observing the GMR effect, calculating the percentage change in resistance of a

material in response to a magnetic field, and determining how temperature affects

the GMR effect;

3. designing an application for the GMR sensor.

183
Procedure:

I. Using a GMR Sensor to Detect Patterns of Magnetic Fields.

The GMR sensor, Figure 1a, can be incorporated into a circuit designed to control the

power to an LED, shown in Figures lb and lc; this device can then be used to sense magnetic

patterns. A common refrigerator magnet (RM) can be used to demonstrate this point. A flat RM

is different in design from many magnets: Instead of a single north and south pole, a dipole,

RMs are arranged in patterns that can be thought of as a set of small horseshoe magnets lined up

next to one another. 5 The black and white areas in Figures 2a and 3 refer to the north and south

poles of magnetic fields, oriented perpendicular to the page. When the poles are aligned in

stripes, magnetic field lines are formed, as shown in Figure 2b.

The Experiment.

ARM with a known magnetic pattem can be used to investigate the way the sensor responds

when passed over the surface of the RM.

1. Try dragging the sensor across the RM in a variety of directions.

2. Once you have established how the sensor responds to a known magnetic pattern, characterize

the other four RMs in Figure 3 in the same way.

3. How does the GMR sensor respond to magnet A of Figure 3? Does the GMR sensor respond

in more than one direction, and, if so, does it respond in the same way in multiple directions?

4. Match the unknown RMs to patterns A-E. What problems, if any, did you have trying to

distinguish among the magnetic patterns?

II. What is Giant Magnetoresistance?

Students can work on the following activities in groups of two or three.

GMR can be observed by measuring the resistance of a material with and without an

applied magnetic field. These values can then be used to calculate a percentage GMR using the

formula

% GMR = [(Pr_ - 19o)/ 19o] x 100%

where #o is the resistance without an applied magnetic field and OHis the resistance with an

applied magnetic field. The percentage magnetoresistance is characteristic of the material at a

given temperature and can be calculated by two methods: dividing by po, which provides a more

conservative value for the MR, or by OH, which is often used for values that appear to saturate at

100% when calculated with 19oin the denominator. The response of the GMR sensor is

dependent not only on the strength of the magnetic field, but also on the temperature. This

dependence can be examined by measuring and comparing the GMR effect at room temperature

and liquid nitrogen temperature.

The Experiment.

1. Strip the protective coating offboth ends of two pieces of wire,

184
2. Connect the end of one stripped wire to pin 1 of the individual sensor by wrapping the wire

around the pin several times (see Figure la). Repeat for pin 4 with the second wire.

3. Set the multimeter to measure ohms. Connect the leads attached to the individual sensor to the

multimeter. Does it matter which multimeter lead is attached to which pin?

4. Measure the resistance of the sensor without a magnetic field present. Record the resistance.

5. Now bring a magnet up to the sensor. Move the magnet around the sensor to find the

orientation that causes the largest change in resistance. Record the resistance.

6. Submerge the sensor in liquid nitrogen (contained in a styrofoam cup) and wait for the

multimeter readout to stabilize. CAUTION: Liquid nitrogen is extremely cold. Do not

allow it to come into contact with skin or clothing, as severe frostbite may result.

7. Bring the magnet next to the outside of the cup that holds the liquid nitrogen and record the

resistance of the sensor with and without the magnet present. Play with the position of the

magnet and the sensor, still submerged in liquid nitrogen, to find the direction that gives the

greatest change in resistance.

8. Using the resistance values, calculate the percentage of the magnetoresistance effect at room

temperature and at liquid nitrogen temperature, 77K. Compare both sets of data. What effect

does the temperature have on the resistance of the material? On the percentage of the

magnetoresistance effect?

III. Design a New Application for a GMR Sensor

The GMR effect has made a significant impact in the computer industry; these materials

are used in the read heads of computer hard drives. The use of GMR materials has enhanced

read head sensitivity, allowing the areal density of hard drives to increase significantly. Read

heads take advantage of the larger magnetoresistive response of GMR materials, which allows

smaller magnetic fields on the hard disk to be read. GMR sensors have also been used in antilock braking systems to determine wheel speed. A magnetic gear wheel provides a defined

number of magnetic "teeth" for the sensor to detect per rotation that can be converted to speed.

The Experiment.

With these applications in mind, what other ways could the sensor be used?

1. Design a new application for the GMR sensor.

2. What kind of detection schemes are possible? Can you keep the GMR sensor constantly lit?

How would you make the GMR sensor blink periodically?

3. How is the GMR sensor oriented with respect to the magnet? Does the orientation of the

magnet matter?

4. What are the advantages and disadvantages of using this design?

5. Describe the application.

Comments:

The concepts an instructor chooses to highlight are entirely dependent on the audience.

For example, the GMR sensor can be used to introduce the concepts of a wheatstone bridge,

ferromagnetism and antiferromagnetism, the composition of materials that exhibit

magnetoresistance, and the mechanism of magnetoresistance in multilayers. 6

185
TheGMRsensoris composedof four resistors made of a GMR material and arranged in

a Wheatstone bridge configuration (Figure 4). An opposing pair of the four resistors is shielded

from the magnetic field and serve as a reference, while the other opposing pair of resistors

responds to the applied magnetic field. The sensor detects the change in resistance when a

magnetic field is present and converts this change into an output, which can be connected to an

amplifier or a transducer such as a buzzer or a light-emitting diode (LED). Figure lb shows a

GMR sensor that has been incorporated into a circuit designed to power a yellow LED.

The GMR structure comprises layers of magnetic (e.g., Fe, Co, Ni) and nonmagnetic

(e.g., Cu, Cr) metals that are nanometers in thickness. The magnetic layers are either a single

ferromagnetic (FM) metal or an alloy of several FM metals, while the nonmagnetic layer is

usually composed of a single element. The FM layers are naturally oriented antiparallel, and the

electrical resistance of the material is relatively high. However, in the presence of an external

magnetic field, the FM layers undergo a reorientation so that the layers are FM coupled, and the

electrical resistance of the material decreases. Figure 5 shows the response of the magnetic

multilayer to the external magnetic field. 7

Use the magnetic field pattern exercise to introduce the concept of magnetic sensing and

to familiarize students with the interaction between the GMR sensor and the magnetic field.

Students should discover that the GMR sensor has an axis of sensitivity that responds to the

magnetic field of the RM when the magnetic field lines are aligned with the axis of sensitivity.

When the axis of sensitivity is oriented perpendicular (rotated 90 ° in the plane of the refrigerator

magnet) to the magnetic field lines, there is no response regardless of the movement of the

sensor on the refrigerator magnet. Magnetic flux concentrators used to enhance the magnetic

field at the unshielded GMR resistors create this directional sensitivity of the sensor. The axis of

sensitivity is labeled for each sensor in Figure 1 (note that the axis is different for the two

sensors). Some magnetic field pattems (i.e., the diagonal patterns D and E in Figure 3 ) may be

more difficult to distinguish than others, so students should be encouraged to predict the

response of the GMR sensor to each of the five magnetic patterns shown in Figure 3 and find a

systematic way to examine the magnets.

Measuring the resistance of the individual sensor gives the students a direct

demonstration of the magnetoresistive properties of the sensor. At room temperature, the

resistance of the GMR sensor decreases in the presence of a magnetic field and a percentage

GMR of-10 % is calculated. The result is similar for liquid nitrogen (LN2), where the

percentage GMR is -14 %. The resistance with and without a magnetic field is much lower

when measured in LN2. This demonstrates metallic behavior; the resistance decreases as the

temperature decreases because of a reduction in the thermal motion of the atoms in the metal. 8

Visit http://mrsec.wisc.edu/EDETC/cineplex/GMR/to see videos of experiments I and II

as well as other demonstrations that can be performed with the GMR sensor.

References:

1. White, R.L, "Giant Magnetoresistance: A Primer." IEEE Transactions on Magnetics. 28,

2482 (1992).

2. Belleson, J.; Grochowski,E. "The era of giant magnetoresistive heads."

http://www.storage.ibm.com/hardsoft/diskdrdl/technolo/gmr/gmr.htm (1998).

3. Treutler, C.P.O. "Magnetic sensors for automotive applications." Sensors and Actuators. A91,

2 (2001).

186
4.Edelstein,R.L.;Tamanaha,C.R.;Sheehan,P.E.;Miller, M.M.; Baselt,D.R.;Whitman,L.J.;

Colton,R.J. "TheBARCbiosensorappliedto thedetectionof biologicalwarfareagents."

BiosensorsandBioelectronics.14, 805 (2000).

5. Campbell, D.J.; Olson, J.A.; Calderon, C.E.; Doolan, P.W.; Mengelt, E.A.; Ellis, A.B.;

Lisensky, G.C. "Chemistry with Refrigerator Magnets: From Modeling of Nanoscale

Characterization to Composite Fabrication." J. Chem. Educ. 76, 1205 (1999).

6. Levy, P.M.; Zhang, S. "Our current understanding of giant magnetoresistance in transitionmetal multilayers." J. Magn. Magn. Mater. 151, 315 (1995).

7. Campbell, D.J.; Lorenz, J.K.; Ellis, A.B.; Kuech, T.F.; Lisensky, G.C.; Whittingham, M.S.

"The Computer as a Materials Science Benchmark." J. Chem.Educ. 75, 297 (1998).

8. Ellis, A.B.; Geselbracht, M.J.; Johnson, B.J., Lisensky, G.C.; Robinson, W.R. Teaching

General Chemistry: A Materials Science Companion. American Chemical Society:

Washington, D.C., 1993; 198.

Acknowledgment:

We thank Kevin Jones and Tim Hazelton at NVE for technical assistance. We are grateful to the

National Science Foundation through the Materials Research Science and Engineering Center

(MRSEC) on Nanostructured Materials and Interfaces (DMR 0079983) for generous support of

this project.

187
(a)

(b)

(c)

Figure 1. (a) Individual GMR sensor (AA002-02) with pin #'s; (b) and (c) GMR sensor

(AG007-07) incorporated into a circuit designed to power a yellow LED.

188
(a) (b)

field lines

back (brown) side

---...d

front (printed) side

arrows indicate

field direction

Figure. 2. (a) Top view of the magnetic pattern of a common refrigerator magnet; and (b) a

cross-sectional perspective of the same magnet, showing the direction of magnetic field lines.

A B C D E

Figure 3. Possible refrigerator magnet Patterns. Note that pattern A is the one shown in Figure

2.

189
Vm (supply)

D B

Figure 4. The Wheatstone bridge configuration of a GMR sensor, where all of the resistors are

made of GMR multilayer materials. R2 and R3 are magnetically shielded.

(a) No magnetic field (b) Ha

Figure 5. (a) The ferromagnetic layers of the magnetic multilayer, shown as light grey layers,

are coupled antiparallel through the nonmagnetic spacer metal, shown as dark grey layers, in the

absence of a magnetic field. (b) When an external magnetic field (He) is applied, the

ferromagnetic layers reorient to form ferromagnetically coupled layers.

190
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INSTITUTE FOR CHEMICAL EDUCATION

Umversity of Wlsconsm-Madason

Department of Chemistry

1101 Madison, Umverslty W153706-1396 Avenue I Prices effective throughJtme 30, 2001 [

Phone 608/262-3033

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Morton Friedman

Columbia University

500 West 120th Street

Room 510 Mudd

New York, New York 10027

Telephone: 212-854-2986

e-mail friedman@columbia.edu

and

Eli Fromm

Director and P. I. Of Gateway Engineering

Education Coalition

fromm@drexel.edu

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Eli Fromm

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COMBINATORIAL APPROACH TO

MATERIALS DISCOVERY

Ichiro Takeuchi

Department of Materials and Nuclear Engineering and

Center for Superconductivity Research

University of Maryland

College Park, Maryland 20742

Telephone 301-405-6809

e-mail takeuchi@squid.umd.edu

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EXPERIMENTS IN ELECTRICALLY AND

MAGNETICALLY ACTIVE POLYMERS:

NOT JUST INSULATING PLASTICS

James V. Masi

Western New England College (emeritus)

242 Spurwink Avenue

Cape Elizabeth, Maine 04107

Telephone 207-767-3196

e-mail masij@hotmail.com

241
iiiiiii_ii%ii!iii

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James V. Masi

242
Experiments in Electrically and Magnetically Active

Polymers: Not Just Insulating Plastics

James V. Masi

Western New England College (emeritus)

Springfield, MA 01119

(207)767-3196, masij@hotmail.com

Abstract: The advent of organic materials for electroluminescent devices has allowed a wide

variety of applications in displays, communications, sensors, and the like. The demonstration of

organic naagnetie materials has offered the challenge of finding polymer (organic) materials in

which there ts sufficient electronic exchange as welt as stability in both thermally and

chemically. The intrmsicailv conductive and semiconductive polymers have allowed designers

the liberties of flexibility and conductivity to meet needs from batteries to solar cells. This paper

gives an overview of this search past, present, and future and the synthesis of promising new

complex polymer building blocks which can yield conductive, semiconductive, luminescent,

ferro-, ferri-, and super-paramagnetic materials for devices of the future in power, storage,

displays, and communications devices. The use of these materials to produce electrically active

polymeric materials has changed our way of thinking about how to fabricate devices with

properties heretofore unrealizable.

Key Words: Electrical Polymers, Magnetic Polymers, Luminescent Polymers, Molecular

Electronic Materials.

Prerequisite Knowledge: The student should be familiar with the basics of materials science,

metallography, and chemistry. Levels at which these experiments are performed are second

semester junior year and either semester senior year. The students are first given lectures the

properties of materials including polymers and magnetic, luminescent and conductive polvTneric

materials (as shown in the append/x). They should have already had a laboratory experiment on

metaiiography and sample preparation.

Objectives: The objectives of these experiments are to show how the unique properties of

polymers lend themselves to applications involving electrical, magnetic, and optical properties

and how they- are incorporated in a variety of devices. These experiments contain all of the

elements of good design, with the caveat that a novelty in structure is sometimes a part of design.

The students learn the process of designing materials for the world of device applications,

analyze those already used, and suggest possible solutions to the problems involved with present

technology.

Equipment and Supplies:

(1) Metallurgical preparation and polishing apparatus (e.g. Buehter Co., Port Washington, NY).

(2) Varieties of monomers (Roche Chemical Div.: Hoffmann-LaRoche Inc., Nutley, NJ; Baker

Chemical, U. of Utah Materials, Salt Lack City. National Starch (Beta Cyelodextrin).

243
(3) Low voltage d.c. and 60Hz power supply (EdaTatmd Scientific)

(4) Miscellaneous graduates, glassware, ovens (Fisher Scientific),

(5) Indium-tin oxide coated glass and plastic (Teckmt Corp., Cranford, N J)

(6) Miscellaneous meters and power supplies.

(7) Metallurgical microscope (Olympus, Zeiss, etc. ).

(8) Small photoresist spinner (Fisher Scientific).

Introduction

Molecular Magnetic Materials

When the early civilizations made the discovery that iron was indeed attracted to lodestone, the

era of magnetism and its devices and effects was launched. After that time, the earliest device

recorded was the compass, an invention of the Chinese. Since then, ferromagnetic (Fe, Ni, Co,

etc.), ferrimagnetic (e.g. F304), and paramagnetic materials have been used in technology

applications such as magnets, magnetic tapes and disks, magnetic resonance imaging contrast

enhancers, and magneto-optic memories, to name a few. Organic/molecular based materials,

with p or d orbital s aiding the magnetic properties, have been a source of scientific curiosity for

a number of years 1,2, but only recently have such materials become a reality 3"4'5.

This new class of magnetic materials is, for the most part, non-metallic, being made from simple

to complex organic molecules. Their structure earl be tmi- or bi-dimensional and need not have

the three-dimensional format necessary for conventional ferromagnetic, ferrimagnetic,

paramagnetic, and antiferromagnetic materials. These materials can be simply fabricated from a

variety of solvents at or near room temperature. These should not be confused with bimetallic

complexes such as those formed by pyrolisis or partial oxidation. 6 Other work postulated the

use of a new class of pi-biradicals called the non-Kekute polynuclear aromatics, shown in Figure

1 below. 3 The high spin nature of these systems should drive

-- _e_d

-,- - 44+

_4

B_J_d

Figure 1

Representation of pi-molecular structure of metaquinodimethane, the associated spins, and

an oligomer

244
ferromagneticcouplingm chargetransfercomplexes.This is bestservedby havingthecenters

covalentlybondedtogether,namely,apolymersystemmadeupof repeatingmolecularsegments

sharingthe frameworkof the high-spinsystems,quinodimethanesbasedon the benzene,

naphthalene, and biDhenyl nuclei.

Figure 2

Possible model for magnetic spin coupling

Figure 2 shows a possible model for magnetic spin coupling where spins align in orthogonal

orbitals in a small spatial region, l Figure 3 shows six possible configurations of parallel and

anti-parallel spins, along with canted ones for reference, to describe paramagnetic+

ferromagnetic, antiferromagnetic, Ferromagnetic canted ferromagnetic, and correlated spin glass

(disordered structure). A description of the materials is given in Appendix A.

II¢',, t\

\¢-- I Ix,

_Pamm.aan et.: _

Itltit

Antilermm_rlnetic

tl.ttt tI

tttttt

,-+,+,IL + f,+,l +

Fe n_+magm eti_

C_ntea Ferrema£1ne_+c | Correl_e_ Spin Gle_:_ I

Figure 3

Spin configuration directions for magnetic types

Experiment 1. Making and testing magnetic polymers

The work described here involves a formulation of a solution, the mechanism definition, and results

for this formulation. These materials are deposiled on a variety of surfaces from alumina to

modified ,4nyl. This meflaod enables the user to deposit a magnetic polymer on a v4de variety of

surfaces and topographies. These polymers retain the electrically insulating properties, while

exhibiting ferronmgnetic beha,40r.

Cyelodextrins, Cyclic oligosaccharides, were discovered approximately 100 years ago. In the

pharmaceutical industry , Cyclodextrins have mainly been used as complexing agents to

increase the aqueous solubility of poorly water-soluble drugs , and to increase their bio245
availablity and stability. Cyclodextrins are produced by a highly selective enzymatic synthesis

consisting of Six, Seven, or Eight glucose monomers averaged in a donut shaped ring, which are

denoted alpha, beta or gamma Cyclodextrin respectively. The specific coupling of the glucose

monomers gives the Cyclodextrin a rigid conical molecular structure with a hollow interior of a

specific volume. This internal cavity, which is hydrophobic in its nature, is a key structural

feature of the Cyctodextrins, providing the ability to complex and contain a variety of "guest"

molecules (e.g. aromatic, alcohol, halides and hydrogen halides, fatty acids and other esters,

ferromagnetic ions, etc ). The guests must satisfy the size criterion of fitting at least partially

into the Cyclodextrin internal cagily, resulting in an inclusion complex. The Empirical Formula

is (C6H1005)7 and is basically a carbohydrate. A graphic simulation of t3-cyclodex-trin is shown

in Figure 4.

Figure 4. Simulation of 13-cyclodextrin with central hole filled with ferromagnetic material.

[courtesy MOLCAD]

Table I shows the important parameters associated with the 13-cyclodextrin used in this work. As can

be seen, the size parameters fit very well with the size of the iron ion ( I. 17A).

Table I: Important molecular parameters of 13-Cyctodextrins (CD)

B-ell

glucose residues 7

moIecular weight 1135

cavity diameter (A) 6-6.6

cavity height (A) 7.9

cavity volume (ml/mol) 262

IL DISCUSSION

246
Procedure

A General

The _ of the process is to treat and polymerize a ferromagnetically modified

eyclodextrin polymer and cast it into solid shapes for use in high-speed magnetic devices (induetors,

transformers). This is done m aqueous solutions, with alcohol added as a dispersant.

B. Materials Needed

Substrates (alumina, printed circuit G-t0, modified, ceramic-filled vinyl, and glass), FeC13,

Beta Cyclodextrin, isopropyl alcohol.

C. The solution

The solution is prepared by mixing 1 mole of FeC13

With 1 mole of 13-cyclodextrin in an aqueous solution. By weight, the amounts are: 26.9 g

FeC13, 16.2 g 13-cyclodextrin, added to 50 g water. Alcohol is added, drop by drop, until the

solution becomes homogeneous in appearance.

D. Polymerization

The material is condensation polymerized by poumag onto the glass substrates and

heating to 85 C until a thick film of the material is formed. This material has a d.p. of about

5000 and is capable of being thermally compression molded into shapes at 150 C.

A electron photomicrograph of sample of the solution dried at 85 C onto a glass substrate is

shown in Figure 5_ The voids are due to shrinkage and lack of wetting. This morphology differs,

dependent on time at temperature.

Figure 5. 13-eyclodextrin:Fe condensation polymerized and baked at 85 C on glass. 1000x.

The properties of the films as measured at 250MHz at room temperature were:

Resistivity: >109 ohm-m

Permeability (N): 70-120

Loss tangent: <10 -3

Coils can be wotmd on the shapes fabricated and relative permeability can be deduced from the

inductance measured on a non magnetic core of the same dimensions.

Conclusions (magnetic)

247
This process offers many advantages over conventional polymerization me,hocks. The process is

smaple0 low-cost, and effective. The materials used are not toxic_ no special procedures need be

used, and multiple applications can be made with great accurac3 _.The surface need not be a plane.

Marking, drilling, and deposition can be done on a variety of substrate topologies. The polymer used

must be non-hydrated, in order to avoid loss in the material at high frequermies due to water. Further

studies.are being performed on other metal/substrate systems with other polymer systems as well.

Luminescent Polymers

Introduction

Electroluminescent devices are showing promise for applications in future flat panel displays.

Current flat panel display technology depends on inorganic light emitting diodes, backlit liquid

crystal displays, and vacuum fluorescent displays with field electron emission onto phosphors.

The problem for manufacturers lies in how to reduce the cost of illuminated displays, while

increasing their capacib' and efficiency. Organic/molecular films may hold the solution to this

problem.

Observation of light emission has been observed in various polymers and copolymers of arylene

vinylene, Potyphenylene vinylene (PPV) being the most efficient to date. However, a number of

conjugated homopolymers, copolymers, and polymer blends have been investigated. These

materials have light emission over the entire visible range. T043 Though imbalances in the

injection and carrier charge transport properties are. partially responsible tbr low efficiencies in

polymer light emitting devices, there is hope of overcoming these drawbacks with the use of

separate transport layers, electron withdrawing groups_ and electron accepting additives and

modifications. In addition to PPV, there are other materials which show promi_. These are:

poly (2,6-quinoline vinylene) (PQV)_ poly (phenylene vinylene-co-quinoline vinylene) (PPVQV),

poly(p-p-yridine) (PPP), poly(phenytene vinylene) (PPV)_ cyano-poly(phenylene vinylene)

(CNPPV), and poly(2,3-d]phenyl-5-hexyl-p-phenylene vinylene) (DP6-PPV). Two of these

compounds are shown in Figure 6. T4 A detailed description of electroluminescent polymeric

materials and structures is given in Appendix B.

PPV PPP

Figure 6. PPV and PPP

248
Experiment 2. Making and testing luminescent polymers

The experimental setup is shown in Figure 7. The transparent electrodes are the same as those

shown in the experiment on Liquid Crystals (NEW Update 2000). The layers are spun onto the

conductive glass using the solvents shown below. Electrodes may either be evaporated or

"'painted" on with conductive silver epoxy. Construction can also be of the SCALE variety as

shown in Figure B2 in Appendix B.

÷ etectmde

- electrode - electrode

ilHIlIIIlIIilillllIIll II ilL_

• _ _ - :_

Substr_tc

CN-PPV

PPV

Transparent

Coarser

Lighl output

Figure 7. Light emitting polymer diode construction

Violet: Oxydodecyl poly(paraphenylene) (DDO-PPP)

-x -Tt* absorption band maximum at 340 nm

-PL band in the violet; 0-0 transition at 400 nm

-Soluble in toluene or THF for processing

Green: unsubstituted Poly(paraphenylenevinylene) (PPV)

-re -rt * absorption band maximum at 400 nm

-PL band in the green; 0-0 transition at 520 nm

-Available as the precursor in aqueous solution for ease of processing

Red: Oxydodecylmethoxy-poly(paraphenylenevinylene) (DOO-PPV)

-_ -_ * absorption band maximum at 510 nm

-PL band in the red; 0-0 transition at 570 nm

-Soluble m toluene

249
The cyano-layer can be fashioned on any of these materials by adding potassium cyanide (1%

solution) to the monomer. The cure cycle is 110 C for 20 minutes.

Measurements of current vs. voltage can be made and tog I vs V can yield the activation energies

and effective bandgap of the materials.

Conductive Polymers

The conductive and semiconductive polymers have properties which allow device, cost, and

interconnection attributes not available with conventional inorganic materials [l 6]. It should be

noted that there are no polymers based on carbon backbones that are intrinsically conductive to

the extent of metallic or carbon/graphite loaded pol3qrters, These polymers are usually made

electrically conductive by adding either dectron donors or acceptors to the host polymer, either

by charge transfer complexes or dopant atoms (as in semiconductors) [17,18]. A comparison of

organic and inorganic materials is given in Figure 8.

Electrical Conductivities

tJ

T

0

c_

K,}

UI

_0  ̧-_.

(am_KI)

_ne_rl

Bol_n "

Water

t,_ine

Zinc oxide

Silica

10_

• 10o

.10-5

.10-_

,10-1s

Figure 8. Electrical conductivities compared

Though silver and copper are, in reality, an order of magnitude higher than polyacetylene, the

organic materials have certain electrical, electrochemical, and optical properties which make

their use preferred. Some of the methods for making polymers conductive are shown in Figure

9. The proposed model for charge transfer is called percolation and in shown schematically as

chain-like pathways for conduction.

250
P_ D_ P_rnV

Figure 9. Percolation through polymers causing conduction

A scanning electron mierograph of Wa_ns,po]y_ce_ylen_e i=sshown in_Figure !0 [!6;].. The ¢ho.inlike structure is quite _4sible in this photo and supports, at least visually, the model of conductive

pathways.

Figure 10. Scanning electron micrograph of trans-polyacetylene [t6]_

Some of the uses for _ese semiconductive and conductive po.lymers are: battery electrodes,

polymer electrolytes for batteries, solar cells, compatible contacts for light emitting polymers,

and high frequency window filters for microwaves, to name a few. Some of the conductive

pol)ariers presently in use are shown in Figure 11.

As newer materials are synthesized and new properties develop, applications will, as for most

new materials, finally find uses for these emerg/ng polymers.

251
S_iconduot_ng and MetalUc P_ly_

c__ _m_oh_¢e_e_

H t4

_wrr_e

$

0

po_yImo_"i_ic m',hyddde)

pol¥ (quinotirJet

Figure 11. Some conductive/semiconductive conjugated polymers

Polyaniline (PANi)

-Available as emeraldine hydroGhloride or as emeraldine base.

This material is easily spun onto a conductive glass sabstrate or an insulative substrate. The

graph of resistivity vs. brf should be made using either a 4-point probe or silver epoxy contacts.

By using an ITO substrate and silver epoxy on the rear of the sandwich, a photovoltaic cell can

be shown to give approximately 0.35 volts at 1 mA/10 sq. cm

Conclusions (General)

The future of magnetic materials using molecular/organic substances as their basis will be

dictated by the abitity of scientists to find new materials or modifiers which fbrce high, coupled

electron spin densities into t-, 2-, or 3-D network bonding using cooperative phenomena. The

potential for modifying the physical properties through conventional organic synthesis

techniques makes this class of materials very attractive to the magnetics community. The

polymer light emitting devices are well on their way to impacting the industry" as easily

produced, low cost devices, They have the present drawback of having lifetimes shorter than

those demanded by the telecommunications industries and the industry as a whole. The

conductive and semicondu_ve polymers have properties that allow device, cost,

electrochemical, electro-optic, electronic, and interconneetion attributes not available with

conventional inorganic materials. This may lead to their use in photomc, electronic, and

magnetic devices to make lower cost, high performance teMcommunications, electrical, and

electronic systems.

ACKNOWLEDGMENTS

252
It is important to recognize the efforts of pioneering researchers and the efforts that they

expended in bringing this science to the level mentioned in this overview. Drs. J. Miller and A.

Epstein of Ohio State University have taken polymeric formulations and turned them into

working devices° both magnetic and luminescent. Dr. A. Heeger of the University of Santa

Barbara and Dr. Ao McDiarmid of the University of Pennsylvania pioneered many of the early

conductive polymer efforts, especially the advances in polyacetylene and other electrically actwe

polka'hers. Dr. T. Skotheim has advanced the understanding of conjugated polymer structures

and allowed many other efforts to be published through his comprehensive treatise on

conducting polymers. For all of these and many, more whose eftbrts have made a substantial

difference, but are not mentioned here, we are forever grateful.

REFERENCES:

1. J. S. Miller and A. J. Epstein, J. Am, Chem,

Soc., 109, 3850 (1987).

2. J. M. Williams et aL, Acc. Chem. Res., 18, 261 (1985).

3. G. Allinson et al., J. Mat. Sct.: Mat'ls m

Etectr., 5, 67 (1994),

4. D. Gatteschi, Adv. Mat., 6, 635 (1994).

5. J. S. Miller and A. J. Epstein, ed. "Proceedings of the Conference on Molecule-Based

Magnets", Motec.Cryst:, Liq. Cryst., 271-274 (1995).

6. A. Lukasiewicz. et al., Mat. Lett:, 14, 127

(1992).

8. J. V. Masi and W. Thibault, New, High Frequency Transformer Topologies, in Proc. of the

EMCWA, IEEE Press, N.J., 1995, pp 157-162.

9. J. S. Miller and A. J, Epstein, C&EN, 30, Oct. 2,(1995).

10. J.H. Burroughs, et al., Nature 347,539 (1990)

11. I. Sokolik, et. at., J. Appl. Phys. 74,3584 (1993)

12. C. Zhang, et al., Synth. Met. 62,35 (1994).

13.R.K. Kasim, et al., Mat. Res. Soc. Syrup. Proc, 488, 51.-56 (1998).

14. A.J. Epstein, et al., Synth. Met. 78 (3), 253

(1996)

15. J.V. Masi, Novel Magnetic Materials for High Frequency Devices, in Proc. of the

EMCWA, IEEE Press, N.J., 2001 to be published.

16. Terje A. Skotheim, I-Icmdbook of Conducting Polymers, Marcel Dekker Publishers, 1986,

1992.

1Z J.R. Ellis and R.S. Schotland, _rvIarket OpporttaTitiesfor Electrically Conductive Polymeric

Systems, Princeton Polymer Laboratories Inc. and Schotland Business Research, Inc., Princeton,

NJ, 1981

18. A,G, MacDiarmid and A,J. Heeger, in Molecular Metals (WE Harfield, ed), Plenum Press°

NY, 1979.

Appendix A. New Magnetic Materials Design

Since standard stand-alone materials gave way to polymeric techniques, the possibilities of

cooperative phenomena became more feasible. Since magnetic materials are only useful below

253
their Curie temperature, this temperature should be above room temperature. To obtain these

higher Curie temperatures, one must induce some order (local disorder leads to random and

inconsistent interactions). In 1985, the first molecule based magnetic materials were reported.l'2

These materials were ionic salts (containing alternating donors and acceptors, of

tetracyanoethylene and tetraeyanoquinodimethane, TCNE and TCNQ in a "...DADA..."

configuration, producing high mtfltiplicity spin radicals. A ferromagnetic [FeCp*2] .+ [TCNE]--

forming chains of alternating donors (cations) and aeceptors (anions)can be modified from

ferromagnetic to metamagnetic by replacing TCNE with TCNQ or when [C3(CN)_]- is added

magnetic coupling is no longer effective. (Cp+ is pentamethyleyetopentadienide). A symbolic

representation is shown in Figure A1. 9

N

ve_ _c,tcmdFigure AI. TCNE and TCNQ salts with ...DADA,..

Up to i991, the Curie temperatures were low, only in the tens of degrees Kelvin. Though the

performance in magnetization in all forms of magnetic behavior degrade with Increasing

temperature, a few materials show promise for the future. 9 Some of these are shown in Figures

A2 and A3.

/_:_p t|lYalIld_llltqq I _ P_ORI

Figure A2. Magnetization vs applied magnetic field for some materials

_zat_orr a

Figure A3. Vanadium salt V(TCNE)x-y(CH2CI_) prepared from V(CO)_

254
As can be seen from the figures above, the magnetic behavior, magnetization, and temperature

profile vary greatly with host (TCNE, TCNQ, etc.), salt (vanadium, lrom cobalL nickel, etc.) and

precursor It may suggest that there Js a greater order than previously suspected, implying that 3-

D order might be more prevalent.

Some new- saccharides, in the class of cyclodextrins (called inclusion compounds) are showing

promise because of their ease of ion incorporation in the "nooks and crannies" of the molecule

[15].

Magnetic Testing

Impedance measurements, giving the relative permeability and dielectric constant as well, and

multi-port tests on the materials can be made on an 8700 series HP Ne_,ork analyzer as shown

in Figure 8. "Donuts" were 3 mm thick, made to fit in the coaxial air line.

Figure 8

Network Analyzer/Coaxia| Setup

High frequency measurements vary on these materials with the vanadium salts showing

permeabilities of 60 at room temperature at 100 MHz. More work needs to be performed on

these materials at high frequencies to determine what models are justified by these

measurements.

Appendix B. Electroluminescent Polymers

The polymers mentioned in the body of this paper have been used to fabricate conventional light

emitting diodes as shown in Figure B 1,

Figure B1. Conventional Diode Structure

255
New devices called system configured a.c. light emitting (SCALE devices are shown in Figure

B2.

Figure B2. SCALE Device

These devices show a wide range of emission wavelengths, dependent upon the composition, as

shown in Figure B3.

O.O [1.1 0.2 &3 [I.4 R5

Molar fr_ion of vin_ene units

PPP - PPV

FierceB3. Variationin ota_ ener0_ (color,wavelength)withc_mpo_on

Some of the advantages of polymer devices include flexibility, semi-transparency, full color

range, diffuse light, large area devices, robustness, low driving voltage, and tow power

consumption.

256
LOW-BUDGET EPITAXY: COPPER ON SILICON

John N. Kidder, Jr.

and

Luz Martinez-Miranda

Department of Materials Science and Engineering Science

University of Maryland

Building 090, Room 2142

College Park, Maryland 20742

Telephone: 301-405-0499

e-mail kidder@eng.umd.edu

Telephone: 301-405-0253

e-mail martinez@eng.umd.edu

257
John N. Kidder

Biography:

John N. Kidder is an Assistant Professor of Materials Science and Engineering at the

University of Maryland, College Park MD. He has A.B. degree from Occidental College

and a M.S. degree from the University of Vermont in Physics and a Ph.D. degree from

the University of Washington in Materials Science and Engineering. At Maryland he

teaches freshmen engineering and undergraduate courses in Microprocessing of Materials

and Electronic and Optical Properties of Materials. His research is in the area of thin film

growth and in-situ process diagnostics.

Luz Martinez-Miranda is an Associate Professor of Materials Science and Engineering at

the University of Maryland, College Park MD. She received B. S. and M. S. degrees in

Physics from the University of Puerto Rico at Rio Piedras and a Ph.D. degree in Physics

from the Massachusetts Institute of Technology. At Maryland Prof. Martinez-Miranda

teaches courses in freshmen engineering, undergraduate Materials Science and

Engineering laboratory, and the Solid State Physics for Materials undergraduates. Her

research is in the area of X-ray diffraction and nano-structured materials.

258
Low-BUDGET EPITAXY: COPPER ON SILICON

John N. Kidder, Jr. and Luz Martinez-Miranda

University of Maryland

Materials Science and Engineering

Key Words:

Thin films, epitaxy, deposition, surfaces, crystal structure, copper, silicon

Prerequisite Knowledge:

Crystal structure, X-ray diffraction, principles of vapor pressure, kinetic theory of gases,

evaporation.

Objective:

To become familiar with thin film deposition by thermal evaporation and the role

of interface energy in thin film formation. The objective is to introduce students to the

principles of thin film growth, generation of an atomic flux, deposition rate, surface

cleaning in silicon processing, surface structure and chemistry, interface energy and

epitaxy, and metallization in semiconductor technology.

Equipment and Materials:

Bell jar thermal evaporator; high purity copper wire; glass and plastic beakers; dilute I-IF

acid, acetone, methanol, deionized water; silicon wafer (001) orientation; scribe; steel and

plastic tweezers; scale; duster or clean dry compressed air; safety garments, X-ray

diffractometer.

Introduction:

This exercise combines a thin film deposition experiment with X-ray diffraction

measurements. This exercise is a good supplement to undergraduate laboratory course

that includes X-ray diffraction by providing a way for students to create their own

samples for analysis. In this experiment copper thin films are deposited on (001) oriented

silicon substrates with two different surface treatments. All of the samples are cleaned

using solvents and high purity water. Some of the substrates are also etched in dilute HF

acid solution immediately prior to the deposition, which removes the native oxide from

the surface and leaves a stable hydrogen-terminated silicon surface. Copper films are

then deposited on the etched and unetched silicon substrates to compare copper films

deposited on the amorphous native oxide and the crystalline surface. To prepare for the

exercise several questions are discussed: Why would a FCC metal film form in one

preferred orientation or texture? What orientation might be expected on an amorphous

surface? What orientation of copper might be expected on a crystalline silicon surface?

How are the Cu(001) planes and Si(001) geometrically similar? These questions can be

discussed in terms of low-energy planes in a crystal and the crystal structure of copper

(face-centered cubic, a=3.61 A) and silicon (diamond, a=5.43 A). The experiment

postulates that the HF etch creates a stable surface that promotes oriented growth with the

Cu(001) planes parallel to the Si(001) surface. (see figure 1)

259
Procedure:

Divide the silicon wafer into small pieces by using a diamond scribe to score the

unpolished side and apply pressure over the edge of a microscope slide. Clean the Si

substrates by soaking in acetone, methanol, and deionized water for approximately 60 sec

at each step and then blow-dry with clean dry gas. Prepare the HF etched samples by

dipping in 10-vol% HF aqueous for approximately 60 seconds. Use acid resistant (i.e.,

plastic) tweezers for this step and hold the sample by the edges. When removing the

silicon piece slowly pull it from the solution. The hydrogen terminated surface is

hydrophobic so the polished surface should be dry when pulled from the solution. Any

droplets on the surface indicate contamination or defects and these samples should not be

used. Remove residual liquid solution on the backside of the wafer and at the edges by

blowing dry. A lab tissue can be used to wick away liquid from the edges. The surface

will reoxidize after several minutes so deposition should be done immediately after the

I-IF etching step. The need for an exquisitely clean surface should be emphasized - a

lesson that reflects processing practices in the semiconductor industry.

To prepare for each deposition, wrap the copper wire on to the evaporation source

(e.g., tungsten filament). Place the samples at a fixed distance from the source (see

figure 2). We recommend placing a shutter between the source and the substrates during

the first few seconds of evaporation to block the flux of impurities emitted from the

surface of the metal source during initial heating. After loading the substrates pump the

system down to below 10.5 Torr. The procedure for pumping down the vacuum

evaporator will depend on what type of system is used. With a modest vacuum pump a

single deposition run can be accomplished within approximatelsy 15 minutes, allowing

several depositions per lab session. Once the system reaches 10- Torr or less, turn on

filament power and turn up current, and then immediately move the shutter to begin

deposition on to the substrate. After a fixed time, rotate the shutter back to the position

between substrate and filament. Turn off filament power, close pump valve, and back-fill

chamber to atmospheric pressure. Remove samples.

The lab can be run as a process line with different students responsible for each

step. The students doing the solvent clean need to use safety glasses, lab coats and

gloves, and the student doing the I-IF etching should also use a acid lab apron and a face

shield. The copper wire should be wiped clean with a solvent and handled with gloves to

minimize surface contaminants. If possible deposit on etched and unetched substrates

simultaneously to allow direct comparison.

X-ray diffraction measurements are required to observe the orientation of the

copper films. This is indicated by a variation in the relative intensity of the Cu(111) and

Cu(002) diffraction peaks. Figure 2 shows an example of 0-20 scans for etched and

unetched samples where a significant increase in the relative intensity of the Cu(002)

peak was observed.

Comments:

Microelectronic technology is largely based on electronic devices fabricated from

layered and patterned thin films. The process for fabric_ition a micro-device from thin

films involves three primary steps: Deposition of a film, lithography for pattern

260
formation, and etching to remove material and form the selectedpattern. This

experimentaimsto usesimpledepositionequipment- a belljar thermalevaporator- to

demonstrateand study vapor-phasethin film epitaxy using technologicallyrelevant

materials.Thisexerciseis agoodintroductionto thin filmprocessingandcanserveasa

prerequisitefor a moreextensivethinfilm processinglab. Theexperimentwasadapted

from anarticleby Longiaruet al.[1] which is an excellent reference for the exercise. In

that article they used a sputtering system but we have found this experiment can also be

done using a thermal evaporator. Bell jar evaporators are generally less expensive and

more available on college campuses, and can easily be operated by undergraduate

students. We adapted a thermal evaporator system used for coating electron microscopy

samples for the deposition exercises.

It may be beneficial to process films of different thickness. This can be done in

two different ways. If it is assumed that the evaporation rate is relatively constant over

that period of time, then for fixed filament power the shutter can be opened for different

periods of time (5, 10, 20 seconds). Another method is to use different weights of wire

and leave the filament on and the shutter open for an extended time (-60 s) to completely

evaporate the piece of wire. In this case the thickness can be roughly estimated using the

mass of the wire, the distance between the source and the substrate, and the density of the

deposited material using the expression:

Film Thickness - Mcu _re [cm]

Pc. (4rcr =)

In this expression, Mc, _,ireis the mass of the wire [grams], r is the distance between the

source and the substrate [cm], and pc, is the density of copper (8.94 g/cm3). This

expression assumes certain assumptions such as that the substrate surface is facing

normal the source (see figure 2) and that and the dimensions of the filament are much

smaller than the distance between the source and the substrate (i.e., it acts as a point

source). The actual thickness may be offset due to the shuttering at the start of the

evaporation, but this expression can be used to generally predict the maximum thickness

and to estimate what mass of wire is needed. A typical range of thickness for this

experiment is 10 - 250 rim.

In summary, the experiment combines a thin film deposition experiment with X-ray

diffraction measurements. This exercise provides excellent hands-on activity to teach

several important topics including, kinetic theory of gases, atomic flux, film deposition,

vacuum science, surface structure and chemistry, and semiconductor processing

practices. It is an excellent module for an undergraduate materials processing laboratory,

and provides a way for students to create their own thin film samples for characterization

experiments (X-ray diffractometry). The experiment can also serve as a platform for labbased lessons in vacuum science, lift-off lithography for circuit fabrication, and

experiments that study process property effects (electrical characterization, roughness).

In future work we hope to develop complementary exercises that involve other deposition

techniques. For example copper can be deposited by simple thermal CVD using

261
Cu(II)2,4-pemanedionate(Cu acac)as a precursor,which is easy-tohandle(not air

sensitive) and non-toxic.[2] Sol-gel spin coating is another straightforward and relatively

low cost approach for depositing thin films which would be appropriate for

undergraduate materials science and engineering laboratory curriculum.

References

[1] "Epitaxy above 10.5 Torr: A Students Introduction to Thin Film Growth and

Characterization" Minsu Longiaru, E.T. Krastev, R.G. Tobin, J. ofVac. Sci. and Technol.

A 14(5) 2875 (1996)

[2] "Materials Synthesis, Processing and Characterization Laboratory Course", Carmela

Amato-Wierda, Univerity of New Hampshire, poster presented at Gordon Conference on

Innovations in College Teaching of Materials Science, Plymouth N.H., July 1998

General references on thermal evaporation

Milton Ohring, "The Materials Science of Thin Films" (Academic Press, San Diego, CA,

1992)

Donald L. Smith, "Thin-Film Deposition: Principles and Practice" (Mcgraw-Hill, New

York, 1995)

262
5.43

Cu(OO]) si(ooo

Figure 1 Atomic arrangements in the (001)

planes of silicon and copper.

shutter

filament

.........._N

"L

Figure 2 Schematic of the filament source,

shutter, and substrate stage in the thermal

evaporator for copper film deposition.

.m

ee--

e-

"- (111)

40

• I •

45

I " I ' I " I ' I ' I ' I

50 55 60 65 70 75 80

2th (deg)

Figure 3 X-ray diffraction data for copper films on (001)Si substrates. Sample (a) was the

unetched substrate and sample (b) was the etched substrate. The copper film deposited on the

etched silicon shows a stronger (001) orientation.

263
264
MAGNETOIMPEDANCE: A USEFUL

PHENOMENON FOR MAGNETIC,

ELECTRIC AND STRESS SENSORS

Raul Valenzuela

Institute for Materials Research

National University of Mexico

P. O. Box 70-360

Mexico 04510

Telephone: 525-622-4653

e-mail monj aras@servidor.unam.mx

265
Raul Valenzuela

266
Magnetoimpedance: a Useful Phenomenon for Magnetic,

Electric and Stress Sensors

R. Valenzuela

Institute for Materials Research, National University of Mexico, Mexico, p.o. Box 70-360,

Mexico D.F. E-malh lnonjaras@servidor.unam.mx

Key Words: electromagnetism, magnetic domains and magnetic domain walls, magnetic

permeability, skin depth effect.

Prerequisite Knowledge: basic knowledge on atomic structure including spin moment,

basic magnetic properties of ferromagnetism.

Objective: to understand a basic electromagnetic phenomenon involving the magnetic

structure of ferromagnetic materials.

Equipment:

1. A magnetically soft ferromagnetic wire or ribbon

2. A permanent magnet (barium ferrite or metallic, NdFeB type), or a solenoid (250

turns) powered by a DC source

3. A signal generator (100 kHz- 10 MHz frequency range, 1 mA RMS current

amplitude)

4. A measuring instrument such as a voltmeter, an oscilloscope, or an impedance

analyzer

5. A standard resistor (10-50 f_)

Introduction:

When a conducting ferromagnetic material (best results have been obtained with

amorphous wires and ribbons in the CoFeBSi system) is subjected to an AC current of

small amplitude (less than 10 mA RMS to avoid any heating of the sample), it shows an

impedance larger than the value corresponding solely to its DC resistance. If a DC

magnetic field is applied, the impedance decreases to a value very close to the DC

conditions. The impedance change increases as the current frequency increases, and is quite

sensitive to the DC magnetic field. This phenomenon is known as Giant Magnetoimpedance (GMI) and has attracted much interest due both to its technological applications

in magnetic field sensors, and to its basic electromagnetic nature.

267
Procedure:

a) Connect in series both the resistor and the ferromagnetic material to the signal

generator (Fig. 1). The purpose of the resistor is to limit the current flowing through

the sample, which is in short circuit since it is a good conductor

b) Connect the measuring device (voltmeter) to the sample ends

e) {Ifa solenoid is available, put the sample inside the solenoid}

d) Establish a small current on the system (for most ferromagnetic materials, a 10 V

drop at 1 MHz is obtained when the current amplitude is in the mA range)

e) Observe the voltage drop when the permanent magnet is far away from the sample

(say, more than 1 m)

f) Place the permanent magnet very close to the sample (it is more efficient if the

magnetic field produced by the permanent magnet is parallel to the axis of the

sample) and observe the voltage drop

g) Move the permanent magnet with respect to the sample, increasing the distance

between them (thus decreasing the magnetic field on the sample); make a plot of

voltage as a function of distance

h) If the system includes the solenoid, carry out measurements at different levels of

DC magnetic field, and plot the voltage as a function of the field

Comments:

The results should show a decrease in the voltage drop in the sample as the DC

magnetic field increases, as shown in Fig. 2 (i.e., the permanent magnet is approached to

the sample), which means that the impedance of the sample decreases under the effects of

the DC magnetic field. This effect, known as magnetoimpedance (or giant magnetoimpedance, GMI) is quite sensitive as compared with giant magnetoresistance (GMR),

since in the former, a few oersteds lead to changes as large as 50% in the impedance value,

while GMR needs at least a few tens or hundreds of oersteds to show such resistance

changes. In fact, as can be seen in Fig. 2, GMI plot shows that the maximum in impedance

appears for a non-zero DC magnetic field, which compensates for the earth's magnetic

field.

Impedance:

While resistances are used to measure the effects of an element in a DC electric

circuit, impedances are used to measure the changes produced by an element in an electric

circuit subjected to an AC current. Impedance, Z, is formed by a real part, Z' and an

imaginary part, Z" and is a vector:

z = z' +jr' (1)

where j is the basis of imaginary numbers, j = "4-1. For calculations, the total impedance is

used, and is calculated as :

Ztot= [(Z')2+ (2") 2]i/z (2)

268
In anAC circuit,thepresenceof a resistor leads to changes in the current amplitude as

shown in Fig. 3, while elements such as capacitors and inductors produce changes not only

on current amplitude, but also on the current phase, Fig. 3. The relationship between

voltage, V, and current phasors,/, is similar to the DC expressions, except that total

impedance is used instead resistance:

I = V Ztot (3)

The variations in Ztot therefore produce proportional variations in voltage (assuming that the

current amplitude is constant):

V= Ztot I (4)

Magnetic Structure:

Ferromagnetic materials are solids formed by atoms that possess a magnetic

moment mainly from non-paired electronic spins. Most of them have transition metals as

iron, nickel and cobalt, which have an incomplete 3d orbital where the electronic spins are

oriented in the same direction. In addition to these magnetic moments, there is an

interaction (known as the "exchange" interaction) that favors a parallel arrangement of

spins of neighboring atoms, see Fig. 4. For antiferromagnetic materials, the arrangement

with the lowest energy is the antiparallel order.

The existence of such a parallel ordering (leading to a high magnetization state) in a

given sample should lead to high magnetic flux around all ferromagnetic materials. We

know that it is not the case, as far as many metallic objects with a high content of iron do

not show any attraction or repulsion forces between them. The explanation for this is that

the generation of a strong magnetic field outside the material needs high energy. The total

energy is decreased by changing the magnetization direction toward the opposite direction

in half the sample. Magnetic "domains" are thus formed; by combining several directions,

"closure" domains are also created to maintain all the magnetic flux inside the sample, as

shown in Fig. 5. Since the magnetization direction in domains oppose each other, the total

magnetization is zero. Magnetic domains are separated by domain "walls", where the spins

of neighboring atoms rotate from the direction of a domain toward the direction of the next

domain, Fig. 6. In the ease of materials such as pure iron, the 180 ° angle between opposing

domains is distributed among some 100-300 atoms [1].

In the case of permanent magnets, a non-equilibrium condition is produced to

maintain more domains with a magnetization in a particular direction than in others, and

therefore to have a stable magnetix flux outside the sample.

When a magnetic field is applied to a ferromagnetic material, it is magnetized by

means of different magnetization processes. For example, the external field can produce a

rotation of all the spins in the sample toward the magnetic field direction. In another

process, the applied field can lead to domain wall movements favoring the increase in

volume of domains with the same direction than the field, at the expense of domains with a

direction opposing the field. If the applied field is strong enough, both the domain wall

movements and the spin rotation processes can lead to the elimination of walls and the total

ordering of spins in the field direction. The sample is then "saturated", as in Fig. 4.

269
In soft ferromagnetic materials, the response to magnetic fields is very sensitive;

domain walls are easily displaced leading to large changes in magnetized volumes, and

hence to large variations in global magnetization. These changes can be measured by the

permeability, _t, which is defined as the ratio between the induction, B, and the applied

field, H. Permeability units are different in the two main unit systems, c.g.s, and SI;

however, the value of absolute permeability normalized by the value of vacuum

permeability, _, is the same in both systems, and this "relative permeability", _tr, is the

most used parameter:

_t_= B / (H _) (5)

Domain wall movements are quite fast and therefore they are able to follow applied fields

of varying frequencies. However, for field frequencies above ~500 kHz, domain walls are

too slow to be able to follow the field, and they show a relaxation. To understand this

relaxation processes, it can be recalled that in all dynamic processes several terms

contribute, as is generally expressed by a motion equation:

mdZx/dt + f3dx/dt + t_c = F(t) (6)

with an inertia term (related to the mass of the system), md2x/dt, a damping term

(associated with the dissipation processes), _dx/dt, a restoring term (tending to taking the

system back to the initial condition), ax, all driven by a force with a given dependence on

time. A resonance is observed when the inertia term (the mass) is comparable to the

damping and the system possess a natural vibration frequency, fs. As the excitation

frequency approachesfs, the vibration amplitude (x) increases, reaches a peak, and drops

down to negative values, before going back to zero as frequency increases further. In

contrast, when the damping term is significantly larger than the inertia term, the system

simply decreases the vibration amplitude as the excitation frequency increases over the

relaxation frequency, fx. In most soft ferromagnetic materials, domain walls have exhibited

a relaxation character.

For field frequencies above any of these two values, only spin rotation is fast enough to

follow the excitation field.

Skin Effect:

When a ferromagnetic conductor is submitted to an AC magnetic field, the strong

variations in magnetic flux inside the material give rise to electric currents due to the

Faraday's law of electromagnetic induction:

emfoc dd_/ dt (7)

Where emfis the electromagnetic force generated by the rate of change in magnetic flux,

d_ / dt. In turn, the electric currents generated produce magnetic fields that are oriented

against the applied field. The global result is that there exists an opposition to the

penetration of the AC field into the material, which can then be limited to a small surface

270
fraction or "skin depth" 8. The skin depth depends on the frequency of the applied field,f

the magnetic permeability, g_, and the resistivity of the conductor, p:

8 = 1/[2= (l&f/P )v2] (8)

The skin effect provides an explanation for the gant magnetoimpedance phenomenon, as

follows. When a ferromagnetic conductor is submitted to an AC current of high frequency

(say above 1 MHz) there are at least two sources of impedance in addition to the DC

resistance: the coupling &the AC magnetic field (generated by the AC current) to the

ferromagnetic domain structure, and the opposition of the material to the penetration of the

AC magnetic field (due to the skin effect). If a saturating DC magnetic field is applied, the

domain walls are eliminated and the spins are oriented into the DC field direction, leading

to a strong decrease in permeability. In agreement with Eq. (7), this results in an increase in

skin depth, and therefore, a decrease in the impedance response.

Applications:

There are many technological applications of GMI, as far as this phenomenon

provides a sensitive relationship between DC magnetic fields an impedance response. The

most obvious is the fabrication of magnetic field sensors, which can be made as quite small

(miniature) devices [2]. An interesting application is a device to detect and control moving

vehicles [3]. Since DC magnetic fields can be obtained in a controlled way from coils

powered by DC currents, it is also possible to provide miniature DC current sensors [4].

Also, since the magnetization processes are affected by mechanical stresses through

magnetostriction, the deformation of the ferromagnetic material leads to differences in the

impedance response, and a correlation between impedance and deformation has been

found. GMI can also be applied in tensile, compression and torsion sensors.

References:

[1] C. Kittel. Introduction to SolidState Physics. Wiley, N.Y., 1995.

[2] M. V_izquez, M. Knobel, M.L. S6nchez, R. Valenzuela and A.P. Zhukov. Sensors &

Actuators A59 (1997) 20

[3] R. Valenzuela, M. Knobel, M. Vhzquez and A. Hemando. J. Appl. Phys. 79 (1996)

6549.

[4] R. Valenzuela, J.J. Freijo, A. Saleedo, M. V_xluez and A. Hernando. J.. AppL Phys. 81

(1996) 4301.

271
signal generator

permanent

maqnet

resistor

voltmeter

Fig. 1. Layout of the equipment required for the experiment.

272
0.25

0.20

0.15

0.05

0.00

iO

J

8 0

J i

8 o.

I t I _ I

-4 -2 0 2 4

Halo (Oe)

Fig. 2. Typical results obtained with as-cast, amorphous CoFeBSi wires, at a frequency of

10 kHz and a current amplitude of 1 mA (RMS). The maximum is not found at Hdc = 0

because of the earth's field, which has to be compensated.

273
/ \j/ _,,\, ,

signal

/ \,, / with no element

/ "-,,,...i

_ /f_k /_ i f_'_ effect of o resistor'

"o....................... _ ......... '__,J ............... \_ y ............ _ "(_h_n9_in_mhii*ud__o"

(change in amplitude

and phase)

[] [] []

Fig. 3. Schematic comparison of effects on amplitude and phase of resistors and inductors,

to help explain the notion of "impedance".

274
atoms with magnetic

moments

saturated sample

domains and domain walls

Fig. 4. Simplified explanation for the appearance of magnetic domains and domain walls

in ferromagnetic materials.

275
276
CHARACTERIZING ALLOY MICROSTRUCTURES

FOR SEMI-SOLID FORMING

Robert B. Pond, Jr.

Department of Electrical Engineering and Engineering Science

Loyola College in Maryland

4501 Charles Street

Baltimore, Maryland 21210-2699

Telephone: 410-617-5563

e-mail Rpond@Loyola.edu

and

Scott N. Hornung

Lucent Technologies

Baltimore, Maryland

277
Robert B. Pond, Jr.

Biography:

Robert B. Pond, Jr. is Chair of the Electrical Engineering and Engineering Science Department at

Loyola College in Maryland. He has a bachelor's degree in Engineering Mechanics from Johns

Hopkins University in Baltimore, Maryland and a Master's and Doctorate of Engineering in

Metallurgical Engineering and Materials Science from the University of Pennsylvania in

Philadelphia, Pennsylvania.

Scott N. Hornung developed this data as a part of his senior design project at Loyola College in

MD. He received a Bachelor's Degree in Engineering Science and he is employed by Lucent

Technologies in Maryland.

278
Characterizing Alloy Microstructures for Semi-Solid

Forming

Robert B. Pond, Jr

Electrical Engineering and Engineering Science Department

Loyola College in Maryland

Baltimore, MD

Scott N. Hornung

Lucent Technologies

Baltimore, MD

Kev Words: Microstructures, Image Processing, Quantitative Metallography, Casting, Semisolid Forming.

Prerequisite Knowledge: Basic knowledge of materials science, phase diagrams, the

relationships between microstructures and phase diagrams, fundamentals of heat treatment, and

competence in metallo graphic specimen preparation and metallography.

Objective: To tmderstand the three-dimensional aspects ofmicrostructure, the relationships

between phase diagrams and microstrucmres mad the metallurgy of semi-solid forming for

commercial applications.

Equipment:

1. Alloy A357.0 prepared for semi-solid forming (1)

2. Small muffle furnace

3. Microhardness machine

4. Metallographic equipment and film or digital camera

5. Compmer, scanner (for film records) and NIH Image software

Introduction:

Properties of alloys are dependent on microstructure. The three dimensional

characterization of microstructure, although important is not often developed in a laboratory

course, because the acquisition and processing of data is usually time consuming and expensive.

However, three-dimensional microstructure characterizations can be easily made within the

scope of a senior engineering project.

In this case a commercial semi-solid forming altmfinum- 7.0 silicon- 0.5 magnesium

alloy was used (A357.0) (Figure One (2)). This alloy was of interest because the thixotropic

properties of the alloy when heat-treated in the liquid plus solid phase field are dependent on the

size, shape, fraction solids, and interconnections between the primary phase particles.

279
Thislaboratoryexerciseprovidesaneasymethodto examinethree-dimensional

microstructuresandspecificallyto measureandcharacterizethemicrostructuresof an

aluminum-silicon-magnesiumhypoeutecticalloyusedfor commercialsemi-solidforming.

1. A specimenisheattreatedandpreparedfor metallography.

2. Thespecimensurfaceisindexedwith threemicrohardnessindentationsandsuccessively

polishedandetched.

3. Themicrostructuraldatais digitizedandanalyzedusingNIH Image(3) software to present

and measure the nature of the microstructure.

Procedure:

The laboratory exercise is augmented by the use of the free software, NIH Image, which

originally was established and is used extensively for characterizing microbiological systems.

This software works as well for evaluating alloy microstructures.

1. The student cut a specimen from aluminum alloy stock (A357.0) for thermal treatment.

2. The specimen was heated to 590 ° C for 20 minutes to simulate the commercial heat treatment

prior to forming and then quenched in water to capture the high temperature primary phase

distribution.

3. A mount of the specimen was metallographically prepared after the thermal treatment.

4. The mount was indexed with three neighboring microhardness indentations. These

indentations provided a means to locate, orient and take sequential micrographs of the same

region.

5. Micrographs were made of the indented area after each micropolishing step.

6. The micrographs were identified, digitized and stored.

7. The computer images were processed, analyzed and displayed using the NIH Image software.

Microstructural features were used to register the successive slices through the

microstructure.

8. The fraction solids of the primary phase, their sizes, shapes and the interconnected nature of

the structure are apparent and accessible for microstructural measurements.

Comments:

The shaping of aluminum alloys heated to a two-phase, liquid plus solid condition is

facilitated when the primary alpha phase is rounded mad interconnected (4). This microstructural

condition allows for the handling of heated blanks of material as a solid. Under shear loads the

interconnections between the solid alpha particles break and the material becomes a slurry,

allowing low temperature forming in casting dies.

The rendering of a three dimensional microstructure for visualization and quantification

is easily and inexpensively done in a metallographic laboratory using the free imaging software.

The successive polishing steps included one-minute of polishing on a wheel using 5 gm alumina

powder fotlowed by a minute each with 1 btm and 0.05 btm gamma-alumina powders. The

etchant, a 1% aqueous solution of hydrofluoric acid was applied for 30 seconds with a swab.

280
Themicrographsweretakenat 100XmagnificationandwererecordedonPolaroidfilm.

Theprintsweredigitizedat aresolutionof 150dpi usingaflat bedscanner.

A singlemicrographfromaseriesis seenin FigureTwoalongwith analyticalresultsfor

thefractionsolidsmadeusingtheNIH Imagesoftware.A montageof partof themicrostructure

is seenin FigureThreeA dynanaicpresentationwasmadeof thesequenceof datafilesin the

formof amovie.

Thesequentialmicrostructuresarelocatedandorientedusingthreemicrohardness

indentations.Theloadusedwas500gf usingaVickersindenter.Thechangein sizeof the

indentationsafterpolishingprovidesameansto measurethedepthof materialremovalfor each

polishingstep.Twoapplicationsof polishingeradicatedtheindentationsandnewindentations

wereplaceddirectlyontopof oldones.

Thestudentwasableto measurethefractionof primarysolidof thealloyin thehigh

temperatureconditionanddemonstratetheinterconnectedstructureof theprimaryphase,which

explainsthethixotropicbehaviorof thealloy.Thestudentalsoexperiencedtheuseof the

laboratoryandsoftwaretoolswhilegaininganappreciationforthethreedimensionalaspectsof

analloymicrostrucmre.

NIH ImagesoftwareoriginallywasavailableonlyfortheMacintoshOperatingsystem.A

Macintoshcomputerneedsto haveanoperatingsystemof 7.0orhigherandavailableatleast16

MB of RAM torunthesoftware.Thesoftwareacceptsimagesin theformof TIFF,PICT,PICS,

andQuickTimefiles.NIH Imageprovidesanalyticalcapabilityfor measuringareas,averages,

centroids,andperimeterlengthsof userdefinedregionsof interest.Thesoftwarealsoperforms

automatedparticleanalysisandprovidestoolsfor measuringpathlengthsandangles.The

programiseasyto useandthedocumentationisveryuseful.All theanalysiswasperformedona

MacintoshG3computerusingtheNIH Imageprogram,developedattheU.S.NationalInstitutes

of HealthandavailableontheInternet

Thereis anewprogramfor Windowsoperatingsystemsthatiscurrentlyavailablefrom

ScionCorporation(5).ThiscompanymadeNIH ImageandnowhasdevelopedaWindows

equivalent,whichisalsofree.

Weanticipatetheuseof otheralloysystemsforlaboratorydemonstrationsof the

influenceof manyvariablesonthemlcrostructuresof alloysystems.Theeffectof heattreatment

of steelsonmicrostructure,theexaminationof differenteutecticmorphologies,the

characterizationof intermetallicsandof porosityandotherdiscontinuities,includingpitting

profilesmaybemadewiththistechnique.Measurementsof compositematerialmicrostructure

andgrainshapesareadditionalareasof interestfor thislaboratoryexercise.

281
References:

(1) Aluminum and Aluminum Alloys, 1993, ASM International, Materials Park, Ohio, pg. 720.

(2) Binary Alloy Phase Diagrams, 1996, Second Edition, CD-ROM Version 1.0, ASM

International, Materials Park, Ohio.

(3) NIHImage software fi'om U. S. National Institute of Health at http://rsb.info.nih.gov/nihimage.

(4) Merton C. Flemings, "Behavior of Metal Alloys in the Semisolid State", 1990 Edward

Campbell Memorial Lecture, 1991, Metallurgical Transactions B, Vol. 22B, June, pp. 269-

293.

(5) Scion Image for Windows from Scion Corporation at www.Scioncorp.com.

282
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500 _

ALomic Per'cent SHicon

io so 3o 40 so so 7o so 9o 1oo

1414°C

300

Al

zo 30 4o _o 60 70 eo oo loo

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Figure One. The binary A1-Si diagram (2) showing silicon composition

(7%) and the semi-solid heat treatment temperature of 590°C.

283
Figure Two. A single microstructural slice.

The fraction liquid (eutectic area) is 22.1%.

The three Vickers indentations were used to

locate and orient the specimen for metaUography.

The three circular registry marks were added later

to spatially coordinate the successive data sets.

284
FigureThree.A montageof alocalareaof microstructure.

Interconnecting points between primary aluminum particles

and re-entrants of eutectic as a source of occluded liquid in

alpha are seen.

285
286
P4 PREFORMING TECHNOLOGY:

PROCESS DE_LOPMENT UTILIZING

CARBON FIBER ROVINGS

Norman G. Chavka

and

Jeffrey S. Dahl

Senior Technical Specialist

Ford Research Lab

SRL MD3135

2101 Village Road

Dearborn, Michigan 48124

Telephone: 313- 322- 7814

e-mail nchavka@ford, com

Telephone: 313-322-7814

e-mail jdahl@ford.com

287
Jeffrey S. Dahl

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THE MAGSET K-12 CURRICULUM PROJECT

Don L. Evans

Director, Center for Research on Education

in Science, Math, Engineering, and Technology

Arizona State University

Tempe, Arizona 85287-5006

Telephone: 480-965-5350

e-mail devans@asu.edu

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LECTURE ACTIVITY WORK KITS FOR

INTRODUCTORY MATERIALS

ENGINEERING CLASSES

Stephen Krause

and

Shahriar Anwar

Arizona State University

1171 N. Tercera Court

Chandler, Arizona 85226

e-mail skrause@asu.edu

Telephone: 480-965-5696

e-mail anwar@asu.edu

325
_ii_iiiiiii

Shahriar Anwar

326
Lecture Activity Work Kits for

Introductory Materials Engineering Classes

Stephen Krause* and Shahriar Anwar

Department of Chemical and Materials Engineering

Arizona State University

Tempe, AZ 85287

Abstract: This paper describes a series of hands-on activities that use student-centered

learning for a diverse group of engineering students enrolled in larger sections of an

engineering core class, "Structure and Properties of Materials". The "Lecture Activity

Work Kits" supplement knowledge development from the more traditional teachercentered blackboard lectures. The "Lecture Activity Work Kits" involve short, l0 to 20

minute, team-based classroom activities, which relate directly to the topical material in the

course at that time. Typical activities include manipulations of crystal structure models,

polymer deformation, and examination or metal, polymer, and ceramic samples. Results of

the activities are being tied to assessment of course objectives and outcomes through

student surveys, quizzes, and tests. An initial assessment of activities by students has been

quite positive. Results and techniques are being disseminated to other course faculty.

There is good progress toward improvements in student interest, participation, and

comprehension in the learning process.

Key Words: Lecture activity work kits, student-centered learning, hands-on activities.

Prerequisite Knowledge: Freshman physics.

Objectives: To involve the students in team based activities to supplement lecture material

topics such as crystal structures, crystal defects, polymers and their deformation, and

classification of materials. In particular, learn to classify materials according to their

electrical, mechanical, thermal & optical properties; learn crystal directions and Miller

indices; identify crystalline defects of vacancies, dislocations, and grain boundaries in 2-D

models; understand principle of condensation polymerization.

Equipment and Materials: 1. Materials "grab bag' consisting of some everyday material

for less than $1 each. 2. Crystal geometry kit consisting of Styrofoam balls held together

with glue or toothpicks, for about $0.50 per model. 3. Crystal structure kit from K_linger

Educational Products (1-800 522-6252 www.klinger-educational.com/), for about $20

each. 4. Crystal Defects Kit assembled with CD ROM jewel case and BBs for about $1

each. 5. Silly putty polymerization kit consisting of Elmer's glue and Borax solution for

about $0.25 each. 6. Metals cold working kit consisting of as-received and annealed

*Contacting author: skrause@asu.edu (480) 965-2050

327
copper wires available from local hardware stores for a negligible amount per kit.

7. Condensation polymerization kit assembled from ball-and-stick models for about $60

per kit. Models are available from Indigo Instruments ( 1-877-746-4764 www.indigo.com)

Introduction

A wide variety of approaches are used today to communicate subject matter in materials

engineering and other technical courses. Although the majority of classes taught in the

Materials Engineering Program at Arizona State University rely upon the traditional

blackboard lecture method, this approach can be supplemented by methods that increase

the involvement of students during the lecture. These methods, which are not unique and

are being used to varying extents at other institutions, include classroom demonstrations

and individual or team-based exercises and experiments. A variation of these methods that

can be used is "Lecture Activity Work Kits". These economical kits have been created for

classes of 60 to 70 students with 20 to 25 teams of 3 to 4 students each. Student

involvement and satisfaction has been measured with surveys and student comprehension

will be measured with test and quiz scores.

The Lecture Activity Work Kit Method

"Lecture Activity Work Kits" are being developed and used for inquiry-based learning in

order to promote a deeper understanding of the course material by shifting knowledge

development from teacher-centered to student-centered learning. This is being achieved by

developing team-based activities that provide direct, hands-on activities that are directly

linked to the course content in structure, processing, and properties of materials (metals,

polymers, ceramics).

A set of a more than a dozen different "Lecture Activity Work Kits" were developed for

an engineering core class, "Structure and Properties of Materials". In the five sections of

this yearly course there are over 200 students enrolled from Bio, Mechanical, Aerospace,

Industrial, and Materials Engineering. The course teaches critical prerequisite content for

disciplinary courses in manufacturing, design, and advanced material classes. Thus, an

enhancement of the understanding of the material presented in this class will have a

positive impact on a variety of subsequent classes in each student's discipline. The kits

were created by two undergraduate students with a small grant from the university's

Center for Research on Education Science, Math, Engineering, and Technology

(CRESMET). Some examples of the activities will now be described.

The Kits

The ftrst kit was a "Materials Grab Bag" (Figure 1), which consisted of real-world

examples of metals, ceramics, and polymers. The objects in a plastic "baggie" were sets

of: cermrfic tile, marble, and chalk; metal coin, large-gage wire, and rock-climbing hook;

and polymer inner tube sample, clear fork, polyethylene dropper, and rubber band. The

student teams were asked to organize the samples into families and then specify what

physical properties were used to develop the classification system. After some time

328
students began to realize differences in behavior of different families of materials based on

thermal, mechanical, electrical and optical properties. The knowledge acquired provided a

lead into upcoming material on atomic bonding (metallic, ionic, covalent, and secondary

bonding) and associated properties. The cost of each kit was a few dollars and some of the

samples were revisited with later activities.

Another two kits used early in the course were the "Crystal Structure Kit" and the "Crystal

Geometry Kit" (Figure 2). In an earlier course assessment, it was shown that students did

not develop an adequate knowledge of crystal geometry and structures. One kit used to

address this problem was the "Crystal Structure Kit". This kit used styrofoam balls stuck

together with toothpicks and glued in place with a small glue heat gun. Small, half-inch

balls were assembled into face-centered-cubic (FCC), body-centered-cubic (BCC), and

hexagonal-close-packed (HCP) structures. Larger one-inch balls were sliced and

assembled into FCC and BCC unit cells. The student teams then used these models to

determine structural features such as atoms per unit cell and stacking sequence of layers in

FCC and HCP structures. The students found the kits helpful in visualizing threedimensional structures and also later, when the kits were reused to study deformation slip

systems and mechanical properties of metals. These were inexpensive kits that cost a

couple dollars each.

The "Crystal Geometry Kit" (Figure 2) used a commercial stick-and-ball simple cubic

structure purchased from Klinger Educational Products for about $20 each. Crystal

geometries were illustrated for directions and Miller index planes. The directions were

created with sticks and the planes with styrofoam cutouts for (100), (110), and (111)

planes. Visualization of the planes (and families of planes) was supplemented by a small

cardboard cube with bevels along edges and comers with all faces labeled with specific

(100), (110), and (111) planes. The students again appreciated the 3-D visualization,

although the effectiveness will be determined in test performance.

Another kit on crystals is the "Crystal Defects Kit" (Figure 3) which is also inexpensive,

about a dollar, and enjoyable to use. It is based on Bragg's bubble raft model of atoms in a

2-D lattice. For the model here a CD ROM case was filled three-quarters with BBs and

sealed with clear tape on the one open edge. There is room for just a single layer of BBs

and when the case is jiggled and tilted it is possible to generate an infinite variety of

configurations of the BBs, which usually include grains, grain boundaries, edge

dislocations, and vacancies. The instructor can also point out these features to the class by

placing the case on an overhead projector and pointing out the defects. The model is a bit

noisy, but that seemed to enhance the enjoyment of the activity by the students.

There are useful kits for each of the material families. For polymers four activity kits were

developed. The first two were an "Addition Polymerization Kit" and a "Condensation

Polymerization Kit" (Figure 4). In the first kit, ball-and-stick models of monomers and an

initiator were given to teams and they were asked to construct models that showed the

mechanisms of initiation, propagation, and termination for addition (or free-radical)

329
polymerization of polyethylene. In the second kit (figure 4) the monomers for nylon 6/6,

hexamethyline diamine and adipic acid were given to student teams. They had to break

and form appropriate bonds in order to give reactions, which gave the condensate

molecule, water, and the characteristic amide linkage group between the two molecules.

As before, students felt this activity helped them understand the 3-D nature of the

molecules as well as the chemistry of the reactions that form polymers. These kits, which

were more expensive, were the Student Organic Chemistry Model Kits obtained from

Indigo Instruments. It took two kits, at $30 each, to make the two sets of polymerization

models. The cost could probably be cut in half if just the components needed for the

specific models had been purchased in quantity separately, since many balls and sticks

were left over.

A third polymer kit was the "Silly Putty Polymerization Kit". With this kit a polymer was

synthesized in a plastic "baggie" from Elmer's glue and borax solution. Solutions were

premixed and placed in plastic vials so that the activity could be done efficiently for teams

in a large class. In one vial there is 20 ml of glue plus 20 ml of water. In the other vial

there is 20 ml of a 5% Borax solution. The two vials are then poured into a baggie and

kneaded for more than five minutes. A viscous moist gel is created that students enjoy

handling. The vials can be returned and recycled for the next demonstration. Although the

knowledge content of this activity is limited the students seemed to enjoy it the most. The

cost of each kit is limited with the vials at 40c each and the consumables about 25c per

activity.

One last description of another kit is the "Metal Cold Working Kit". With this kit samples

are given to all students in class since they just consist of 6" lengths of large gage, 1/8"

diameter copper wire. Large gage copper wire can be purchased from a local electrical

supplier or Home Depot. It is heavily cold-worked in the as-received condition and can be

softened by annealing at 600°C for 15 minutes. Samples of as-received and of annealed

wire are given to the students for comparison of yield strength and for cold working of

annealed material. Although this is a simple and inexpensive exercise, the students

develop an appreciation of the degree of strengthening possible by cold work.

A number of other Activity Kits have been created, but will only be given here by title.

There have been "Grab Bag Kits" also created for polymers, metals, and ceramics. A

"Polymer Deformation Processing Kit" has been used with a Ziploc "baggie" and a

polyethylene. Other kits are being worked on for hardening of steels and precipitation

hardening of aluminum alloys. Other kits being considered are related to solar cells,

transistor behavior, electrical conductivity, piezoelectric crystals, and fracture toughness.

If anyone has activities, or suggestions on activities, in these or other areas please contact

me (skrause@ asu.edu).

Short assessments of the use of "Lecture Activity Work Kits" in comparison with previous

classes without the kits were conducted. The results are quite positive as shown below by

survey results of students in a larger class of 51 students. The responses vary from 1 to 5

330
correspondingto "stronglydisagree"to "stronglyagree".

1)Interestin subjectmatterisincreasedm 4.34

2) Subjectmattermoreeasilyunderstood-- 4.26

3) Homeworkmoreeasilyunderstoodm 3.64

4) Opportunitiesfor classroomparticipationareincreased_ 4.30

5) Overall,myperformancehasbeenenhanced_ 3.89

6) In thefuture,I wouldprefergreaterusageof thekits -- 4.13

The surveygenerallyshowsa strongendorsementof "LectureActivity Work Kits" by

students in most areas. However, the survey also indicates that the kit activities should be

more closely tied in with homework and also course outcomes. It should be possible to

modify the activities so they are more closely linked with student work and course

outcomes.

Summary and Conclusions

A brief summary of the advantages and disadvantages of the "Lecture Activity Work Kits"

method of teaching materials engineering courses is summarized below. The advantages of

the technique include":

* increased participation of students in class

* increased attention of students during filling in notes

* increases student involvement and opportunities for interaction in large classes

* increased highlighting of important content and concepts

* increased student thinking, questioning, and dialogue

Some disadvantages of the "Lecture Activity Work Kits" technique include:

* increased time required for activities reduces amount of course content

* logistic issues in preparing, distributing and collecting kits in larger classes

* development of"Lecture Activity Work Kits" consumes some time

The main goal of this article on "Lecture Activity Work Kits" has been to illustrate the

concept and give some examples, which could be expanded upon. These kits do not

replace the other insightful, full-length, laboratory-based materials science and engineering

experiments, many of which have bee described at this conference. Rather, a series of

short activities have been created to complement lecture content, especially in larger

classes. If anyone would like the write up on any of these activities please contact me for

these (skrause@ asu.edu).

Overall, the "Lecture Activity Work Kits" technique has proven to be a useful method to

enhance communication of subject matter in materials engineering by shifting toward

student-centered learning that improves student participation in lectures and enhances

student learning. It has the flexibility to be adapted by instructors by varying the particular

kits that are used and provides a basis for instructors developing their own kits. The

modular format allows easy sharing and modification of content by other instructors

teaching courses with similar content.

331
o

6

e.i

r_

;r..,

332
L_ER'S BAND FORMATION IN STEEL

Mike L. Meier

and

Aaron Broumas

Department of Chemical Engineering and Materials Science

University of California, Davis

Davis, California 95616

Telephone: 530-752-5166

e-mail mlmeier@ucdavis.edu

333
Mike Meier

Biographical Information:

Michael L. Meier received his B.S. in Materials Engineering from North Carolina State University in 1979

and his M.S. (1986) and Ph.D. (1991) in Materials Science and Engineering from the University of

California, Davis. Aider a two-year post-doctorate position at the Universit/it Erlangen-Nilrnberg in

Erlangen, Germany he returned to UC Davis where he is now the director of Materials Science Central

Facilities.

Aaron Broumas is in his junior year at the University of California, Davis and is majoring in materials

science. He is proficient in metallography, specimen preparation techniques, scanning electron

microscopy and EDS which he learned outside of normal courses. He has yet to take his core materials

science courses. Aaron is currently working full time in Materials Science Central Facilities supporting

users of and operating our two scanning electron microscopes. He is also engaged in the analysis of dust

samples collected over Puerto Pica and in the northem deserts of Chinal '

334
LUDERS BAND FORMATION IN STEEL- VIDEO

Mike L. Meier, Aaron Broumas

Department of Chemical Engineering and Materials Science

University of California, Davis

Davis, CA 95616

Keywords: Mierostructure, microstructural evolution, tensile testing, digital video, L_ders bands, upper

yield stress, lower yield stress.

Prerequisite Knowledge: Basic knowledge of the following is required: mechanical properties of lowcarbon steels, formation and propagation of Lt_ders bands, tensile testing, digital video using the PC and

basic video editing techniques.

Objectives: The objectives of this paper are:

1. To describe how we made a video showing the formation and propagation of Ltiders bands during

tensile deformation of a low-carbon steel

2. Provide instructions on how to make a video for classroom instruction

3. Encouraged others to create and share their own videos of in-situ observations or other materials

processes.

Also, projects such as this are excellent student laboratory projects and produce course materials that an

instructor can use in the cl_sroom, and which the student can show to friends who might be interested in

majoring in materials seienee and engineering.

Equipment: The equipment used to make the videos consisted of the following:

• Oven - An oven capable of reaching 300°C.

• Tensile testing system - in this case an Instron model 4204 (computer controlled, 50 kN capacity)

• Digital camera- A CCD video camera with composite video output.

• Video Capture - The computer used in this project was a 733 MHz Pentium Ill-based PC running

Windows 98. It had 256 MB of SDRAM and a 30 GB ATA-100 hard drive. The video capture

board, a miroVIDEO DC30 Pro, was capable of digitizing full motion video at 640x480x24 bits and

30 frames per second (fps).

• Video editing software - Adobe Premiere 5.1

• Optical Microscope - the microscope used in this experiment was a Zeiss-Herrberg stereo-zoom

microscope capable of providing magnifications from 5 to 75X and at a working distance of several

inches.

• Illumination - Fostec light source utilizing a quartz lamp and ring or dual-light pipe fiber optic

illuminators.

• Other Microscopes - an FEI XL30-SFEG scanning electron microscope was used to obtain highresolution images of the Liiders bands while a metallograph was used to obtain color images of the

Lilders bands at ordinary magnifications.

335
Introduction: Liiders bands formation and propagation are fascinating aspects of the deformation of a

number of materials. This can be seen in figure 1 as the curious feature of the stress-strain curve, the

upper and lower yield strengths and yield point extension. This behavior is characterized by an initially

high yield stress followed immediately by a sudden drop in stress. With continued straining the stress

stays nearly constant for several percent strain before normal strain hardening behavior begins. This

behavior always elicits questions from students. An explanation involves a discussion that deals with how

dislocations break free of the solute atoms, a localized process which produces the L_aders bands which in

turn propagate until they cover the whole specimen. Ltiders bands may appear as elongated surface

markings or depressions, often visible with the unaided eye. Many textbooks contain pictures of Ltiders

bands we can show to the students, or, we can polish up a specimen and let the students watch the Ltlders

bands from during a tensile test. If this is not convenient then one can use our video that shows Ltiders

bands forming and propagating on the surface of a polished steel tensile specimen.

In this video project, specimens of steel were annealed, polished and tensile tested. Changes in the surface

of a specimen observed using an optical microscope were recorded using a VCR and a PC-based digital

video capture system. In this paper we describe how this was done.

Procedure:

Materials

The steel used in this experiment was a 1-inch (25.4 mm) wide, Va-inch (3.175 mm) thick strip of 1018

steel. These were machined into tensile specimens having a gage length of 1.50 inches (38.1 mm) and a

gage width of 0.50 inches (12.7 mm).

Heat Treating

The tensile specimens were annealed in air at 300°C for one hour then air cooled. The objective of this

heat treatment was to maximize solute locking of dislocations without causing much grain growth.

Specimen Polishing

After heat treating the specimens were mounted in a specially designed holder (figure 2), ground and

polished using an automated polisher/grinder (8-inch wheels, 240-600 grit SiC, 6 I_m diamond) and finally

with 0.05 micron alumina on a flocked cloth (Buehler's Micropolish B on Microcloth). The result was a

set of fiat and highly polished steel tensile specimens (figure 3).

Tensile Testing

Tensile testing was conducted using crosshead speeds ranging from 0.6 mm per minute to over 6 mm per

minute. In all tests the lower erosshead was stationary while the upper erosshead moved at the specified

rate. During each test the load-elongation data was recorded and saved to disk.

Video Capture

Several tests were done to allow us to monitor Liaders bands activity at different magnifications. A stereozoom microscope was mounted horizontally and focused on the surface of the specimen. The

magnification of each video segment was noted by recording images of a ruler. A color video camera was

attached to the microscope's C-mount adapter and its output was connected to the PC, a VCR (in case the

PC video capture failed) and to a color monitor (figure 4). After making a few short test recordings to

ensure everything was working properly the video capture system and the VCR were started and a few

seconds later the tensile test was started. The video was recorded at the highest available resolution and

336
flame rate (640x480x24-bits, 30 fps).

A total of seven tests were conducted and recorded, many giving poor results due to poor lighting. Proper

illumination of the specimen was difficult due to the highly reflective nature of the specimen and the low

contrast of the Ltiders bands. The original setup consisted of a color camera with a macro lens and a fight

source consisting of a dual light-pipe illuminator and a polarizer (figure 5). These problems were solved

by doing all recordings using the stereo-zoom microscope and a ring illuminator (figure 6). The resulting

videos were similar to mierostruetures seen using dark-field illumination. The specimen itself appears

dark with bright edges and the Liiders bands showed up as bright streaks on the otherwise dark specimen.

Video Processing

All video processing was done on the same PC that was used for the video capture. Adobe Premiere was

used to create the title screens, transitions and micron bars, to cut and splice the video and to assemble the

final video. The final video shows segments of three different tests. It starts by showing the whole

specimen as it is deformed. About half way through the video two segments showing the close-up views

of individual Liiders bands. The final video was produced in three formats: 640x480x24-bits,

320x240x24-bits and 160x120x24 bits, all at a frame rate of 15 fps. These videos were also accelerated so

that their runtimes would be less than the recommended three minutes.

CD-ROM

The videos, the data from the tensile tests, several frames from the videos and SEM and optical

microscope images were written to a CD-ROM.

Comments: Videos such as this one are challenging projects and fun to do with students. They have the

added benefit of producing something which can be used to help teach other students. This project

requires a thorough understanding of the phenomenon, the testing procedures, advanced computer skills

and a knack for presenting the results in a straightforward manner. It also requires a degree of creativity

and promotes a sense of ownership which motivates students to do their very best work.

This video, like the videos showing the orange peal surface develop in annealed brass that we made a few

years ago [1], was meant to be used as a short video clip in which the instructor provides the background

information and narration. The appendix at the end of this paper summarizes some of the details of the

sharp yielding phenomenon and Ltlders band formation.

This video, the tensile test data, and still images may be downloaded from our web site at

www.matsci.uedavis.edu/meier/NEW-Update2001. Note that the 640x480 video is a 108 MB file and the

320x240 video is in the neighborhood of 40 MB. Download times may be impractical and you will also

need enough hard drive space to store these large files. If you would like to get a copy of these videos you

can write or email the authors to request copies of the CD-ROM.

References:

1. M.L.Meier, K.H.Ewald, The Un.d.e.rlying Structure of Eneineerin_ Materials, Proceedings of the

National Educator's Workshop-Update 98, Brook_haven National Laboratory (1998).

337
800 -

600 - --

0_

4oo200

J

0

0.00 0.05 0.10 0.15 0.20

Strain

Figure I Stress-strain curve for a low-carbon steel. Not the upper and lower yield stresses.

338
Figure 2 The fixture used to hold the

specimens during grinding and polishing.

Figure 3 Tensile specimens before and after

polishing.

Figure 4 The original setup showing the tensile

tester, the camera and illumination setup, the

computer, VCR and monitor.

339
Figure 5 The original camera and lighting

setup, The camera and macro lens are

mounted on a tripod. The ilhtmination

system consists of a dual-light pipe quartz

illuminator and a polarizer.

Figure 6 The final setup used for the closeup shots. The ring illuminator provided the

best results when videoing the polished

steel specimens.

Appendix

This appendix provides a more detailed description of the phenomenon of upper/lower yield point

phenomenon and of Ltklers band formation and propagation. [1 ]

General Aspects

Consider a tensile test conducted at a constant rate of strain. Strain rate due to dislocation processes can

be expressed as

iz = pbv (1)

340
where p is the density of mobile dislocations, b is the magnitude of the Burgers vector and v is the average

velocity of the mobile dislocations. At the upper yield stress the strain rate is

and at the lower yield stress the strain rate is

Since the strain rate is constant

we can write

_u = PJ_% (2)

_L = pLbvL" O)

_= _L = % (4)

Pu VL

PL vv" (5)

The relationship between stress and velocity is generally written as

v = _ (6)

where _ is the shear stress acting on the dislocations and m is the strain rate sensitivity. Combining

equations 5 and 6 we can express the ratio of the upper and lower shear stress in terms of the ratios of the

densities and velocities of dislocations

%= PL _

(7)

This last equation summarizes the general aspects of the upper/lower yield stress phenomenon. At the

upper yield stress the mobile dislocation density is low but the average dislocation velocity is high. At

lower yield stress there are many more mobile dislocations but they are not moving as fast. Ltkters bands

are nucleated at the upper yield stress and propagate at the lower yield stress with PL and vL representing

the deformation that is occurring in a narrow zone ahead of the advancing Ltiders band.

Advanced Aspects

Please note the dependence of the ratio of upper and lower yield stress on the strain rate sensitivity m. The

strain rate sensitivity of a material is measure of the stability of the neck that forms at the UTS which is in

turn related to strain hardening index n=etrrs, a measure of the material's resistance to necking. The strain

rate sensitivity can readily be measured from the Liiders strain and the initial slope of the stress-strain

curve [2].

1 Aa

- e,, (8)

m (I

341
The early theories of Cottrell-Bilby [3] and others were given in terms of solute atom locking of

dislocations. Initially, dislocations are pinned but at the upper yield strength they break away, the mobile

dislocation density increases, the dislocation velocity decreases and the stress decreases to the lower yield

stress. A later theory proposed by Petch [4] addressed the effect of grain size on the upper yield stress. At

the upper yield stress only a few grains contain mobile dislocations and these dislocations move quickly

relative to the average velocity for the whole specimen. As more grains acquire mobile dislocations the

velocity drops, the macroscopic stress drops and so does the stress required to penetrate grain boundaries.

A Ltiders band forms and from that point on the number of active grains remains constant as it propagates

through the specimen.

The Hall-Petch equation

1

a = a/+kd 2 (9)

where d is the grain size and t_is a the inherent strength of the material without grain boundaries, defines

the lower yield stress. In Perch's model t_is expressed as

o/= o o + Aoolo _ 1 (10)

where ao is the inherent strength when all grams are deforming uniformly and N is the number of active

grains per unit volume. The difference between the upper and lower yield stresses is given by the second

term in the equation above.

As for the lower yield stress, an important factor is the extension of deformation past or through grain

boundaries. The lower yield stress was seen as the stress forcing grainoboundaries ahead of the Lflders

band and the propagation of the Lt_ders band involves a process of generating dislocations in the next

grain, adjacent to the boundary.

Practical As_v_ts

It is difficult to measure the true upper yield stress due to practical difficulties in testing, such as the

specimen design, grip design, alignment, etc. Consequently the lower yield stress is usually considered the

material's yield strength. When these difficulties have been eliminated experiments have shown that the

upper yield stress can be twice as high as the lower yield stress.

Ltiders bands, also called stretcher strains, are unsightly and may spoil the finish during sheet forming

operations. Prior rolling can minimize this, but strain aging can restore it. Strain aging sufficient to cause

stretcher strains can occur after a few days at room temperature or only an hour at 60-100°C.

References

1. Honeycombe, The Plastic Deformation of Metals, Edward Arnold, London, pp.149-157 (1984).

2. U.F.Kochs, A.S.Argon and M.F.Ashby, Thermodymanics of Slip, Pergamon Press, Oxford, pp. 261-

264 (1975).

3. A.H.Cottrell and B.A.Bilby, Proc. Phys. Soc, A62, 490 (1949).

4. N.J.Peteh, The Upper Yield Strength of Polycrystalline Iron, Acta Met. 12, 59 (1964).

342
TRANSMISSION ELECTRON MICROSCOPY OF

SELF-ORGANIZED MAGNETIC STRUCTURES

IN Lao.67Sro.33Mn FILMS

Lourdes Salamanca-Riba

and

L. J. Martinez-Miranda

Materials and Nuclear Engineering Department

University of Maryland

College Park, Maryland 20742-2115

Telephone: 301-405-0253

e-mail martinez @ eng.umd.edu

e-mail riba @ eng.umd.edu

343
Lourdes Salamanca-Riba

Biography:

L. Salamanca-Riba is a Professor of Materials Engineering in the Department of Materials and

Nuclear Engineering at the University of Maryland-College Park. She received her BS degree in

Physics from the Universidad Autonoma Metropolitana, Mexico City and her PhD degree in

Physics from the Massachusetts Institute of Technology. At the University of Maryland she has

been involved in teaching courses in electron microscopy, electronic properties of materials and

defects in materials. Her research interests are in the areas of effect of defects on the physical

properties of materials for devices, semiconductor quantum structures and self assembly in

semiconductors.

L. J. Martinez-Miranda is Associate Professor of Materials in the Department of Materials and

Nuclear Engineering at the University of Maryland - College Park. She received her bachelor's

and master's degrees in Physics from the Universidad de PuertoRico in Rio Piedras, a bachelor's

in Music degree from the Conservatory of Music of Puerto Rico and her doctoral degree in

Physics from Massachusetts Institute of Technology. At Maryland she has been responsible for

designing the junior level laboratory undergraduate courses with the help of her colleagues, and

has taught the introductory design course and the physics of materials course. Her research

interest is in X-ray scattering from liquid crystals and solid films.

344
Transmission Electron Microscopy of Self-Organized

Magnetic Structures in Lao.67Sro.33Mn Films

L. Salamanca-Riba and L.J. Martinez-Miranda

Materials and Nuclear Engineering Department

University of Maryland

College Park, MD

Key Words: Transmission electron microscopy (TEM), electron diffraction, structure

identification, self-organized structures, magnetic structures, thin fihns

Prerequisite Knowledge: Basic knowledge of diffraction, Bragg's Law, concept of reciprocal

lattice and its relation to the real space lattice, Fourier transform.

Objectives:

• To understand the dependence of diffraction on structure factor from crystals with different

structul'es,

• To understand the relationship between real space imaging and diffraction as Fourier

transforms of one another.

• To become familiar with the capabilities of TEM in the analysis of the structure of thin films.

• To learn the concept of dislocation formation in thin films.

Equipment:

1. A high resolution transmission electron microscope

2. High resolution scanner

3. One plan-view and one cross-sectional TEM samples of a La0.67Sr0.33MnO3 (LSMO) thin film

containing MnO inclusions and deposited on LaA103 by pulsed laser deposition (PLD).

4. A computer with image processing software and photo shop.

Introduction:

Lal.xSrxMnO3 (LSMO) is a magnetic oxide that shows a very large change in its electrical

resistance in the presence of a magnetic field. The elements in the LSMO are ionic, namely,

3+ + 3+ 4+ 2

La , Sr 2 , a mixture of Mn and Mn , and O ". The properties of the LSMO depend on the

3+ 4+ 3+ + Mn /Mn ratio, which can in turn be controlled by the La /Sr: ratio and the oxygen content.

To obtain films with desirable properties it is necessary to control the composition of the LSMO.

In this project the structure of LSMO films grown by pulsed laser deposition on LaA103

substrates is studied for the ch_acterization of a two-phase material. During the deposition of the

films the LSMO transforms into two phases. The transformation takes place by phase separation

in the form of self-assembled structures. One phase consists of columns of 1VmO with square

base that extend from the film/substrate interface to the film surface embedded in a matrix of

LSMO (second phase). The MnO remains epitaxial with the matrix and with the LaA103

substrate. The columns have a different structure (cubic, a =0.445 nm)) from the LSMO matrix

(tetragonal, a =0.38 nm, c=1.32 ran) in which the out-of plane interplanar distance of the LSMO

345
and that of the MnO are approximately the same. In contrast, the in-plane interplanar spacings

are different giving rise to in-plane misfit dislocations between the MnO and the LSMO.

This exercise is carried out after the students in the class have performed a standard x-ray

diffraction experiment so that they are already familiar with Bragg's Law, Miller indices, and the

concept of diffraction in general. In this project, electron diffraction patterns are obtained from

the LSMO film and substrate. The pattern from the substrate is used for calibration. Images are

obtained using objective apertures of different sizes to include the transmitted or direct (BF)

beam only, a diffracted (DF) beam only, the transmitted and several diffracted beams at the same

time. The table below shows the different types of pictures that are obtained in this experiment

with an explanation of how to carry them out.

Name

Selected area

diffraction pattern

Abbreviation

SADP

Bright field image BF

Dark field image DF

High resolution

electron microscopy

HREM

Explanation

Pattern of the (hkl)

reflections allowed

by the structure factor

of the sample

Image of the sample

using only the

transmitted (not

diffracted) beam

Image of the sample

using only one

diffracted (hkl) beam

Image of the sample

formed by the

interference of

several beams

(transmitted and

diffracted beams)

How to carry out

1. Insert a selected area aperture

to isolate the area that we

want the SADP pattern from

2. Switch to diffraction mode

and the diffracted beams are

observed on the screen

3. Take a picture

1. Obtain a SADP

2. Insert a small objective

aperture to select only the

transmitted beam

3. Go to imaging mode

4. Increase the magnification to

-50,000X

5. Focus on the image and take

a picture

1. Obtain a SADP

2. Insert a small objective

aperture to select only one

diffracted beam

3. Switch to imaging mode

4. Increase the magnification to

-50,000X

5. Focus on the image and take

a picture

1. Obtain a SADP

2. Insert a larger objective

aperture that includes the

transmitted beam (at the

center of the aperture) and

several diffracted beams

3. Switch to imaging mode and

increase the magnification to

346
-400,000X

4. Focus on the image and take

a picture

Procedure:

The class is divided in groups of five to six students so that they all can see the

microscope screen. Each group works with a graduate student or postdoctoral fellow who

operates the TEM. The students are required to obtain the following images from the LSMO thin

film sample.

a) A SADP from an area including both the MnO inclusions and the LSMO matrix.

b) A bright field (BF) image of the thin film at a magnification of approximately 50,000X.

c) Two dark field (DF) images, one using a diffracted spot from the MnO inclusions and one

with a diffracted spot from the LSMO matrix, also at a magnification of-50,000X.

d) A high-resolution lattice image from the film (approximate magnification of 400,000X).

Note: the pictures can be taken from either the plan view or the cross-sectional sample, or both

(if time allows).

After the demonstrations the students are asked to

a) Scan the TEM negatives obtained dur-ing the laboratory session and print the pictures. Note

the scale on each negative. Label the phases in the bright and dark field images. Examples of

the pictures obtained in a), c) and d) are shown in Figures 1-4.

b) Obtain the interplanar distances, di from the diffracted spots from the MnO and LSMO using

the formula di =L£/ri, where L is the camera length printed on the negative of the SADP, _,

the wavelength of the electrons used (0.00197 nm for 300,000 KeV) and ri is the distance

from the transmitted beam to a diffracted beam.

c) Perform necessary image processing by adjusting the contrast to the images and

d) obtain the fast Fourier transform of the different regions in the high resolution images and the

diffraction pattern.

e) Compare the interplanar distances obtained from the diffraction patterns to the ones obtained

from the FFTs from the high resolution lattice image of each region (MnO inclusions and

LSMO matrix). To get interplanar distances using the FFTs the students use the HREM

image of the substrate for calibration.

Comments:

Prior to the laboratory demonstration the students are introduced to the operating

principles of the TEM and how the various image types are obtained. The students are also asked

to read a reference paper on the structure of LSMO films, _ which contains images like the ones

they have to analyze in this experiment. They are also introduced to the differences and

similarities between a transmission optical (light) microscope and a TEM. The instructor also

explains briefly how a TEM sample is prepared so that the electrons can actually go through it

without being completely absorbed.

347
To help visualize the relationship between real space lattice and reciprocal lattice the

students are asked to compare

• The FFT obtained from the diffraction pattern to the lattice image and

• The FFTs from the MnO and LSMO regions in the lattice image to the corresponding

spots in the diffraction pattern.

The instructor also demonstrates how by the different DF images one can identify which

regions of the sample give rise to the different spots in the diffraction pattem. Namely, the dark

field images obtained with MnO spots contain bright regions where the inclusions are and a dark

background for the matrix. The contrast is reversed when the spot selected for the dark field

image is from the matrix. (See Fig. 2)

During the demonstration, and later when the students print the pictures, the instructor

emphasizes the fact that dislocations can be clearly seen at the interfaces between the inclusions

and the matrix in the plan view images while they are not visible in the cross section images.

This is because the out of plane interplanar distances are continuous across the interfaces (i.e.,

the (002) MnO spot overlaps with the (006) LSMO spot). In contrast, in the plan view images

none of the MnO spots overlap with any of the LSMO spots.

The instructor describes how the LSMO film has formed a fairly regular structure of

columns of MnO in a LSMO matrix even though nothing special was done during the deposition

of the film. This is an example of self-assembled structures in a magnetic material.

Acknowledgments

This work was supported by the National Science Foundation (MRSEC) under grant No. DMR

00-80008

References:

1. Y.H. Li, L. Salamanca-Riba, Y. Zhao, S.B. Ogale, R. Ramesh and T. Venkatesan, J. Mater.

Res. 15, 1524-7 (2000).

348
0 • • @ •

@ @ 0 @ 0

®®% 8 _ ®®

lift 200

eo eo 0 _ eo

®®®e $ %®0

0 @ @ 0 @

• • 0 ® •

@ LaSrMnO matrix

• MnO phase

dhkl = 2L_/2r

Fig. 1 SADP of LSMO film. Superposition of two pattems as shown in schematic on right is

indicative of two structures present in the film.

349
350
THE ATOMIC MASS UNIT AND THE

AVOGADRO CONSTANT:

AN APPROACH TO INTRODUCE THESE CONCEPTS

Carlos E. Uma_a

Department of Materials

School of Mechanical Engineering

University of Costa Rica

San Jose, Costa Rica

Telephone: 506-207-4548

e-mail caruma @terraba.f'mg.ucr.ac.cr

351
Carlos E. Umafia

352
THE ATOMIC MASS UNIT AND THE AVOGADRO CONSTANT:

AN APPROACH TO INTRODUCE THESE CONCEPTS

Carlos E. Umafia

Department of Materials

School of Mechanical Engineering

University of Costa Rica

San Jos6, Costa Rica

KEY WORDS: Absolute and relative scalar quantities, International System of Units (SI),

isotope, mass spectrometer.

PREREQUISITE KNOWLEDGE:

Have an introduction to the atomic mass parameters and a basic understanding of the Dempster

spectrometer.

OBJECTIVES:

1. To analyze scalar quantities and propose an atomic mass nomenclature.

2. To explain in a logical sequence how the atomic mass unit and the Avogadro constant are

defined and related to each other.

3. To show how the values of these constants have been changing during the last thirty years.

INTRODUCTION:

Most textbooks in the fields of chemistry, physics and materials science present an incomplete or

a weak treatment of the origins and fundamentals of the atomic mass unit and the Avogadro

constant. Sometimes explanations do not follow a logical sequence or the key concepts are

omitted. As a result confusion or misunderstanding about these basic constants is usually

generated amongst students and even amongst instructors.

Two main problems are identified: In the first place it is not usually clearly stated that mass

spectrometers play a very important role concerning the necessity of having a relative atomic

mass unit definition, due to the fact that absolute atomic masses cannot be experimentally

obtained with mass spectrometers. Secondly the direct relationship existing between the

Avogadro constant and the atomic mass unit is not usually well established.

It is the intention of the author that the content of this paper should be helpful as an introduction

to these topics in any basic course in chemistry, physics or materials science.

SCALAR QUANTITIES:

In order to make the demonstrations on which this work is based, it is necessary to go beyond the

traditional definitions and take into account that scalar quantities actually consist of two

components: a coefficient or numerical value and some sort of unit that defines the nature of the

scalar quantity, e.g., mass, energy, length, etc. These units are either absolute or relative. The

absolute units are the ones defined by the International System of Units (SI) and are classified

into basic and derived units. The relative units consist of absolute units modified by numerical

coefficients other than one (See Appendix A). Some examples of relative units are:

353
The angtrom [A], defined as: [A] = 10 q0 [m]

Where: 10 -10 is the numerical value of the relative unit [A].

The meter [m] is a basic SI unit.

The electron volt is also a relative unit and is defined as: [eV] = 1.602 x 10 q9 [j]

Where: 1.602 x 1019 is the numerical value of the relative unit [eV]

The joule [j] is a derived SI unit.

The atomic mass unit is also a relative unit but it will be analyzed in the following sections.

NOMENCLATURE:

Regarding the atomic mass parameters representation, it is important in the first place to promote

the use of international symbols. For quantities not defined, it is convenient that symbols

proposed, at least be in agreement with most occidental languages. Two basic parameters are the

atomic mass unit and the atomic mass. In English the first quantity is usually identified as a.m.u.

(Atomic mass unit) and in Spanish as u.m.a. (Unidad de masa at6mica). Nevertheless, and

regardless of the language, the international symbol that must be used is %'. This symbol was

adapted in 1960 by the IUPAP and the IUPAC [1]. On the other hand the letters A.M. stands for

atomic mass while in Spanish the letters M.A. (masa at6mica) represent atomic mass. In this

work the letter M is proposed and used as the symbol for mass. It has the advantage of avoiding

language influence.

Since the atomic mass is a scalar quantity that can be either expressed with absolute or relative

units, it is necessary to introduce symbolic expressions to take into account both cases. The

absolute atomic mass ofan isotope IX will be represented as M/N(_X)[kg], where M/N(Az X) is

the scalar numerical value and [kg] the absolute unit in kilograms. A and Z are the atomic mass

number and the atomic number respectively. The relative atomic mass will be represented as

MN(_X)[u ], where MN(_X)isthescalarnumericalvalueand [u] the relative atomic mass

unit.

THE MASS SPECTROMETER, THE ATOMIC MASS UNIT AND THE ISOTOPIC

RELATIVE ATOMIC MASS CALCULATION:

Mass spectrometers are instruments used to find out the relative atomic mass of isotopes. Its

operation requires the use of a standard isotope to calibrate the spectrometer. The standard used

by international agreement is the 12C isotope and it is arbitrarily assumed that the absolute atomic

mass of this isotope is equal to 12 [u]. In other words:

[u]: M/_('2C) [kg] (1)

12

Which can also be expressed as:

[ul=UN[kg ] (2)

Where: u N is the numerical value of the relative atomic mass unit [u].

354
The exact value of M_ (12C) is unknown and for that reason the results obtained with the mass

spectrometer are given in terms of [u] as is shown below.

The mass spectrometer measurements are based on adjustments of magnetic or electric fields [2].

The adjustment values "V" of the parameters that represent those fields are directly proportional

to the isotopic atomic masses. For that reason it is possible to establish the following proportional

relationship:

V(12C) _ 12-[_/l

v(;x)-,

Which can be expressed as an equation, from where the numerical value of the relative atomic

mass of an isotope is obtained as it follows:

MN (; X)=12 AVv_

Where:

V(12C) = Adjustment value for the _2C isotope

V(;X):Adjustmentvalueforthe (z)isotope

(3)

At this point it is important to emphasize how relative atomic masses are experimentally obtained

without either knowing the 1Zc absolute atomic mass or requiring the Avogadro constant.

With the mass spectrometer it is also possible to obtain the natural isotopic abundance percentage

of the elements with a natural abundance different to 100%. The combination of these

percentages with the M N(IX) values gives rise to the weighted average of the isotopic relative

atomic masses, --M,v(zX ). Since more than one isotope are now involved, the symbol A is

omitted. In Appendix B it is shown how MN (z X) is obtained.

THE RELATIONSHIP BETWEEN THE AVOGADRO CONSTANT AND THE ATOMIC

MASS UNIT:

_X By definition, one mol of an isotope ;,z ! is an absolute scalar quantity with a numerical

coefficient equal to the numerical value of the relative atomic mass M x (_ X) times 10 "3.

Expressed as an equation,

1Mo1:MN(;X).IO-3[kg] (4)

Taking into account that one mol is a mass amount composed of N atoms, each one with an

/ A

absolute mass given by MN (z X)[kg]; it then follows that,

MN(; X).lO-3[kg] = M_ (; X).[kgl. N (5)

355
Hence, N =MN(;X)'IO-3

M/N(AzX) (6)

By substituting for [u] from equation (2)into the relative atomic mass expression M N (zAX)[u],

the following equation is obtained

M N(zAX)[u] : M N (; X) UN[kg ] (7)

From where it follows that the absolute atomic mass is given by

(8)

By combining equations (6) and (8), it is deduced that:

N- 10-3 (9)

b/N

In this way it is demonstrated that for a given b/N value there is a constant amount N of atoms in

a mol. When uN is defined according to equation (1), the number N is known as the Avogadro

constant N A.

TI-IE EXPERIMENTAL ORIGIN OF N A :

The numerical value of the atomic mass unit u N depends on the numerical value of the absolute

atomic mass of the 12C isotope. However, as was mentioned before, this value is unknown and

therefore N Acannot be calculated from equation (9). The value of N Ais experimentally obtained

and has been changing through the years as a result of worldwide research that is being done

trying to achieve a more accurate value by developing more sophisticated experiments. Table 1

lists four N Avalues and the years when they were reported.

There are also experimental efforts being carried out in order to obtain directly the value of uN

[3]. However the values reported until now are calculated by applying the experimental N Aresults

in equation (9), as can be confirmed in Table 1.

Table 1. Some values of the Avogadro constant and the corresponding atomic mass unit reported

at different years.

NA* U [kg]* Year Reference

6.022169(40) X 10 23 1.660531 (11) X 10 -27 1969 [4]

6.022045(31) X 1023 1.660565 (9)X 10.27 1973 [5]

6.0221367(36) X 1023 1.6605402 (10) X 10 -27 1986 [6]

6.02214199(47) X 1023 1.66053873 (13) X 10 -27 1999 [7]

* The numbers within brackets are the standard uncertainty.

356
ADDITIONAL COMMENTS:

Finally it is important to mention that the atomic mass unit [u] should not be assumed to be

numerically equivalent to the proton or neutron mass. All these quantities are independent from

each other as it is deduced from the following facts:

1. The proton and neutron isolated masses are not equal, and when these particles joint to form a

nucleus their masses become smaller and probably remain different.

. The isotopic relative atomic masses obtained from mass spectrometers include the electron

masses that remain in the atom after ionization. In other words if the atomic mass unit is

/ A

defined as (M_v (z X)/A) [kg] in such a way that any isotope of any element can be used as a

reference, then the numerical value M/N (_ X)/A will be different in every case while proton

and neutron masses remain constant. Observe that the established M_ (12C)/12 value is only

a specific case out of many possibilities.

REFERENCES:

1. B.W. Petley, "The atomic mass unit", IEEE Trans. Instrum. Meas. Vol. 38. N°2. April 1989.

2. K.W. Whitten, K.D. Gailey and R.E. Davis,"General Chemestry", Saunders College

Publishing, 3th edition, 1980.

3. M. Glas_r,"Proposal for a novel method of precisely determining the atomic mass unit by the

accumulation of ions", (PTB) Physikalisch-Technische Bundesanstlt, Braunschweig, Germany,

Rev. Sci. Instrum. 62(10), 2493-2494 (1991)

4. B. N. Taylor, W. H. Parker, and D. N. Langenberg, Rev. Mod. Phys., vol.41, pp.375-496, July

1969.

5. E.R. Cohen and B.N. Taylor, "The 1973 least-squares adjustment of the fundamental physical

constants", J. Phys. Chem. Ref. Data, vol. 2, pp. 663-734, 1973.

6. E.R. Cohen and B.N. Taylor, "The 1986 adjustment of the fundamental physical constants",

CODATA Bulletin 63, Oxford, U.K.: Pergamon, and Elmsford, N.Y, : Maxwell, Dec. 1986.

7. P.J. Molar and B.N. Taylor, CODATA Recommended Values of the Fundamental Physical

Constants: 1998, available at NIST site: http://physics.nist.gov/cuu/Constants/index,html

ACKNOWLEDGMENT:

The author wishes to thank the Universidad de Costa Rica ( Vicerrectoria de Investigaci6n), la

Fundaci6n de la Universidad de Costa Rica para la Investigaci6n

(FUNDEVI) and the Ministerio de Ciencia y Tecnologia - Conicit for giving financial support to

attend the NEW : UP DATE 2001.

I also want to thank Prof, Allan Bloomfield for reviewing the grammar and vocabulary of this

paper.

357
Appendix A. SCALAR QUANTITIES

SCALAR QUANTITY )

NUMERICAL VALUE (N.V) + [UNITS]

+ +

ABSOLUTE SI UNITS

IA.U]

I

RELATIVE UNITS

[R.U]

BASIC DERIVED

I I

___. BsoL TESC AR0 ANTIT -'5

Nv'fau1 ./

But, R.U = RUN [A.U]

r

N.V [R.U] J

Where RUN = Absolute numerical value of relative units

Substituting R.U and comparing absolute and relative scalar quantities it is obtained:

N.V / = N.V.R.UN

358
AppendixB. THEWEIGHTEDAVERAGEOFTHEISOTOPICRELATIVEATOMIC

MASSES

Supposethereis anarbitraryamountof anelement(zX) with a total relative mass given by

Mr (z X)[u]. Let us assume that the element has only two natural isotopes with the following

characteristicsl:

Isotope Relative Atomic Mass [u] Natural Abundance %

(Tx) M (Tx)

If the total number of atoms in the sample is taken as N, it is deduced that:

Mr(zX)[u] = MN(Az_X)[u] %(Az_X)N + MN(_X)[u ] %(_X)N (A1)

100 100

Dividing both members by [u] and N and substituting Mr (z X) for --MN(z X) it follows that:

N

100 100

Where: MN (z X) is the weighted average of the isotopic relative atomic masses.

(A2)

Finally it is important to establish that the symbolic representation of any element in the periodic

table, according to the nomenclature already proposed, is the following,

Z

(,x)

 N(zX)

For the silicon, as an example, the meaning of the symbols is:

Z =14

(z X) =Si

MN(zX) =28.086

1 The demonstration applies to elements with any number of natural isotopes.

359
360
THE ONSET OF TENSILE INSTABILITY

Mike L. Meier

and

Amiya K. Mukherjee

Department of Chemical Engineering and Materials Science

University of California, Davis

Davis, California 95616

Telephone: 530-752-5166

e-mail mlmeier @ ucdavis.edu

361
Mike L. Meier

362
THE ONSET OF TENSILE INSTABILITY

Mike L. Meier, Amiya K. Mukherjee

Department of Chemical Engineering and Materials Science

University of California, Davis

Davis, CA 95616

Key Words:

Tensile test, mechanical properties, Young's modulus, yielding, strain hardening, geometric

softening, necking, modulus of toughness, modulus of resilience, fracture.

Prerequisite Knowledge:

Basic knowledge of mechanical properties in tension, digital data acquisition and spreadsheets.

Objective:

Introduction of mechanical properties obtained from tensile testing with an emphasis on being

able to fully analyze the data, in particular the phenomenon associated with the onset of necking.

Equipment:

1. Cylindrical tensile specimens

2. Extensometer

3. Tensile test system of suitable load capacity and which acquires data digitally.

4. A computer with Microsoft Excel, Corel Quattro Pro, or another suitable spreadsheet

program.

Introduction:

In this experiment the plastic deformation behavior and the onset of plastic instability of some

common structural alloys is investigated. The usual mechanical properties are measured from

stress-strain curves, but in addition, strain hardening behavior and the onset of plastic instability

are studied. Much more is happening during a tensile test than is listed in standard materials

properties data tables. The goal of this experiment is to investigate these additional phenomena.

Elastic Deformation: When an isotropic material is loaded to stresses below the yield point and

then unloaded again all of the deformation is immediately recovered. This behavior is usually

associated with the linear portion of the stress-strain cur-ve, although not all materials exhibit this

linear-elastic behavior; for example, rubber is an exception. But for many materials the

resistance to deformation in this region is given by Young's modulus Y, which also is often

represented by an E, is simply the slope of the stress-strain curve in the linear region

Aft

Y- Ae" (1)

where o is the true stress and e is the true strain. When measuring Young's modulus one must

take into account the stiffness of the testing machine. Ideally, the machine should be perfectly

363
stiff but in reality its stiffness may be in the neighborhood of 200,000 pounds per inch. A low

machine stiffness will introduce errors in the measured modulus as given by

1+ A° Yl l

Ymeas_rcd = Y gLo] (2)

where Ao is the initial cross-sectional area of the specimen, Lo is the initial gage length, Yis the

correct value of Young's modulus and K is the stiffness ofthe testing machine [1]. The error in

the measured modulus results primarily from errors in measurement of elongation. The

specimen is a monolithic part while the testing machine has the grips, clevis pins, threaded parts

and moving parts that mesh better when loaded means the specimen is generally stiffer than the

testing machine. Consider also that the modulus is the ratio of stress, a large number, to strain, a

small number. The result is very sensitive to errors in the denominator.

When conducting a constant crosshead speed test one can compute the stiffness of the testing

machine K using the equation

(3)

where _ is the crosshead speed and F is the loading rate [1 ]. Or, one can use an extensometer to

measure strain directly from the specimen, or one can attach strain gages to the specimen.

Yielding: Yielding occurs when deformation changes from being mostly elastic to mostly plastic.

By this definition the method of measuring the yield strength may seems somewhat arbitrary,

which it is, however, standard methods have been established so that everyone will get the same

result. In fact, there are a number of standard methods available and the method used varies

depending on the type of yielding behavior (gradual, sharp, upper/lower), industry, or country.

Offset techniques are used when yielding is gradual while sharp and upper/lower type yielding

behaviors are easily read from the stress-strain curve. In the ease of the upper/lower yielding

364
behavior which is characteristic of carbon steels and a few other alloys the lower yield stress is

taken as the yield strength due to the fact that (1) accurate measurements of the upper yield

strength are difficult to make and (2) the lower yield stress is the stress where normal,

homogeneous plastic deformation begins.

Strain Hardening: Plastic deformation can occur by three different processes: diffusional

processes, twinning and dislocation motion. The contribution of diffusional processes is

important at high homologous temperatures, T > 0.6 Trap, and twinning might account for up to a

few per cent strain. Dislocation processes are the dominant deformation mechanism of plastic

deformation at normal temperatures. Considering only the contribution due to dislocation

processes, a shear stress acting parallel to the slip plane causes these dislocations to move

through the lattice. As they move they may encounter obstacles such as solute atoms, particles,

grain boundaries and other dislocations, effectively impeding their motions until the stress is

increased enough to allow the dislocation to overcome the obstacle. As the dislocations glide,

climb and cross-slip through the lattice additional dislocations were being generated and start

moving through the lattice. With this ever increasing dislocation density the distance between

them decreases, they encounter each other more often, and it becomes increasingly difficult to

deform the material. This process is called strain hardening.

There are two well known equations that depict the strain hardening phenomenon. The

Hollomon equation describes strain hardening as a power law function of stress and strain after

yielding. Hollomon's equation is

0 = KE n (4)

where o and e are true stress and strain, n is the strain hardening index and K is the strength

coefficient which is equal to the stress at e=l. The second equation is Ludwik's equation which

is often preferred because, unlike the Hollomon equation, it does not suggest that strain

hardening begins at the very start of the tensile test. It includes a term for the yield stress ao

o = Oo+ Ke" (5)

where ao is given by

= 1-n (6)

In cases where the material has already experienced some plastic deformation (e0=prior strain)

the following equations represent strain hardening:

o = (7)

o = ao+K(e+%)". (8)

365
]'he strain hardening index n is a constant for a given material and can range in value from 0 to 1

but is typically in the range of 0.2 to 0.5. The strain hardening index can be written as

dlog(o) _ e do"

n - dlog(e) o de (9)

and it can evaluated numerically or graphically from the slope of a plot of log(o) -vs- log(e)

where n is equal to the slope of the resulting line. If the Hollomon equation is obeyed the line

will be straight, but if the Ludwik equation represents the data or the specimen had been

deformed prior to the tensile test the line will be concave up (figure 1). In these cases the values

of a o and eo must be known in order to determine the value of n.

2

1000

i

i

"Ludwi_

Lud

100

w

g

_ik

:li

ff

f H¢

I

i

t'1 J"

j"

0.00 0.01 0.10 1.00

TrueStrain

Figure 1. Log-log plots of stress-strain curves calculated using Hollomon's equation,

Ludwik s equation and Ludwik s equation with 10_ prior straining. (K=500 MPa, n=0.3,

E=207 MPa)

The above equation allows one to express strain hardening do/de in terms of the rate of increase

of stress with respect to strain. Rewriting it as

do o

= n- (10) de e

shows that the rate of strain hardening (slope of the stress-strain curve) is proportional to the

stress divided by strain.

366
Strain Rate Hardening: Most materials are sensitive to the rate of deformation, especially at

elevated temperatures. This behavior often obeys a power law expression such as

0 = A_ _ (11)

where A is a constant at given temperature and metallurgical condition, d is the true strain rate

and m is the strain rate sensitivity. This equation can be combined with the Hollomon equation

for a general description of the plastic deformation of materials

o = B_E ". (12)

At low and ambient temperatures the rate of strain hardening is significant, 0.2<n<0.5, while the

rate sensitivity is small, 0.001<m<0.01. At higher temperatures just the opposite is true and the

strain rate sensitivity can reach values as high as 1.0 (Newtonian viscosity) while the strain

hardening index may approach zero. A value of m=0.5 is considered characteristic of

superplasticity, a condition where elongations of 100's even 1,000's percent strain are possible

due to the stability of the neck that may forms at the UTS.

While the strain rate sensitivity can effect the flow stress, it is more important in terms of its

effect on ductility. Increased strain rate sensitivity slightly increases the strain at which the

material starts to neck, but more significantly it can extend ductility considerably by stabilizing

the neck. As the specimen begins to neck the strain rate in the necked region increases and due

to the strain rate sensitivity the stress in this region increases and thus the neck stabilizes. So

while the strain hardening index is a measure of a material's resistance to the onset of instability,

the strain rate sensitivity is a measure of its resistance to necking.

Tensile Strength; The tensile strength Srs [formerly called the ultimate tensile strength (UTS) but

now considered an obsolete term] is the maximum nominal stress. This property represents the

load bearing capacity of the material. It also occurs at the strain where necking begins. The

subsequent drop in stress beyond this point is due to the geometric softening associated with the

localized thinning and deformation of the specimen.

If a true stress-true strain curve could be obtained directly from a tensile test, rather than an

engineering stress-strain curve, one would find that there is no maximum stress prior to failure.

There would appear to be no tensile strength. That is not to say that necking has not occurred or

that there is no tensile strength, but that other methods must be employed to determine its value

and the strain at which it occurred.

There are several methods for determining the tensile strength Ors from a true stress-strain curve.

One method is to plot both the true stress and the rate of strain hardening against true strain as

shown in figure 2. The point where these two lines intersect marks the tensile strength and the

strain where necking begins. This method is expressed in the following equation

o = Ors when do = o. (12)

de

367
12.

(d

or}

o

CO

-I

#-

1000

800

600 -

400

200

0

0.00

s

i

0.10 0.20 0.30 0.40 0.50 0.60

True Strain

m

Stress-Strain

Rate of Strain Haranetng

Figure 2. Stress-strain and rate of strain hardening curves calculated using the Hollomon equation.

(K=500 MPa, n=0.3)

While this relationship may be derived from the Hollomon equation it also works for stress-strain

behaviors which do not obey the Hollomon equation.

The above equation also gives us a second method of determining the tensile strength - the unit

subtangent method. Using this method the tensile strength may be found by locating a point on

the true stress-tr-ue strain curve which has a subtangent of unity (intersects the strain axis at strain

Ers "1). Furthermore, it may be shown that

do o

(12) o = Ors when de l+e

This is Considrre's criterion, a third method for determining the tensile strength. It is also a

graphical method that requires a plot of true stress versus nominal strain whose origin is set at the

yield point. The tensile strength Ors is obtained by drawing a subtangent from a nominal strain of

-1. The nominal tensile strength Srs is the point where this line intersects the stress axis. (See

figure 3.) If power law hardening is observed then Considrre's criterion may also be used to

derive one last expression for the tensile strength

Srs = Kn n(1 - n) l-'. (13)

Onset of Plastic Instability: Generally, the strain at the maximum load marks the onset of plastic

instability. For annealed materials the rate of strain hardening immediately after yielding is

368
L

100

0

-1.00

Figure 3.Consid_re's construction fordetermining the tensile strengths (Srs--V=271 MPa, Ors=A=388 MPa) of a ductile

material.The stress-straincurve was calculated using Hollomon's equation (K=500 MPa, n=0.3).

relatively high, but as deformation continues, the rate of strain hardening steadily decreases. At

the same time the specimen is becoming thinner. Eventually the rate of strain hardening and

specimen thinning are equal. Beyond this point the rate of specimen thinning is greater than the

rate of strain hardening and deformation is unstable, i.e., necking begins. The instability will

start in some part of the specimen where an inhomogeneity (soft spot, adjacent to a hard spot) or

at a machining defect (stress concentration) exists. Once localized deformation begins the stress

in this region will be higher than elsewhere, causing deformation to become even more localized,

leading to the formation of a macroscopic neck.

For rate insensitive materials, the onset of unstable deformation occurs at the strain where

maximum load is obtained. It was mentioned earlier that the strain hardening index is a measure

of the resistance to the onset of instability. It can be shown that the strain hardening index for

rate insensitive materials is equal to the true strain where necking begins.

ers = n (14)

For rate sensitive materials the onset of necking will differ but only slightly. The most important

aspect of rate sensitivity is that it tends to stabilize the neck, decreasing its degree of localization,

and extending ductility well past ers.

Ductility and Localized Deformation: During nonuniform deformation stresses are concentrated

in the necked region of the specimen, leading to a more complex, triaxial, stress state.

369
Bridgeman [2] has developed a method for computing the stress distribution in the necked region

and making corrections to the stress-strain data based on the radius and area at the root of the

neck.

The onset of instability often marks the limit of useful deformation. However, neck growth is

slow at first and additional straining can occur before the instability is either noticeable or

significant. The amount of straining beyond this point is affected primarily by the strain rate

sensitivity of the material. For example, maximum load is often reached at about 10-15% strain,

which is usually around half the strain to fracture for rate insensitive materials (m ~0.01).

Superplastic materials, however, have high rate sensitivities (m-0.5) and may be strained

hundreds and even thousands of percent. The maximum load, however, occurred at around 10%

strain. The high rate sensitivity stabilized the neck.

Fracture: With continued plastic deformation a material accumulates damage associated with

dislocation processes. Dislocations that pile up at grain boundaries and other obstacles earl form

mierocracks. Tensile stresses can open these into voids which grow and eventually coalesce,

forming larger cavities. Final fracture occurs when the number and sizes of internal voids is

sufficient to exceed the material's ability to withstand the applied load. These voids introduce

stress concentrations which can lead to the spontaneous growth of a single crack. (This behavior

is the subject of the field of fracture mechanics.) Inspection of the fracture surfaces permits

determination of the fracture process involved, i.e., brittle, shear, or ductile. Close inspection of

the cup-and-cone fracture surfaces of a ductile material may reveal areas where void formation

and coalescence occurred and the area through which the final rupture occurred. A scanning

electron microscope is usually required to determine whether the crack propagated

intergranularly or transgranularly and how much plastic deformation occurred as the crack

propagated.

The strain to fracture is not an intrinsic property of the material. It also depends on the specimen

geometry. An expression that relates specimen geometry to ductility is

A0_r_

ey = C L--T (15)

where C is a proportionality constant [3]. Ideally, comparisons of strain to fracture should be

made using specimens of identical design. If this isn't possible, the comparisons should be made

on similarly shaped specimens. Corrections based on the AV2/L ratio may be made. ASTM 370

describes how to make comparisons of round and fiat specimens.

Procedure:

Pre!mmtion

I. Plot true stress versus true strain for a hypothetical material using either the Hollomon or

Ludwik equation. Experiment with the values of K and n to see how their values effect the

results. Note the value of the stress as true strain approaches 100%.

2. Determine the tensile strength for the stress-strain curve in the question above.

370
3. Calculate and plot an engineering stress-strain curve using the data calculated in question 1.

4. Compile mechanical properties data on the specific materials to be tested.

5. Note the specifications of the tensile tester and compare them to the load and elongation

requirements for the tensile tests.

6. For the crosshead speed you plan to use, determine the data acquisition rate you will need in

order to record enough data in the elastic region to be able to determine Young's modulus.

Materials

Specimens made of plain carbon and low alloy steels, aluminum, and plastics are available. All

specimens are round with threaded ends. They all have a 2 inch gage lengths and either an 0.236

or 0.505 inch diameter.

Tensile Testing

Inspeet the equipment and become familiar with how it operates. Check the calibration of the

load cell and extensometer and make adjustments as required.

Select a specimen to test and measure and record its gage length, diameter, etc. Note the

specimen's composition and processing, and then estimate the maximum load that will be

generated during the tensile test.

Tensile test the specimen to failure. During the test monitor the load and elongation and watch

the specimen carefully to see when necking begins.

After the specimen fractures, remove the broken halves and note the geometry of the fracture and

the fracture surfaces. Do not try to fit the halves of the specimen back together again as this will

damage the fracture surfaces. You'll probably want to examine the fracture surfaces under a low

power microscope or a scanning electron microscope.

Data Analysis

Perform a comprehensive analysis of the data from the tensile tests by importing the data into

your spreadsheet program. Construct the stress-strain curves and measure all of the usual

mechanical properties including the energy capacities of the material. Analyze the strain

hardening behavior and finally, investigate the onset of tensile instability.

Stiffness: Determine the value of Young's modulus using a regression or best fit routine. How

does your value compare to the published value?

Optional: Repeat this analysis using data from a tensile test which did not utilize an

extensometer. Compare this value to the previous value. This value is typically a factor of 10 to

20 lower than the value obtained using an extensometer. Determine the stiffness of the testing

machine.

371
Gqneral M echaoical Properties: Compute the other basic mechanical properties that may be

obtained from a tensile test.

Stress

Yield strength, (upper and lower, offset, etc.)

Tensile strength (stress at maximum load)

Stress at fracture

Strain

Strain at yielding

Strain at the onset of necking (observed and from the stress-strain curve)

Strain at failure

Reduction of area at failure (measured from the specimen)

Energy capacity

Work required to cause failure (area under the whole load-elongation curve)

Modulus of resilience (area under the elastic portion of the stress-strain curve)

Modulus of toughness (area under the whole stress-strain curve)

Compare these properties to those in reference books.

Strain Hardening: Use a least squares or regression analysis to determine the values of n and K in

the Hollomon equation. Comment on the values obtained. Are these typical values? Does the

Hollomon equation do a satisfactory job of representing the stress-strain behavior of these

materials?

Tensile Strength: Determine the tensile strength using the engineering stress-strain data. Next,

determine the tensile strength using the rate of hardening method. Finally, locate the tensile

strength on the true stress-strain curve using only the value of the strain hardening exponent. Do

all three methods give the same answer?

Optional: Construct a graph similar to figure 3 to determine the tensile strength.

Onset of Instabili.ty: At what point in the test did you first observe necking of the specimen?

Compare this to the strain where maximum load (tensile strength) occurs on the stress-strain

curve. Do the Hollomon strain hardening index and strain at the onset of instability coincide?

Fracture: Examine the fracture surfaces of each specimen. Did fracture occur in a ductile or

brittle manner?

Measure the final cross-sectional area of the fractured specimen and compute the true stress at

fracture. Compare this to the engineering stress that was obtained at the same strain and the true

stress that the Hollomon equation would predict. One would expect it to be lower. Why? Was

it?

372
Comments:

The analysis of the data requires mostly basic spreadsheet skills and the ability to lay out the

solution to problem in a sensible and organized manner. A typical spreadsheet will include a

header section (owner, file name, creation and revision dates, etc.), a parameters section (gage

length, gage area, crosshead speed, etc.), and a results section where the results of the analysis of

the data are listed.. The bulk of the data will be in 10 or more columns containing, starting with

column 1, the original load-elongation data, elongation data corrected for the toe of the curve,

load-elongation data converted to the desired units, nominal stress-strain calculated from the

load-elongation data, true stress-strain data calculated from the nominal stress-strain data, and

additional columns which are required to measure selected mechanical properties. Building this

spreadsheet can be quite a task unless one lays it out in a simple and direct manner.

The difficulty of the analysis ofthe mechanical properties from the columns of raw data can

range from the use of simple @max0 and @sum0 functions to the more advanced regression

analysis procedures. Other clever teehniques may have to be devised to be able to determine the

offset yield strength (if appropriate). In addition, one must also construct appropriate graphs that

both illustrate each property and verify that the analysis has been done correctly. For example,

after using a regression routine to determine the value of Young's modulus, one should then

calculate the elastic portion of the stress-strain curve using this value and plot it along with the

experimental data. One should then calculate the linear elastic portion of the stress-sWain curve

again but this time applying a strain offset so one can see where this line crosses the experimental

stress-strain curve. To accttrately locate the offset yield stress one can then subtract the measured

stress from the calculated stress and the search the column of data to find the value closest to

zero. Similar procedures and graphs should be used to determine the tensile strength using the

rate of hardening method, for fitting the Hollomon equation to the strain hardening region of the

stress-strain curve, etc.

Employing the rate of strain hardening method to determine the true tensile strength and the

onset of instability requires plotting the slope of the true stress-strain curve. Due to the noise in

real experimental data the result will be unacceptable unless a smoothing technique such as box

car smoothing is employed. We have found that averaging over 21 and sometimes many more

data points gives good results.

References:

1. P.P.Gills and T.S.Gross, Effect of Strain Rate on Flow Properties, ASM Metals Handbook 9_

edition, volume 8, page 44, (1985).

2. Bridgeman, P. W., Transactions of ASM, v.32, pp. 553-574, (1944).

3. Wyatt, Oliver H. and Dew-Hughes, David, Metals, Ceramics and Polymers, Cambridge

University Press, London, p. 143, (1974).

4. Polakowski, N.H. and Ripling, E.J., Strength and Structure of Engineering Materials,

Prentice-Hall, New Jersey, (1966).

373
Biography:

.Michael L. Meier received his B.S. in Materials Engineering from North Carolina State

University in 1979 and his M.S. (1986) and Ph.D. (1991) in Materials Science and Engineering

from the University of California, Davis. After a two-year post-doctorate position at the

Universit/it Erlangen-N_nberg in Erlangen, Germany he returned to UC Davis to set up new

research laboratories and to manage the laboratory teaching program. He is now the director of

Materials Science Central Facilities.

Amiva K. Mukhefiee received his M.S. degree in Physical Metallurgy from the University of

Sheffield (1959) and D.Phil. degree in Metallurgy and Science of Materials from Oxford

University, England (1962). From 1962-65 he was associated with the Lawrence Berkeley

National Laboratory and the Department of Materials Science at the University of California,

Berkeley, where he worked on application of dislocation theory to the understanding of thermally

activated deformation mechanisms in crystalline materials. He was a Senior Scientist at the

Battelle Memorial Institute in Columbus, OH (1965-66) primarily working on fracture and

failure processes in engineering materials. In 1966 he was the first faculty recruited in the area of

materials science at the University of Califomia, Davis and he has been instrumental in

developing the materials science program with his colleagues there since. He was promoted to

full professorship in 1970.

His current research activities are in the areas of creep properties of metal and intermetallics,

superplasticity, high temperature cavitation and failure phenomenon, synthesis, characterizations

and processing of nanometals for enhanced plasticity including superplasticity, elevated

temperature deformation characteristics of nanocrystalline thin film metallic multlayers, and

processing and properties of nanoeeramic composites for improved fracture toughness, creep

resistance as well as superplastieity. Mukherjee has published over 350 research papers in

journals and conference proceedings. He is a past Chairman of Materials Science Division of

ASM International and of the Editorial Board of Metallurgical Transactjon_s. He received the

Distinguished Teaching Academic Senate Award, University of California, Davis (1978); Special

Creativity Award for Research, NSF (1981); Alexander yon Humboldt Senior Scientist Award,

Germany (1988); AT&T Foundation Award from Amer. Soc. for Engineering Education (1988);

University of Tokyo Centennial Gold Medal (1990); Albert Easton White Distinguished

Teaching Award, ASM (1992); University of California Prize and Citation for Distinguished

Teaching and Scholarly Achievement (1993); Pfeil Medal and Prize for Creativity in Research,

Institute of Materials, U.K. (1994); the Bochvar Medal in Metals Physics from the University of

Moscow (1996), Humboldt Professor, Max Placnk Institute, Germany (1997); and Senior Fellow,

Ecole Polyteehnique Federale Lausanne, Switzerland (2000).

374
Appendix A - Symbols, Conversion Factors and Equations for Stress and Strain

Symbols

Symbol Description

F Force

L Length

D Diameter

A Area

S Engineering stress

e Engineering strain

o True stress

¢ True strain

t Thr_.e

preferred Units

N

mm, cm or m

mm, cm or m

mm2,cm2or ms

MPa

MPa

S

Conversion Factors

,Description

Mass

Force

Length

Area

Stress, pressure

Energy, work

Conversion Factors

1 kg = 2.207 lbs

1 N = 10_ dynes = 0.2248 lbf

1 in = 25.4 mm = 2.54 cm = 2.54x10 "2m

1 in 2 = 645.16 mm 2 = 6.4516 cm _ = 6.4516x10 "4m 2

1 MPa = 1 MN/m 2 = 145 psi

1 J = 107 ergs = 6,242x!0_ _eV = 0.239 cal

Stress and Strain

Nominal

Stress F

a o

Strain

AL

e -

Lo

F

A

&4

Ao E _

: 2 _ D° (See note !)

Strain Rate e -

Ae 1 AL

At L o /it

de

dt

Note 1: Constant volume is assumed (AoLo = AjLf).

375
The true stress and strain can be written in terms of the nominal stress and strain, as long as the

specimen has not started necking, by the equations

and

a = s(e+ 1)

e = In(e+ 1).

Elastic Moduli

Modulus

Young's Modulus

Equation

AO E,Y-

_e

Poisson's Ratio v = ---, For eonstantvolume v = 0.5

e

Shear Modulus G - A'_ _ y. 1 K3(1-2v)

Bulk Modulus K -

A¥

Ao_

AV

V

2(1 + v) 2(1+ v)

G 2(1+ v)

3(1-2v)

376
Appendix B - Sample Data from the lnstron 4204 Universal Tester, Header and First 10

Data Points

Sample id : ALUMINUM

Version : 1.08

Machine : 4200

Report file# : 45

X conversion : .03937008

Y conversion : ***********

Sample rate : 5.00

2nd Sample rate : 1.00

A/D range : 0

Calib type : AUTOMATIC

Calib load : 11240.4500

Temperature : 25

Xhead speed : .1000

Test type : TENSILE

Bar type : E-45

Break check : 10.00000

Load limit : 11240.45000

Test date : 30 Dec 1994

Version date : 30 May 1991

Robot used : NO

Operator : Mike Meier

X A/D offset : .0000

Y A/D offset : .0000

Extensometer : STD

Autostart : OFF

Geometry : RECTANGULAR

Calib extens : .0000

Humidity : 50

Units type : SI

# specimens : 1

Entry dimens : YES

Thresh delay : 4.49618

Extens limit : .98425

Sample dimensions :

A: .2500 B: .0559 C: 1.0000 D: 1.0000 E: NO

Specimen _ : 1 Test end status : I0

Maximum load : 414.305 Max load point # : 235

Max extens : .140 Max extens pnt # : 420

I 2nd. Speed I Extn. Remv i Relx Strt l Range Chg i

Point # ............

Number of points : 420

Specimen dimensions :

A: .2500000 B: .0559055 C: 1.0000000 D: 1.0000000 E: NO

Transverse gauge: .........

Auxiliary Specimen Inputs:

Auxiliary Sample Inputs:

Calculations from Instron:

Maximum ............ i............ Break ............. j

Load Displ. Strain ILoad Displ. Strain J

414.32 .84252E-01 ********** ********** ********** **********

........... Peak 1 I

Load Displ, Strain I

I, .000060, .000000

2, .000390, .000000

3, .000720, .000000

4, .001140, .000000

5, .001470, .000000

6, .001720, .000000

7, .002050, .000000

8, .002470, .000000

9, .002720, .000000

377
Appendix C - Sample Spreadsheet for 7075 Aluminum

This appendix shows the summary page of the spreadsheet used in the analysis of the tensile test

data for 7075-T651 aluminum. Measured values are generally close to the reference values. The

accuracy of the analysis of the strain hardening behavior was improved somewhat by assuming a

prior strain of 0.02.

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378
FIRST ROBOTICS COMPETITION

Lori Aldridge

Northwestem High School

2503 W. Main Street

Rockhill, South Carolina 29732

Telephone: 803-417-0863

e-mail laldridg@rock-hill.K12.sc.us

379
Lori Aldridge

380
Photograph from the 2000 P1RST Robotics

Competition National Championship.

The suggestions provided in this document are designed to help

your team develop successfully during the Competition season.

The information has been gathered from both rookie and

veteran team participants. Remember, not all teams are

identical, and what worked for one may not work for all. Read

this through and see if any of the ideas work for you. If you

need more suggestions, please contact FIRST.

Start Now

Our teams have provided us with the best advice "Start

now." They have told us many times that getting people

from diverse areas on board early saves time.

Involve as many people as possible

Involve as many individuals as you think your team can

manage. If you must select only a portion of the students who

show interest, remember that one of the strengths of the FIRST

Begin Computer Training Now

Learning cqmputer programs ahead of time such as CAD-CAM,

drafting, or drawing can also be helpful by speeding up the

design process and keeping the cost of "testing" prototypes

within budgets.

Parents

Inform parents about the program by sending home information

from FIRST and the school. Include them in your recruiting

Robotics Competition experience comes Dom involving meetings or have the students make presentations on the team's

students who are not usually attracted to this type of program. Pr9gress. Open houses or family days at the school or work

They can add new ideas and perspectives to your team ......... faciliiy axe a great opportunity to introduce, parents to the

Share the Excitement =

Work with your team partners to recruit team members from

both your company/university partner and team school. Call

FIRST for information packets, event programs, or articles

from the national press and set up an information table in the

corporate cafeteria or at a staff meeting. We also have videos

of past Competitions which are sure to get others excited and

interested in becoming involved.

Take the time to explain

Some of the students you work with may never have set foot

in a machine shop or used a small hand tool. For the first time

many will see how their math and science classes are applicable

to "Real World" situations. In order to engage the students, be

prepared to explain complicated concepts and formulas at a

level students will comprehend.

Develop a Team Attitude

Many of our team members have commented that the design

and build phase of the Competition is the most intensive work

they have experienced. To help things run smoothly, many

start at the beginning of the school year with Team Building

Workshops that include student, teacher, and corporate team

members. Some teams practice brainstorming using the

previous year's game. This also serves to recruit new team

members and renew the interest of those returning,

project.

School

Include teachers from outside the science and math

departments, Art classes can help design team logos, computer

instructors can teach programs, and the shop or tech ed teachers

are valuable resources for everyone: Use all the resources of

your school to recruit team members. Some schools have their

own television studios and in-house broadcast facilities through

which videos of the Competition or student-produced

documentaries of your progress can be shown. Involve the

school administration. Permission sIips, insurance issues, and

school district clearance are sometimes necessa_' to allow the

students to travel off-site, to work on the machine, or to travel

to tournaments. Your school administration can support your

team by conducting open houses, school assemblies, pep rallies,

or by providing meeting and building space.

Community

The community can support other team needs, such as

fundraising and carpools. Students in the same neighborhood

can arrange for carpools for travel to and from the work site.

Local businesses may donate "'fuel" for long work sessionspizza and doughnuts are always popular. Teams come to the

Competition in uniform, Local merchants can supply teams

with Team T-shirts, hats, and buttons. Create a team of students

to organize fund-raisers and recruit support.

For Inspiration and Recognition of Science and Technology

200 Bedford Street, Manchester, NH 03101 • 800-871-8326 ° 603-666-3906 phone ° 603-666-3607 fax ° http:llwww.usfirst.org

Proj./Comp/2OOllMktToolKWTeam Information Letter 0900

381
Use real world Business Models

Some successful teams use a corporate model to organize their

efforts. They distribute vision and mission statements, strate#c

goals, time frames, and they outline, document, and distribute

team responsibilties. Teams can create mini corporations

complete with design, manufacturing, marketing and budget

departments. Even if your te,am doesn't go to tiffs extent, teams

within a team have worked very well.

Divide Responsibilities

Job descriptions, applications, and interviews may allow team

members to choose their areas of interest and help team

oNanizers assign responsibilities. You may divide into goups

to accomplish specific tasks. Keep each other up-to-date on

progress.

Acquire Facilities

If your school administration is unable to provide a facility or

work space for your team you will need to find a place where

you can set up shop, have meetings and work on the robot.

Also, learn the procedures for acquiring materials or having

shipments delivered to your work site. If permission, keys, or

badges are required for access, get clearance now for all team

members to enter facilities. You will not have time during the

design and build phase to address these issues.

Choose your traveling team

If you have to choose who will travel and who will stay

behind, create a plan for making those decisions. Remember,

as a coach you do not have to make these decisions alone.

Ask the students to decide on a plan. Their sense of diplomacy

and level of maturity will surprise you. Be clear about your

expectations of those who make the trip. Talk about

acceptable behavior, team spirit, and "gracious

professionalism." Be ready to handle emergencies and report

good news back home quickly.

Spread the Word

Spreading the word, about your FIRST team among team

members and their extended families is a good start. But

think BIG! Promote your involvement both in your school

and in your community. Use newsletters to recruit team

members, a cheering section, or new supporters. Have your

school board members, administrators, town or city mayor,

and corporate CEOs visit your work site and get your local

papers and television stations involved. Again, have students

assist your public ol community relations staff Tiffs will

broaden the type of role models you can provide.

Team Promotional Materials

• Team Media Kit

- Competition videos

• Competition trifold

° Information packets

° How to start a FIRST Team

• Mentoring Guide

For FIRST Program Information

Customer Service - 800-871-8326

menu option 2

Engineering Support- 800-871-8326

menu option 2

FIRST

For Inspiration and Recognition of Science and .Technology

200 Bedford Street

Manchester, NH 03101

800-871-8326

603-666-3906 phone

603-666-3907 fax

http://www.usfirst.org

ProjdCompl2OO1/MktToolKitJTeam Information Letter 0900

382
__ FIRST ROBOTICS

FIRST HOW T0 WORKSHOP

Forinspiration and Recognition ofScience and Technology

I www,suggested web site resources.com I

%&

www. u_first.org

www.first-sme, org

(_ www.sharingfirst.mit.edu/

qt

www.robotfcs, nasa.gov

www. m eta Iin motion, corn

www, ch iefdeIphi.com

www.tearnbosch,org

www.f) rstl egoIeague, org

kL1s; 6 @No.too;/,#of_

South Carolina State Museum

August 30, 2001

C'r_C

383
Executive Summary

Dean Kamen

President of DEKA Research & Development Corp.

& Founder of FIRST (For Inspiration and Recognition of Science and

Technology)

Dean Kamen is an inventor, an entrepreneur and a tireless advocate for science and technology.

His roles as inventor and advocate are intertwined -- his own passion for technology and its

practical uses has driven his personal determination to spread the word about technology's virtues

and by so doing to change the culture of the United States.

His vast knowledge of the physical sciences, combined with his ability to integrate the

fundamental laws of physics with the most modem technologies, has led to the development of

breakthrough processes and products.

As an inventor, Dean holds more than 1.50U.S. and foreign patents, many of them for innovative

medical devicesthat have expanded the frontiers of health care worldwide. While still a college

undergraduate, he invented the first wearable infusion pump, which rapidly gained acceptance

from such diverse medical specialties as chemotherapy, neonatology and endocrinology. In 1976

he founded his first medical device company, AutoSyringe, Inc., to manufacture and market the

pumps. At age 30, he sold that company to Baxter International Corporation. By then, he had

added a number of other infusion devices, including the first insulin pump for diabetics.

Following the sale of AutoSyringe, Inc., he founded DEKA Research & Development

Corporation to develop internally generated inventions as well as to provide R&D for major

corporate clients. Dean's more recent inventions include: the HomeChoice TM dialysis machine,

developed for Baxter (Design News' 1993 Medical Product of the Year), the Crown Stent

designed for Johnson & Johnson, and the latest invention, the Independence TM 3000 IBOT TM

Transporter, also developed for Johnson & Johnson. The IBOT, a personal transporter that was

developed for the disabled community was unveiled in 1999. It can climb stairs, traverse sandy

and rocky terrain and raise its user to eye-level with a standing person. All three of these products

represent extraordinarily innovative responses to extraordinarily daunting challenges.

384
A decade ago Dean founded F12RST (For Inspiration and Recognition of Science and

Technolcgy). and ever since has remained its driving force, its guiding spirit, and, in the eyes of

thcusands of students across the country, its personal embodiment. F11v,ST uses wholesale

marketing and media techniques to motivate the next generation to want to learn about science

and teehnology. Dean has personally recruited scores of the top leaders of American industry,

education and government in this crusade. As a result, the national championship of the FIRST

Robotics Competition. which teams professional engineers with high school students from across

the count.w., has set a new record each of the last four years as the largest non-Disney event ever

he!d at Walt Disney World's Epcot Center. The 2000 event attracted almost 400 teams and has

impacted tens of thousands of students -- many of them women or minorities from large urban

schools.

With the success of the FIRST Robotics Competition, FIRST introduced the FIRST

LEGO League (FLL) in 1999 as a means of expanding FIRST's reach to expose younger

children to the science and technology fields. As a result of a partnership between FIRST

and the LEGO Company, FLL offers hands-on experience for 9-14 year-old kids to

explore and invent their own robotic creations. FLL has experienced tremendous growth,

reaching more than 25,000 children in the U.S. since its inception.

In addition to his own attempts to master science and technology, Dean has received significant

public recognition for his crusade on behalf of science and engineering. He was, for example,

labeled by Smithsonian Magazine "the Pied Piper of Technology" and profiled by the New York

Times as "A New Kind of Hero for American Youth".

Dean has received several prestigious awards:

• In 1994 Dean received the Kilby Award which celebrates those who make extraordinary

contributions to society through science, technology, innovation, invention and education.

• The Heinz Award was awarded to Dean in 1998 in Technology, the Economy and

Employment for a set of inventions that have advanced medical care worldwide.

• Dean was awarded the National Medal of Technology by President Clinton in 2000 for

inventions that have advanced medical care worldwide, and for innovative and imaginative

leadership in awakening America to the excitement of science and technology.

385
REGIONAL COMPETITION AWARDS

FIRST will hold an Awards Celebration at each Regional Competition.

judging panel will present the following awards:

At these events, a special

DaimlerChrysler

Team Spirit

This award celebrates extraordinary enthusiasm and spirit through an exceptional partnership and

teamwork.

Delphi

°'Drivin_ Tomorrow';s Technolo_vr_'_

This award celebrates an elegant and advantageous machine feature. This award recognizes any aspect

of engineering elegance including, but not limited to: design, wiring methods, material selection,

programming techniques, and unique machine attributes. The criteria for this award are based on the

team's ability to concisely verbally describe, as well as demonstrate, this chosen machine feature.

General Motors

Industrial Desi._

This award celebrates form and function,in an efficiently designed machine which effectively achieves

the game challenge.

Johnson & Johnson

Sportsmanship

This award celebrates outstanding sportsmanship and continuous gracious professionMism in the heat of

competition, both on and offthe playing field.

Motorola

This award celebrates machine robustness in concept and fabrication.

Xerox

Creativity

This award celebrates creative design, use of a component, or a creative or unique strateg3" of play.

Imagery

This award celebrates attractiveness in engineering and outstanding visual aesthetic integration from the

machine to team appearance.

Leadership in Control

This award celebrates an innovative control system or application of control components to provide

unique machine functions.

Incredible Play

This award celebrates the team or alliance displaying the most incredible play of the elimination rounds,

including a formidable defensive or offensive move or strate_. The recipient of this award is decided

upon by FIRST teams via on-site ballot vote at each regional competition.

#1 Seed

This award celebrates the team which is the top seed at the conclusion of the qualifying rounds.

Featherweight in the Finals

This award celebrates the l_ightest machine participating in the elimination matches.

Copyright I_ 2000 FIRST AWARDS

386
Highest Rookie Seed

This award celebrates the highest seeded rookie team at the conclusion of the qualifying rounds.

Rookie All-Star

This award celebrates the rookie team exemplifying a young but strong partnership effort, as well as

implementing the mission of FIRST: to inspire students to learn more about science and technology.

Judges' Awards

During the course of the competition, the judging panel may encounter a team whose unique efforts,

performance, or dynamics merit recognition.

Regional Finalist

This award celebrates the team or alliance which makes it to the final match of the competition.

Regional Champion

This award celebrates the team or alliance which wins the competition.

Copyrigh! O 2000 FIRST AWARDS 4

387
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391
Sharing Your News

How to Reach The Media

Use the information in this kit to help you share news about your team's invoivement in the FIRST

Robotics Competition. We recommend that you identify one or two team members who can be in charge of

contacting the news media for the duration of the project.

If you have questions about publicizing your team, FIRST national media coordinators are available to

help. Call, fax, or e-mail:

Carolyn Eggert or Barbara Trevett

MSA, 20 Park Plaza

Boston, MA 02116

617-695-6364

msacse@aol.com

What is news?

Everyone has their own definition of news.., in this case, there are several exciting activities and personal

stories to share with the news media. For example:

1. You are a group of students building robots from scratch. Invite reporters to visit you while you are

building your unique robot. Let reporters see that you started building your robot from a simple crate of

nuts, bolts, and wires.

2. You are programming your robot to accomplish a specific task. Once your robot is built, invite

reporters to watch you "test" your robot.

3.

4.

You are preparing your robot and your team for regional competitions. If there is a competition in your

hometown (or somewhere nearby), invite reporters.

What happens during the last week of putting together the robots? Packaging it for shipment? Working

day and night to make sure things are just right?

5. You are learning real-life science - your participation in the FIRST Robotics Competition could lead to

a career in science. Talk to your teammates about why your involvement on the team is so important

and what you hope this experience will do for you in the future. Share this information with your local

news media.

6. Do any of your team members have personal stories of achievement that lead them to becoming part of

your FIRST team?

7. How does this "intellectual" competition compare to athletic competition? Do you use some of the

same skills in preparing for competition?

8. Do you have cheerleaders, marching bands rooting for you on the sidelines?

How do I contact newspaper and television reporters?

First, find out the names, addresses, phone and fax numbers of your local newspapers and TV stations. Call to

find out which reporter is interested in covering news about:

• EDUCATION

• SCIENCE

• HUMAN INTEREST STORIES

* BUSINESS NEWS

392
FIRST TEAM PRESS KITS

Let's get some press coveraoeV

Page 2

When you have a list of reporters, think about what will interest them. To introduce your team and the FIRST

Robotics Competition, use the press releases in this kit. Just fill in the specifics about your team and sponsor.

Now, send it off to the reporters.

As your team pro_esses...for example, when you start to build the robot, let reporters know about it.

1. SEND (via mail or fax) a news release that answers the following questions:

• WHO: Who are you? (FIRSTRobotics Competition event, team name, school, sponsor)

• WHY: Why are you calling?---Why are you writing this news release?

• WHAT: What is interesting about your participation in the FIRST Robotics Competition ?

• WHERE: Where are you doing it? (Provide exact location, room numbers andphone numbers in

case they need directions)

• WHEN: When are you dobzg it? (DATE, TIME)

• CONTACT: If they need more information, who has it? Who can they call if they want more

information?

2. CALL THEM

Introduce yourself and tell them why you are calling. Keep in mind that reporters get so many requests, they may

not remember receiving your news release. Be prepared to give them a quick description on the phone and after

your conversation, FAX the news release to them.

Remember, reporters are busy and are working on deadlines. They may not respond to your news release or call

- but feel free to follow up with them.

An& if they are not able to cover your first event, t_ a_ain.

. BASIC RULES OF THE ROAD

• Always refer to the our pro_am -- as: FIRST Robotics Competition

• Always refer to ?our team sponsor whenever writing or talking about your team. Your sponsor makes it

possible for you to enter the competition.

• When writing the news release type with double spaces.

• When describing FIRST, use one of these descriptions:

Founded in 1989 by New' Hampshire entrepreneur and inventor Dean Kamen,

FIRST (For Inspiration and Recognition of Science and Technology) is a

non-profit organization that brings together an alliance of business,

education, and government organizations through innovative programs to

inspire today's youth in rhe areas of science, engineering and technology.

Visit the FIRST web site at <w_w.usfirst.org> for more information about

the FIRST Robotics Competition, and other programs developed by FIRST to

inspire youzh of all ages.

The rest of this kit offers sample press releases and fact sheets about FIRST Robotics. Feel free to use them to

promote re_onal competztions or as background information for reporters.

Please send copies of an? coverage you may receive (articles or news clippings, etc.,) to MSA, 20 Park Plaza,

Boston, MA O2116. And remember, call if you have any questions or need help with publicity.

393
FIRST TEAM PRESS KITS

Let's get some press coverage!

Page 3

EXAMPLE A: Press Release for Regional Competition

PRESS RELEASE

National Media Contact: Team Contact:

Barbara K. Trevett [Contact name, school and team number]

(617) 695-6364 (AREA CODE/NUMBER)

For immediate release Region's students prepare to clash

[addtoday'sdate] on the 'intellectual playing field'

CITY, STATE (DATE) -- Students at more than (number of) schools in the (major city) region this

week are pumping up for one of the biggest games of their young lives -- the annual FIRST Robotics

Competition. Instead of fine-tuning their shooting style or defensive play, these students test the limits of their

own imaginations--using robots they have designed and are sending into technological battle against robots from

other FIRST competitors.

In this clash of robots and their student handlers, all the trappings of traditional school sports

showdowns--referees, cheerleaders and time clocks--will surround feverish competitors on the "intellectual

playing field." Adding to the tension and excitement is the prospect of participating in the national championship

for the student teams' marvelous machines at the competition finals at Disney World's EPCOT Center at

Orlando, FL in April.

The FIRST Robotics Competition, centered on a new "challenge" each year, is designed to convince

young people that science can not only be exciting and rewarding but is as much fun as traditional sports. Details

of the annual challenge are kept secret until being unveiled at the "Competition Kickoff" each year, with all

teams having an equal start in a fiercely contested day-long event.

Founded in 1989 by New Hampshire entrepreneur and inventor Dean Kamen, FIRST (For Inspiration

and Recognition of Science and Technology) is a non-profit organization that brings together an alliance of

business, education, and government organizations through innovative programs to inspire today's youth in the

areas of science, engineering and technology. FIRST is developing multiple programs to inspire youth of all

ages. For more information, visit the FIRST web site at <www.usfirst.org>. Or call (Team Contact name and

phone number).

###

394
FIRST TEAM PRESS KITS

Let's get some press coverage!

Page 5

EXAMPLE B: Press Release highlighting sponsors

National Media Contact:

Barbara K. Trevett

(617) 695-6364

For immediate release

[add today' s date]

PRESS RELEASE

Corporate Contact:

[name and title]

(AREA CODE/NUMBER)

[Headline should include sponsoring corporations and universities. For example:]

University and _ Corporation Partner with Students from

__ School to Prepare for Robotics Competition

CITY, STATE, (DATE) -- (Insert number, spelled out) middle and high schools in the (name of region)

will each send their own unique robots into the (location of competition site) contest over the two-day event. The

participating schools are (list):

A number of (name of FIRST region)'s top corporations and universities that have partnered with the

students on a FIRST team, providing their expertise in technology, science and business organization. They

include: (list all corporations and universities, alphabetically):

Founded in 1989 by New Hampshire entrepreneur and inventor Dean Kamen,

FIRST (For Inspiration and Recognition of Science and Technology) is a non-profit organization that brings

together an alliance of business, education, and government organizations through innovative programs to inspire

today's youth in the areas of science, engineering and technology.

Visit the FIRST web site at <www.usftrst.org> or (corporate contact name and number) for more

information about the FIRST Robotics Competition.

###

395
We're Looking for News

Please complete this form and fax to Barbara Trevett of MSA, at 617-695-6366.

Team Name:

Team Member Name:

City:

Team Member Phone:

Local Newspaper Name:

Age: ___

State: _ Zip:

E-mail Address:

Address: City:

Phone: Fax:

Important local TV station names, addresses, phone & fax:

Team Number:

School:

State: __ Zip:

About You

Why are you involved ?

Tell us about you (where are you from? Do you have siblings? Have your siblings been involved

with FIRST?)

396
Whatis yourroleontheteam?

How manyhoursaweekdo youspendworkingontherobot/team?

Haveyoueverdoneanythinglike thisbefore?If yes,what?

If no,wouldyoudoit again?

Is there anything special you would like us to know? Has anything happened (better grades new

career inte_st) as a result of your joining the FIRST team?

Is there anyone else on your team you think has an interesting story to share? Why?

In your opinion, what is the most important part of the robot-building process?

Remember, we are doing our best to find stories for newspaper and television stations.

We'll be sorting through a lot of information - provided by YOU.

Thanks for all of your help! And GOOD LUCK!

397
398
FIRST

Robotics

om ition

\

\

\

\ \

How To Guide

399
Generic Time Line

September

• Select high school

• Teachers all recruited

• Meet regularly to define roles set up student selection criteria

• Applications to join team

• First cut on applications

• FIRST applications due

• Student recruiting presentation to potential new student team members

• Adult professional recruiting

• Determine where the team will meet

• Identi_ and secure equipment

• Secure funding do fundraising

October

Student interviews

Announce students who made the team

Parent meeting; expectations

Distribute SPI catalogs to engineering team

Discuss overall mission and theme for the year

Mentoring packet received from FIRST

November

t Review last year's rule book and FIRST website to gain insight into Ist year deadlines,

Chairman's Award, team logo, tee-shirts, buttons, etc.

• Students selected

• Assign student job responsibilities

• Meet weekly

• Initiate PR contacts

• Fundraising

• Finalize location for robot work

• Finalize playing field location

• Assign team members to monitor websites (FIRST, Teams)

• Safety training

• Team building

• Site preparation

December

Team registration deadline

Meet weekly

Finalize student roles

Engineers all _cruited

Team building exercise

Devise "Table of Contents' for scrapbook/video

Determine purchasing method

Set expectations with adult team members

Make reservations

January

Meet as required: brainstorming

Kickoff- Saturday, January 8, 2000 in Manchester, NH

400
• See'RobotTimeline'

• Team profiles, logos

• Design

• Animation

• PR - follow-up

• Chairman's Award

February

March

April

Meet as required: design, build, test, rebuild

Animation

PR - follow-up

Complete Chairman's Award submission by deadline

Note shipping dates for robot

Team numbers of Regional parties due

Practice

PR - follow-up

Team meetings

Compete in Regional competition

Team numbers for National party due

Compete in Nationals

PR - follow-up

Have a few parties, get some sleep

ROBOT TIMELINE

** Kickoff on Saturday, January 8 **

week 1:

understand game, brainstorm strategy & design, build playing field, post kit parts and

functions

week 2:

brainstorm design, choose concept design, refine concept design, start detail drawings

week3:

mule hardware running, driver/human practice, work on detail drawings, start some

fabrication

week 4:

driver/human tryouts, continue fabrication, complete detail drawings, redesigns

week 5:

driver/human practice, initial robot b.ujld, testing, rebuild, repair, and retest multiple times

week 6:

driver/human practice, rebuild and retest multiple times, paint

401
Chairman's Award

The Chairman's A_vard is the highest award that FIRST bestows upon a team. The award

recomaizes an extraordinary, partnership effort by a team during and beyond the competition

season. The Chairman's Award finalists and winner are selected by a panel of competition judges

based upon a ten minute review of the teams' Chairman's Award submission, team member

interviews, specific judging criteria for the award, as well as format and length restrictions, and

submission deadlines which can be found in the competition manual each year.

The Chairman's Award submission is documentation of your team's 'story'. It is more than a

book or a video, it is documentation of the essence of your team. A good way to approach your

Chairman's Award submission is to treat it as a permanent record of your team through the eyes

of the students. Document team activities that show the partnership you have developed within

your team. Consider including human-interest stories and pictures of team members working

together. Also include team activities which help spread the FIRST message. These can include

things like engagement of a school district, government officials and/or business leaders,

presentations and demonstrations at schools and civic functions, recruitment and mentoring of

new teams, fundraising, design and build phase experience of your team, and community

involvement. Teams will often include things they feel make their team unique. The possibilities

are enaTess!

Documentation of your Chairman's Award submission can be submitted in many forms as

outlined in the current Competition Manual. Creation of the documentation can be an

oppommi_ty to engage students in desktop publishing, digital photography or video production.

Unique is great, but keep it simple; it does not need to be fancy or professionally done to be a

good submission, but it must be well organized and convey your message succinctly. Many

teams in the past have created their submission as a printed document while others have created a

video. There is no right or wrong way to create a Chairman's Award submission as long as it

follo_vs the FIRST _idelines. Approach the creation of your Chairman's Award submission the

same x_ay you approach the building of your robot - develop a plan and follow it. If possible,

make a copy of your Chairman's Award submission to keep for your own records. Some teams

duplicate some or all of their submission to give to their own team members and for team

marketing activities.

When considering v, hether to create a Chairman's Award submission or not, be practical. Think

about all of the activities >-our team will need to do before the ship deadline and the number of

people you have to complete them -- don't commit to something that you cannot follow through

on. It is discouraging to team members who put in the effort if there is no end product.

Every" FIRST team is unique and many go beyond the basic requirements for a FIRST team.

While there is only one team selected as The Chairman's Award winner, every team can get

satisfaction from the things they have accomplished which make them a Chairman's Award

quality team, so if you have the time and the resources, create a Chairman's Award submission --

for >'ourself and for FIRST. The experience of creating this documentation is invaluable.

402
Fundraising

Fundraising is one of the least attractive tasks at first glance and the most difficult for most

teams. Fundraising serves two roles in the development of your team. First the chosen

fundraising activity raises money for some of the expenses your team will incur during the

FIRST experience. Activities such as raffles, candy sales, and car washes are only but a few of

the ideas teams have used successfully. Your chosen activities will depend upon your team,

community, available time and student resources. Start early, have a plan and do not be shy,

always ask for more and give back more to the sponsor than expected.

Second, the fundraising activity serves to bond team members together and give them a sense of

purpose early in the FIRST experience. Earning their own way and contributing to the team

effort is an important aspect of team development that should not be overlooked. Consider

having students participate in fundraising even if your team is fortunate enough to have their

funding fully covered.

Community support is important. Do not overlook sources of funding locally. This includes

additional sponsors and general donations that may include refreshments (for work times),

materials to build with and cash donations.

Media/PR

The FIRST experience has proven to have a positive affect on the lives of the young people in

America, this is a proven fact. Your team's efforts aimed at Media/PR are efforts to let others

know all of the great things that your team has accomplished, while at the same time spreading

the news about FIRST. Articles in local publications, radio and TV spots are but a few examples

of media that can serve to strengthen your team. Doing great things, changing the way education

looks at math and science have more power if others are aware of your activities. Establish strong

bonds with the local media, provide them with interesting angles on your team and its activities

and the effects of your program on the lives of youth. Spread the word!

Marketing

In this instance, marketing is defined as the things a team does to establish its identity.

Marketing efforts result in a team being 'known' for something. This section will attempt to

explain some of the marketing efforts that have been successful for other FIRST teams. This

section will not cover communications or public relations; those are what a team does to promote

its already established identity.

Now the disclaimer: What follows are some ideas that have helped teams establish their

identities in the past. The future has yet to be written, and new teams should not depend on just

these ideas as they establish their'Awn identities!

The way a team acts and looks at events and competitions is a key ingredient of the team's

identity. Some teams have a well-defined schedule of tasks and responsibilities for each

403
(Marketing- continued)

competition.Someteamsdependonkeypeopleto leadimportanteffortswhenthetimeseems

rigjat.Someteamshaveadresscode,withspecificdetailsonwhatisacceptableandwhatisnot.

Someteamsareinstantlyrecognizablebecauseof thewaytheydress!A keyelementingetting

theteamto actasateamisto communicatehetasksandexpectationswell in advanceof the

events.If teammembersknowwhattheteamis goingto bedoing,theyaremuchmorelikelyto

be ableto help.Someideasto help builda consistentidentity: passout a 'roles and

responsibilities' checklist; have team meetings before and after events to discuss the good, bad,

and ugly; make sure the roles of task leaders are clearly defined; make sure everyone knows and

follows the schedule. Some things that past successful teams have done: a well-executed and

well timed cheer, a _oup of seats in the same place every day, a set procedure for the cheering

section before/durinJafter matches, a concerted effort to clean up after each other at the end of

the day.

The goodies that teams give out and trade at events are also part of the team's identity. These

'trinkets and trash' leave others with a lasting impression of the team. They don't have to be

expensive or complicated! Some common trading items include buttons, dog tags, key chains,

and pens or pencils. Some less common items include stopwatches and noisemakers. In addition

to trading items, many teams also give items away. Some common giveaway items are candy,

business cards, cookies, scorecards, team brochures, and, did we mention food? Originality

counts!

The events that a team orchestrates or participates in (at any time of the year) help establish that

team's identity. Perhaps they are known for tutoring middle school students or cleaning up a road

near school. Perhaps they have had some well known fundraising events. Some teams have

floats in parades. Teams should look to their overall mission (yes, teams should define their own

mission!) as a guiding force for what types of events they orchestrate or participate in.

Many teams publish information about their team or about FIRST as a way to inform their

community or start new teams. Team newsletters, team pictures distributed to school officials,

informative _ides on how to make college/career choices, and informative guides on how to

start/maintain FIRST teams are all examples.

Another means of publishing information is a team website. More and more teams find this a

convenient and efficient way to distribute information to anyone who wants it. While it is quite

common for teams to include basic information about school, sponsor, and activities on their

website, many teams go much further. Discussion forums, chat servers, email list servers,

scouting reports from recent regionals, robot pictures, how-to guides on various subjects,

informational articles, upcoming events, and private team-only areas are some examples of useful

website content. Providing a service that other teams need is a sure-fire way to get a popular

website!

404
Travel Coordinator

If possible, identify one person who will coordinate all aspects of team travel. This cuts down on

confusion and duplication of efforts between the school and the corporation.

For air travel, make reservations as early as possible to minimize costs and maximize your

chances of traveling at your desired times. If possible deal with the airlines directly and ask for

group reduced rates. All travelers are required to have photo identification at the airport and will

be required to pass through metal detectors. Each piece of luggage must have a luggage tag with

the owner's name, address, and a phone number. Students should be reminded that airport

personnel will ask all travelers questions. This must be taken very seriously and is not a time for

joking around.

You will need to make ground transportation arrangements to and from the airport. In Florida, if

not staying at a Disney hotel, you will also need to arrange ground transportation to and from the

Competition.

Hotel packages which provide mealarrangements can save you time and in many cases money. It

will make things simpler for you. Many hotels offer buffet or coupon services. Having breakfast

together offers the team an opportunity to start the day together. FIRST often arranges for travel

companies to provide packages, which include room and meals. Make hotel arrangements with

the travel provider or hotel as early as possible.

The hotels and airlines will generally require the finalized list of travelers about 30 days prior to

travel.

Animation

Start your animation team as soon as possible learning the animation software. Have computers

identified and reserved with the animation software installed as soon as possible. Use the most

powerful/fastest computer you can for final rendering. The amount of RAM is critical to the

performance of the computer. Slower computers can be used to create objects and save them to

disk for later import. Practice rendering and transferring to video tape early so that you have time

to work out the process. There are many low cost video cards that have video out and will handle

the process of putting your animation to VHS tape.

Develop a storyboard before starting the animation, and stick to it. Careful planning and

development of the story will save you many hours of work. It is important that you divide the

animation among the animation team maximizing computer time. A calendar of deadlines and the

ship date should be posted as a reminder.

Participation in this competition will allow students to develop skills in design and animation.

This animation is a good opening act for many team activities and demonstrations after the

competition has concluded.

405
Mentor Sign Up Form (send in registration package or email)

FIRST is starting a Team Mentor program this year administered from the FIRST Web site. The

Mentor program is aimed at making the 'FIRST Experience' a little less stressful for the rookie

teams and others needing assistance. Your team can help in this process by agreeing to be a

mentor. As a mentor, your team would be listed on the FIRST web site and in printed material as

a resource.

Please consider being a mentor resource. The amount of time and effort you will provide will

depend on the needs of the team seeking help. Most of all, you will answer questions, give

guidance and direct them to resources available in the FIRST community.

Please send this completed form to Theresa Clement at FIRST. tclement@usfirst.org or call

(800) 871-8326. ext. 432.

Select a main contact for this mentor program.

Main contact information ............................. print please

First Last

Team # Team Name

Phone # ( )

City.

Business

School

Best time for a phone contact:

E-Mail

State

Burnout and Retention

All teams need to be aware that in the course of events, that a change in a team's structure will

allow your team to evolve. Students, engineers, teachers and the roles that they play on a team

o_en fluctuate with the needs of their personal and professional lives. Adjusting to these changes

o_en puts stress on the structure of the team. The community of FIRST will support each other

wi± all the resources 5hat are available. The true power of FIRST is the willingness of teams to

assist each other in difficult times and rejoice with each other in their successes. With this in

mind, we all need to share our expertise and lend a hand to a team that may be having a change in

team structure.

View change as a healthx condition that serves to stren_hen and bind your team.

Ask for assistance if there is a need.

Lend a haad and do wha:ever your team can to assist others.

Understand you are not alone.

Educate e_ers as to the resources that are available.

We all s_ the VALI.-E in a strong FIRST organization.

406
THE CENTER FOR THEORETICAL AND

COMPUTATIONAL MATERIALS SCIENCE

James Warren

Director, Center for Theoretical and

Computational Materials Science

Theoretical Physicist

Metallurgy Division

Materials Science and Engineering Laboratory

National Institute of Standards and Technology

100 Bureau Drive, Stop 8554

Gaithersburg, Maryland 20899-8554

Telephone: 301-975-5708

e-mail jwarren@nist.gov

407
408
409
410
_,_i_ _,,

411
412
LOAD TESTING OF TEMPORARY

STRUCTURAL PLATFORMS

Harvey Abramowitz

Ralph E. Bennett HI, PE

John Bennett (student)

Rick J. Hendrickson (student)

Caris Koultourides (student)

and

Brandon W. Tredway (student)

Department of Engineering

Purdue University - Calumet

2200 169th Street

Hammond, Indiana 46323

Telephone: 219-989-2473

e-mail harveya@calumet.purdue.edu

Walter Kuehariski (student)

Construction Technology

413
Harvey Abramowitz

414
Load Testing of Temporary

Structural Platforms

um_v

_ La4t

Load Testing of Temporary

Structural Platforms

Harvey Abramowitz

Department of Engineering

Ralph E. Bennett 11I, PE

Department of Construction Technology

Engineering Students

John H. Bennett, Rick J. Hendrickson,

Caris Koultourides and Brandon Tredway

Construction Technology Student

Walter Kucharski

415
Background

1. Scaffold Platform is Weakest Link of

Temporary Structure

2. Current Platform Design is Based on

Static Loading

Background (cont)

3. Normal Platform Usage Includes

Application of Dynamic Loads

e.g., Workers Jumping and

Material Dropped onto Structure

416
Needs

1. Develop Standardized Dynamic

Loading Test Procedure

2. Develop Dynamic Loading Design

Criteria

Objectives

For Temporary Structural Platforms, such as

Scaffolding Planks

lo Introduce Student to Concept of

Dynamic Loading, as Compared to

Static Loading

2. Demonstrate a Method for Determining

Dynamic Loading

417
Obiectives (cont)

For Temporary Structural Platforms, such as

Scaffolding Planks

3. Compare Theoretical and Actual Static

and Dynamic Loading Results

4. Develop and Recommend Dynamic

Loading Criteria

Prerequisite Knowledge

The Student

1. Should be Familiar with PC's

o Should be Familiar with Determining a

Stress Strain Curve, and the MOE

(Including Fiexural)

418
Testin A aratus

• Static

• Dynamic

Static Testin A aratus

Vibration Analysis Machine

DynaMOE tm

/

419
420
E d

OF

f2WL3

2.46gi

n

m

f2WS4

2.46glL

421
INPUTS

• WEIGHT

• LENGTH / SPAN

• HEIGHT / DIAMETER

• WIDTH

OUTPUTS

• DENSITIES

• f

• I

• EI

422
423
Conventional

Three Point Test Assembly

Vlew

Fron_ View

Static Testin A aratus

Actual Static Load Apparatus

Tinius Olsen Testing Machine

424
D namic Testin A aratus

Designed,and Built

(Senior Projects)

D namic Testin A aratus

_'EIGHT

=2 h

_k_// .......

_ _HI]IST I = _

;5o+ II

425
Samples Tested

I. Solid Sawn Wood Plank

a. Finish

i. Rough

ii. Dressed

b. Types

i. Southern Yellow Pine

ii. Douglas Fir

Samples Tested

2. Manufactured Wood Plank

a. Veneer Type

i. Horizontal

ii. Vertical

b. Suppliers

i. 3 Manufacturers

426
Manufactured Wood Plank

VariablesTested

Solid Sawn & Manufactured Plank

1. Span 4. Moisture Content

2. Height 5. Stiffness

3. Width 6. Specific Gravity

427
VariablesTested

Load Tests

1. Static Load

2. Dynamic Load

Solid Sawn & Manufactured Plank

Test Procedures

Static-No n destru ctiv e

• Measure Plank Width,

Weight & Length

• Calibrate DynoMoe

Test Apparatus

• Vibrate Plank

• Read & Tabulate

MOE, Weight &

Frequency

Static - Destructive

• Insert Test Platform

into Tmius Olsen

Testing Machine

• Set Platform Span

• Set Deformation Dial

• Calibrate Tinius Olsen

Testing Machine

• Read Applied Load at

Prescribed Deflections

428
Solid Sawn & Manufactured Plank

Test Procedures

Dynamic • Raise Weight

• Inspect Apparatus • Center Plank on Span

• Install Force Link, Force • Set Test Weight at Proper

Link Cable & Moveable Height

Support • Release Weight

• Read & Record Load from

• Set Span Length Peak Meter

• Install & Power Quick • Re-raise weight to

Release Prescribed Drop Heights

• Power Peak Meter & Until Failure Occurs

Hoist • Read & Record Load from

• Calibrate Force Link & Peak Meter Until Failure

Peak Meter Occurs

Results and Discussion

429
T ical D namic Loadin Results

I'=_ ========================= .......4

0 3 6 0 12

_m9 height{in)

FiG.13-5 berr_,ahon of impac.t factor (,) impact load. (I,) Deflechon under impact

!oa.'!. (,i) Dellectlon under _radually applied load _ (,I) Equivalent gradually

3[:I._LI_,{I Io._'l t(J f?lve S()mrcdeflection as _mpa,:t load 'd

430
Equation for Theoretical

Equivalent Static Loads

s =(1 +•/1+ 2h) SsT

¢5' ,ST

Dynamic Loading Results

TABLEI: DYNAMIC LOADING RESULTS

Rank MOE MOtE

DynarTic Static

(xl06psi) (xl06ps0

Southern Rne 1.50-3.00 2.02-2.80

Douglas Fir 1.75-2.60 bid

Horizontal Veneer A 1.97-2.35 ND

Horizontal Veneer B 1.90-1.99 1.872-2.050

Vertical Veneer 1.75-2.42

biD:.Not Deterrrined

Density Moisture Ratio

Content Experimental/

(IbJin 3) (%) Theoretical

.020-.029 10.00-13.00 1.41-2.21

ND 11.00-12.50 1.51-2.67

.024-.026 12.50-16.50 1.52-1.88

0.019 14.50-16.00 1.22-1.60

1.975-2.403.021-.026 9.25-12.75 1.40-1.65

Thickness 1.50-1.63 in

Wr_tln 9.06-11.75 in

Length 96.00-145.13 in

431
Ratios

Experimental/Theoretical

Range

1.1-2.4

Results and Discussion (cont)

Manufactured wood planks have less

variable stiffness characteristics

than solid-sawn scaffold planks.

432
Results and Discussion (cont)

• Manufactured wood planks have a

more predictable ultimate failure

load range than do solid sa.wn

planks.

Results and Discussion (cont)

• Laminated joints or laminated

veneer placement in manufactured

planks, like annular rings spacing,

knot size and placement of solid

sawn scaffold planks, proved to

affect specimen dynamic resistance.

433
Dynamic Loading Criteria

Recommendation:

Safety Factor > 3 _

to Prevent Failure

Summary

Concept of Dynamic Loading Introduced

• Method for Determining Dynamic

Loading Demonstrated

• Comparison of Equivalent Static and

Actual Dynamic Loads Made

A Safety Factor of at Least 3 is

Recommended as the Dynamic Loading

Criteria

434
NON-LINEAR ACOUSTIC SYSTEM

FOR DAMAGE ASSESSMENT

Yulian Kin

Purdue University Calumet

Hammond, Indiana 46323

Telephone: 219-989-2684

e-mail kin @hwi. ¢alumet.purdue.edu

and

Alexander Sutin

Eric Roades

Karen Dalton

Kimberly Bateman

435
Yulian Kin

436
Non-Linear Acoustic System for Damage Assessment

Yulian Kin

Alexander Sutin

Eric Roades

Karen Dalton

Kimberly Bateman

Key Words:

Fatigue, fatigue damage, crack, non-destructive fatigue testing, non-linear acoustic

instrumentation

Prerequisite Knowledge:

Fatigue crack propagation

Basic understanding of oscilloscopes and function generators

Failure prediction techniques

Objective:

Damage assessment on the basis of wave modulation change.

Equipment:

1. Digital Oscilloscope with FFT capabilities

2. Digital Function Generator

3. Piezoelectric Ceramic Sensors (Disc, 10mm by 2mm)

4. High Pass Filter (20-40 kHz cutoff)

5. Striker

6. BNC to Alligator leads

7. Test Specimens, damaged and undamaged (for reference)

Introduction:

This project is based on a nonlinear acoustic approach to damage detection. This

approach is based on the fact that cracks, surface flaws, disbonding or other damage have

high nonlinear elasticity. This causes nonlinear acoustic responses, especially the

modulation of an ultrasound wave passing through a crack [1]. These responses were of

particular interest in the conducted experiments.

In these experiments, the specimens were induced with a high frequency ultrasonic wave

and a low frequency vibration, and the interaction modulation provided a reliable

measure of the quantity of the accumulated damage. This method is known as nonlinear

wave modulation spectroscopy (NWMS) [2]. The physical nature of this modulation can

be explained with the help of a simple model. Consider the sample in Fig 1, with a single

crack as the only flaw. The method uses the interaction of a high-frequency ultrasonic

signal, transmitted through the part, with the low-frequency vibration of the part. The

low-frequency vibration alternates between compression and dilation of the flaw.

Suppose the ultrasonic signal has a frequency at least an order of magnitude larger than

437
the low-frequency signal, and that the amplitude of the low-frequency vibration is

sufficiently large to close the crack during the compression phase (Fig. 1a), and to open it

during the subsequent tension (Fig. lb). During the dilation phase of the low-frequency

cycle, the high frequency signal is partially decoupled by the opened crack. This reduces

the amplitude of the high-frequency signal that passes through the crack. During the

other half of the low-frequency cycle, the signal produces compression and the crack is

closed. The closed crack does not decouple the ultrasonic signal and the amplitude of the

transmitted signal increases. This results in amplitude modulation of the ultrasonic signal

as shown in Fig. 2; i.e. observation of low amplitude during the dilation part of the lowfrequency vibration signal and high amplitude during its compressive phase. Fourier

transformation of this signal reveals sideband frequencies that are the sum and difference

of the frequencies of the ultrasonic and vibration signals. The presence of these new

frequency components is a clear sign that a flaw or crack is present.

,f¢;a>_ .t_ :.

f.,i!i:'i_:2?

b

L

Figure 1. Crack Behavior Under Low

Frequency Vibration (a) in compression

Co)in tension.

T!

b

Figure 2. Amplitude modulation of probe

signak (a) vibration, (b) ultrasonic signal.

Specimen:

Tests were conducted on three Ford Alternator Housings. (Figure 3) Two of the

housings exhibit damage, one visible and one not apparent to visual inspection. The third

housing is undamaged and is used for reference purposes.

Figure 3. Ford Alternator Housing (test specimen).

438
Experimental Setup:

The basic electrical setup of the system is shown in Figure 4. A signal generator,

generating a sine wave signal is connected to an input sensor attached to the specimen. A

constant high frequency sinusoidal wave is inputted. A second, output, sensor on the

specimen is connected to the oscilloscope through a high pass filter. The impact from the

striker or firing mechanism induces low frequency vibration into the specimen. The

striker is equipped with a sensor used for synchronization with the digital oscilloscope,

which conducts spectral analysis of the received signal.

Signal

generator I

synchronization

Oscilloscope I

IHi!h,Pass FilterI

I

Sample

Figure 4. Electrical Schematic

Figure 5. Current Lab Setup. Figure 6. Mock-up of future instrumentation.

Observations:

It can be seen that the modulation (high level side components) takes place just after the

impact in the damaged specimen. (Figure 7) The undamaged specimen has no such side

components. (Figure 8)

439
1-ScL-Ot

1H:4l:44

! ,

.......i.............. !.....i........

[1 i I ..........,dt, , .....

2.5 _Is

5¢DW TRI_EA

NOR_L

Figure 7. Spectral analysis of the sample

with a tiny crack

:-Oct-81

16:33:49

_.:P5 (F_T(1) )

i] .[ V _(2

2 : v

: I * i

: F _ F

.............................. I....I •

....... il................. _ Ii........ IE

L I ! i

_ 7.e ms

2.5 _,'s

Figure 8. Spectral analysis of intact sample.

Applications:

The NWMS experiments, described and demonstrated here, possess two significant

benefits for detection of nascent damage. First, its sensitivity to damage is orders of

magnitude greater than competing techniques. Second, its ability to examine the entire

part at one time allows rapid and efficient testing of complex specimens. The possible

applications of this method are the observation of fatigue damage in buildings, bridges,

aircraft, automobiles, etc. This technology would allow for more accurate maintenance

schedules, safer supports, and preventative repair measures of the damaged structures.

References:

1. Didenkulov I.N., Sutin A. M., "Nonlinear Acoustic Technique of Crack

Location," American Institute of Physics Conference Proceedings, no. 524,

pp.329-332, 2000.

, Chudnovsky A., Kin Y., Sutin A. "Non-Linear Acoustic Technology for the

Investigation of Structure Damage". SEM Annual Conference on Experimental

and Applied Mechanics, Portland Oregon, # 184, 2001.

. Sutin A. "'Quantitative Nondestructive Evaluation in Reliability Assessment of the

Aging Aircraft Structure Components". Smart Material Design Inc., Highland

Park, IL. Report, F49620-99-C-0038. 2000.

. Kin Y., Sutin A., Chudnovsky A. "Non-Linear Acoustic Instrumentation for

Detection of Damage in Aging Metal, Plastic, and Composite Structures". Eighth

Annual International Conference on Composites Engineering, Tenerife Canary

lslands, Spain, 2001.

440
MOTORLESS MOTION WITH NiTi:

A SENIOR DESIGN PROJECT

Suzanne Keilson

and

Robert Redfield

Department of Electrical Engineering and Engineering Science

Loyola College

4501 North Charles Street

Baltimore, Maryland 21210

Telephone: 410-617-2722

e-mail skeilson@loyola.edu

and

Michael Guarraia

currently at Lockheed Martin Corp.

441
Biographies:

Michael Guarraia graduated from Loyola College in May, 2000 with a degree in Engineering

Science specializing in Materials Science, and is currently employed at Lockheed Martin

Corporation and is pursuing his MBA at Loyola College.

Robert Redfield graduated from Loyola College in May, 2000 with a degree in Engineering

Science specihlizing in Materials Science, and is pursuing a medical career.

Suzanne Keilson, assistant professor, at Loyola College since J994, has worked in various areas

of materials science, including point defects in crystals and biomaterials. She also does research

in biosensory systems (the auditory system) and signal processing.

442
Motorless Motion with Ni-Ti: A Senior Design Project

Michael Guarraia*, Robert Redfield, Suzanne Keilson

Electrical Engineering and Engineering Science

Loyola College, Baltimore, MD

*currently at Lockheed Martin Corp.

Key Words: Nickel-Titanium alloy, shape memory alloys, senior design, motorless motion,

robotics, biomechanics

Prerequisite Knowledge: Knowledge of basic materials science, electronics and mechanics. An

introductory materials science course covering phase transitions and alloys. In addition,

undergraduate courses in mechanics and electronics and some review in biomechanics and

robotics would prove helpful.

Objective: To understand the interaction between design, design criteria and materials

properties. Design of an application based on a materials property study/exploration. Can be

used as both a "cookbook" lab to build and understand some basics of mechanics, materials, and

electronics in the context of a robotics application, or in a more open-ended form to explore the

interrelationship between design, design constraints, and materials properties.

Equipment and Materials:

Erector Millenium ®set:

screws, nuts, frame members, plastic spacers

Ni-Ti wire:

Dynalloy ® NITINOL (8 meters)

Electronic components:

Resistors (15 ohms), batteries (9 volt), switches (single pole double throw, one for each

robot digit), circuit board for mounting, sheet metal box to contain circuitry, Dremel® tool

cutter, rubber bands and/or biasing springs, two-part epoxy

Introduction:

Design course:

The senior design capstone course at Loyola College is intended to be a culmination of

undergraduate coursework. All students in both the electrical engineering and engineering

science programs take the same course and learn project management and professional skills

together. The design project should consider realistic engineering constraints such as cost, time,

manufacturability (such as the ability to solder parts together), and power consumption. From

the students' perspective, some of the project goals include gaining a more thorough

understanding of a material and its properties (based on theoretical knowledge and current

manufacturing practice), to design a socially benefcial project, and to construct a working model

443
under the aforementioned constraints. The budget constraints are $400 for the design team and

the time constraint is that all work, beginning in September, is completed by the end of April.

The goal of this project was to develop a senior design project around the principle of

motorless motion utilizing the shape memory properties of a Nickel-Titanium (NiTi) alloy.

Ultimately, this was incorporated into a working prototype of a three-fingered robotic hand.

The material (NiTi):

NiTi or NIT1NOL (named for the alloy development at the Naval Ordinance Laboratory)

has been getting increasing attention in a number of applications including eyeglass frames,

fishing lures, cellular phone antennas, medical guide wires, and surgical tools. The particular

alloy composition that is generally used is 55 weight % Ni and 45 weight % Ti. The crystal

structure of NiTi is the B-2 structure, and is similar to the BCC structure, but with two differing

atoms in the unit. The nickel atoms are on the cube corners and the titanium is in the center of

the unit cube (Figure 1).

The NiTi alloy exhibits two very unique properties that have great potential for

application. The first is superelasticity. This is the ability to undergo excessive stress (to the

point of substantial elastic deformation) without plastic deformation. It is also called mechanical

memory, whereby the deformed part returns to its pre-deformed or constrained shape upon

release of the stress, The other unique property of NiTi is the shape memory effect. This is the

ability to return to a predetermined shape by heating the material. This is also sometimes called

thermal memory. These effects are achieved via a phase transformation (Figure 2). At the

relaxed or low temperature state, the material is in a martensitic phase; upon heating above a

critical temperature the NiTi goes into an austensitic phase (high temperature form). The

recursive phase transformation returns the structure to its original mechanical configuration.

Design Project:

During the brainstorming sessions, some project ideas that were generated included using

the superelastic properties of NiTi for its dynamic qualities in rock climbing gear, using the

shape memory effect for safety devices such as sprinkler systems or in valves, or snake-like

flexible objects. The actuation of the NiTi was seen to be similar to the action of human

muscles. It is well known in biomeehanics that muscles act in pairs, as one element of the pair

contracts the other extends to create the appropriate smooth control of motion around a joint.

The tendons are the whitish tissue that attaches the muscle to the bone and the muscle will

usually wrap itself over the joint. As the muscle contracts, force is exerted on the joint forcing it

to move or rotate. These same principles ofbiomechanics were applied in this design project.

An anchoring point, joint design, and biasing spring were some of the necessary elements to

create a potentially useful robotic part (Figure 3).

The final project idea was a three-fmgered robotic hand. Many researchers are intrigued

by the far-ranging potential of robotic applications. What makes this example so interesting is

that no gears, hydraulics or motors are used for actuation of the moving parts. Some of the

advantages to this design, which relies on a materials property of the NiTi alloy as compared

with more conventional mechanical designs, are its high strength-to-weight ratio, small size,

silent operation, low power requirements, easy maintenance, and potential biocompatibility.

Additionally, NiTi possesses very good corrosion resistance. The alloy forms a thin oxide layer

(TiO2) on the exterior, which is more corrosion resistant than stainless steel. It is already in use

as surgical equipment, so its use in prosthetic devices is certainly a possibility as well. As with

444
other robotic designs, this would also have the advantage of being able to work in extreme

environments for extended periods of time 1.

Most of the design specifications were determined through a combination of extensive

experimentation, trial and error, and literature and web research. From the basic information

about the material, it was known that upon receiving a specified amount of current, which causes

heating, the NiTi contracts as its phase changes. Key design issues were the diameter and length

of wire, and the amount of current required for resistive heating (which would cause the

necessary phase transformation, thus inducing contraction and movement of the robotic part).

The percent composition of the alloy determines the percent shape change, which in turn

determines the total movement of the robotic fmger. For the material purchased for this project, a

maximum length change of 6.6 % was observed. Geometric parameters of the design such as

minimum bend radius and the corresponding minimum radius of the pulleys were set to avoid

fatigue and destruction of the alloy matrix.

The final design used 150 _trn diameter Dynalloy ® NiTi, requiring a current of

approximately 0.4 amps to fully contract the wire. The fmger members were constructed from

an Erector ® set. The mechanical properties of the metal and plastic spacers from the set played

an important role in the final design, as discussed in more detail in the procedures section. The

design evolved through a number of iterations in order to achieve some desired level of

performance.

Testing was necessary in order to f'malize design parameters 2. One of the tests performed

was for the thermal characteristics of the plastic spacers. They were used for the pivot point of

the joint. The NiTi, upon applying a current, heats up to 70 °C, a sizeable thermal challenge for

plastic, which also must withstand repeated heating cycles for the lifetime of the robotic part. A

conservative test was performed in which the spacers were placed in an oven and placed under

load, edge on (diametrically). All spacers withstood an environment of 90-95 ° C for 10 minutes

with no observable deformation, even under a load of 52.1 grams. Another test that was

performed was a radial strength test of the finger and pivot joint configuration. This was done to

get an idea of how strong the individual robotic fingers would be. The design was able to

achieve a maximum 50 degree rotation of the joint upon joule heating with a load of 70 grams

and a maximum 90 degree rotation with a 10 gram load.

A working prototype was meticulously constructed giving the students great satisfaction

3

and meeting all of the design criteria and learning objectives (Figure 4).

Procedure:

To duplicate the process of building a robotic hand, one starts with a single "fmger" or

digit. Some examples of the early design evolution of the project are shown in Figure 5. A

single finger with a single hinged joint consists of four frame members used in pairs to create

two segments attached at the hinge joint. A segment is made by two frames held together by

screws and nuts and separated by plastic spacers. For each such finger, a complete electrical

circuit must be created. The NiTi wire is fixed at the proximal spacer (attachment point to the

base of the "hand") and runs to the hinge joint. A groove should be cut in a plastic spacer to

accommodate one end of the loop of NiTi wire, which is then secured with epoxy into the

groove 4. This plastic spacer, residing in the hinge joint must be rigidly fixed to the distal

segment, but free to spin about the screw axis, in order to insure rotation of that distal segment

445
(Figure 6). In the final design a rubber band provides the restoring force (acts as the

complementary muscle in the muscle pair), and wraps around the entire digit.

When the NiTi contracts under heating, the wire, which is fixed to the outer diameter of

the plastic spacer, creates a torque around the axis of the spacer. If the distal segment is rigidly

attached to the spacer, it too will rotate in response to that torque 5. This is what gives rise to the

gripping or grasping motion of the fingers. When the current is turned off and the NiTi wire

relaxes to its original length, the rubber bands (or biasing springs) supply the force to rotate the

distal segments back to their original positions, releasing the "grasp" of the robotic hand. The

basic circuitry is very simple, with each finger employing its own mechanical switch placed on

the sheet metal box and a simple resistor (15 ohms) and battery (9 volts) connected in series in

the NiTi wire loop (Figure 7). When the switch is thrown and the circuit is closed, current flows,

thereby heating the NiTi. No safety or automated options were placed in this initial prototype.

The operator must open the switch to prevent the wire from overheating or damaging the spacers.

No attempt was made to coordinate the operation of the digits. These are all possible extensions

to the basic design 6.

Comments and Instructor Notes:

1. Another possible environment to employ the NiTi robotic hand is in a clean room, especially

for silicon wafer and IC manufacturing.

2. This also helps to emphasize the point that the design process is an iterative one, and that

testing plays a crucial role in product development.

3. Total expense report for the project was $273.

4. Great care must be used with the plastic spacers and the wrapping of the NiTi wire. When the

finger is loaded and the current is increased, the plastic spacer can be cut or damaged.

5. Due to the constraint of the percent contraction of the NiTi, a direct attachment of the wire to

the distal segment would only have resulted in a small radial motion about the joint. With this

design about 70 degrees of rotation is achievable. This is applying a mechanical principle akin

to that of gearing ratios. By attaching the NiTi to a small diameter spacer, you can achieve

maximal rotational output for that percent length change.

6. Several possibilities for design expansion and projects exist, such as more complicated joints

and robotic action, and utilizing a computer or digital interface to control the circuitry. The

robotic hand could also be put under remote or radio control. Variable contraction and feedback

systems could be explored to control the grip of the robotic hand to enable it to pick up objects of

varying weight, size, and fragility.

References:

Duerig, Melton, Stockel, and Wayman. Engineering Aspects of Shape Memory Alloys. Boston:

Butterworth-Heinmann. 1990.

446
Porter, Easterling.

1992.

Web sites:

www.dynalloy.com

www.sma-ine.com

www.nitinol.com

Phase Transformations in Metals and Alloys. New York: Chapman & Hall.

Acknowledgements:

Thanks to Dr. Robert Pond Jr. for his invaluable editorial and teehnical input.

Figure 1 B2 structure of NiTi alloy

Nickel

Titanium

447
Fig. 2

_,*,,r -,¶._,'C_ -'*r "_," '_'--',_.' _'_ ' L

_..t.#+++_4. 4.++

lOuerig, Melton,_ockel, Wayman. EngineeringAspects of _h_pe Memo_yAlloys. Boston:Butterworth-Heinemann. 1990. (p. 11)

Forearm Flexors

(inner Head:

Figure 3. Analogy between biomechanical operationof a muscle and NiTi robotic action.

NiTi

I ° I

Contraction upon heating

Joint

448
Figure 4. Photos of prototype robotic hand. Different views.

Figure 5. Some examples of the design evolution of the robotic digit.

A55Y : #_

J=/3/9_

t I

449
Figure 6. Schematic of final design of a single "digit". Securing wire around the plastic spacer

allows for more angular motion of segment (yellow arrows) for a given length change of NiTi wire.

Steel Erector Set

Members

Plastic Spacers

NiTi

Figure 7. Electrical circuit for control of NiTi phase transition. Note that current is only at 75% of

the current for maximum contraction (0.4 amps).

switch

\

.1

9V

15 Ohms

x

0.3 A

NiTi wire loop to digit/plastic

450
AN INSTRUCTIONAL SOFTWARE

PACKAGE ON FTIR SPECTROMETRY

Leonard W. Fine

L. Avila

and

B. Venkataraman

Department of Chemistry

Columbia University in the City of New York

Havemeyer Hall

New York, New York 10027

Telephone: 212-854-2017

e-mail f'me @chem.columbia.edu

451
Leonard W. Fine

B. Venkataraman

452
AN INSTRUCTIONAL SOFTWARE PACKAGE ON

FTIR SPECTROMETRY

L. AVILA, L. FINE AND B. VENKATARAMAN

Department of Chemistry, Columbia University, NY, NY 10027

We have developed an interactive software package on the theory and practice of

spectrometry. While the focus of the package is on an experimental technique us_

chemical analysis, the mathematics, physics, and engineering of the technique are

emphasized. In particular, the package illustrates how the Fourier transform and

interferometery are combined to extract spectral information from interferograms.

After introducing the Fourier Transform with illustrations and applications drawn fro

different fields (e.g. music and medicine), the software turns the user's attention to

question of how the Fourier Transform and interferometry work together in recordir

infrared spectrum. It starts by showing how the Michelson Interferometer is used t_

determine an absorption spectrum with a monochromatic light source. From there

expands to a two-frequency light source and then to a polychromatic light source sl

how the principles are the same, just that the interferogram gets more complex. Is

related to resolution and optimum usage of apodization functions are also discuss_

Where possible, interactive animations have been included to help explain concepl

example, in a section contrasting a dispersive spectrometer with an FTIR spectrorr

user "walks" through the instrument with the components "clickable" to view additio

information or simple animations on the working principle of the component.

453
454
SUBSTRATE ANALYSIS

GRIT BLASTING

Rodney D. Jiggetts

Metallurgy Division (855)

National Institute of Standards and Technology

100 Bureau Drive, Stop 8555

Gaithersburg, Maryland 20899-8555

Telephone: 301-975-5122

e-mail rodney.j iggetts@nist.gov

F. Biancaniello

S. Ridder

S. Mates

M. Stoudt

R. Schaefer

P. Boyer

455
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470
THE DYNAMIC YOUNG'S MODULUS

R. E. Smelser

E. M. Odom

and

K. V. Organ

Mechanical Engineering Department

University of Idaho

Moscow, Idaho 83844-0902

Telephone: 208-885-4049

e-mail rsmelser@uidaho.edu

471
iiiiiiiiiiiiiiiiiiiiiiiiliiiiii

Ron Sinelser

RONALD E. SMELSER

Ronald E. Smelser is a Professor of Mechanical

Engineering at the University of Idaho. He holds a

Bachelor's degree from the University of

Cincinnati, a Master's degree from MIT, and a Ph.

D. from Carnegie Mellon University. Prior to

joining the faculty at the University of Idaho, he

worked for fourteen years at U. S. Steel, Alcoa, and

Concurrent Technology Corporation. He currently

teaches the mechanics, materials, and Sophomore

Laboratory courses and is involved with the Idaho

Engineering Works (IEW). The IEW is a group of

graduate students who develop leadership skills

through mentoring the Senior Design progra_

under the tutelage of faculty. His interests include

materials process' modeling, structure-property"

relations of materials, and material failure and

fracture. He is a member of ASME, ASEE, and

AAM. He has published numerous papers on

materials processing and fracture and has

contributed to the ASEE Annual Conference.

EDWIN M. ODOM

Edwin M. Odom, an Associate Professor of

Mechanical Engineering at the University of Idaho,

obtained his undergraduate and graduate degrees

from the University of Wyoming. His interests

include experimental mechanics and the design

process. Dr. Odom joined the University of Idaho

in 1992 and takes an active interest in the ME

Machine Shop as a key element in design education.

The ME department benefits enormously from his

experience in the US Army at the Material Test

Directorate as well as his experience as a gas

turbine design engineer for the General Electric

Company. Dr. Odom developed the Sophomore

Laboratory. He also maintains an avid interest in

the subject of creativity and management and is a

recognized leader in the areas of team dynamics and

leadership styles. He was recognized for his role in

the development of the Senior Design program and

the IEW by a university teaching award in 1998.

K. V. Organ

Kevin V. Organ is a candidate for the Master of

Science Degre e in the Mechanical Engineering

Department at the University of Idaho.

472
THE DYNAMIC YOUNG'S MODULUS

R. E. Smelser, E. M. Odom, and K. V. Organ

Mechanical Engineering Department

University of Idaho

Moscow, ID 83844-0902

Key Words: Young's Modulus, Pendulum, Bending, Moments of Inertia

Prerequisite Knowledge: A knowledge of statics and a curiosity to learn.

Objective: The elastic modulus of a material is of primary importance in mechanical design.

The determination of this modulus for thin rods is quite difficult. Traditional methods using

strain gages or extensometers are problematic. Applying strain gages around small diameter rods

is difficult. Extensometers can be damaged and can bend the thin rods when mounted on them.

The experiment measures the elastic modulus of thin rods using the principles of dynamics.

This experiment employs a simple apparatus to determine a fundamental property of

engineering materials. The experiment provides a rich ground for introducing and discussing the

difference between mass moments of inertia and area sectional properties. The analysis of the

experiment also offers an opportunity to explain engineering approximations and how to validate

the approximations.

Equipment and Methodology: We employ two torsional pendulums connected by a thin rod to

determine the elastic modulus of the rod, Fig. 1. The pendulums are set into a small amplitude

vibration in a horizontal plane. The pendulums place the rod in pure bending. The moments that

bend the rod are related to the geometry of the deformation and the elastic modulus through the

moment - curvature relationship. The moments created by the rod on the pendulums determine

the period of the vibration of the pendulums. The period of vibration is easily measured with a

stopwatch. The oscillations are a function of the applied moment and the mass moment of inertia

of the pendulum. The coupling of the two systems allows the determination of the elastic

modulus of the rod. The details are explained in the following experiment.

Figure 1. The torsional pendulum apparatus.

473
THE DYNAMIC YOUNG'S MODULUS

Introduction:

One of the most common design requirements for engineered structures is an elastic

response. An elastic structure returns to its initial geometry when the force is removed. To

achieve this response, a designer often uses the Young's modulus or the elastic modulus to

design the structure. Young's modulus is a material property that linearly relates the material

stretching to the force that causes the stretching or deformation. If the material obeys this linear

relationship, we call the response linearly elastic or simply elastic. Why is this desirable in

design?

The material deformation is described using a computed quantity called strain, e. The

material deformation, d, is the difference between the specimen length before the load is

applied, L,, and after the load is applied, L I . The ratio of the deformation to the initial length of

the specimen, L_, defines the engineering strain. The force, F, causing the deformation is

usually divided by the initial cross-sectional area of the member, Ai, to give the engineering

stress, o-. Can you think of reasons why engineers use these definitions for stress and strain?

Ly -L, 6 F

- - or= (1)

L i L, A i

The Young's modulus, E, relates the stress to the strain linearly.

cr=Ee (2)

This linear relationship together with Eqs (1) allows designers to predict the amount of

elongation of a part subjected to a certain amount of load. It also allows the determination of the

load if the part is to only deform by a known amount. Be sure that you can useEqs (1) and (2) to

show this.

Objective:

The objective of this experiment is to determine the Young's modulus of wire-like

specimens of engineering materials using a torsional pendulum device.

Laboratory Equipment:

1. Torsional pendulum apparatus.

2. Stopwatch.

Procedure:

The following figure shows a plan view of a torsional pendulum device. The specimen

that is being studied is attached between the two arms of the pendulum device. The specimen is

long compared to its cross section. The specimen is bent into a circular arc. These are

474
FSpecimen

a

/

i

P

Plan View of the Torsional Pendulum

characteristics of a beam. In Mechanics of Materials, you will study the deformation of beams

and the way that they are bent. Many relationships will be developed. One important

relationship that relates the bending moment, M b, the elastic modulus, and the geometry is

M b = EIA (3)

P

This is the moment-curvature relationship, p is the radius of curvature of the deflected beam,

and I A is the area moment of inertia of the cross section about the neutral axis of bending. For a

beam with a circular cross section, the area moment of inertia is

I A = JAyZdA = lzcr ' (4) 4

Statics tells us that there is an equal and opposite moment, Mr, to the bending moment

M b acting on the pendulum arm, M, = -M e . This moment acts to restore the pendulum arm to

its original position. From elementary physics, we know that Newton's Law of Motion tells us

that forces on bodies produce accelerations, F = ma. There is an analogous relationship for

moments.

M = I,,a (5)

In Eq. (5), 1,, is the mass moment of inertia, and _z is the angular acceleration. The mass

moment of inertia for rectangular bars oriented as shown in the figure is

475
I m =Lr2dm =lm(a2 +c _) (6) 12

Here, m is the mass of the pendulum arm, and the dimensions of the arm are shown in the

figure. You will study Eq. (5) in more detail in dynamics.

The angular acceleration is related to the angle of rotation by

d20

a = (7)

dt 2

Combining Eqs (3), (5), and (7) and recognizing that M = M, = -M b , we have

d20 EIa

I n = M r = -M b = _

dt 2 p

(8)

The minus sign shows that the moment produced by the beam on the pendulum arm acts to

restore the arm to its initial position. The radius of curvature can be eliminated fromEq. (8) by

using geometry. The neutral axis of bending does not deform, and the length equals the

specimen length. The specimen length, l, is related to the radius of curvature by the arc length.

l = 2pO (9)

We can rewrite Eq. (8) as

d20 - 2EI A 0 (10)

dt 2 I,, l

This is the differential equation for a simple harmonic oscillator. You will study this in more

detail in your differential equations course. The period of oscillation, T, is

T = 2_r [ Iml

2EIA

(11)

Rewriting Eq. (11) gives the elastic modulus as

(12)

To fred the Young's modulus, you will measure the time required to complete

approximately 50 oscillations of the pendulum. This will need to be done several times to give

reliable statistics for the period of oscillation. The period of oscillation is

476
total time

Ttotalcycles

Why do we need to make multiple measurements for the period? How can you characterize the

quality of your data?

Laboratory Write-up:

Follow the instructions for writing a quality laboratory report. How do ,,'our values for

Young's modulus compare with the values provided in a standard reference for elastic properties?

Also find two other sources for Young's modulus. Are the various sources consistent? How well

should they compare? You measured r, a, c, m, and T during this experiment. An error in

which of these would cause the most error in the resulting calculation of Young's modulus? Include

the answers to all the questions posed throughout the laboratory description in your report.

Data Sheet

Data that you will need before you begin the experiment:

Specimen Steel Wire

Radius of the wire specimen, r, 0.092/2 in

Length of the wire between pendulum arms, l,

Mass of the pendulum arm, m,

Length of the pendulum arm, a,

Width of the pendulum arm, c,

12in

Period of Oscillation, T

Trial

1

2

3

4

Average

Std. Dev.

Time (see)

95

49

25

58

Oscillations

(cycles)

100

50

25

6O

Period

(sec/cycle)

0.95

u 0.98

1.00

0.97

0.98

0.02

Elastic

Modulus (GPa)

208

215

219

212

214

4.3

477
Comments:

1. A secondexperimentwasconductedon a 0.062 diameter steel rod. The period of oscillation

was 2.2 seconds. This gave a modulus of 208 GPa.

2. Figure 1 shows the torsional pendulum apparatus. The design using the dumbbell-shaped

arms allows the device to be compact and keeps it on a scale suitable for a tabletop device.

° The experiment shows the difference between area moments of inertia and mass moments of

inertia. This encourages the discussion and understanding of these two important measures

in mechanics and provides concrete examples of these difficult concepts.

. The dumbbell-shaped arms also allow a further discussion of the parallel axis theorem. This

is often only briefly discussed in introductory mechanics courses. The dumbbell arms also

allow for easy adjustment of the period of oscillation for specimens of different dimensions.

Different end weights allow easy adjustment of the mass moment of inertia.

° It is recommended that the students measure the weight or mass of the components that

comprises the pendulum arms. This, together with the part dimensions, allows the

computation of the mass moment of inertia. It is important for students to understand that

one should not simply take density values from textbooks and use that together with

dimensions to calculate mass. Errors can result in the modulus calculations since the

textbook values are averages.

, The apparatus demonstrates the fact that the wire specimen is inextensible. An initial

prototype was constructed using instrument bearings to support the pendulum arms. The

beating supports introduced a severe damping into the system. The damping was the result

of the wire trying to move the bases that held the bearing needles. The bearings would have

been successful if the nodes of the vibrating wire were located on the pivots. This is not

practical given the requirement to accommodate various wire sizes. We use nylon fishing

line connected to lure swivels to accommodate the small inward motions of the oscillating

pendulums. This also gives an extremely low friction suspension of the arms.

. The connection of the wire to the apparatus has also proved to be a challenge. The

connection must ensure the theoretical boundary condition of a fixed end on the specimen.

The fixed end condition is only approximated by a setscrew or a similar attachment. The

lack of complete constraint can be handled by using an effective length of the wire in the

theoretical development. The determination of an effective length is difficult. We have

found that one solution is to embed the wire and attach it with solder in a bolt with a drilled

hole. This is shown in the following figure.

478
8. Pro/ENGINEER®drawingswill be suppliedon requestfor a smallfeeto coverthecost of

reproduction.

Bibliography:

1. F. P. Beer and E. R. Johnston, Jr. (1997) Vector Mechanics for Engineers, Statics and

Dynamics, Sixth Edition, WCB McGraw-Hill.

2. R.A. Serway and R. J. Beichner (1999) Physics for Scientists and Engineers, Fifth Edition,

Saunders College Publishing.

3. G.F.C. Searle (1933) Experimental Elasticity, Second Edition, Cambridge University Press.

479
480
CASE STUDY: USING A NEURAL NETWORK TO

IDENTIFY FLAWS DURING ULTRASONIC TESTING

A. Kayabasi

Glenn S. Kohne

and

P. J. Coyne, Jr.

Loyola College in Maryland

Department of Electrical Engineering and Engineering Science

4501 N. Charles Street

Baltimore, Maryland 21210

Telephone: 410-617-2249

e-mail kohne@loyola.edu

e-mail pcoyne@loyola.edu

481
Alp Kayabasi is a Lead Technical Specialist at United Parcel Service Information

Services in Timonium, Maryland. He has a bachelor's degree in Electrical Engineering

from University of Maryland at College Park, a master's degree in Engineering Science

from Loyola College in Maryland and a master's degree in Electrical Engineering from

University of Maryland Baltimore County. He is an adjunct faculty member at Loyola

College and Towson University.

Mr. Glenn S. Kohne earned his BSEE (High Honors) at the University of

Maryland in 1970. He completed his MES in Digital Systems at Loyola College in 1981.

He worked as a Lead Electrical Engineer with Raytheon Co. in

Massachusetts, served as a Lieutenant Commander in the USPHS for 10 years,

and is currently an Associate Professor of Electrical Engineering at Loyola College.

His interests include teaching, developing educational software, and flying.

Paul J. Coyne, Jr. is a Professor of Electrical Engineering and Engineering

Science at Loyola College in Maryland. He has bachelors and master's degrees in

Electrical Engineering from the University of Delaware. He received his Ph.D. in

Applied Sciences-Metallurgy/Materials Science also at the University of Delaware.

Further information on teaching and research activities is available at his homepage,

http://eees.loyola.edu/-coyne/.

482
Case Study: Using a Neural Network to

Identify Flaws during Ultrasonic Testing

A. Kayabasi, G. S. Kohne and P. J. Coyne, Jr.

Loyola College in Maryland

Department of Electrical Engineering and Engineering Science

Baltimore MD 21210-2699

Key Words: neural networks, ultrasonic nondestructive evaluation.

Prerequisite Knowledge: A basic exposure to windows based applications to operate the

program, NeuraIM, and a mathematical background which includes elementary calculus and

linear algebra.

Objective: The construction of a neural network implemented in software which can be trained

to classify objects based on certain features and then when presented with new objects to classify

them based on previous experience.

Equipment and Materials:

1. A personal computer using the Windows 95/8 to execute the downloadable software.

2. A set of numeric data with which to train the neural network to classify objects.

3. A subsequent set of similar data, which must be classified.

Introduction:

A neural network or more formally an artificial neuronal network involves the

implementation, either in hardware or software, of a parallel distributed processing computation

structure or neurocomputers that is capable of tasks such as pattern recognition in nondestructive

testing, which is the example chosen for this case study. These neurocomputers can function

similarly to the human brain, although they are not limited to this function. It is estimated that

the human brain is composed of 10 II neurons; each connected to 104 other neurons [1 ], which

implement a massively parallel computation structure capable of very complex tasks, some still

far beyond the capabilities of the today's computers.

The neuron is the fundamental processing unit in the brain and in the artificial neuronal

network. Each neuron, Figure 1, receives inputs from many other neurons or from sensory

processing elements. Each input is weighted, positively or negatively, by a connection strength

and then combined or summed. When the weighted-combined inputs exceed a threshold, the

neuron fires or activates its output line, which is then used as the input to another neuron. The

key to this parallel processing unit is the connecting weights, which have been arrived at as a

result of evolution in humans but must be learned or trained, in an artificial neuronal network.

Additionally, many artificial neurons use a constant input or bias, Figure 1, to increase the ability

of the neuron to learn complicated relationships.

483
Thehumanoperator in a particular nondestructive test learns, by experience, to recognize

that certain features, such as a particular shape on an oscilloscope trace, correlates with a certain

condition of the piece under test. If we wish to assist the human operator with a neural network,

the same procedure must be followed. The network must be presented with a sequence of input

features and the corresponding characteristics of the piece under test. During this training phase

the connecting weights are adjusted such that the difference between the network output, which

is an indicator of the state of the test piece, and the desired output are reduced. This weight

adjustment gives the network a memory of the correlation between the trace characteristics and

the corresponding state of the test piece. After a suitable training period, the neural network

should be tested with features from a different test piece, much as one would test an

inexperienced operator after training.

This case study will focus on the utility of neural networks for the development of a flaw

size identifier, which could be used as part of a computer-based classifier of flaws during

ultrasonic pulse-echo nondestructive testing. Additionally, the various options available and

decisions required in the selection of particular neural network topologies as well as the

corresponding training and testing signals will be presented.

A number of decisions are required for the construction of a neural network to be

used as a pattem recognizer. The first decision concerns whether the physical implementation of

the network will be in hardware or software. A software implementation, on a general-purpose

computer, was selected to maximize flexibility. The next decision concems the numeric

characteristics of the data at the input, at internal nodes, and at the output. The data values can

be either continuous or discrete and either bipolar or unipolar. Given that the source of the data

is an electrical signal, which is bipolar and continuous; the use of bipolar and continuous data

should maximize the information provided to the network. The selected data values will be taken

from a digitized version of the electrical signals.

The next decision concerns the network architecture, the interconnection of the network

nodes and the number of layers of nodes. A feed-fovward network topology allows a flow of

information only from the input layer of nodes to the output layer of nodes, which may proceed

through one or more hidden layers of nodes. A feedback configuration would allow signal

information to flow from the output node layer or any hidden node layer to previous layers. A

feed-forward network will be implemented in this ease study since a feed-forward network avoids

stability problems inherent in feedback topology. A single hidden layer of nodes was selected

and since this proved successful the complexity of additional layers was avoided.

The next decision concerns the neuron activation function and the inclusion of a bias term

at each neuron. There are two general categories of activation functions: a hard limiting

threshold for activation or a continuous activation function, which may take on a variety of

mathematical forms. While the hard limiter more closely mimic the human neuron, the

continuous activation function was selected based on constraints imposed by the training or

learning algorithm. A sigmoidal activation fimction for bipolar data was selected as shown below

where Y,represents the summation of the neuron inputs as shown in Figure 1.

484
ACTIVATION (E) = A(Y.) -

2

1 + exp(-Y)

1 (1)

A bias term allows a constant input value, in this case unity, to be connected to each neuron

through an adjustable weight. This allows a greater degree of flexibility [2] as the neural network

learns the relationship between the input and the output during training.

Given a signal characteristic and neural network architecture; a mode for learning and a

learning rule must be selected. There are two general categories of learning modes - supervised

and unsupervised. Since the desired network output, i. e. the identification of the simulated flaw

was known during training, the supervised learning mode was selected. The training rule

selected was the backpropagation rule or the generalized delta rule [3], which minimizes the

mean square error of the difference between the desired or target output and the current output

by making incremental adjustments in the connecting weights between layers in the neural

network proportional to the difference between the desired output and the current output. A

portion of a two-layer feedback neural network is illustrated in Figure 2. The updated weight

linking the jth hidden node to the k th output node, Wjk n+l, at the n+l instant in the training

sequence is given by

Wjk n+l = Wjk n + AWjk. (2)

Wjk n is the prior weight and AWjk is the weight adjustment given by

AWjk = kc (Dk - O:)A' (E:)Z_, (3)

where lrc is the data dependent learning rate constant, Dk is the desired kth output node value,

O kn.is the kth output node value at the n thinstant, A' (_-_n)k is the first derivative of the activation

function at the k th output node at the nth instant, and Z_ is the output value at the jth hidden

node at the nth instant. The first derivative of the activation function in the weight adjustment

equation is what necessitates using a continuous activation function. The weight adjustment

equation for the weights connecting the bias to each neuron is the same except that Z_ is set

equal to unity in Equation (3).

The updated weight linking the ith input node to the jth hidden node (Figure 2), Vij n+l, at

the n+l instant in the training sequence is given by

Vijn+l = Vijn + AVij. (4)

Vij n is the prior weight and AVij is the weight adjustment given by

485
AVu=,r E(Wj:(D -O n)A' n A' (Zj)X, n ,

k

(s)

where Z (wj: (D k - O: )A' (E:)) acts as an effective error at the jth hidden node by propagating

k

back the error from all the output nodes weighted by the appropriate connecting weight,

A' (Ej) is the first derivative ofthe activation function at the jth hidden node at the nth instant,

and Xi is the value at the ith input node. The weight adjustment equation for the weights

connecting the bias to each neuron is the same except that Xi is set equal to unity in Equation

(5). Given a physical implementation, the characteristics of the intemal data, network

architecture, an activation function, a learning mode, and a leaming rule; the remaining decisions

will be based on the experimental data used for training and testing.

The preceding neural network has been implemented as a windows application called

Neural-1. This application, example input fries and users guide is downloadable as a selfextracting compressed file from the software area on one of the author's homepage,

http://www.kohne.net/. All parameters discussed in the paper are adjustable from the windows

interface including the size of each layer in the neural network.

Procedure:

Flaws were simulated using the polished cross-section of acrylic rods immersed in water

at 22°C. Table I fists the simulated flaws, their respective cross-sections, the range of distance

that the samples were placed relative to the transducer wearplate, the number of experiments

available, and the neural network output binary code for each sample.

The simulated flaws were positioned at varying distances from a Panametric TM V 114

transducer, 1.91 cm. in diameter, with the flaw cross-section parallel to the wear plate. The

transducer-amplifier system, a Panametric TM 5050 P/R operated in the pulse-echo mode,

generated short pulses of longitudinal ultrasonic waves with a nominal center frequency of

1 MHz. The first echo from each simulated flaw was amplified and stored in a LeCroy TM 9400

digital oscilloscope configured to sample the return echo at a sampling frequency of 100 MHz.

The data was then electronically transferred to a computer for analysis.

The next decision required was the selection of relevant echo features, which would be

presented to the neural network during training and the subsequent testing phase. The features

selected were dictated by two factors. The input features should require a minimum of

preprocessing, with no human interaction, and the number of features should be small so as to limit

the number of data sets required for training the network. A lower bound [4] on the number of

training sets required is given by a product of the number of different samples to be classified, five

in these experiments, and the minimum of the number of input features/nodes or the number of

hidden nodes, which are both to be determined. Given these constraints, time domain samples of

each echo were used as input to the neural network. The samples were taken directly from the

LeCroy TM data file representing each echo. The samples were taken after the echo voltage

exceeded a negative going threshold. A total of eight samples were taken, skipping twenty samples

486
betweeneachselectedsample.Theseallowedthemajorportionsof each echo to be represented by

voltage deflections at pre-set points on the time axis. Figure 3 illustrates an example echoes from

sample b with the corresponding data samples used in the analysis indicated by asterisks. While

eight samples would not correspond to a correct data reduction of the sampled echo; it does allow

a mixture of both amplitude information and time location information about each echo. In

addition to greatly reducing the number of potential input features, this scheme simplifies the

preprocessing phase, which would otherwise require a feature extraction exercise to identify

amplitude features, time features or any transform domain features.

The eight sample input values define the number of nodes at the input of the neural net,

while the number of nodes in the hidden layer was set to five for most of the experiments. The

output layer of the neural network was set to three nodes, as determined by the binary encoded

identifications listed in Table I. The desired output values are set to a three-bit binary code, with

three binary digits allowing the classification of eight different items although only five were used

in these experiments. Variations on the actual binary code assignments showed no effect on the

networks ability to recognize samples. The output coding was motivated by the desire to reduce

the number of connecting weights in the overall neural network. A logical alternative to this

output identification scheme would have been to have the number of output binary digits equal to

the number of different samples. In this scheme, in order to identify a given sample, only one

output binary digit equals one while the remainders are at minus one. This would have been the

next course of action if the training and subsequent testing were unsuccessful in correctly

identifying the samples using a binary encoded version. Additionally, the number of nodes in the

hidden or intermediate layer was varied to illustrate the effect of this variable. The final decision

prior to training the neural network was the selection of initial connecting weight values. All

connecting weights were set to random numbers between -0.5 and 0.5, using a Nguyen-Widrow

normalization [3].

Note that the target values are in binary but the network output is continuous to assure

the existence of the derivative of the activation function as stated earlier. An adjustable error

was allowed when comparing the network output with the target values. A correct match of

network output and target values occurs if all network output values are within 0.2 of the target

values. The adjustable parameter is a required input parameter at the windows application

interface.

A data set consists of eight samples from an echo with the corresponding output or sample

identification binary code listed in Table I. The fifty-seven data sets were ordered from sample a

through e, with each sample ordered in increasing distance from the transducer face. This allowed

for three different types of training and testing on the neural network. Experiment H1 used half of

the data sets to train, selecting every other data set, and the remaining half to test the network, with

Experiment H2 reversing the training and testing data groups. Experiment T1 used one-third of

the data sets to train, selecting one data set and skipping two data sets, and testing with the

remaining two-thirds of the data sets, with Experiments T2 and T3 each using a different one-third

of the data sets for training and the remaining two-thirds for testing. Experiment Q1 used oneforth of the data sets to train, selecting one data set and skipping three data sets, and testing with

the remaining three-fourths of the data sets, with Experiments Q2, Q3 and Q4 each using a

487
differentone-forth of the data sets for training and the remaining three-fourths for testing. Each

training run was continued until the training error was reduced to a preset root-mean-square

(RMS) value. Multiple training runs, each with a different set of initial random network weights,

were done to maximize the percent correct before a single testing run was executed. The RMS

error was reduced during training only when a series of training runs failed to achieve a ninety

percent correct testing run.

Table II list the results of all experiments performed on the neural network with eight

input nodes, five nodes in the hidden layer, and three nodes in the output layer. In all cases the

network weights were started at random values, even when a training sequence was repeated

with a smaller RMS goal. Given the network size, a desired minimum number of training sets

should be greater than 25. The H-series experiment exceeds this goal, while both the T-series

and Q-series use less than the desired minimum. This will allow some exploration of the

exactness of this minimum number of training sets.

The H-series of experiments have the highest percent correct in testing on average for 0.1

RMS training error as expected, since these two experiments used the largest data sets for

training. Subsequent random starts for the H2 series with a smaller RMS goal leads to an

increase in the percent correct in testing to the lower 90% range with the network able to

memorize, 100% recognition, the input training set at 0.05 RMS training error. The T-series of

experiments had a somewhat lower percent correct in testing on average for 0.1 RMS training

error than the H-series as would be expected since less information was provided in the training

phase. As the training was extended to 0.01 RMS training error the percent correct in testing for

the T-series also increased to the low-to-mid 90% range. This illustrates two expected results.

Increasing the number of training samples or the length of training increases the percent correct

recognition in testing. The T-series results seem to indicate that a maximum number of training

set at 25 is a conservative estimate.

The Q-series of experiments proved to have the most variability. The percent correct for

0.1 RMS training error ranged from the low 60%'s to upper 70%. Two causes for this are

possible. First, the effect of the random start can put the initial weights near a global minimum

that produces a high percent correct or the initial weights may position the start point near a local

minimum which has a much lower percent correct. The algorithm, which reduces the RMS

training error, adjusts the weight values to move down an error surface, which may have many

local minima. This is illustrated by the poor results for the Q4 experiments. Secondly, a small

training set may provide insufficient information to form a general solution to the problem at

hand. This is also illustrated by the Q4 experiments which never produced a percent correct

above the low 80%'s range, but the other Q-series experiments were able to generalize to a

percent correct which went into the 90% range. In the case of increasing the training time by

reducing the RMS error, it is possible for the network to memorize the training data as opposed

to obtaining a general solution to the problem at hand. If this occurs, subsequent testing with

data not used in training should reveal a low percent correct and thus identify this shortcomings

of the neural network. The Q4 experiment with a 0.0001 RMS error showed that the network

did not form a general solution to the problem it just memorized the training data.

488
Figure 4 illustrates the percent correct for the Q3 experiment as a function of the number

of training iterations for three different numbers of nodes (three, five, eight), in the hidden layer

of the neural network. The results indicate that a network with more internal neurons will learn

more quickly and will be able to generalize a better solution to the problem at hand. The figure

also indicates only a modest improvement when eight internal neurons are used as opposed to

five. No general solution exists for the correct number of neurons in a hidden layer, but a general

rule would start with a low number of neurons in the hidden layer and then increase the number

the until an acceptable solution is reached.

Comments:

A neural network can be trained to recognize samples using features in time traces of

ultrasonic echoes. The complexity of the network is limited by the quantity of training/testing

data available. In general, the more complex a network is the better the generalization of a

solution for the problem under study. The quality of the training set and the length of training

limit the success of the neural network. The potential for a network to arrive at a local minimum

with a high RMS error is possible, but this can usually be avoided by using a quality training set.

The windows based application Neural-1 can be used to solve a very general class of

problems. Any length input vector, with continuous or discrete values, can be used; the length

equals the number of neurons in the input layer. The number of hidden neurons can be varied,

starting with a small number relative to the size of the input layer. The form and size of the

output layer would be problem dependent. The algorithm is based on the contents of Chapter 6

of Fausett's textbook [3].

References:

1. J. M. Zurda, Introduction to Artificial Neural Systems, West Publishing, St. Paul (1992).

2. B. Widrow and S. D. Stearns, Adaptive Signal Processing, Prentice-Hall, Englewood Cliffs

(1985).

3. L. Fausett, Fundamental of Neural Networks: Architectures, Algorithms, and Applications,

Prentice-Hall, Englewood Cliffs (1994).

4. K. G. Mehrotra, C. K. Mohan, and S. Ranka, IEEE Trans. on Neural Net., 2, 6 (1991).

Table I: Sample designation, sample cross-section area, variation in

sample-to-transducer distances, the number of experiments available, and neural network output

code for each sample.

SAMPLE AREA DISTANCES NUMBER OUTPUT

(cm2) (cm) CODE

a 45.8 1.809-10.922 14 1 -1 -1

b 1.31 1.267-10.054 13 -1 -1 -1

c 0.709 0.024-5.556 9 -1-1 1

d 0.312 1.730-7.588 10 -1 1 1

e 0.0855 0.072-10.486 11 -1 1 -1

489
Table II: Results for all experiments performed on a neural network with an eight-five-three

structure.

Experiment Percent used Percent used RMS Percent Correct

in training in testing Error Train / Test

HI 50.9 49.1 0.1 100 / 96.4

H2 49.1 50.9 0.1 89.3 / 82.8

0.05 100 / 89.7

0.01 100 / 93.1

T1 33.3 66.7 0.1 84.2 / 81.6

0.05 100 / 89.5

0.01 100 / 92.1

T2 33.3 66.7 0.1 84.2 / 78.9

0.05 100 / 78.9

0.01 100 / 92.1

T3 33.3 66.7 0.1 94.7 / 89.5

0.05 100 / 89.5

0.01 100 / 94.7

Q1 26.3 73.7 0.1 93.3 / 78.6

0.05 100 / 88.1

0.01 100 / 92.9

Q2 24.6 75.4 0.1 85.7 / 74.4

0.05 100 / 93.0

Q3 24.6 75.4 0.1 85.7 / 65.1

0.05 100 / 86.0

0.01 100 / 93.0

Q4 24.6 75.4 0.1 85.7 / 62.8

0.05 100 / 65.1

0.01 100 / 76.7

0.001 100 / 83.7

0.0001 100 / 81.4

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494
DEMONSTRATIONS OF SOME FUNDAMENTAL

CONCEPTS CONCERNING FUELS AND ENGINES

John J. Fortman

Professor Emeritus of Chemistry

Wright State University

Dayton, Ohio 45435

Sponsored by Wright-Patterson Air Force Base ARL/ML

Telephone: 937-775-2188

e-mail john.fortman@ wright.edu

495
Biography:

John J. Fortman is Professor Emeritus of Chemistry at Wright State University, Dayton, OH,

where he has taught for 36 years. He received his B.S. from the University of Dayton in 1961

and his Ph.D. in physical inorganic chemistry from the University of Notre Dame in 1965. At

WSU he has received six outstanding teaching awards and was appointed the Robert J. Kegerreis

Distinguished Professor of Teaching. In 1998 he was recognized with the Chemical

Manufacturers Association National Catalyst Award for Outstanding College Chemistry

Teaching. He has published 71 papers with almost half of them dealing with chemical

demonstrations. He has given many presentations at national meetings and for eight different

states or regional meetings of high school chemistry teachers. As a tour speaker for the

American Chemical Society he has given over 200 local section talks in 49 of the 50 states.

496
Demonstrations of Some Fundamental Concepts Concerning

Fuels and Engines

John J. Fortman

Professor Emeritus of Chemistry

Wright State University

Dayton, OH 45435

Sponsored by Wright Patterson AFB ARL/ML

Key Words: Combustion, fuels, engines, fires, explosions, demonstrations, analogies.

Prerequisite Knowledge: Basic ideas of chemical reactions, the piston function in the internal

combustion engine.

Objective: Demonstrations presented are suitable for both younger students and high school and

college classes. An appreciation of how fundamental scientific knowledge can explain the

technology of useful applications can be gained.

Equipment and Materials: See the instructions for the individual experiments under the

Procedure section.

Introduction: In order to produce combustion one needs a fuel, a source of oxygen, and an

initiator. This is presented in a surprising manner using a burning book while relating this

information. Carbon dioxide and oxygen gases are produced to illustrate the difference between

gases which do or do not support combustion. The vapor nature of burning is illustrated with a

demonstration which dates back to Michael Faraday and his lectures on the candle. This open

burning of fuel vapor which occurs when the fuel and oxygen come from different sources and

burn at the interface of mixing is contrasted to explosions which occur when the fuel and oxygen

gases are pre-mixed. Since oxygen is the limiting reagent there is a need for an exhaust stroke in

order to have repeated explosions which produce thrust. The timing cycle in a four-cylinder

four-stroke internal combustion engine is shown by a participatory analogy. A visual illustration

is presented comparing a rapid rough explosion and a slower smooth explosion and the

difference is related to the octane rating of fuels for anti-knock.

Procedure:

, The Three Things Required for Combustion (1)

A book bursts into flames while one reads from it that you need a fuel, a source of oxygen,

and an initiating spark or flame in order to have combustion. The workings of the trick book

is shown to expose fire proof ceramic ribbon saturated with cigarette lighter fluid which

supplies the fuel vapor and a battery operated glow bar which initiates its combustion which

the oxygen in the air. The need for the oxygen is illustrated when the book is closed,

497
suffocatingtheflame. "Burning"booksmaybepurchasedfrom suppliersof magicproducts

ormadewith instructionsgiveninreference1.

2. GasesWhichSupportor DoNot SupportCombustion.(2,3)

(a) CarbonDioxideDoesNotSupportCombustion.

Oneor two alka-seltzertabletsaredroppedintoa600mL beakerwhichisaboutone-fourth

full of water.Insertaburningsplintintothetopof thebeakerandit will gooutsinceCO2

doesnot supportcombustion.SinceCO2isheavierthanairthegaswill remaininthebeaker

for alongenoughtimeto dothesecondpart. If airis circulatingoverthebeakertoorapidly

theCO2gasmayescapefromthebeakertooquicklyandtheflameisnotextinguished.

(b) OxygenGasDoesSupportCombustion.(3)

In asecond600mL beakerplaceaboutone-thirdof thecontentsof anenvelopeof dryyeast.

Pourin some3%hydrogenperoxideuntilthebeakeris one-fourthto one-thirdfull. Suds

will startrisingupin thebeaker.(Justasyeastwill releasecarbondioxidefrom sugars,

ingredientsin thedryyeastwill catalyzethereleaseof oxygengasfromhydrogenperoxide;

thereis nocarbonpresent).Touchthetopof thefoamwithaglowingsplintandit will burst

intoflamesasoxygendoessupportcombustion.

NowyoumayplacetheburningsplintintotheCO2beakerandtheflamewill gooutbut

removeit whileit is still glowing. Returntheglowingsplintto the02foamandit will again

burstintoflames.With alittle practiceyoucancyclethesplintbackandforth sixormore

times,ignitingandextinguishingtheflame.Foramorehumorouseffectgetabig smileon

yourfaceandshiftbackandforthonyourfeetlike ayoungboyplayingwith matches.

3. TheVaporousNatureof theFuelin Combustion(3)

Makeabout100mL of a 50:50mixtureof waterandethyl(ormethylor isopropyl)alcohol

andaddalittle sodiumchlorideto maketheflamemorevisable.Placeit in alargecontainer

andthoroughlywetaclothtowelin it. Squeezeouttheexcessliquid anddrapethetowel

overarod. Light theclothfromthebottomafterdyingyourhands.(Theburninghandstrick

istoodramatic!)Afterit hasflamedfor awhileextinguishthefireby givingit aquickjerk

usingapairof tongs.Thetowelwill notbeburnt.

4. AlcoholExplosionsDemonstratingCombustionin anInternalCombustionEngine.(4)

A copyof reference4 is attached.Reprintedwith permissionof Chem13News.PartA

describesthedemonstration.

5. TheNeedfortheExhaustStroke(4)

Theprocedureis giveninthelastparagraphofPartA ofreference4, whichis attached.

498
6. An AnalogicalDemonstrationof theFourStroke,FourCylinderEngine.(4)

SeePartB of theattachedcopyofreference4. Full sizedmastersof thefiguresaresupplied

for makingoverheadtransparencies.

7. DemonstrationsContrastingRoughandSmoothAlcoholExplosionsforAnalogyto Octane

Rating(5,6)

About25to 40mL of methanolisshakenandswirledin a5-gallonplasticwaterjug for 10to

15secondsto hastenthevolatilizationof theliquid andto makethegasconcentration

uniformthroughoutthebottle. Thestopperorlid isremovedandtheexcessliquidalcoholis

pouredout. Thejug isplacedbehinda shield,thelightsaredimmed,andalongfireplace

matchorkitchenmatchtapedto ameterstickisbroughtoveror slightlyintothemouthof the

bottle. Blueflamesarethrustoutof themouthof thebottlefollowedbysomedancing

flamesof burningvaporinthecenterof thejug. Thisrapid,roughexplosionof methanolcan

becomparedto thecombustionof low octaneratedfuelswith straightchainhydrocarbons.

In asecondjug thedemonstrationisrepeatedusingcool70%isopropanolwhichproducesa

slower,lessviolentexplosionfollowedbyring of flamesmovingdowntheinsideof hejug.

Thissmoother,slowerexplosioncanbecomparedto combustionof high-octanefuelswith

branchedhydrocarbons,whichismoresuitablefor drivingthepiston.

Beforereuseeachjug shouldbetotallyfilled withwaterto exhausttheoxygen-depletedair

andallowedto fully dry.

Themostimportantprecautionsto betakeninthesedemonstrationsare:

• never use a glass bottle;

• pure oxygen or any gas mixture with a concentration of oxygen higher than air should not

be used;

• when using methanol or ethanol, neither the alcohol nor the bottle should be heated above

room temperature;

= plastic jugs should be replaced when they begin to show grazing, frosting, or cracking;

• Safe _tyshields must always be in place, because even the mildest of these explosions have

some chance of the bottle shattering; and, of course safety goggles must be worn.

Comments:

This program in its entirety gives a short course in combustion reactions of fuels relevant to use

in engines. Individual experiments can be used to focus on specific aspects if desired. The

experiments all have an element of danger as they involve fires and explosions so proper safety

precautions must be followed. In particular explosions of alcohols in jugs given in section 7 of

the procedure have led to several serious accidents due variations of "short cuts" in the

instructions. A more complete list of safety concerns are given in reference number 6.

499
References:

1. R. Battino and J. Fortman, "The 'Burning' Book - a Guide to Its Construction", Chem 13

News, Number 249, p. 18, May 1996.

2. J. Fortman, "Complementary Demonstrations #6: Gases Which Support or Do Not Support

Combustion," Chem 13 News, Number 236, p. 13, January 1995.

3. J. Fortman, "Updated Versions of Some Demonstrations Faraday Used with His Christmas

Lectures on 'The Chemical History of a Candle'," Chem 13 News, Number 205, pp. 9-12,

September 1991.

4. J. Fortman, "Demonstrating the Chemistry of the Internal Combustion and Jet Engines:

Alcohol Explosions," Chem 13 News, Number 285, pp. 10-11, May 2000.

5. J. Fortman, "Safety Precautions for the 'Ring of Fire' and 'Whoosh Bottle' Demonstrations"

Chem 13 News, Number 277, p. 1, September 1999.

6. J. J. Fortman, A. C. Rush, and J. E. Stamper, "Variations on the 'Whoosh' Bottle Alcohol

Explosion Demonstration Including Safety Notes," J. Chem. Educ. 76, 1092-3 (1999).

500
Demonstrating the chemistry of internal combustion and jet engines:

alcohol explosions

John Jr. Fortman

Department of Chemistry

Wright State University

Dayton OH 45435

Students often know more about the mechanics of a car engine

than they know about the chemical reaction that propels them.

The following demonstrations will, help them to understand the

chemistry that occurs in both car and jet plane engines.

A. An enclosed explosion--the internal combustion

engine in a car

Two 3d nails are pushed through opposite sides of a

polyethylene bottle (125 mL to 500 m/in size) which is also

fitted with a cork. (Clear plastic bottles must not be used,as they

may shatter.) The nails must be in tight and almost touching.

By pushing the nails through the walls without drilling holes, the

plastic will seal around the nails and if some water is placed in

the bottle the internal rusting of the nails will secure the nails

better than glues, which might soften at firing

temperatures. When firing occurs the nails should be

pointed towards the side walls of the room and not

towards the audience.

Two to five mL of alcohol (ethanol, methanol or 2-

propanol) are placed in the bottle. It is stoppered and

shaken. The excess liquid can be poured out before

firing to show that this is a vapor phase reaction. A

Tesla coil is brought in contact with one of the nails

causing a spark to jump between the nails and firing

the cork to the ceiling. 1,2,3 Alternatively, the spark

may be supplied by a push button ignition device

(used on many gas barbecue grills) that has been

modified with two lengths of wire and alligator clips. 4,5

Water-proof wick or electrical rocket ignitors s could

also be used but they are harder to relate to the spark

plug in the internal combustion engine.

You may want to ask a member of the audience to

repeat this demonstration. If you immediately

restopper the bottle and add more alcohol the bottle

will not fire again. Ask the volunteer or the class why

not. The reason is that the bottle lacks sufficient

oxygen. 2 Fill the bottle with water, empty it, add

alcohol, shake and then repeat. It explodes again.

After the students have seen that the second

explosion cannot occur without first exhausting the

cylinder and taking in a fresh air fuel mixture, the

lesson can be connected to the four strokes in a

cylinder of the internal combustion engine: intake,

compression, power and exhaust.

B. An analogical demonstration of the four stroke,

four cylinder engine

Ask for four volunteers from your audience, perhaps those who

like to do line dances. Line them up shoulder to shoulder facing

the audience. First have them practice the up and down stroke

of the piston by having them bend their knees and go up and

down like an =ump-pah" band. Then tell them that their two fists

will represent the va'l'v_s, their left fists being the intake valves

and their right fists being the exhaust valves. When their fists

are against their shoulders the valves are closed and when

extended they are open. Refer them to an overhead

transparency of Fig. 1 and slowly lead them through the four

steps beginning with them upright with the left fist extende,d and

squatting down (the intake stroke). They now bring their left

Four Cylinder, Four Stroke Engine Dance

=

ke

I1.

III.

!

Intake Stroke

•Power Stroke

Compression Stroke

IV.

Exhaust Stroke

10 CHEM 13 NEWSMay 2000

Fig. 1.

501
Four Cylinder, Four Stroke Engine Dance

Timing

Cylinder Cylinder Cylinder

1 2 3

Power Stroke Exhaust Stroke

Fig. 2.

Compression

Stroke

fists to their shoulder and straighten back up (the compression

stroke). Together they all say "boom" and stoop down again

with both fists at their shoulders (the power stroke). Finally they

extend their right arms upwards with fist open (the exhaust

stroke). You may have them practice the four steps together

several times before you break the news to them that to

represent a real engine they must each be doing a different step

at any given time. Show them an overhead of Fig. 2 and point

out that the correct firing sequence has the outer pair in phase

with each other but out of phase with the middle two. For mass

and power balance the firing sequence is 1-3-4-2, so point at

the correct student and sing "BOOM - boom - BOOM - boom."

While everyone is still laughing thank them for participating and

send them off with a suggestion that they practice before the

next school dance or variety show and they may start a new

dance craze.

C. An open explosion--a jet engine

About 25 mL of methanol or ethanol is shaken in a 5 gallon

plastic water jug. Remove the cap and pour out the excess

.31coho]. Place the bottle behind a safety shield. Dim the lights

and bring a match taped to a meter stick over the mouth of the

jug. A blue flame will shoot out and flames will dance and

pulsate in the jug as more air is sucked in. Compare this to the

thrust of an external-combustion jet engine. This is an old

demonstration, which has apparently been passed on without

being formally published. The first citable reference of which I

am aware was at the BCCE at Purdue in 19887 and there have

been several newer modifications. 8,9,1°

Cylinder

4

©

Intake Stroke

CAUTION

There have been recent warnings of bottles shattering during

this experiment. 11'12 Do not use a glass bottle; do not use

alcohol above room temperature, and do not use oxygen in any

higher concentration than found in air.

Always use a safety shield. A more

complete analysis of this experiment and

its safety requirements has been

published _3along with a shorter warning. TM

Literature cited

1. J.W. Bozzelli, Journal of Chemical

Education, December 1983, pages

1069-1070.

2. B.Z. Shakhashiri,"Vapor-Phase

Oxidations," Chemical Demonstrations,

University of Wisconsin Press, Madison

Wl, volume 2, 1985, pages 216-219.

3. L. Summerlin, J.L. Ealy, Jr., =The

Methanol Cannon," Chemical

Demonstrations: A Sourcebook for

Teachers, American Chemical Society

Publications, Washington DC 1985,

page 170.

4. R. Battino and J.J. Fortman, Journal of Chemical Education,

February 1992, page 172.

5. H. Brouwer, Journal of Chemical Education, April 1993,

page 329.

6. J.J. Fortman and J. Schreier, Journal of Chemical

Education, April 1993, pages 328-329.

7. M.H. Bailey, Abstracts of the Tenth Biennial Conference on

Chemical Education, Purdue, IN, 1988, Abstract No. 295

and handout.

8. D.A. Robinson, 209th ACS National Meeting, Anaheim, CA,

April 1995, Abstract No. CHED-038.

9. D.A. Robinson, 211th ACS National Meeting, New Orleans,

LA, March 1996, Abstact No. CHED-061.

10. W.C. Deese, CHEM 13 NEWS, November 1996, pages 8-9.

11. C. Lee, Journal of Chemical Education, May 1998, page 543.

12. W.C. Deese, CHEM 13NEWS, May 1998, page 3.

13. J.J. Fortman, A.C. Rush, J.E. Stamper, Journal of Chemical

Education, August 1999, pages 1092-1094.

14. J.J. Fortman, CHEM 13NEWS, September 1999, page 1. •

SLATER micro SCIENTIFIC

A "small" Canadian business

Trays, pipettes and Micronews letter

RR # 2, St. Marys ON N4X 1C5

Tel: 519-349-2540 New fax: 519-349-2043

E-maih alslater@quadro.net

May 2000/CHEM 13 NEWS 11

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HARDNESS INDENTATION ANALYSIS

Richard J. Fields

MATLS B252

National Institute of Standards and Technology

100 Bureau Drive, Stop 8553

Gaithersburg, Maryland 20899-8533

Telephone: 301-975-5712

e-mail rj f@nist.gov

and

Thomas A. Pierce

Student

Norfolk State University

700 Park Avenue

Norfolk, Virginia 23504

e-mail tapnsu@yahoo.com

505
Richard Fields

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Thomas Pierce

506
Hardness Indentation Analysis

R. J. Fields and T. A. Pierce

National Institute of Standards and Technology

Gaithersburg, Maryland

Key Words:

Hardness testing, indentation, metals, mechanical properties, and residual stress.

Prerequisite Knowledge:

Physics (mechanics and optics) and algebra.

Objective:

Demonstrate the usefulness of hardness testing for characterizing the mechanical properties of

metals and show the effect of residual stress on hardness measurements.

Equipment and Materials:

Hardness tester, pieces of metal, optical fiat, and monochromatic light source.

Introduction:

Hardness is measured by forcing a hard sphere or diamond brale into a surface using a known

load; the size (area or depth) of the resulting indentation is a measure of the hardness. {1 } The

hardness is related to other mechanical properties. The ease and speed of hardness testing makes

it the measurement of choice by industry, especially for quality control. Besides simply

characterizing the hardness of a product, hardness testing can be used to analyze structures. For

example, it can be used to find welds in structures and to determine if some regions are brittle.

{2} Its value is affected by residual stresses in metals and it is the purpose of this experiment to

show this effect.

Procedure:

Hardness testing of several metals will be carried out using a typical hardness tester. The

hardness test will be explained and the measured value correlated with known mechanical

properties of these metals. The test will then be used to scan across a weld in a steel plate to

show how mechanical properties vary in a weldment. To demonstrate how residual stresses

effect the measurement, a metal bar will be bent. The hardness will be measured on the top and

bottom surface. An analysis will be worked through showing how to separate the actual

hardness from the residual stress effects. The magnitude of the residual stress will be

determined. Finally, a block of metal will be repeatedly indented and its curvature monitored,

using an optical flat and monochromatic light, to demonstrate the build up of residual stress by

507
indentation.Analysisandplottingwill beusedto elucidatethephenomenon.

Comments:

A complimentary copy of NIST's Recommended Practice Guide for Rockwell Hardness

Measurement of Metallic Materials will be provide to each attendee.

References:

1. Annual Book of ASTM Standards, Metal Test Methods and Analytical Procedures, Vol 03.01,

Publ. by ASTM, West Conshohocken, PA, 2000.

2. ISO Standard 14271, "Vickers hardness testing of resistance spot, projection and seam welds",

ISO Geneva Switzerland.

Bibliography:

Rockwell Hardness Measurement of Metallic Materials, Samuel R. Low, NIST Spec. Publ. 960-

5, U. S. Government Printing Office, Washington, D. C., 2000.

The Hardness of Metals, David Tabor, Publ by Clarendon Press, Oxford, England, 1951

5o8
OVERVIEW OF NEW:UPDATE 2002

W. Richard Chung

Department of Chemical and Materials Engineering

San Jose State University

San Jose, California 95192-0082

Telephone: 408-924-3927

e-mail wrchung@email.sjsu.edu

509
Richard Chung

510
511
512
513
514
515
516
517
518
17 th National Educators' Workshop Schedule

October 13-16, 2002, San Jose, California

Date/Ti SUNDAY MONDAY

me

7:00- N/A Breakfast

8:00 Reception

8:00- N/A Plenary Session

10:00 &

Presentations

' SEMl/Ultrateh Stepper

10:30- N/A

12:00

10:00- ' '' N/A " :Coffee Break/Exhibits

10:30 . . ,

Presentations

TUESDAY

Breakfast

Reception

8:00-9:00 a.m. Bus travel to IBM

" 9:00 a.m. Plenary Session

Host: Dr. John Ba____n

IBM Almaden Research Center

Auditorium A&B

- Qverview: Fut_re Computing

- Single-atom CrvoToniC ST?¢[.

Coffee Break

WEDNESDAY

Breakfast

Reception

Plenary Session

&

SEMlfUltrateh

Stepper

Coffee

(2 Demos availablg in Foyer now thru to . Break/Exhibits

Lunch t_me) ; '

(Poster set-up time)

Hot Topics/Tutorials and Demos :_

' IBM ..... :

• I

SEMI/Ultrateh Stepper

12:00- -' N/A ' 'Luncheon

13:00

13:00- Lab'Tonrs Plenary Plenary

15:00 and Sessions Sessions

Networking Mini- Miniworksho_ Workshop

Dr, Susan open

Chang

AIaterhtls

Coffee Break

Mini- Mini17:00 Reception, workshop. . Workshop

15:00- ....... i_offee

15:30 Break

15:30- Welcome

Dean Kirk

Engineering Dr. Susan open

Bldg, SJSU Chang

Plenary 1_[aterials

Sessions Analvsisa

N/A Reception in Hotels 18:00-

21:00

i

Aud. A [ Aud. B

Hot Topics F Hot Topics B

A (Four 20-

(Four 20- I min. talks) Demos

min talks) ' " " 1

- Luncheon '

1:30 p.m. Plenary Session

Audltorium A &B

. lnvffedpresentations

2:30 p.m. Posters, Lab Tours,

Coffee

Aud. A Aud. B

Presentations HighSchooi/Comm

unity College

Track

Banquet at Teeh Museum?

Presentations

SEMI/UItrateh

Stepper

Box Lunch

Collaborative Effort

(advisory board

meetings)

Collaborative Effort

(advisory board

meetinss)

519
A Proposal for Mini Workshops for NEW:2002

Mini Workshops to be conducted at Seagate on Monday, October 14, 2002

Location:

Seagate Recording Media

311 Turquoise Street

Milpitas, CA 95035

Contact Person:

Dr. Susan Chang

Executive Director

Material Analysis and Tribology Testing

(408) 941-5403

Susan.S.Chang@seagate.com

Format and Topics: (12- 5PM)

Lunch and refreshments may be provided by Seagate (will work with company

authoritiest)

An overview of disk manufacturing process (1 hour)

Tour of the manufacturing facilities (30 minutes)

The attendees will then participate in a chosen area to get their hands-on experience:

The workshop size is limited to 10 people per area.

1) Failure Analysis

2) AFM/MFM (Atomic Force Microscopy/Magnetic Force Microscopy)

3) Corrosion engineering

4) Tribology

5) Measurement of Surface Texture

6) Disk Characterization

7) Function Tests

8) Measurement of Magnetic Properties

520
NEW-2002

Tuesday, October 15, 2002

IBM Almaden Research Center

Tentative Program

(version 9/27/01)

8:45 a.m.

9:00 a.m.

- Overview:

Buses arrive at IBM. Visitor badging.

Plenary Session Auditorium A and B

"Computing: The Future is not What it Used to Be"

- "Manipulating Single Atoms on Surfaces - the Cryogenic STM"

10:00 a.m. Coffee Break Aud. Foyer

[Posters to be pinned up now; formal session later]

Hands-on STM demos - (remote)

Hands-on Simulation of Ion-Solid Interaction (SRIM at 5 computers in Foyer)

[These demos, and coffee, to remain available thru the a.m.]

10:30 a.m. Hot Topics / Tutorials and Demos

[Parallel activities; attend the 20-min. talks of your choice]

Aud. A:

Holographic Storage

Magnetic Tunnelling - Spintronics

Polymer Synthesis / Flat Panel Displays

MEMS

Aud. B:

Ion Beam Modification of Materials

Multi-scale Modelling - Fracture

Focused Ion Beam Technology

Materials Characterization

Foyer: [continuing]

Hands-on STM Demos

Hands-on Simulation of Ion-Solid Interactions

521
12:10 p.m.

1:30 p.m.

2:30 p.m.

Lunch IBM Cafeteria

Plenary Session Auditorium A and B

Poster Session and Lab. Tours

[Refreshments during l_ster session]

[Tours will make brief stops at 3 or 4 labs of interest]

3:40 p.m. Presentations

[Parallel sessions in Aud. A and Aud. B]

5:00 p.m. Return to buses

Aud. A/ Aud. B

522
523
524
CARBON FIBER: THE MATERIAL OF THE FUTURE

C. David Warren

Oak Ridge National Laboratory

Building 9204

P. O. Box 2009, MS 8050

Oak Ridge, Tennessee 37831-8050

Telephone: 865-574-9693

e-mail WarrenCD@ORNL.GOV

525
C. David Warren

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578
SMART MATERIAL ACTUATORS

Charlie E. WoodaH

Student

Won J. Yi*

Waiter Golembiewski

and

gyo D. Song

Department of Technology

Center for Material Research

Norfolk State University

700 Park Avenue

Norfolk, Virginia 23504

Telephone: 757-823-8105

e-mail ksong@nsu.edu

brickcha@hotmail.com

*ICASE

NASA Langley Research Center

579
Charlie Woodall

Kyo D. Song

580
Smart Material Actuators

National Educators' Workshop

October 14 - 17, 2001

at National Institute of Standards and Technology

Charlie E. Woodall, Won J. Yi*, Walter Golembiewski and Kyo D. Song

Department of Technology, Center for Material Research, Norfolk State University

*ICASE, NASA Langley Research Center

Key Words: Piezoelectric, Unimorph, Smart Materials, THUNDER and Actuators

Prerequisite Knowledge: Basic knowledge of electronics, electromagnetic wave

propagation, smart materials° rectenna operations

Objective: To provide the proof of concept that smart materials can be actuated by

microwave power.

Equipment and Materials:

1. Anechoic chamber

2. Narda X band horn antenna model 601A (8.2 - 12.4GHz)

3. JPL 6 x 6 rectenna array

4. Hewlett Packard 8684B signal generator (5.4 - 12.5GHz)

5. Logi Metric Amplifier

6. Adjustable recycle time delay relay (HDFA Series by Amperite)

7. Hameg Instruments Oscilloscope (HM1507 150MHz 200Ms/s Analog/Digital)

8. Tekronix DMM916 (Analog/Digital Multimeter)

9. Resistors (1.5 ohm, 2.7 ohm, 3.9 ohm, 5.6 ohm, 1.2k ohm, 3.5k ohm, and 270k ohm)

10. THUNDER (Thin Layer Composite Unimorph Ferroelectric Driver and Sensor_)

11. Coaxial cables and wiring fixtures

Introduction:

An experimental study of a smart materials actuator driven by microwaves is presented in

this paper. A proof of concept experiment using THUNDER (Thin Layer Composite

Unimorph Ferroelectfic Driver and Sensor) Materials has been set up and demonstrated

using microwaves. The smart material actuator system driven by microwaves may have

applications, such as the Next Generation Space Telescope (NGST) with fragmented

optics control.

Procedure:

A feasibility experiment was set up and demonstrated using a microwave source to

provide the power needed to actuate the smart materials, as shown in Fig. 1.

581
A combinationof signalgeneratorandamplifierprovided20W of microwavepowerto a

Nardahorn antennaat a frequencysettingof 8.5GHz. The 20 W microwavepower

irradiateda JPL(JetPropulsionLaboratory)6 x 6rectennaarray.Therectenna,whichis

a rectifier and an antenna,convertsthe microwavepowerinto DC power. The horn

antenna,the 6 x 6 rectennaarray,and the requiredwiring fixtures were inside an

anechoicchamberasshownin Fig.2(a)and2(b). All otheritemslistedin theequipment

andmaterialsectionwereexternallyconnectedto thehornantennaandtherectennaviaa

backplateat the rear of the chamber. The Nardahorn antennais connectedto the

amplifierby a coaxialcable,andthesignalgeneratoris connectedto theamplifierby a

separatecoaxial cable. The 6 x 6 rectennaarray is connectedto the exteriorof the

anechoicchamberbymeansof a dualoutputBNCconnector.Thedistancebetweenthe

hornantennaandthe6x 6 rectennaarraywas65cm.

Comments:

In this experiment, the Narda horn antenna's 20 W microwave power was converted into

a measured 192 V DC by a digital multimeter. The estimated current being produced

from the 6 x 6 rectenna array was 0.38mA. This was computed using various measured

resistor values and the measured voltage across each resistor. The DC voltage output of

the 6 x 6 rectenna array was connected to the resistors in separate operations, and the

current through each of the resistors was calculated.

A schematic diagram of the experimental setup is shown in Fig. 3. The positive terminal

of the rectenna was connected to the normally open connection of the recycle timer, and

the negative terminal was connected to the common/ground connection as shown in

Fig.4. A R-C circuit was constructed using a THUNDER and a 27K ohm resistor. One

of the two terminal connections of the R-C circuit was connected to the recycle timer's

normally open connection, and the other was connected to the common/ground. The

recycle timer setting was set at .5 seconds, which was the recycle timer's fastest setting

possible. The Amperite recycle timer had a range of settings from 0.5 seconds to 24

hours. This time setting was verified with a Hameg Instruments Oscilloscope. The

measured capacitance of THUNDER was 260nF.

When the recycle timer switch was closed, the path of least resistance for the R-C circuit

was via the THUNDER, thus charging the circuit. When the recycle timer switch

changed to the open position, the connection between the rectenna and the THUNDER

was broken. The voltage polarity at this point was reversed. The THUNDER and the

resistor circuit performed in the same manner as a capacitor and a resistor in a R-C circuit

when a voltage was applied or removed.

This on/off switching of the recycle timer created a pulse to demonstrate that the

THUNDER device could be actuated by a microwave power. This pulse was captured in

a pictorial. The pulse rise and decay times were measured as 0.5 and 0.3 sec,

respectively.

582
THUNDER is a ferroelectric device made of multiple layers of materials, typically

stainless steel, aluminum and PZT (Lead Zirconate Titanate) piezoceramic. These layers

of materials are sandwiched together with an adhesive bond. A piezoceramic material is

composed of randomly oriented crystals or grains. By applying electrodes to the ceramic

and a strong DC electric field, the dipoles are aligned in the direction of the electric field.

By aligning in this manner, the smart material will have a permanent residual

polarization. The result of this polarization is a change in the geometric dimension.

Through the piezoelectric effect, THUNDER has the capability to expand or contract,

based on the polarity of the voltage applied. When the applied voltage is positive,

THUNDER will flatten, and if the applied voltage were negative, the THUNDER arches.

References:

1. T.K.Wu, "Multiband FSS," in T. K. Wu (Ed.), Frequency Selective and GridArray,

John and Wiley & sons, New York, 1995.

2. W. Schneider, J. Moore, T. Blankney, D. Smith, and J. Vacchione, "An UltraLightweight High Gain Spacecraft Antenna," IEEE Antennas Progagat. Int. Symp.,

Seattle, WA, June, pp. 886-889, 1994.

3. T.H. Lee, R. C. Rudduck, T. K. Wu, and C. Chandler, "Structure Scattering Analysis

for Sea Winds Scatterometer Reflector Antenna Using Extended Aperture Integration

" r l and GTD, IEEE Anetnnas P opaga. Int. Symp., pp. 890-893, Seattle WA, June

1994.

4. W.C. Brown, et at., US Patent 3 434678, Mar. 25, 1969.

5. W.C. Brown, "Experiments involving a microwave beam to power and position a

helicopter," IEEE Trans. Aerosp. Electron. Syst., Vol AES-5, No. 5, pp. 693-702,

1969.

6. W.C. Brown, "Solar Power Satellite Program Rev. DOE/NASA Satellite Power

System Concept Develop. Evaluation Program," Final Proc. Conf800491, 1980.

7. J. Schlesak, A. Alden and T. Ohno, "A microwave powered high altitude platform,"

IEEE MTT-S Int. Microwave Symp. Dig., pp. 283-286 1988.

8. W.C. Brown, "Design study for a ground microwave power transmission system for

used with a high-altitude powered platform," NASA Final Contractor report 168344,

Raytheon Rpt. PT-6052, 1983.

9. NASA JPL, "Patch Rectenna for Converting Microwave to DC Power," NASA Tech

Briefs, Vol. 21, January, p. 40, 1997.

10. Brown, W. C., Draft of Paper Prepared for Presentation at the 8th Biennial

SSI/Princeton Conference on Space Manufacturing, May 6-9, 1987.

Biography:

Dr. Kvo D. Song is a P.I. of Faculty Awards Research (FAR) ftmded by NASA

starting March 5, 1998 to March 4, 2002. He has been involved in many research

projects, such as: Hypersonic Flow Research, Testing high temperature materials for

Scram-jet Engine Components, Study on effects of atomic oxygen on space materials,

583
and Smart materials research for Next Generation Space Telescope (NGST) under NASA

supported grants. Mr. Charlie Woodall is a senior student in Computer Technology at

Norfolk State University. He is a retired Navy engineer who had been working 23 years

on communication system. Dr. Won Yi is working as a research scientist at NASA

Langley Research Center. His specialized area is high voltage, pulse power, and lasers.

Dr. Golembiewski is an Associate Professor working at Computer Technology. He has

considerable experience in the design and testing of circuitry and communications.

Note: * The subject mater is under the invention disclosure (LAR 15754-1) at NASA

Langley Research Center.

M icrowave Driven Actuator

Set-Up

Anechoic Chamber

THUNDER ]

9 V DCTimerRecycle 1_

L PAD

Figure 1: Block diagram

Figure 2(a): Inside the anechoic chamber Figure 2(b): The rectenna inside the

anechoic chamber

584
= =

1"1_ [.....

__1_

T

1

Recteana (_i 92 _,,t_

!L38 mA

Figure 3: Schematic diagram

Figure 4: Recycle timer and THUNDER

585
586
COLLOIDAL SELF-ASSEMBLY PHENOMENA

O, C. Wilson, Jr.

and

L. J. Martinez-Miranda

Department of Materials and Nuclear Engineering

University of Maryland

College Park, Maryland 20742-2115

Telephone 301-405-0253

e-mail martinez @ eng.ttmd.edu

587
Biography

Otto C. Wilson, Jr. is an Assistant Professor in the Department of Materials and Nuclear

Engineering at the University of Maryland. His undergraduate and graduate education

(M.Sc. and Ph.D.) was completed at Rutgers University in Ceramic Science and

Engineering. Otto has developed the BONE lab (Biomimetics, Orthopedics, and

Nanomaterials Exploration) at UMCP where he and his students are studying ways to

improve the synthesis and remodeling response of hard tissue implants. Additional

reserach areas include composite research and microwave processing of materials. He

enjoys teaching classes in biological materials and biomaterials and is actively involved

in K-12 educational outreach.

L. J. Martfnez-Miranda is Associate Prof. of Materials in the Dept. of Materials and

Nuclear Eng at the University of Maryland - College Park. She received her bachelor's

and master's degree in Physics from the Universidad de Puerto Rico in Rio Piedras, a

bachelor' s in Music degree from the Conservatory of Music of Puerto Rico and her

doctoral degree in Physics from Massachusetts Institute of Technology. At Maryland she

has been responsible for designing the junior level laboratory undergraduate course with

the help of her colleagues, and has taught the introductory design course and the physics

of materials course. Her interest is in X-ray scattering from liquid crystals and solid

films.

588
Colloidal Self-Assembly Phenomena

O. C. Wilson, Jr. and L. J. Martfnez-Miranda

Department of Materials and Nuclear Engineering

University of Maryland

College Park, MD 20742

Key Words: Colloid, self-assembly, silica, hydrous iron oxide, akageneite, chemical

precipitation

Prerequisite Knowledge: Basic chemistry and physics of light diffraction

Objective: To observe the influence of self assembly and order on the propagation of

light in colloidal cystals

Equipment and Materials: Oven capable of heating up to 100-120 C, chemical

glassware (beakers, pipettes), magnetic stirrer and stir bar, high speed centrifuge

(minimum speed is 3000 rpm), deionized water, tetraethyl ortho silicate (TEOS),

ammonium hydroxide (reagent), ethyl alcohol, FeC13.9H20, urea, glass microscope

slides.

Introduction:

The discovery of x-rays in the early 1900's by Bragg opened up a whole new

world by providing a tool that allowed materials scientists to probe the atomic structure of

crystalline materials. By definition, a crystal is a material that exhibits long range atomic

order where atoms occupy specific locations on a crystal lattice. The basic building unit

of a crystal is the unit cell. The unit cell is the smallest arrangement of atoms that can be

translated in three dimensional space to build the crystal lattice. The basic equation that

relates the atomic plane spacing (d), the wavelength of the incident radiation (_), and the

angle of diffraction (0) is known as Bragg's Law and can be expressed as follows:

nL = 2d sin0 (1)

The geometry of diffraction event for a crystalline material is shown in Figure 1. With

state of the art transmission electron microscopes, scientists can now actually see

regularly spaced atomic planes in biological and synthetic materials by visualizing

features that are on the order of a 0.1-1 nmo

Although we can not directly see a crystal lattice with the unaided eye because the

wavelength of x-rays is too short for our eyes to detect, there are optical analoques to

diffraction that can be readily observed. The brilliant, iridescent colors of some species of

beetles and butterflies result from the diffraction of visible light from regularly spaced

structural units that have dimensions on the order of the wavelength of visible light (300-

700 nm). Another example of optical diffraction in nature involves the semi-precious

gemstone opal. In natural opal, uniformly sized amorphous silica (SiQ) spheres form

589
undergeologicalconditionsandslowly settleinto closepacked,orderedarrays.High

temperaturesin excessof 1000 °C cause the particles to partially sinter and form bonds

between particles that give the opal structural integrity. The colors that are observed in

opal result from the interplay of light with the regularly spaced planes of monodisperse

silica spheres based on equation (1). If the planes are not ordered properly, the light that is

diffracted from the opal interacts in a destructive manner and the resulting opal has a

white appearance and is sometimes called milk opal. It is possible to make synthetic opals

based on the availability of chemical techniques to synthesize submicron silica spheres

with uniform (monodisperse) size (Stober et al., 1968). Typical chemicals for this process

include tetraethylorthosilicate (TEOS), ethyl alcohol, water and ammonia. The water

promotes a hydrolysis based chemical reaction that breaks the bond between the Si atom

and the ethyl functional group and allows the Si-O to form various species that can

polymerize and form a long chain network that results in the formation of uniform

spheres of various sizes from a few nanometers (nm) up to microns in size. Synthetic

opals are produced commercially by synthesizing uniform silica spheres in large

quantities and allowing the particles to settle into ordered, crystalline arays by slow

sedimentation or solvent removal.

The diffraction of light from ordered arrays of non isotropic (rod shaped) particles

can also give rise to interesting diffraction phenomena. Akageneite (_-FeOOH) is the the

most famous inorganic system in this class of materials. It can be formed by the slow

hydrolysis of aqueous solutions of iron (Ill3 chloride (FeC13, typically 0.03-0.06 M). In

order to form particles with a suitable degree of monodispersity, aging times can be as

long as a few months to a year. For this system, patience is a virtue and yields a nice

reward because the bright, iridescent colors that can be observed for this system are very

remarkable. Under the right conditions, the akageneite particles self assemble into

ordered two dimensional rafts where all the particles are oriented perpendicular to the

plane of the raft as shown in Figure 2. Numerous layers of these rafts can form and the

spacing between successive raft layers determines the conditions for color formation.

These layers are called Schiller layers

In recent years, a number of unique applications for colloidal crystals are being

investigated as more elegant methods are devised to control the spatial extent and degree

of ordering. One of the more far reaching applications for colloidal crystals with a big

technological payoff involves the use of self assembled colloidal crystals that can control

the propagation of light and other types of electromagnetic radiation. These "photonic

crystals" are projected to revolutionize the information age by making it possible to make

optical based computer systems.

Procedures:

Synthesis of monodisperse silica spheres

A.) Pour 85 ml of 200 proof ethyl alcohol into a 200 ml beaker. Place the magnetic stir

bar in the solution and stir on the magnetic stirrer at a moderate rate.

B.) Add approximately 2 ml of tetraethyorthosilicate (TEOS) to the ethyl alcohol

solution. Allow a few minutes for the liquids to completely mix

590
C.) Carefully measure out 10-15 ml of reagent ammonium hydroxide (12 M) and add to

the TEOS/ethyl alcohol solution. Caution: Make sure that this is done under a fume

head due to the very strong ammonia vapors that will be present.

D.) Allow the solution to stir for 3-t0 hrs. You can have students observe the reaction for

the first 10-15 minutes and record the time that it takes for the initially clear solution

to turn light blue in color. This time corresponds roughly to the induction time (the

time it takes for the nuclei to reach a sufficient size to scatter visible light). The

explanation for the bluish color of the solution is related to the phenomena that

accounts for the blue color of the sky i.e. scattering of light by very small particles

(molecules, colloids). After more time has elapsed, students can observe the solution

gradually turn milky white and opaque.

E.) After aging for 3-10 hrs, the silica particles should be washed to remove excess

ammonia. This can be accomplished by placing the silica suspension in centrifuge

tubes or bottles. Centrifuging the suspensions at 3000-5000 rpm will cause them to

settle to the bottom of the tube (or bottle). Carefully pour of the clear supernatant

liquid, replace with fresh water, and re-disperse particles by shaking or using an

ultrasonic bath or probe. The first wash should be performed using ethyl alcohol, and

subsequent washes should be done in water. During centrifugation, you may observe

the formation of colored regions in the sediment cake that forms on the bottom of the

centrifuge tube. Five to ten centrifuge cycles should be sufficient. After the last wash

in water, re-disperse the silica spheres in ethyl alcohol and centrifuge one more time.

Pour off the alcohol and re-disperse the silica particles in a minimum amount of ethyl

alcohol (approximately 25-50 ml).

F.) Opals can be formed by three methods. In method 1, concentrated suspensions of

silica spheres can be allowed to settle into ordered arrays on the bottom of glass

sample vials (20 ml). Vivid colors will be seen in the ordered sediment that forms on

the bottom of the beaker. Method 2 involves carefully removing the ethyl alcohol by

evaporation at room temperature or under moderate heat (60 °C) in an oven. The

resulting silica compact may appear white and chalky, but if it is placed in ethyl

alcohol or water, it will bubble and display opalescent colors. The bubbles occur

because the liquid displaces the air that occupies the pores that exist between adjacent

particles. Method 3 is the quickest method. Drops of the concentrated silica

suspension in ethyl alcohol can be placed on microscope slides and allowed to dry

(within a few minutes). Instruct the students to view the flat "opals" in transmitted

light and reflected light in which the slide is perpendicular to the light source and then

have the students view the flat opal at an angle to the incident light. Students should

be able to see that there are specific angles which cause opalescent colors to appear.

Synthesis of monodisperse akageneite rods

A.) Add 4000 ml of de-ionized water to a gallon sized container. Weigh 54 grams (0.2

mol) of FeC136H20 and add this to the water. Allow to dissolve and place in a quiet

location for a few months. The solution will turn from the initial brown color to a

591
moredarkerbrown,turbidsuspensionsastheakageneiteparticlesnucleateandgrow.

Alternatemethod:Ureaandheatcanbeusedto makeakageneiterodsthatarenot as

uniform in sizebut still displayirridescentphenomenaif a shorterexperimentis

required.Add 30 g of urea to 1O0 ml of deionized water and then add 5.4 grams of

FeC13"6H20. Use a magnetic stirrer to stir the solution on a hotplate at 90-95 oC for 3-

5 hrs. The initial pH of the solution will be 2-3, but the urea hydrolyzes and produces

carbonate and hydroxide ions that raise the pH of the solution to a final value of 6-7.

B.) The particles should be washed by centrifugation using water. Higher speed may be

required (10,000-15,000 rpm). After cleaning the particles, they should be redispersed in a minimum volume of water (50-100 ml) and allowed to settle. It may be

easier to observe the formation of Schiller layers by putting some of the suspension

into a 20-40 ml sample bottle and tilting it on an angle and allowing the suspension to

sediment undisturbed for a few day. Iridescent colors will be visible in the sediment

layer.

Student exeercises:

Calculation for estimating particle spacing using Braggs law

A.) Using the flat opal, have students measure the angle that corresponds to opalescent

color formation. This could be done using a protractor. Note the color or colors that

can be seen for a particular angle. Find the wavelength of light that corresponds to the

particular colors that are observed. This value (in nm) will be used for 1 in equation 1.

The angle q represents the angle at which the colors were observed. Setting n= 1 for

this example, students can calculate the spacing for the array that roughly corresponds

to the silica particle diameter.

Building a structural model for the opal and Schiller layers

A.) Opal: Uniform size marbles or ping pong balls can be distributed to students for

stacking layers of the balls in a close packed structure to form a large scale model of

opal.

B.) Schiller layers: Straws can be bundled together in large mats. Placing 2-3 mats on top

of each other at various spacings will give students a visual picture of what happens in the

case of the self assembly of rod shaped particles into colloidal crystals.

Comments:

The chemical synthesis procedures may be too extensive in terms of time and

resource availability. Alternate arrangements can be made to accommodate these cases

such as preparing the colloids beforehand, getting the colloids from commercial sources,

or contacting the authors to request samples. The silica should be easy to obtain from

commercial suppliers, but the akageneite is probably not available.

References:

1.) W. Stober, A. Fink, and Bohn, "Controlled Growth of Monodisperse Silica Spheres in

the Micron Size Range," J. Colloid Interface Sci., 26, 62 (1968).

592
THE MAGIC OF CRYOGENICS

Daniel P. Vigliotti

James B. Alcorn

Brian P. Marsh

and

Nicole A. Neumeyer

National Institute of Standards and Testing

Division 853

325 Broadway-360

Boulder, Colorado 80303-3328

Telephone: 303-497-3351

e-mail vigliotti@boulder.nist.gov

593
Daniel P. Vigliotti

594
The Magic of Cryogenics

Daniel P. Vigliotti, James B. Alcom, Brian P. Marsh, Nicole A. Neurneyer

Materials Reliability Division

National Institute of Standards and Technology

Boulder, Colorado 80305

Key Words: bimetallic; brittle; coefficient of thermal expansion; contraction; cryogenics;

ductile; levitation; liquid nitrogen; magnetism; pressure; superconductor.

Prerequisite Knowledge: The presenter should be familiar with safety precautions involving

cryogenic liquids.

Objective: The purpose of this presentation is to introduce teachers to a demonstration that

exposes K-12 students to a variety of scientific areas through experiments using liquid nitrogen.

This presentation demonstrates how changing the temperature of materials changes their size and

shape. During the presentation, there are many opportunities to explore subjects for which

changes in temperature are important such as magnetism, biology, the relationship between

pressure and volume, and the composition of air. Students may perform some of the experiments

in this presentation.

Equipment_:

1. Liquid Nitrogen In Dewar

2. Insulated Container

3. Styrofoam Cups

4. Funnel

5. Tongs

6. Leather Gloves

7. Safety Glasses

8. Popgun

9. Balloons

10. Steam Engine

11. Brass Ball And Ring

12. Bimetallic Knife

13. Strips Of Soft Steel

14. Strips Of Rubber

15. WoodBlock

16. Superconductor Kit

17. Carnation

18. Banana

19. Mighty Miniature Mass Mover

List of Demonstrations:

1. Popgun

2. Exploding Balloon

3. Steam Engine

4. Contracting - Expanding Balloon

5. Bimetallic Knife

6. Brass Ball and Ring

7. Rubber and Metal Strips

8. Carnation

9. Banana

10. Mighty Miniature Mass Mover

11. Superconducting Magnet

"Contribution of NIST; not subject to copyright.

If you have questions about acquiring any of these materials, contact Daniel P. Vigliotfi at 303-497-3351 or

vigliotti@boulder.nist.gov.

595
Presentation:

This presentation deals with cryogenics. The word cryogenics comes from the Greek language,

kryos, meaning "cold", and genic, meaning "the production of'. The teacher should ask the

question, "What is the coldest temperature that anyone has experienced outside?" You will get a

range of answers from about 0 °C (32 °F) to -40 °C (-40 °F). Next ask .................

the coldest temperature ever recorded on Earth and where was it?" The correct answer is -106.7

°C (-160 °F) at the South Pole. Now inform the students that this presentation involves liquid

nitrogen and that the temperature of liquid nitrogen is -196 °C (-320.5 °F). Liquid nitrogen is so

cold that if it touches the skin, it will damage the skin causing a burning sensation just as if one

puts their hand on a red-hot stove. It may cause a blister to form, which is really due to a severe

case of frostbite. Basic safety precautions should bestated 1to the classroom prior to beginning

the demonstrations: 1. Do not pick up anything that falls on the floor. 2. Do not touch anything

unless told to. Remind students that it is important to_ follow these rules because liquid nitrogen

kills cells. This is the very same liquid that a doctor may use to kill warts.

Liquid nitrogen has many uses m industry. Since liquid nitrogen is inert, meaning it does not

readily react with other compounds, it is used to freeze frozen foods available in the grocery

store. Conveyer belts move foods through a "cold tunnel" that is cooled by liquid nitrogen to

about -184 °C (-300 °F). Freeze-dried foods are sprayed with or immersed in liquid nitrogen to

freeze them very quickly. Similar techniques are used to freeze blood and other human cells.

Liquid nitrogen is also used in the medical field to perform cryosurgery.

Liquid nitrogen is a colorless, odorless liquid, such that when poured into the insulated container,

it will look like steaming water (See Figure 1). When the insulated container is full, the liquid

nitrogen will then look like boiling water (See Figure 2). The liquid nitrogen will continue to

boil violently until the inside of the insulated container reaches -195.6 °C (-320 °F). At this

point, the liquid nitrogen will appear relatively stable. However, the liquid will continue to

slowly turn into a gas (See Figure 3).

Figure 1 - Pouring Liquid Nitrogen Figure 2 - Liquid Nitrogen Boiling

Violently

596
Figure3 - LiquidNitrogenStabilized

At thispoint,ask the students, "Is it a good or a bad thing that this liquid is turning into a gas and

we are breathing it?" Most students will say it is a bad thing. We will later determine this is not

true, because nitrogen is a gas that comprises much of our atmosphere. As a follow-up question,

ask the students, "What is in the air that we breathe?" Most classes will say oxygen, smog,

hydrogen, and carbon dioxide. This immediately leads into a new subject: "Where does the

carbon dioxide in this room come from?" In every classroom, usually one student knows that it

comes from people exhaling. Now discuss the process of photosynthesis. After students name

as many gases as possible that make up air, ask: "Does anyone know which gas makes up most

of the air that we breathe?" The majority of students will agree that most of what we breathe is

oxygen. Most students are surprised to find out that only 21% of the air is oxygen but 78 % is

nitrogen, which leaves only 1% for all other gases including carbon dioxide. (If the students

understand percentages, use them; however, younger students may need further explanation.)

DEMONSTRATIONS:

Pressure-Volume-Temperature Relationships (Experiments 1-4):

The first set of experiments will examine one interesting characteristic of liquid nitrogen as it

changes into gas. During this process, it increases in volume about 700 times. In the dewar

there is about a gallon of liquid nitrogen. If we could remove the cap and all of the liquid

nitrogen were changed into a gas, then it would take 700 dewars of that same volume to catch all

of the gas. That is a dramatic increase in volume.

1. Popgun

This experiment uses a popgun (See Figure 4) to show the result of liquid nitrogen heating up

and taming into a gas. Use a styrofoam cup to remove a small amount of liquid nitrogen from

the insulated container and pour it into the popgun. (Make sure that a string is attached to the

cork prior to demonstration to ensure that it does not fly away and cause damage.) Quickly force

the cork into the popgun. It will immediately pop off (See Figure 5). You may continue to force

the cork into the popgun and it will continue to pop off until all of the liquid nitrogen has turned

into a gas. By the time all of the liquid turns into gas, the sealed end of the popgun will be white

and smoking. This is oxygen and water condensing on the outside of the popgun.

597
Figure4- Popgun Figure5 - CorkPoppingOff Popgun

2. Exploding Balloon

Next, we will inflate a balloon using the expansion property of liquid nitrogen. Take the funnel

and put it in the balloon. Seat the balloon around the funnel with your fingers and pour in a

small amount of liquid nitrogen using the styrofoam cup (See Figure 6). As soon as a small

amount is in the balloon, remove the funnel, pinch the balloon closed, and shake the balloon to

keep the liquid nitrogen from freezing the bottom of the balloon (See Figure 7). The balloon will

infla_e, and if there is enough liquid nitrogen inside, the balloon will expand to its limit and

explode (See Figure 8).

Figure 6 - Pour Liquid Nitrogen in Balloon Figure 7 - Shake Balloon

Figure 8 - Balloon Exploding

598
3,SteamEngine

The next experiment uses a steam engine (Figure 9) to demonstrate the expansion property of

liquid nitrogen. (Before beginning the presentation, ensure that steam engine is in proper

working condition.) Since, most students can identify with a steam locomotive, ask students to

explain the principle of a steam engine. (Older students may be able to explain it.) Explain that

on a steam locomotive the boiler is filled with water. Fire is used to boil the water to create

steam. This gteam trapped in the boiler creates pressure that is guided through a series of pipes

and vanes to cylinders containing pistons. The pistons are connected to the wheels, which make

the locomotive go down the tracks. Explain that we will create pressure to run the flywheel on

our steam engine; however, we need neither water nor fire, just the heat in the room. Remove

the whistle and the relief valve from the top of the steam engine. Put the funnel in one of the

holes and pour about half a styrofoam cup of liquid nitrogen into it (Figure 10). Quickly install

the whistle first, and then the relief valve. Give the flywheel a light spin to get it started. The

flywheel will turn at a high rate o}"speed and slow down when all of the liquid nitrogen rams into

gas. As the liquid nitrogen coon the steam engine, oxygen and water will condense on the boiler

(See Figure 11).

Figure 9 - Steam Engine Figure 10 - Pour Liquid Nitrogen into Steam

Engine

Figure 11 - Flywheel Turning, Oxygen

and Water Condensing on Boiler

599
4° Contracting - Expanding Balloon

We will now use a balloon to demonstrate how gases contract when exposed to cryogemc

temperatures while simultaneously making dry ice. Blow up a balloon until it is slightly larger

than the insulated container (See Figure 12). Push the balloon directly into the liquid nitrogen

(See Figure 13). The balloon wilt begin to shrink where it touches the liquid nitrogen. You must

periodically rotate the balloon in the surface of the liquid until the balloon is collapsed (See

Figure 14). At this point, you K_ay ask the students what gases are in the balloon. Because you

exhaled into the balloon to inflate it, some carbon dioxide is present inside in addition to the

exhaled nitrogen from the air you breathed into it. :The carbon dioxide has contracted and frozen

into a small block of dry ice. (Also, the water vapor in your breath has been frozen into small

particles of ice.) You can demonstrate that dry ice has formed in the balloon by shaking the

balloon, and listening for the dry ice bouncing around inside of the balloon. Before the balloon

heats up and inflates, return it tO the container to shrink it again. After the balloon collapses

again, quickly remove it and set it on the table for the students to see. (See Figure 15) The

balloon will warm up quickly and start to inflate again. (See Figure 16) Because the rubber in

the balloon is not of a consistent thickness, the balloon will appear distorted as it inflates and will

probably explode before completely inflating.

Figure 12 - Inflate the Balloon Figure 13 - Push the Balloon into Liquid

Nitrogen

Figure 14 - Rotate the Balloon to Shrink

Balloon

Figure 15 - Balloon Deflated

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Figuret6 - BalloonReinflatesDuetoExpandingCarbonDioxide

Coefficients of Thermal Expansion (Experiments 5-6):

Describe the coefficient of thermal expansion as, loosely speaking, the rate at which something

expands or contacts as a function of temperature. Materials are tested and assigned coefficients

of thermal expansion at various temperatures. These coefficients are valuable to engineers when

they are designing and choosing materials with which to build things such as buildings, bridges,

ships, submarines, spaceships, and satellites. It is important to choose materials that when

bonded together are compatible by expanding and contracting at approximately the same rates

when they are exposed to changes in temperature, rather than at different rates, which could

damage them.

5. Bimetallic Knife

There are two materials with very different coefficients of thermal expansion. The bimetallic

knife is made of brass bonded to steel. At room temperature, the knife is straight (See Figure

17).

Figure 17 - Bimetallic Knife at Room Temperature

After the knife is submerged in liquid nitrogen and removed, the knife is significantly bent (See

Figure 18). Brass has a high coefficient of thermal expansion and will become shorter when it is

cooled. Steel has a lower coefficient of thermal expansion and does not shrink nearly as much as

601
thebrass Thesteelis forcedto bend,asthe brassgetsshorter.Thereforebrassandsteelare

thermallyincompatibleif theshapeof astructureis to bepreservedandnotwarped

Figure18- BimetallicKnifeBentDueto Changein Temperature

6.BrassBall and Ring

In contrast to the bimetallic knife, here are two objects of the same material and therefore having

the same coefficients of expansion and contraction. We have a brass ball and a brass ring (See

Figure 19). The brass ball is sized so that it just fits through the ring (See Figure 20) The brass

ring is submerged in the liquid nitrogen for about two minutes When the ring is removed, it has

shrunk enough that the bat1 can no longer fit through the ring (See Figure 21)

Figure 19 - Brass Ball and Ring

Figure 20 - Brass Ball Just

Fits Through Ring

Figure 21 - Brass Ring Shrunk;

Ball Will Not Go Through Ring

602
Transition from DUctile to Brittle (Experiments 7-8):

To the Students, define brittle as hard, rind, fragile, and not flexible A brittle object breaks

easily and shatters when it breaks. Define ductile as being elastic, able to bend and then recover

its original shape undamaged. A ductile object is hard to break, but easy to bend

7o Rubber and Metal Strips

This experiment shows that rubber is very ductile at room temperature but becomes extremely

brittle at cryogenic temperatures. Show the flexibility of a strip of common rubber by bending it

between your finger and thumb (See Figure 22). Drop the rubber strip into the liquid nitrogen

and have a student volunteer to put on some leather gloves. Using tweezers, quickly remove the

rubber strip from the liquid nitrogen, put it in the students gloved hand, and ask the student to try

to bend it. Instead of flexibly beiading, the rubber is now rigid and inflexible and will snap into

several pieces (See Figure 23).

Figure 22 Flexible Rubber Strip Figure 23 - Brittle Rubber Strip

It is easy to see that rubber is ductile at room temperature; it is not as easy for students to think

that steel, aluminum, or other metals can be ductile For applications of ductile metals, you may

talk about the following examples' Think about the steel that will be used to build a skyscraper in

California where there is a very good chance that the building will experience an earthquake.

Ask the students, "Would you want to use ductile or brittle steel?" Think about an airplane

wing. Again, ask them, "Have you ever been on an airplane that is flying in rough weather?"

Most students will say yes. Then ask if anyone was able to look out the window and see the

wing tip. Question, "What was the wing tip doing?" The careful observer will have noticed the

wing tip was bouncing up and down. That means that the aluminum in the wings must be

ductile If the aluminum were brittle, the wings would break and fall off. To display this, take a

metal strip and bend it between your fmger and thumb (See Figure 24). The metal strip will

bend easily. Submerge the bent metal in the liquid nitrogen and have a student volunteer put on

some leather gloves. Using tweezers, remove the bent metal from the liquid nitrogen and hand it

to the student to try to bend it (See Figure 25). It will snap very easily. In fact, it will take less

force to break it than it did to bend it to the same deflection at room temperature

603
Figure 24 - Flexible Metal Strip Figure 25 - Brittle Metal Strip

8. Carnation

Next, hold a carnation, (See Figure 26) and ask whether a flower is ductile or brittle. It is usually

difficult for a class to reach a consensus because of our previous definitions of ductile and brittle.

A carnation is soft and flexible but it is also fraNle. Therefore it is obviously ductile. Before

submerging the carnation in the liquid nitrogen, tell the students that you are going to put the

flower into the liquid nitrogen and then take it out. Ask if they think it will look the same or will

it look "yucky". Remember, we said earlier that when liquid nitrogen touches skin and warts, it

kills cells. Most will say that it will look '3rocky" Remove the carnation and they will see that

it looks normal, except that it appears to be smoking. Now is the time to ask for an adult

volunteer (as this should not be done by students). Submerge the flower in the liquid nitrogen

again (See Figure 27). Explain to the volunteer that you will remove the flower and shake most

of the liquid nitrogen off so that his/her hand will not be frostbitten, when he/she slowly crushes

the flower. Remove the flower, shake off all liquid nitrogen and then quickly hold it over a

paper towel for the volunteer to slowly crush the flower (See Figure 28). The petals will break

off easily and will sound somewhat 1kke glass shattering (See Figure 29). The petals are so

delicate that they will warm up and become ductile almost immediately upon hitting the paper

towel

Figure 26 - Carnation Figure 27 - Carnation Submerged in Liquid

Nitrogen

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Figure28- CrushingCarnation Figure29- PetalsFalling

Creating Toughness at Cryogenic Temperatures (Experiment 9):

9. Banana

For this experiment, hold up a banana and ask the students for the best use of a banana. They

will say bananas should be eaten. Ask if any of them have ever used a banana as a hammer. Of

course nobody has, because when you try to pound in a nail, it will stick in the banana (See

Figure 30). Demonstrate this, then remove the nail and submerge the banana in the liquid

nitrogen (See Figure 31). Explain that you can create toughness in materials by making them

cold, although, it is difficult to determine whether something has gone beyond tough and has

become brine. The banana will need to stay submerged for approximately five minutes. This is

a good time to review some of the concepts that have been discussed to this point. You may also

ask for questions. Put on the leather gloves, and take the banana by the warm end sticking out of

the container and try to pound the nail into a piece of wood (See Figure 32). You want to break

the banana to display that it is frozen all the way through. You may have to hit the banana hard

in order to break it (See Figure 33).

Figure 30 - Nail in Banana Figure 31 - Banana Submerged in Liquid

Nitrogen

605
Figure32- BananaPoundingNail in Wood Figure 33 - Banana Breaking

Electrical Resistivity (Experiments 10-12):

10. Mighty Miniature Mass Mover

The "Mighty Miniature Mass Mover", contains electronic circuitry, a capacitor, a switch and a

copper coil positioned in a Petri dish (See Figure 34). The electric charge stored in a capacitor is

dumped into a coil to create a magnetic pulse that is opposed by an electrical eddy current in the

dime. A dime will be placed on the coil and repelled by the magnetic forces created by the

currents. The capacitor is a storage device for electrical charge. When the capacitor is

discharged, it sends current through the coil that creates an electromagnetic reaction for an

instant The magnetic field produced by the electromagnet induces eddy currents within the

conducting dime and causes it to jump away fi:om the electromagnet

First, demonstrate what happens at room temperature Plug in the unit to charge the capacitor.

Place a dime on top of the coil and push the button to discharge the capacitor. Note that the dime

is repelled only slightly.

Then, with the styrofoam cup, pour liquid nitrogen into the Petri dish, covering the coil. Once

the coil has reached liquid-nitrogen temperature, place the dime on the coil and again push the

button to discharge the capacitor (See Figure 35). The lower resistance in the coil will atlow a

greater electrical current to flow and cause the dime to be repelled higher than during the initial

test.

Repeat the above procedure, but this time with the dime also cooled to liquid-nitrogen

temperature The opposing field created in the dime is now even greater, and the dime will be

repelled even higher (See Figure 36)

606
Figure34-MightyMiniatureMassMover Figure35- DischargingtheCapacitor

Figure36- DischargingtheCapacitorwithColdDime

11.Superconducting Magnet

This kit contains a ceramic superconducting magnet made from yttrium, barium_, and copper

oxides. It is important to point out that superconducting behavior only occurs in superconductors

at cryogenic temperatures. Superconductors are strongly diamagnetic. That is to say that they

will repel a magnet. The kit also contains a rare-earth magnet and a Petfi dish (See Figure 37).

This experiment will demonstrate levitation. Position the superconducting magnet in the Petri

dish. Use a styrofoam cup to fill the Petri dish with liquid nitrogen. Continue to fill the Petri

dish until the superconducting magnet reaches liquid-nitrogen temperature and no longer causes

the liquid nitrogen to boil vigorously. Place a styrofoam cup upside down on the table. Remove

the superconducting magnet from the Petri dish and set it on top of the cup. Place the rare-earth

magnet above the superconducting magnet (See Figure 38). Start the levitated rare-earth magnet

spinning by pushing down on one edge. It will spin with little resistance (See Figure 39). The

levitated rare-earth magnet will spin above the superconducting magnet until it warms up. When

it is no longer superconducting, the magnet will no longer levitate and will drop into the cup.

607
Figure37- PetriDish,Rare-EarthMagnet, Figure38- Rare-EarthMagnetLevitating

SuperconductingMagnet

Figure39- Rare-EarthMagnetSpinning

Acknowledgement:

Specialthanksto PhyllisWright,CareerAwarenessandResourceEducation(CARE)

Coordinator,for herremarkablededicationto theprogramandforfurnishingthiskit.

Thiscryogenicskit is availablefromtheCAREprogramattheNationalInstituteof Standards

andTechnology,Boulder,CO2. TheCAREprogramwasestablishedin 1979to promoteinterest

andawarenessin mathandscience.Awarenessandexplorationof thesciencesareencouraged

throughsciencekits,videos,field trips,andpresentationsbythescientificstaff.

Somepartsof thiskit areavailablecommerciallyandsomepartsareproducedbyNIST

Divisionsin Boulder,Colorado.

2Phone: 303-497-3244 E-mail:phyltis.wright@nist, gov

608
MOLECULAR DYNAMICS SIMULATIONS OF

CRACKING PHENOMENA IN POLYMER

LIQUID CRYSTALS (PLCs)

Witold Brostow

Laboratory of Advanced Polymeers

and Optimized Materials

Department of Materials Science

University of North Texas

Denton, Texas 76203-5310

e-mail brostow @unt.edu

Ant6nio M. Cunha

Department of Polymer Engineering

University of Minho

4800 Guimaraes

Portugal

and

Ricardo Sim6es

Laboratory of Polymers

Department of Materials Science

University of North Texas

Denton, Texas 76203-5310

e-mail rsimoes @unt.edu

609
Ricardo Sim_es

Biography:

Ricardo Simoes is a PhD student of Materials Science and a Teaching Assistant of Physics at the

University of North Texas, Denton, Texas. He has a 5-year bachelor's degree from the University

ofMinho, Guimaraes, Portugal. He is a member of the Ordem dos Engenheiros and the Society of

Plastics Engineers (SPE). He is the President of the North Texas Chapter of SPE and the vice-chair

of the organizing committee ofPolychar - World Forum on Polymer Applications and Theory.

610
MOLECULAR DYNAMICS SIMULATIONS OF CRACKING PHENOMENA IN

POLYMER LIQUID CRYSTALS (PLCs)

Witold Brostow (a), Antrnio M. Cunha (b), and Ricardo Sim_es (a, b)

(a) Laboratory of Advanced Polymers and Optimized Materials (LAPOM), Department of

Materials Science, University of North Texas, Denton, TX 76203-5310, USA;

brostow@unt.edu; http://www.unt.edu/LAPOM/

(b) Department of Polymer Engineering, University of Minho, 4800 Guimaraes, Portugal

Key Words: crack propagation, computer animation, molecular dynamics, polymer simulation.

Prerequisite Knowledge: Basic knowledge of polymer systems, interaction potentials, mechanical

properties, failure analysis and reliability of polymeric materials. Some knowledge of computer

graphics and animation is advised.

Objective: To study the cracking phenomena in PLCs and to develop tools to graphically represent

crack formation and propagation, while at the same time creating the basis for the threedimensional representation of polymeric, metallic or ceramic systems.

Equipment and Materials: PC with Windows environment and Microsoft Visual C++.

Introduction:

Reliability of polymeric materials is important not only for scientists and engineers, but also

for all the users of these materials, that is, for all of us [1, 2]. The users do not know about the

chemistry of synthesis, processing, thermodynamics, or rheology. However, when buying a product

that contains polymeric components, they want appropriate quality assured. Although mechanics of

polymers exists for quite some time, there are still no answers to fundamental questions such as:

"where does a crack begin" or "how does it grow". Scanning electron microscopy (SEM) allows us

to study the surface of cracks after fracture has occurred; however, it provides no information to

answer the questions above. For obvious reasons these issues are important also for students of

Materials Science and Engineering (MSE) and related disciplines. There is by far not enough about

computer modeling and simulations in MSE textbooks.

An approach exists to answer these questions: computer simulations. One can create a

polymeric material on a computer, apply an external force to it, and observe how cracks form, how

they propagate through the material, and how fracture eventually occurs. A particular problem with

computer simulations is the large amount of information they produce. Effective methods to

analyze this information are therefore needed. The solution found was three-dimensional (3D)

graphical representation of the results through OpenGL rendering.

Procedure:

One can use two methods [3]: Monte Carlo or Molecular Dynamics. Cartesian coordinates

are assigned to each segment of each polymeric chain. The chains are contained inside a

rectangular box. The segments interact according to interaction potentials. Different potentials

611
dictate the behavior of different types of segments. In the Monte Carlo method, developed by

Norbert Metropolis and Stanislaw Ulam [4], the particles are moved one at a time; for this reason

this method is more adequate for equilibrium properties.

In the molecular dynamics method, originally developed for gaseous molecules by Berni J.

Alder and his collaborators [5], all particles are moved simultaneously. Besides the cartesian

coordinates, each particle is also assigned three momentum components along the cartesian axis. In

this way it is possible to observe and follow the movement of the particles - chain segments in our

case - and also to observe the effect of applied external forces.

An obvious question is: what happens when a particle wants to escape the system? The

problem was solved by applying boundary conditions; it is considered that the system space is full

of periodic copies of the basic rectangular box, which are usually called "ghosts". Whenever a

particle is displaced outside the basic box, its "ghost" automatically enters the box from the

opposite side.

In order to graphically represent the results of the simulations, a 3D graphics program was

written. This program represents the segments as solid spheres in the coordinates calculated by the

simulation, as shown in Figure 1. An animation of the cracking phenomena as a function of time

can be obtained by changing the position of the particles at each simulation step, as shown in

Figure 2. The reason for the use of the OpenGL environment in Microsoft Windows operating

system is the accessibility, since the program will run in any common secretary computer, without

need to resort to supercomputers.

Comments:

In spite of the advantages, the simulations require advanced knowledge of molecular

physics, polymer science and engineering, and computer programming. For this reason, the number

of simulations of polymers under stress producing deformation is limited. Stress relaxation

simulations for single-phase polymers [6] also exist.

In our current simulations we consider two-phase polymeric systems - as is the case of

polymer liquid crystals [3]. The rigid phase with high concentration of liquid crystal segments

forms islands in the matrix consisting of flexible segments. Each polymer liquid crystal chain

contains both types of segments.

Generally, cracks could be expected to appear inside the islands (since they are rigid), or

inside the matrix (which is flexible and therefore has little resistance to stress) on the boundary" of

the two phases. In the conference, we will present results that will allow us to answer this question.

Some of our results were already published in 2001 [7]. In the conference we shall present

those results along with other unpublished ones.

Although our simulations are dedicated to polymer liquid crystals, the developed method

can be adapted to other single-phase or two-phase polymer systems. The simulations allowed us to

observe interesting features about the cracking phenomena.

612
Thegraphicprogrammingimplementedallowsforrepresentationof anythree-dimensional

structures.Thistypeof graphicalrepresentationof polymericsystemsisstill practicallyinexistent,

however,its usesandadvantagesareobvious.A particularlyinterestingpossibilityof OpenGL

graphicprogrammingisits useasaninstructionaltool.It simplifiesteachingthestructureof twophasepolymers,thestep-wisepolymerizationprocessandthe3Darrangementof theresultingnonlongitudinalpolymericchains,asshowninFigure3.Thesamemethodcanbeusedto represent

structuresof metalsandceramics.

Acknowledgements:

Weacknowledgefinancialsupportof theRobertA. WelchFoundation,Houston(Grant#B1203)andtheFunda_oparaa Cienciae aTecnologia,3°QuadroComunit_riodeApoio,Lisbon.

References:

1.W.BrostowandR.D.Corneliussen, editors,FailureofPlastics,Hanser,M0nchen- Wien- New

York 1986,1989,1992.

2.W. Brostow,editor,PerformanceofPlastics,Hanser,Munich- Cincinnati,2000.

3.W.Brostow, chapter15in MechanicalandThermophysical Properties of Polymer Liquid

Crystals, W. Brostow, editor, Chapman & Hall, London, 1998.

4. N. Metropolis and S. Ulam, J. Amer. Statist. Assoc. 44, 335 (1949).

5. B.J. Alder and T.E. Wainwright, J. Chem. Phys. 27, 1208 (1957).

6. S. Blonski, W. Brostow and J. Kub_it, Phys. Rev. B 49, 6494 (1994).

7. W. Brostow, M. Donahue III, C.E. Karashin and R. Simoes, Mater. Res. Innovat. 4, 75 (2001).

613
!

Figure I - Visualizing the simulated PLC in tkree-d_mensions.

Rigid segments are represented as dark spheres and flexiNe segments are represented as

light spheres. The material represented has 3 layers, each with 30 chains of 50 segments.

614
1 3

2 4

Figure 2 - Some ff_es from the animation of the cracking phenomena. Crack formation

and propagation up to failure can be visually observed as an animation. Rigid segments

are represented as dark spheres and flexible segments are represented as light spheres

615
Figure 3 - Three-dirnensioi_al representation of non-longitudi__at polymeric chffms, For

ease of visualization, each chain has been represented in a different shade of gray.

616
DEVELOPMENT OF A DEFORMATION

PROCESSING LABORATORY

Richard B. Griffin

Mahan Hall, C&ME (2001 - 2002)

United States Military Academy

West Point, NY 10996-1792

845-938-4093

Richard.Griffin@USMA.edu

K. Ted Hartwig

Robert Barber

Tiffany New

and

Ibrahim Karaman

Mechanical Engineering Department 3123

Texas A&M University

College Station, Texas 77843-3123

Telephone 979-845-9779

e-mail rgriffin@mengr.tamu.edu

617
Richard B. Griffin

618
National Educators Workshop

New: Update 2001

Development of a Deformation Processing Laboratory

Authors

Richard B. Griffin, K. Ted Hartwig, Robert Barber, Tiffany New, and Ibrahim Karaman

MEEN Dept. 3123

Texas A&M University

College Station, TX 77843-3123

Abstract:

Deformation processes have substantial effects on the mechanical properties of materials.

A recent innovation called equal channel angular extrusion (ECAE) has been developed.

The ECAE process forces a billet around a sharp comer and as a result large uniform

simple shear strain is induced into the billet. This is opposed to the nonuniform strains

associated with conventional area reduction extrusion, where a billet is forced through a

die orifice. Since the die inlet and outlet chambers maintain the same cross-section in

ECAE, the geometry of the billet remains the same before and after the extrusion, which

allows the billet to be processed multiple times resulting in high strains. A

comprehensive comparison of the effects of rolling, conventional extrusion, and ECAE

has been developed into a laboratory activity for a junior level materials/manufacturing

course. A comparison between deformed grid patterns of extruded copper and Play-Doh

specimens from a small extrusion press are compared. Hardness measurements on

deformed copper specimens are used to validate these results. Deformation is carried out

at room temperature on one-inch square ECAE and one inch diameter copper bars.

Explanations of the deformation processes and results from the laboratory activity are

discussed.

Introduction:

Deformation of material components can significantly alter the properties and

microstructures of the material. Of the many available methods of material deformation,

extrusion is one of the most common. The extrusion process first appeared in a 1797

patent to Joseph Bramah for a lead press (Sheppard)[ 1]. The application of this method

to a common engineering procedure occurred in the late 1800's. Since then, extrusion has

grown and changed to incorporate a broader range of methods. With current advances,

extrusion maintains its potential in diverse engineering applications.

There are multiple extrusion techniques. One method, conventional extrusion,

reduces the cross-sectional area of a billet of material by forcing the specimen through a

die orifice under high pressure (Dieter)[2]. The setup for this method can be seen in

Figure 1. Usually, solid and tubular shapes are created; however, irregular crosssectional shapes can also be fabricated using this method. The large forces that are

required often result in extrusions being performed near the recrystallization temperature.

In metals, these temperatures correspond to increased ductility and decreased flow stress

619
(ASM Committee on Cold Extrusion)[3]. Extrusion at lower temperatures is possible and

useful mechanical properties often result.

n_ I- ' _ _'_:_:__:__:_:__:!

Figure 1: Equipment Setup for Conventional Extrusion Deformation

The deformation process causes changes in material characteristics. As the billet

is pushed through the die, high hydrostatic pressure occurs within the block of material.

The pressure results from the compressed material being constrained as it is pushed

through the die. The imposed conditions of the deformation method can have effects on

the success of the extrusion. Under the correct conditions, many materials that are

difficult to deform are easily extruded at high temperatures. Temperature, speed, friction,

and the extrusion ratio are the main parameters that affect the extrusion process. Internal

voids and pores are healed, and crack propagation is inhibited. Also, the course

microstructures within the starting material are effectively broken down [2]. The

material exhibits significant changes as a result of this deformation process.

The extrusion ratio (R) is defined as the ratio of the original cross-sectional area

(Ao) of the sample, which is also the cross-sectional area of the extrusion chamber, to the

extrudate cross-sectional area (A0 (R = Ao/Af). The true strain for conventional

extrusion (et) is found as the natural log of the extrusion ratio:

et = In (Ao / A0 = In (R). Eq. 1

The pressure required for conventional extrusion (P) is related to the extrusion ratio and

the true strain:

P= k .Ao. In (Ao/Af) =k®Ao ®_t. Eq. 2

The extrusion constant, k, is dependent upon the friction, flow stress, and any

inhomogeneous deformation [2]. The interdependence between the extrusion variables

enables the process to be easily altered to fit many material requirements.

There are certain disadvantages to the conventional method of extrusion. This

process usually induces a nonuniform deformation field in the billet.* Strain

Special "stream line" dies can be made which produces uniform strain but such dies are

costly to design and manufacture.

variations are seen from the front to the back of the extrusion in longitudinal and

transverse directions. This nonuniformity of deformation results in variations within the

microstructure and the properties of the extruded material. Areas with exaggerated grain

growth are often found after hot extrusion [2].

620
A relatively new innovation in extrusion processes is equal channel angular

extrusion (ECAE) (Segal)[4]. The hallmark of this method is that the die inlet and exit

channel cross-sectional areas are nearly identical. Instead of forcing the specimen

through a die, the billet is forced around a sharp comer between the exit and inlet

chambers; this can be seen in Figure 2. The billet experiences uniform, simple shear

stress instead of the nonuniform stress experienced in conventional extrusion [3]. Since

the shape of the billet does not change during extrusion, the sample can be extruded

multiple times resulting in high strains. These uniform, unidirectional, and extremely

high deformations that result from relatively low pressure and load are not easily

achieved with conventional extrusion [4]. The virtually unlimited plastic strain that the

specimen earl experience causes changes in material characteristics.

Figure 2: Equipment Setup for ECAE Deformation

The total strain for N extrusion passes is a function of the angle (2d_) between the

extrusion channels and is:

et = 2. N ®cot (_) / 4 (3). Eq. 3

The equivalent reduction ratio (RR) is also related to the 2dp angle:

RR= exp (2®N,,cot (d_)/ _/(3).Eq. 4

The percent reduction in area (All) is a function of the reduction ratio:

AR = (1-(1/RR)) ®100. Eq. 5

The pressure for extrusion (P) can be derived as a function of flow stress (c_o) as:

P = 2 *ao ,cot (qb)/ _/(3). gq. 6

The conventional extrusion process has drawbacks that can be avoided with the

new ECAE innovation. Uniformity of strain and distortion reduce variations of properties

within the material. Also, the ability to process bulk materials in ECAE adds to its

positive aspects.

The effects of different processing techniques on materials can result in variations

in meehanical properties and in microstructure. A comparison of the deformation patterns

621
and hardness values of extruded specimens are utilized to determine strain uniformity.

this laboratory activity students are provided the opportunity to examine the effects of

annealing on specimens deformed by ECAE, conventional extrusion, and rolling..

In

Procedure:

Modeling the Process

In order to model conventional extrusion deformation, an experiment is

performed using a two-colored checkerboard array ofPlay-Doh (Kridli)[5]. The PlayDoh billets are extruded with data collected at various points in the operation.

Photographs of the sample are taken before extrusion, during extrusion at small strains,

during extrusion at larger strains, and after extrusion. The extruded sample is cut apart to

photograph the deformed cross-section after extrusion is complete. The geometrical

alterations of the arrayed blocks are analyzed to determine the shear strains in the sample.

Each block of the arrayed Play-Doh sample is considered as a single strain element for

strain field calculations. The strain variations are examined as a function of the block

locations.

Deformation Processes

Students' process annealed oxygen free copper samples (400°C for 30 rain.), with

a 6.5 cm 2 (1 inz) cross-sectional area by rolling, conventional extrusion, and equal

channel angular extrusion at room temperature. The students do the rolling, while the

ECAE and conventional extrusion are done by a research associate and observed by the

students. For the laboratory, the students use solid specimens. However, prior to the

laboratory split and gridded specimens were prepared for helping the students compare

the two extrusion processes. The temperature, punch speed, and extrusion pressure-ram

displacement curve for each process are recorded. An examination of material

characteristics (hardness and metallography) before and after the extrusion processes

illustrates differences in the processing methods. The extrusion press is a 250 ton MTS

test machine with a 20 in stroke and a maximum ram speed of 2.5 in/s.

The extruded copper sample is cut into appropriate specimen sizes for Rockwell

hardness measurements, which are completed according to ASTM standard E10.

Some specimens may be mounted, ground, and polished for Vickers

microhardness measurements (utilizing ASTM standard E384), in comparing between the

original billet and the processed specimens. The Vickers microhardness tests are not

typically done during laboratory classes.

The distorted grid patterns and quantified grid distortions for the extruded,

gridded samples are utilized to determine the strain of the sample and the regions of

nonuniform deformation. The hardness values and strain fields that are found are utilized

in the comparison of the two extrusion methods. The uniformity of strain can be

determined with these measurements.

An analysis of the effects of different annealing temperatures on the processed

copper specimens is also undertaken. Students select the number of specimens and the

temperatures and times for annealing. The processed samples are cut into appropriate

pieces for the different heat treatments. Samples of each processed specimen are annealed

for thirty minutes at room (typical) temperature (_ 25°C), 100°C, 150°C, 175°C, 200°C,

300°C, and 400°C in an air furnace. Hardness measurements are completed on each

annealed specimen to determine the amount of recovery. These measurements are also

622
used for determination of the recrystallization temperature of the copper, which is about

225°C, as shown in Figure 3. Annealing has significant recovery effects on the properties

of deformed specimens. Figures 3 and 4 illustrate the effect of annealing temperature, for

a constant time, on the recrystallization temperature of material tested.

Optical metallography is undertaken on the initial annealed samples, the

deformed specimens, the deformed specimens annealed at 200°C for thirty minutes in air,

and the deformed specimens annealed at 400°C for thirty minutes in air. The samples are

prepared by first cutting, mounting (use cold mount), and polishing sections from

samples representing each deformation method. The variations in grain size and shape are

compared for a better understanding of the microscopic effects of cold working and

annealing.

iiO -

_ioo!

_9o.

-_ 80_

70

(#)

=_ ao

_5o

4o

Nao

i

so 100 150 200 250 30o 3_0 4oo 450

Temperature (deg. C)

Figure. 3. Hardness variation of the rolled specimen as a function of annealing

temperature.

100 200 300 400

Tem_ratum (deg_C)

--¢-- ECAE-Top to

Bottom

ECAE-Front to

Back

-_,,- C/E-Left to

Right

---_- Rolling-Top to

Bottom

500

Figure 4. The variation of the hardness as a function of the annealing temperature.

623
Discussion:

The deformation patterns of the extruded specimens are compared for uniformity.

The pattern on the ECAE extruded sample was uniform; the deformed squares all

displayed a uniform geometrical change that is shown in Figure 5. This uniform shape

change is correlated to a uniform strain field. However, nonuniform deformation can be

viewed for the bottom 10% of the sample; this was attributed to friction experienced by

the bottom of the billet during the extrusion process. The uniform strains associated with

ECAE should be supported by uniform hardness values on the cross-section of the

processed samples. The deformed microstructure should also display uniform

microscopic alterations The uniformity of properties in ECAE increases its applicability

to numerous engineering applications.

D

lf--q I'ol

Figure 5. Deformation grid for ECAE deformation.

A significantly different situation is encountered in the analysis of the

conventionally extruded specimens The deformed grid pattern shown in Figure 6 is

nonuniform; center grid squares experienced greater size and shape changes than on the

specimen edges. Variations in hardness values on the cross-section of the extruded

specimen show that there are varying amounts of cold work across the billet. The

nonuniform hardness profile is also seen in the rolled specimen, which should experience

greater hardness values at the edges of the sample The deformed microstructures should

further support these findings. Nonuniform distortion causes nonuniform properties, and

this may cause difficulty in structural applications

The effects of annealing on the properties of the samples are most notable near the

recrystallization temperature, where the heavily worked structure recrystallizes to strain

free well defined grains, The specimens annealed near the crystallization temperature

(approximately 160°C) experience a significant decrease in hardness values. Variations in

hardness between specimens annealed at temperatures lower than the recrystallization

temperature are much less dramatic. Microstructural analysis should delineate the stages

of recrystallization and grain growth as the grain structure changes. The experimental

results elucidate the results of deformation and annealing giving a greater understanding

of cold working and material response to heat treatment. The variation in hardness values

624
shown in Figure 7 is used to demonstrate the variation in processing for the three

processes used during the laboratory.

-T-V

m

m _ -d

Figure 6. Deformation grid for conventional extrusion deformation.

B-r

7

g6_

fD I --=-_

0 100 200 300 400 500

Temperature (deg_C)

- _.... _ ECAE-Top

to Bottom

-_ ECAEFront to

Back

--_-_ C/E-Left to

Right

_, ,,,RollingTop to

Bottom

Figure 7. The effect of different annealing temperatures on the standard deviation of

hardness values of copper.

The ECAE deformed material exhibits less variation in the standard deviation of

the hardness values than either of the other two deformation processes as the specimens

were traversed,

Conclusion:

The laboratory groups evaluated three methods of deformation and, were able to

compare the relative characteristics of ECAE, conventional extrusion, and rolling. The

students were able to choose different annealing times and temperatures and observe the

results of their choices. For evaluating the effects of annealing temperature, they used

hardness testing. In addition, they used Play Doh to model the deformation process.

625
References:

1. Sheppard, T., Extrusion of Aluminum Alloys, Kluwer Academic Publishers,

1999.

2. Dieter, G.E., Mechanical Metallurgy, Third Ed., McGraw-Hill, t 986.

3. ASM Committee on Cold Extrusion, "Cold Extrusion," Metals Handbook,

Volume 4, pp.475-489.

4. Segal, V.M., "Materials Processing by Simple Shear," Materials Science and

Engineering A197, 1995, pp.157-164.

5. Kridli, Ghassan K., "Visio-Plastic Modeling of Metal Forging and Extrusion,"

National Educators' Workshop: Update 99, 2000, pp. 477-480.

626
BIPMAP (Binary Isomorphous Phase Map)

AN INTERACTIVE COMPUTER TOOL

FOR PHASE DIAGRAM INSTRUCTION

J. Csernica

J. Stolk 1

M. E. Hanyak

and

V. Subramanian

Department of Chemical Engineering

Bucknell University

Lewisburg, Pennsylvania 17837

Telephone: 570-577-1257

e-mail csernica@bucknell.edu

_eurrent address:

Franklin W. Olin College of Engineering

1735 Great Plain Avenue

Nedham, Massachusetts 02492

627
Jeffrey Csernica

628
BIPMAP (Binary Isomorphous Phase Map) - An Interactive

Computer Tool for Phase Diagram Instruction

J. Csernica, 1. Stolk 1, M.E. Hanyak, V. Subramanian

Department of Chemical Engineering

Bucknell University

Lewisburg, PA, 17837

Abstract

BIPMAP, a program that can be accessed over the internet, is designed to assist with phase

diagram instruction for beginning materials science students. Using a mouse and/or navigation

buttons, the user can select a point anywhere in a binary isomorphous phase diagram to view

information including phase amounts and compositions. Schematic alloy microstructures are

also shown, which, together with corresponding color-coded phase fields, tie lines (in two-phase

regions), and numerical results, help students visualize concepts such as the lever rule and

microstructural development.

Key words: Equilibrium, phase diagram, solubility, mlcrostructure, lever rule.

Introduction

The understanding and proper use of metallurgical phase diagrams is typically considered a vital

component of introductory materials science instruction, with textbooks (1,2) devoting entire

chapters and/or self-paced tutorials (3) to this topic.

A number of web-based computer tools dealing with phase diagrams are also available, which

are generally intended to supplement traditional textbook information. These include sites at the

University of Southampton (4) and Virginia Tech (5), which include self-paced lessons that lead

students through phase diagram definitions and concepts. These useful sites contain text,

pictures, graphics, quizzes and hyperlinks to phase diagram related topics, much as static

renditions of textbook content. Both offer a phase diagram page which allows the user to click

on a few pre-designated points to see schematic images of alloy microstructures.

Electronic renditions of phase diagrams designed for experienced users, with varying levels of

interactivity, are also available. These include CD-ROM collections from ASM (6) and the

BiPhaser Trial (7).

lcurrent address: Franklin W. Olin College of Engineering, 1735 Great Plain Ave.. Needham, MA 02492

629
FromourexperiencewithintroductorymaterialsscienceinstructionatBucknell,wefelt thata

needexistedfor adifferenttypeof electronicphasediagraminstructionaltool. Majorgoalswere

thatit betrulyinteractive(ableto respondto students'freeandunstructuredexploration),and

appropriatefor beginners,with aninterfacedesignedto organizeanddisplayinformationto help

studentsconceptualizeandintegratephasediagrambasics.Theresult,appliedto abinary

isomorphousystem,is calledBIPMAP. Thisis ainteractJava-basedappletwhichcanbe

accessedat:

www.departments.bucknell.edu/chem_eng/bipmap

KeyFeatures

Diagram. As seen in Figure 1, which is a grayscale snapshot of the BIPMAP screen, the

majority of the screen area is taken up by the phase diagram itself, with appropriate temperature

and composition axes. Represented is the actual Bismuth-Antimony (Bi-Sb) phase diagram (8).

Not visible in Figure l's black-and-white rendition is the color-coding visible on the computer

monitor, which provides connection with some other features described below. In particular, the

liquid solution region is blue, the solid solution region is red, and the two phase region is white.

Selection and Movement of Composition-Temperature Point. Any point within the phase

diagram can be selected with a mouse click, to a resolution of 0.25 wt% Sb and 1.25 °C. Once a

point has been established, it can be moved horizontally or vertically using the sets of fast ("if")

and normal motion buttons to the upper right of the diagram. This makes it possible for constant

temperature or constant composition (heating and cooling) analyses.

Quantitative Results Display. The boxes below the cursor motion buttons on the right of the

screen indicate the coordinates of the currently selected composition-temperature point, and the

equilibrium state or constitution of the alloy at that point. The state information given includes

the phases present, phase compositions, and relative phase amounts (in this order, as that mimics

the order information is normally attained manually from the diagram). Some of this

information is color-coded to match the diagram. For example, the individual liquid and solid

phase fractions are displayed in blue and red, respectively.

Tie Line. When a point is selected in the two phase region, a tie line is drawn. This line is

"inverse" color-coded. That is (see Figure 1), the right arm of the tie line is colored blue (liquid

region color), and the left arm is red (solid region color). The color-coding helps students make

the connection between the desired phase amount in the lever rule and the appropriate segments

of the lever. Also, vertical dashed lines are dropped at the ends of the tie line to indicate

individual phase compositions on the abscissa (also displayed in the results box).

Microstructure. While only simplified schematics, we feel that the representative

microstmctures shown in the lower right box are instrumental in helping students conceptualize

the meaning of phase diagram navigation and the quantitative results that are displayed. Again,

630
color-codingto matchthephasediagramregionsis employed.Forvarioussolid/liquidfractions,

themicrostructurewill showredsolidgrains,containedin ablueliquid matrix(seeFigure2 a-d).

At low solidfractions,smallsphericalnucleiarepresent.As highersolidfractionsare

encountered(say,uponcoolingin thetwo-phaseregions),thesesamenucleigrow(for

simplicity,nonewnucleiareadded).Whenthesphericalgrainsimpinge,astraightgrain

boundaryis formed.

In-Class Use and Assessment

In Spring 2001, BIPMAP was introduced to a group of 32 first-year chemical engineering

students in their required introductory materials course. With no in-class introduction to the

program, they were referred to the site as part of a homework assignment, the text of which

appears in Appendix A. Many of the standard textbook question types concerning concepts such

as melting point, solubility, liquidus temperature, phase composition, and the lever rule are

appropriate for such exercises. Later in the semester and prior to an examination covering phase

diagram topics, another assignment asked students to first answer on paper questions dealing

with the Bi-Sb diagram, then check their answers using BIPMAP. At that time, they were asked

to complete an electronic survey which asked for their feedback on the program.

The student survey response to the use of BIPMAP and its features was overwhelmingly

positive. Table 1 summarizes averages responses on a 5-point scale (1 = strongly disagree, 5 =

strongly agree).

Question

1. BIPMAP was easy to use.

2. The labels on the results display are self-explanatory.

3. BIPMAP helped me understandphase diagrams.

Avg.

Response

4.69

4.08

4.44

4. The color coding of the tie lines aided my understanding of the lever rule. 4.38

5. Pictures of the microstructures helped me understand what happens physically

when an alloy is cooled/heated. 4.63

6. BIPMAP is a good learning tool. 4.75

7. I would consider using BIPMAP as a review tool for subsequent exams. 4.55

8. I would recommend using BIPMAP in future Science of Materials classes. 4.91

Table 1. Average student responses to 5-point scale questions on BIPMAP survey

(1 = strongly disagree, 5 = strongly agree)

631
In particular, we see that students strongly felt the software was an effective learning tool that

should be used agmn in the course, and they benefited from some of its key features like the

microstmctures and colored tie lines.

We also asked tor written responses describing what students liked about BIPMAP, and what

they saw as areas for improvement. Again, we were pleased that students favorably commented

on many of the design features of the program, and overwhelmingly felt that it helped them

understand phase diagrams. Comments also suggested that students spent a good deal of time

with the program beyond the straight solution of the homework problems. Suggestions for

improvement were few, although some suggested added features, and several thought there

would be a benefit to including more (and more complex) phase diagrams. Table 2 contains

several representative comments.

1. BIPMAP has helped me greatly in understanding phase diagrams. I am a visual learner, so to have a

program like this was quite beneficial.

2. The interface was very easy to use.

3. I like that I can make can make up my own problems and then check to see that I am doing the right

thing, and am not confused about compositions vs. amounts.

4. I liked the way I could check instantly my hand calculations, and observe trends as I move the cursor

in different directions.

5. I like the color coded tie lines.

6. The pictures of the microstructures were especially helpful.

7. It gives me a good idea of how the phase diagram really works.

8. If you didn't know how to use phase diagrams, you could learn just by doing this.

9. Perhaps have an area where you can type in coordinates.

10. You could add a more complicated phase diagram, with a eutectic point.

Table 2. Representative student comments from BIPMAP survey.

Summary

The BIPMAP phase diagram program is an effective learning tool for the beginning study of

phase diagrams. Introductory materials science students can comfortably learn and use BIPMAP

at their own pace. We plan to expand the program beyond the binary isomorphous case to

include a simple eutectic diagram. [Instructors with experienced students may find eutectic

632
diagrams at the BiPhaser Trial site (7) useful.] Materials science faculty and students are

encouraged to try BIPMAP, and the authors welcome comments which can be sent to

csernica@bucknell.edu.

References

1. Callister, W.D., Materials Science and Engineering - An Introduction, 5 th ed., Wiley, New

York, 2000.

2. Shackelford, J.F., Inlroduction to Materials Science and Engineering, 5 th ed., Prentice-Hall,

Upper Saddle River, New Jersey, 2000.

3. Ashby, M.F., Jones, D.R.H., Engineering Materials 2 - An Introduction to Microstructures,

Processing and Design, Pergamon Press, New York, 1986.

4. Phase Diagrams, www.soton.ac.uk/-pasrlZ

5. 96 Class Project; Phase Diagram Basics,

www.sv, vt.edu/classes/MSE2094_NoteBook/96ClassProj/proj.html.

6. Binary Alloy Phase Diagrams CD-ROM Demo Disk, ASM International, Metals Park, OH.

7. BiPhaser Trial, www. home. ivm.de/-gollog/biuk, htm.

8. Metals Handbook - Metallography, Structures and Phase Diagrams, vol. 8, 9 t_ ed., ASM

International, Metals Park, OH, 1989.

633
T

E

M

P

E

R

A

T

U

R

E

° C

650

600

650

500

450

400

350

300

250

WEIGHT PERCENTAGE ANTIMONY (£b%)

Figure l. Grayscale snapshot of BIPMAP screen with coordinate of

45 wt% Sb and 465 °C selected.

a b C d

Figure 2. Schematic solid/liquid (light/dark) microstructures at

solid percentages of: (a) 10; (b) 20; (c) 85; (d) 100.

634
Appendix A - sample first homework assignment

I. Open the BtZPMAP program, using the link at the course "lecture" homepage.

Place the cursor at the left edge of the diagram (0% Sb), and use the click-buttons to move it up and down. Find

as precisely as possible the melting temperature of Bi. Note the changes in the "results" windows to the right of

the diagram as you move through the melting region. What is the melting temperature?

Similarly, move the cursor and use the progam to find answers to the following:

2. At 500 °C. a mixture containing 20 wt% Sb exists as a single phase liquid. If more antimony is added to this

system, at what concentration would the solubility be exceeded (indicated by the presence of a second phase)?

3. A mixture of antimony and bismuth (70 wt% Sb) is heated to 650 °C to form a well mixed liquid. This liquid is

slowly cooled to room temperature.

a) At what temperature does the first solid form, and what is the composition of this solid?

b) At what temperature will the mixture contain equal amounts of liquid and solid and what are the

compositions of each phase at this temperature?

c) At what temperature will the mixture contain l0 wt% liquid, and what are the compositions of each phase

at this temperature?

d) At what temperature will the last amount of liquid disappear?

e) Collect information from the program, and then make a plot of the liquid composition (wt% Sb) as a

function of temperature in the range of 300 - 650 °C.

635
636
TEAPOT DRIBBLES & LADLE POURS

Edward L. Widener

School of Technology

Mechanical Engineering Technology

Purdue University

Knoy Hall, Room 119

West Lafayette, Indiana 47907-1317

Telephone: 765-494-7521

e-mail elwidener @ tech.purdue.edu

637
Ed Widener

638
TEAPOTDRIBBLES& LADLEPOURS

byEdwardL. Widener,PE

PurdueUniversity,METDepartment

West.Lafayette, IN

KeyWords: Open-channel flow;potential-flownets;capillarity;surfacetension.

PrerequisiteKnowledge:ConsistentUnits= F,L, T, t

Force(F)= Mass(m)x Acceleration(a)

Velocity(V) = Length(L) / Time (T)

Acceleration = Velocity / Time

Stress (s) or Pressure (p) = Force / Area (A)

Capillarity (c) = Force / Length

Weight (w) = Force

Absolute or Dynamic Viscosity (v) = Stress x Time

Objectives: To specify dimensions; to contrast surface ten sion and tensile stress;

to test theory with observations; to investigate flow-nets; and to explore

molten-metal pouring.

Equipment & Supplies: Several teapots, pitchers, and drinking glasses

Several beakers or graduated cylinders

Assorted paper cups or plastic tumblers

Tap water (between 0 - 1O0 degrees Celsius)

Catch basin (sink or tub)

Abstract: Why do bad teapots dribble on your fine linen tablecloth? Some physics books

blame surface tension (capillarity) between the hot-tea and china-pot; but simple

experiments disprove simplistic explanation. The "wetting" ability of liquid water is

enhanced by temperature rise, as surface tension decreases. Also, changing the materials

of a liquid-solid interface may greatly change capillarity. But bad teapots still dribble.

Misshapen spouts cause spillage, regardless of metal-ceramic-plastic material selection.

Applications are obvious: 1)Broad-crested weirs; 2)Dam spillways; 3)Molten-metal

ladles; 4)Flow-nets; 5) Fourdrinier wires on Table-rolls.

Introduction: Early courses in Materials tend to stress solids, but fluids are fascinating.

Pouring liquid from one container into another is an example of"open-channel flow".

Spills of hazardous material are unacceptable, so design of vessels is important. Must we

suffer the "bottom-teeming" of molten steel, from ladles with costly maintenance? Let us

explore some "dribble phenomena", using a collection of various cups, cans, jars, and

tumblers. Classify by differences in diameter, height, taper, flare, wall thickness and lip.

Procedure:

1) Start with a simple plastic cup of clear styrene (SPI #6, ASTM-PS). Note its

tapered shell, thin-wall, circular cross-section, and sharp lip. Fill with water and

pour swiftly, discharging a convex arc into your tub. This free-falling stream

639
looksbraidedandturbulent,becausesurfacetensionpullstheflattenedoverflow

intoaroundjet, thenrotatesintoanoval,thenroundagain.As thecupempties,

yourstreamwill separatemoreabruptly,with lesstendencyto dribble.Thus,

whencomparingvessels,refill ateachstartup.

2) Refill the same cup, pour more slowly, and form a different stream. After curving

around the lip, this stream will separate from the lip to make an "S-curve". This is

a convex/concave inflection, which falls into your tub. Aiming cream at your

coffee mug would require some "offset".

3) Refill the same cup, pour even slower, and form a third type of stream. Curving

around the lip, this stream flows on the outside wall of the cup, separating at the

bottom to form a backward arc (concave) into your tub. Aiming cream at your

coffee mug requires even greater "offset".

4) Refill the same cup, but squeeze the rim into an oval, before pouring fast and

slow. This tends to exacerbate dribbling, to produce simultaneous forward and

backward streams, or to exhibit unstable movement (front to back).

5) Shift to a paper cup, which allows a sharply-folded "V-lip", makes our

stream more 3-dimensional, and reduces dribbling. This accounts for the pointed

lip on lab beakers and cream pitchers.

6) Finally test your teapots, which have various side-outlets, curvatures, extensions,

and end configurations. The best design has a hooked spout and downward freefall. However, this is vulnerable to chipping and breaking. We need a slip-on

attachment, suitable for any spout.

Conclusion: Dam spillways and broad-crested weirs are described by 2-dimensional

flow-nets, with streamlines (flux) intersected by isobars (pressure) at right angles. These

so-called "potential-flow fields" apply as well to electric current, heat transfer, gravity

pull, magnetism, and solid mechanics. For an "ideal fluid" (having no energy losses from

friction, viscosity, hysteresis, or capillarity) there is a unique flow-net for any given

boundary-condition. The solution can be found by sketching (graphics), arithmetic

(relaxation), conforrnal mapping (algebra), or finite elements (software). Thus, water and

air are virtually ideal fluids, as are many industrial fluids. Thomas Jefferson designed

"self-scouring plows" with conic sections (hyperbolic). Therefore, teapot dribble can be

predicted for "potential-flow" boundaries. Similarly, water is hydraulically pumped

through paperformer wires, running over "table rolls".

Acknowledgements:

1) "Teapot Experiments", Scientific American Magazine, Puzzles & Games, Simon

Gardner (ed), circa 1970.

2) "The Amateur Scientist", C.L.Strong (ed), Simon & Schuster, NY,1960.

3) "Fluid Mechanics for Hydraulics Engineers", Hunter Rouse, Dover, 1960

4) "McGraw-Hill Dictionary of Scientific & Technical Terms", 5ta ed., 1994.

640
NATIONAL COMPOSITE CENTER AND

DIRECTED FIBER PREFORMING

Tobey Cordell

National Composite Center

2000 ComposRe Drive

Kettering, Ohio 45420

Telephone: 937-369-1174

e-mail tcordell@compositecentr.org

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Form Approved

REPORT DOCUMENTATION PAGE OMBNo.OZO4-O_Se

Public reporting burden for this collection of information is estimated to average 1 hour per response, including the t_me for reviewing instructions, searching existing date sources,

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1. AGENCY USE ONLY (Leave blank) 2, REPORT DATE 3. REPORTTYPE AND DATES COVERED

June 2002 Conference Publication

4. TITLE AND SUBTITLE 5. FUNDING NUMBERS

National Educators' Workshop: Update 2001

Standard Experiments in Engineering, Materials Science, and Technology WU 772-30-10-32

6. AUTHOR(S)

Compiled by Edwin J. Prior, James A. Jacobs, and Said Jahanmir

7. PERFORMING ORGANIZATION NAME(S)AND ADDRESS(ES)

NASA Langley Research Center

Hampton, VA 23681-2199

9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES)

National Aeronautics and Space Administration

Washington, DC 20546-0001

8, PERFORMING ORGANIZATION

REPORT NUMBER

L-18193

' 10. SPONSORING/MONITORING

AGENCY REPORT NUMBER

NASA/CP-2002-211735

11. SUPPLEMENTARY NOTES

Prior: Langley Research Center, Hampton, VA; Jacobs: Norfolk State University, Norfolk, VA; Jahanmir: National

Institute of Standards and Technology (NIST), Gaithersburg, MD

12a. DISTRIBUTION/AVAILABILITY STATEMENT 12b. DISTRIBUTION CODE

Unclassified--Unlimited

Subject Category 23 Distribution: Standard

Availability: NASA CASI (301) 621-0390

13. ABSTRACT (Maximum 200 words) ' ' '

This document contains a collection of experiments presented and demonstrated at the National Educators'

Workshop: Update 2001 held in College Park, Maryland, October 14-17, 200 l.

14. SUBJEOTTERMS

Materials; Experiments; Education; Stmctm'es; K-12; Materials Science; Composites;

Plastics; Nanomaterials; Metals; Testing; Ceramics; Polymers; Optical materials;

I Materials curriculum

17. SECURITY CLASSIFICATION

OF REPORT

Unclassified

NSN 7540-01-280-5500

18. SECURITY CLASSIFICATION

OF THIS PAGE

Unclassified

18. SECURITY CLASSIFICATION

OF ABSTRACT

Unclassified

15. NUMBER OF PAGES

724

16. PRICE CODE

,,,r , m

20. LIMITATION

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UL

Standard Form 298 (Rev, 2-89)

Prescribed by ANSI Std, Z39-18

298-102