bluuebunny/crossref_metadata_2025 huggingface dataset:
Sulfur Content of Carbon Steel Plate Material for Dished End Manufacture by Cold Spinning
Authors: Dutta T , Chandawale RG , Vanchinath SA
Published: March 2009

Over many years SA 516 Gr. 70 plate material is being used for the construction of boilers and pressure vessels and has become a standard of the industry. However a typical failure of this material during dished end manufacture has troubled the manufacturer on and off. Many times lamellar separation takes place along the central line of the thickness visible at the edges of the dished ends after cold spinning.

In this present study we have carried out a customized shear test to ascertain the effect of sulfur content on the susceptibility of the SA 516 Gr. 70 plate material to fail by shear along the plane of segregation.

This study indicated that the presence of central segregation is a critical factor to induce reduction in the shear strength. As the sulfur content goes down the segregation line disappears and the shear strength also increases. At 0.01% maximum sulfur best results are obtained. It was supported by the field observation of failed dished ends, where failures are observed with plates with typical sulfur content of 0.02% and above.
Composite Materials: Testing and Design, Thirteenth Volume
Authors: Hooper SJ
Published: March 2009

Description

Features research on current test and analysis methods applied to composite materials and structures. The world's leading experts in the field present 14 peer-reviewed papers covering the following key topics:

• Composite Design;

• Interlaminar Fracture Toughness Characterization;

• Interlaminar Fracture Mechanics;

• Compression Testing;

• Metal Matrix and Ceramic Matrix Composties;

• Shear Testing and Laminate Analysis;

• and General Analysis Techniques.
Life Prediction Methodology for Titanium Matrix Composites
Authors: Johnson S , Larsen J , Cox B
Published: March 2009

Description

This collection of work represents the tremendous progress that has recently been made toward the characterization and modeling of Titanium Matrix Composites (TMCs), including microstructural aspects, stress analysis, and life models. 29 papers divided into five sections cover:

• Interfacial Properties and Microstructure

• Fiber Bridging Behavior

• Inelastic Material Behavior and Modeling

• Fatigue

• and Life Predictions.
Steel Forgings: Second Volume
Authors: Nisbett EG , Melilli AS
Published: March 2009

Description

Contains information on the latest state-of-the-art technology in steel forgings research. 25 comprehensive, peer-reviewed papers from the world's leading professionals in the field offer the most current manufacturing techniques, applications and testing developments. Key areas explored:

Pressure vessel and nuclear forgings -- 6 papers examine such topics as forged stainless steel reactor piping, steam generator forging developments and forgings designed for high pressure hydrogen environments in the petrochemical industry.

General industrial forgings -- Process model development for the optimization of forging disks, forging hammer force calculation,thermally induced residual stress relief and improved high strength steels toughness are among the issues covered in 11 papers.

Turbine and generator forgings -- 8 papers discuss topics ranging from martensitic stainless steels development for turbine rotors and blades, to vast technological developments in superclean steel forging, and high pressure/low pressure rotor shafts in a modified high temperature steel.
Composite Materials: Testing and Design: Twelfth Volume
Authors: Deo RB , Saff CR
Published: March 2009

Description

Features the most current test and analysis methods applied to composite materials and structures, as well as this decade's latest technological developments in composites.

21 papers from the world's leading experts in the field focus on the following categories:

• Environmental Effects Testing,

•Design Allowables and Damage Tolerance Testing,

• Textile and other Advanced Composites,

• and Design, Analysis and Test Techniques.
Fire Resistance of Industrial Fluids
Authors: Totten GE , Reichel J
Published: March 2009

Description

Comprehensive, international overview of traditional, current and newly proposed fire resistance testing methods for industrial fluids.

14 peer-reviewed papers from leading researchers in the field address the following industrial fire prevention issues: Fundamental principles of fire resistance testing • New testing procedures that will dramatically impact the fire-resistant ranking of hydraulic fluids both in the USA and abroad • Previous and current testing methodologies and limitations • Spray flammability tests Innovative testing methodology • Potential toxicity of fluid combustion by-products • Pool fire burning modeling and characteristics.

A critical resource for fluid manufacturers, turbine oil and hydraulic fluid suppliers, users of fire resistant fluids in mining, aerospace, steel and automotive industries, maintenance engineers, testing laboratories, insurance companies and government agencies responsible for fluid test and selection.
An UHMWPE Homocomposite for Joint Prostheses
Authors: Mosleh M
Published: March 2009

A homocomposite consisting of an ultra-high molecular weight polyethylene (UHMWPE) matrix and an ultra-high molecular weight polyethylene reinforcing phase is introduced. While the chemical compositions of the bulk and fibers are the same, the fibers have a higher strength and a higher melting temperature due to their high degree of molecular orientation. The homocomposite was manufactured by compression molding of randomly oriented fibers and UHMWPE resin in a mold. The molding temperature was chosen to be slightly higher than the melting temperature of the matrix but below that of the fibers. Mechanical properties of the homocomposite such as the elastic modulus, and tensile strength are improved when compared with the properties of ultra-high molecular weight polyethylene. The homocomposite also exhibits a lower friction coefficient and a significantly higher wear resistance in dry sliding which are desirable properties in bearing applications. Due to the biocompatibility of polyethylene, the homocomposite may be acceptable as a bearing material in joint prostheses pending exhibiting improved tribological behavior in lubricated and simulated wear testing.
Pavement Evaluation of Roads in the Sub-Saharan Region
Authors: Claros GJ , Oduro-Konadu E
Published: March 2009

This paper presents experience gained in the evaluation of pavement structures in the sub-Saharan region of Africa for the design of rehabilitation and maintenance alternatives. Most of the pavement structures in this region are very light with thin layers of subbase and base materials. The surfaces are sometimes single surface treatments or thin layers of asphaltic concrete. The evaluation of these pavement structures was made using state-of-the art equipment such us FWD equipment and laboratory resilient modulus equipment to test soils and asphalt samples. Backcalculation software such as ELMOD and Modulus 5 was used to characterize the pavement materials. This characterization was supplemented with laboratory tests of resilient modulus characteristics of soil and asphalt concrete samples.

This paper discusses the limitations and advantages of backcalculation software and how the backcalculated moduli compared with a laboratory measured resilient moduli of undisturbed samples. This comparison is also used to evaluate the correction factor (C=0.33) included in the AASHTO DARWin software. This correction factor reduces the backcalculated subgrade MRin the determination of the required structural number for the design.

Comparison of test procedures AASHTO T294-94, SHRP P46 and a variation of the P46 protocol, which uses grouting to secure the loading plates to the sample, is also included in the paper. Based on the above comparison, a practical procedure for routine testing of resilient modulus of soil samples is proposed. Design of the rehabilitations was done using the AASHTO DARWin software and mechanistic analysis. Comparison of these two methods of design is presented in the paper with practical recommendations for their use.
Considerations for a Performance-Based Specification for Bituminous Crack Sealants
Authors: Masson J-F , Lacasse MA
Published: March 2009

Crack sealing is an invaluable method of pavement maintenance that extends pavement service life. Notwithstanding the evident positive aspects attributable to crack sealing, crack sealants themselves often fail prematurely when exposed to harsh climatic conditions in which temperatures can range from -40°C to +40 °C. Based on a review of the performance concept applied to construction materials and a critical assessment of the current ASTM specification (D 3405) for bituminous crack sealants used in cold climates we propose a modified yet systematic approach towards developing a performance-based specification for bituminous crack sealants. The specification would permit the selection of sealants for very cold climates and would allow predicting the probable effective life based on a numerical model.
Advances in Fatigue Lifetime Predictive Techniques: 3rd Volume
Authors: Mitchell MR , Landgraf RW
Published: March 2009

Description

The latest information on methods for predicting and understanding fatigue failures in materials and structures.

17 peer-reviewed papers cover:

• metal matrix composite complexities;

• analysis methods for multiple failure mechanisms;

• cyclic and creep loading experimental approaches;

• thermo-mechanical fatigue in polymer matrix composites;

• non-destructive methods for detecting damage;

• damage mechanics;

• crack initiation and growth prediction techniques;

• microstructural effects on fatigue cracking behavior;

• and design method development and application for dealing with fatigue in components and structures.

Invaluable for design engineers, researchers, materials engineers,and metallurgists.
Durability Testing of Nonmetallic Materials
Authors: Herling RJ
Published: March 2009

Description

Durability testing of nonmetallic materials has been a common practice in many industries, such as paint and coatings, plastics,textiles and building materials. The role of this testing is expanding from a basic research tool to that of a quality control technique and predictor of service life. This change has necessitated the development of new procedures for exposing and evaluating materials and analyzing data.

STP 1294 addresses these developments with 14 peer-reviewed papers. In three sections:

• Characterizing Natural and Accelerated Exposure Environments and Samples

• Correlating Natural and Accelerated Durability Testing

• and Predicting Service Life.
Zirconium in the Nuclear Industry: Eleventh International Symposium
Authors: Bradley ER , Sabol GP
Published: March 2009

Description

From its inaugural meeting in Philadelphia in 1968, the ASTM Symposium on Zirconium in the Nuclear Industry has been the premiere vehicle for discussion and documentation of the scientific and technological bases for the utilization of zirconium-based alloys in water-cooled reactors. The eleventh conference in this symposium series, held in September 1995 in Garmisch-Partenkirchen, Germany, continued this tradition of excellence. Attendees to this conference numbered 209, representing 16 countries. After careful peer review and editing, forty-one technical papers presented at this conference are published in this book. The highlights of the oral discussions have also been captured and appear at the end of each paper. This publication also includes two papers that are significant contributions to zirconium technology which served as the basis for the authors receiving the W. J. Kroll awards for 1993 and 1994. In Garmisch-Partenkirchen the awards for these years were presented to J. A. L. Robertson and to the team comprised of Friedrich Garzarolli, Heinz Stehle, and Eckard Steinberg, respectively. These Kroll Award papers represent historical as well as technical significance for the use of zirconium alloys in the nuclear industry.
Corrosion Testing in Natural Waters: Second Volume
Authors: Young WT , Kain RM
Published: March 2009

Description

STP 1300 examines the latest technical information available for the corrosion engineering community. In addition to data on evaluation techniques for studying corrosion, this new and updated volume includes the final results of a five-year worldwide study on corrosion behavior of metals in seawater.

8 peer-reviewed papers:

• Monitoring Biofilm Formation in Power Plant Environments

• Modeling of Marine Corrosion of Steel Specimens

• Seawater Corrosivity Around the World: Results from Five Years of Testing

• Twenty Year Field Study of the Performance of Coatings in Seawater

• Crevice Corrosion Testing of Austenitic, Superaustenitic, Superferritic,and Superduplex Stainless Type Alloys in Seawater

• Statistical Analysis of Pitting Corrosion in Condenser Tubes

• Corrosion Coupon Testing in Natural Waters: A Case History Dealing with Reverse Osmosis

• Desalination of Seawater

• and Comparison of Current Reversal Chronopotentiometry (CRC) and Small Amplitude Cyclic Voltammetry (SACV) Method to Determine the Long-Term Corrosion Tendency of Copper-Nickel Alloys in Polluted and Unpolluted Seawater Under Jet-Impingement Conditions.
M3D III: Mechanics and Mechanisms of Material Damping
Authors: Wolfenden A , Kinra VK
Published: March 2009

Description

STP 1304 contains the latest research results on the fundamentals and applications of techniques for measuring and interpreting damping in all types of solids.

The world’s leading experts in the field have presented 28 comprehensive papers covering various aspects of damping, including both fundamental research and technological applications. Topics explored include: Nonlinear effects of boundaries; • Viscoelastic damping; • Grain boundary damping; • High temperature damping; • Ceramics; • Martensitic and solid-liquid phase changes; • Magnetomechanical damping; • Elastothermodynamic damping; • Layered and intercalated materials; • Modeling; and • Longitudinal and flexural vibrations.
Comparison of Dry Scrubber and Class C Fly Ash in Controlled Low-Strength Material (CLSM) Applications
Authors: Dockter BA
Published: March 2009

Controlled low-strength material (CLSM) is a cementitious material, commonly a blend of portland cement, fly ash, sand, and water, that is usually flowable and self-leveling at the time of placement. It is generally used in nonstructural applications below grade where low strengths are desired. In these cases, the mature strength of the CLSM is intended to be no stronger than that of the surrounding soils.
Utilization of Recycled Glass as Aggregate in Controlled Low-Strength Material (CLSM)
Authors: Ohlheiser TR
Published: March 2009

Incoming glass from curbside recycling programs is successfully being utilized as aggregate replacements. The colored glass that can not be used by local bottle manufacturers is crushed to a 1/2 in. (12.5mm) material and used in various construction projects. The most successful use of processed glass aggregate (PGA) to date, has been in replacing up to 100% of the aggregate in controlled low-strength material (CLSM). It has proven to be successful and has gained acceptance by contractors in the Boulder, Colorado area.
Development of Engineering Properties for Regular and Quick-Set Flowable Fill
Authors: Pons F , Landwermeyer JS , Kerns L
Published: March 2009

The purpose of this paper is to report relationships that have been developed in a study performed in Tulsa, Oklahoma, for bearing strength, diggability, and subsidence for regular and quick-setting flowable fills. The bearing strength parameters measured were California bearing ratio (CBR) and subgrade modulus (k). These parameters are typically used in the design of engineered backfill, subgrades, and pavement bases. More easily measured parameters such as hand-held mortar penetration resistance and 3 by 6-in. (76 by 152-mm) cylinder unconfined compressive strength through 365 days were also determined. Aggregate base CBR test values are presented to serve as benchmarks for comparing to CBR values of flowable fills since aggregate base has been used extensively and CBR values are widely known and used in the engineering and construction communities. This paper also presents an economic analysis and a controlled full-scale diggability assessment of regular and quick-set flowable fills. The results of our testing program, excavatability assessment, and economic analysis demonstrate the advantages of quick-setting flowable fills over regular flowable fills for use in street/cut repair applications.
Admixture Enhanced Controlled Low-Strength Material for Direct Underwater Injection With Minimal Cross-Contamination
Authors: Hepworth HK , Davidson JS , Hooyman JL
Published: March 2009

Commercially available admixtures have been developed for placing traditional concrete products under water. This paper evaluates adapting anti-washout admixture (AWA) and high-range water-reducing admixture (HRWRA) products to enhance Controlled Low-Strength Materials (CLSMs) for underwater placement. A simple experimental scale model (based on dynamic and geometric similitude) of typical grout pump emplacement equipment has been developed to determine the percentage of cementing material washed out. The objective of this study was to identify proportions of admixtures and underwater CLSM emplacement procedures that would minimize the cross-contamination of the displaced water while maintaining the advantages of CLSM. Since the displaced water from radioactively contaminated systems must be subsequently treated before release to the environment, the amount of cross-contamination is important for cases in which cementing material could form hard sludges in a water treatment facility and contaminate the in-place CLSM stabilization medium.
Fly-Ash-Based Controlled Low-Strength Material (CLSM) Used for Critical Microtunneling Applications
Authors: Green BH , Staheli K , Bennett D , Walley DM
Published: March 2009

A controlled low-strength material (CLSM) has been successfully used in two microtunneling applications. This CLSM, developed at the U.S. Army Engineer Waterways Experiment Station (WES), is a mixture of ASTM Class C fly ash, ASTM Type I portland cement, bentonite, and water.

The CLSM was first used during the microtunneling field trials at WES to stabilize a tunnel excavation while retracting the microtunneling machine through unstable, flooded, running sand. The void left by the retracted tunnel machine was filled with the CLSM to provide continuous support to the excavation and avoid settlement of the ground surface.

Based on the success of the WES tests, the CLSM was used on a second microtunneling project in Newark, California. The CLSM was used to stabilize the soil surrounding the sheet-piled shaft that would be used to launch a microtunnel boring machine. The use of this fly-ash-based CLSM greatly improved the stability of the soils and safety of the shaft during the launch. The use of the CLSM also provided cost savings in excess of $100,000 on the Newark project.
Construction of CLSM Approach Embankment to Minimize the Bump at the End of the Bridge
Authors: Snethen DR , Benson JM
Published: March 2009

The Oklahoma Department of Transportation and Oklahoma State University School of Civil and Environmental Engineering are currently conducting a research program to evaluate options to minimize approach embankment settlement. The research program involves construction of three new bridges on U.S. 177 north of Stillwater, Oklahoma. Five of the six approach embankments/abutment backfills were constructed using different construction materials and methods. The constructed approach embankments include: unclassified borrow (control section), geotextile reinforced wall, controlled low strength material, dynamically compacted granular backfill, and flooded/vibrated granular backfill. The approach embankments/abutment backfills have beeninstrumented to measure earth pressure on the abutment walls, settlement and lateral movement of the approach embankments, and groundwater conditions. The paper documents the design and construction of the CLSM approach embankment and reviews the instrumentation data collected to date.
Use of Controlled Density Fill to Fill Underslab Void
Authors: Mason TF
Published: March 2009

During the removal of a portion of a warehouse slab for the United States Navy, a large void that was caused by water erosion was discovered. The void was created behind a concrete seawall by years of tidal and current action. Conventional granular backfill material was considered but was dismissed as being nearly impossible to install and compact. Controlled density fill (CDF) was proposed and accepted as an acceptable backfill method.

Access holes were drilled along the exterior of the warehouse to allow easy placement of the CDF. A bulkhead made from sandbags was installed in the void to prevent the CDF from flowing past the limit of approved work. The CDF was installed over a period of two days to lessen lateral pressure on the sand bag bulkhead and vertical pressure on the bottom of the void adjacent to the concrete seawall.

By using controlled density fill, the project was successfully completed quickly and at a fraction of the original estimated cost using conventional granular backfill materials and methods.
Ten-Year Performance Record of Non-Shrink Slurry Backfill
Authors: Brinkley D , Mueller PE
Published: March 2009

Over ten years ago, the City of Prescott, Arizona, first installed a non-shrink slurry as a controlled low-strength trench backfill material. Since then, the process has become a standard for all utility trench installations. The non-shrink slurry backfill is a controlled low-strength portland cement concrete product with a compressive strength of 120 to 150 psi (827 to 1034 kPa) in 30 to 60 days and has a 0-inch slump. Prior use of aggregate backfills resulted in a failure rate of greater than 80 %. The City has re-excavated numerous trenches filled with the slurry material and successfully removed the slurry from various pipe systems including water, sewer, natural gas, electric, telephone, cable, and fiber optic installations. The City of Prescott now requires this controlled low-strength slurry in all trench restoration work. The failure rate over a ten-year period has been less than 1 %.
Proposed Standard Practice for Installing Buried Pipe Using Flowable Fill
Authors: Howard A
Published: March 2009

This paper will present a proposed new ASTM standard “Standard Practice for Installing Buried Pipe Using Flowable Fill” describing how to use “flowable fill” (CLSM, CDF, Soil-Cement Slurry) for installing buried pipe. There are six different ASTM Committees that prepare and oversee standards for pipe products and their installation. Rather than the six different committees developing separate flowable fill installation standards for their particular pipe, there should be only one standard for the engineering community to use. Contractors and specifiers should be more willing to use flowable fill if there is only one set of procedures and instructions. Familiarity with the material and its application may reduce the cost of installing pipe.
Specifications and Use of Controlled Low-Strength Material by State Transportation Agencies
Authors: Riggs EH , Keck RH
Published: March 2009

Controlled low strength material, CLSM, was not used by state transportation agencies until recently, although its use in general construction dates back to the early 1970's. The documentation of its present inclusion by many states is important in the progress of the technology of this relatively new material. States surveyed include Alabama, Florida, Georgia, North Carolina, South Carolina, and Virginia. The individual specifications are reviewed and compared. Testing methods are also discussed, along with representative data from laboratory and field test reports. Finally, a composite specification is suggested based on the consensus of the ones reviewed.
Tribology of Hydraulic Pump Testing
Authors: Totten GE , Kling GH , Smolenski DJ
Published: March 2009

Description

STP 1310 is the only publication of its kind addressing the critically important area of modeling and testing hydraulic fluid lubrication regimes in hydraulic pumps. In addition to an in-depth overview, 28 comprehensive peer-reviewed papers cover the following keyareas:

Lubrication Fundamentals -- 4 papers explore the potential application of basic tribological principles to solve lubrication problems arising from a broad range of pumps and motors.

Pump Testing -- A comprehensive selection of the most commonly used pump tests as well as new pump testing proposals are addressed in 15 papers.

Fluid Cleanliness -- 3 papers examine the predictability of fluid contamination on pump wear.

Bench Test Development -- Innovative bench testing procedures currently under evaluation to enhance or replace current testing approaches are explored in 6 papers.

This publication is an invaluable resource for hydraulic mainten and and systems engineers, hydraulic pump manufacturers, designers and test personnel, oil manufacturers and producers, end users of hydraulic equipment, and fluid formulation specialists.
International Symposium on Safety in Baseball/Softball
Authors: Hoerner EF , Cosgrove FA
Published: March 2009

Description

Provides interested baseball/softball parties with new recommendations,guidelines, and suggestions on how baseball and softball programs, equipment, and facilities can be made safer. Whether you are concerned with the scientific intricacies of bat and ball research or how to best manage baseball/softball programs, this publication offers the most diverse collection of baseball/softball safety related data and information available.

10 comprehensive, peer-reviewed papers from a wide range of experts cover state of the art products, materials, technology, epidemiology and program operations critical to baseball and softball. Specific topics addressed include:

• The physics of baseball/softball equipment

• The latest advances in protective equipment

• Innovative baseball/softball field design

• Improved operations and maintenance systems

• Spectator safety management

• The causes of baseball/softball injuries.
Environmental Toxicology and Risk Assessment: Modeling and Risk Assessment Sixth Volume
Authors: Dwyer FJ , Doane TR , Hinman ML
Published: March 2009

Description

The urgency and importance of properly conducting a risk assessment,and all the various attributes of the assessment, will remain a significant issue for years to come. STP 1317 explores the use of modeling in developing risk assessments for a variety of environmental situations, including human-health assessments, site-specific assessments, and ecosystem-level assessments.

32 peer-reviewed papers examine several aspects to consider when conducting a risk assessment, including:

• When is Risk Assessment the Right Tool?

• Communication of Risk Assessment

• Model Selection and Problem Analysis

• Data Quality and Uncertainty.
Insulation Materials: Testing and Applications, 3rd Volume
Authors: Graves RS , Zarr RR
Published: March 2009

Description

STP 1320 features the most current information from the world's leading experts on thermal insulation materials, systems and measurement technology.

34 peer-reviewed papers convey state-of-the-art research in the following comprehensive areas: • Fenestration Testing • System Testing • Materials Testing/Properties • Models & Materials • and Test Methods.

Two sections on performance feature 10 papers examining such topics as an innovative self-drying thermal insulation concept, thermohygric performance corrosion prevention, external corrosion cracking, and how building materials hold up against wide ranging temperature and humidity conditions.
Site Characterization and Design of On-Site Septic Systems
Authors: Bedinger MS , Fleming JS , Johnson AI
Published: March 2009

Description

On-site septic system technology is undergoing dramatic changes and advances with increased effort and thought placed on the effective and economical design of on-site systems. STP 1324 addresses these changes with 25 peer-reviewed papers in three sections:

Septic System Operation and Evaluation -- 7 papers, including a comprehensive inspection procedure for evaluation of septic systems; distribution box performance in septic tank-soil absorption systems; domestic wastewater and the sodium factor; and the use of low-pressure systems to provide even distribution of septic tank effluent in septic filter fields.

Septic System Site Characterization and Design -- 9 papers, including a pressure system design spreadsheet; problems associated with disturbed soils; man-made materials used to produce high-quality effluent; and an empirical procedure for analysis of mounding in the vadose zone in the evaluation of the viability of large septic systems.

Alternative Systems and Component Design -- 9 papers, summary of a study to determine the suitability of used tires as a substitute for drainfield aggregate in standard sewage disposal systems; field performance of chamber leaching systems ; alternative design for wastewater treatment
Fatigue Debonding Characterization in Composite Skin/Stringer Configurations
Authors: Cvitkovich MK , O'Brien TK , Minguet PJ
Published: March 2009

The objective of this work was to investigate the fatigue damage mechanisms and to identify the influence of skin stacking sequence in carbon epoxy composite bonded skin/stringer constructions. A simple four-point-bending test fixture originally designed for previously performed monotonic tests was used to evaluate the fatigue debonding mechanisms between the skin and the bonded frame when the dominant loading in the skin is flexure along the edge of the frame. The specimens consisted of a tapered flange, representing the stringer, bonded onto a skin. Based on the results of previous monotonic tests, two different skin layups in combination with one flange layup were investigated. The tests were performed at load levels corresponding to 40, 50, 60, 70, and 80% of the monotonic fracture loads. Microscopic investigations of the specimen edges were used to document the onset of matrix cracking and delamination and subsequent fatigue delamination growth. Typical damage patterns for both specimen configurations were identified. The observations showed that failure initiated near the tip of the flange in the form of matrix cracks at one of two locations, one in the skin and one in the flange. The location of the 90° flange and skin plies relative to the bondline was identified as the dominant layup feature that controlled the location and onset of matrix cracking and subsequent delamination. The fatigue delamination growth experiments yielded matrix cracking and delamination onset as a function of fatigue cycles as well as delamination length as a function of the number of cycles.
Effect of Stress and Geometry on Fatigue Crack Growth Perpendicular to Fibers in Ti-6Al-4V Reinforced with Unidirectional SiC Fibers
Authors: John R , Jira JR , Larsen JM
Published: March 2009

Critical turbine engine and aircraft components fabricated from continuous fiber-reinforced metal matrix composite (MMC) will experience cyclic loads during service, and many of these components typically contain crack initiators. Hence, extensive characterization of the fatigue crack growth behavior of a model MMC ([0]8 SCS-6/Ti-6Al-4V) was initiated by the USAF Wright Laboratory. This paper discusses some of the results of the experimental and analytical investigation of fatigue crack propagation in [0]8 SCS-6/Ti-6Al-4V. Automated fatigue crack growth tests were conducted using middle tension, M(T), specimens at 23°C with a stress ratio of 0.1. During some of the tests, the crack opening displacement profile was measured to verify the stress distributions predicted by fiber-bridging models. The results are also compared with those available for SM1240/Ti-6Al-4V under tension and bending fatigue loading. This study showed that the shear lag model assuming a constant value of τ can be used to predict bridged crack growth perpendicular to fibers in SCS-6/Ti-6Al-4V and SM1240/Ti-6Al-4V over a wide range of stress levels and under tension and bending fatigue loading conditions. The predictions of partially bridged and unbridged crack growth, crack opening displacements, and slip lengths correlated well with the data. The value of the fiber/matrix interfacial shear stress, τ, was the same for SCS-6/Ti-6Al-4V and SM1240/Ti-6Al-4V, implying that the bridging mechanism of the SMI240 fiber is identical to that of the SCS-6 fiber at room temperature. The results also indicate that the onset of fiber failure could be predicted using the bundle strength as the critical value.
An Experimental Investigation of Transverse Tension Fatigue Characterization of IM6/3501-6 Composite Materials Using a Three-Point Bend Test
Authors: Peck AW
Published: March 2009

As composites are introduced into more complex structures with out-of-plane loadings, a better understanding is needed of the out-of-plane, matrix-dominated failure mechanisms. This work investigates the transverse tension fatigue characteristics of IM6/3501 composite materials. To test the 90° laminae, a three-point bend test was chosen, potentially minimizing handling and gripping issues associated with tension tests. Static testing of 50 specimens of nine different-sized configurations produced a mean transverse tensile strength of 61.3 MPa (8.0 ksi). The smallest configuration (10.2 mm wide, span-to-thickness ratio of 3) consistently exhibited transverse tensile failures. A volume scale effect was difficult to discern due to the large scatter of the data. Static testing of 10 different specimens taken from a second panel produced a mean transverse tensile strength of 82.7 MPa (12.0 ksi). Weibull parameterization of the data was possible, but due to variability in raw material and/or manufacturing, more replicates are needed for greater confidence. Three-point flex fatigue testing of the smallest configuration was performed on 59 specimens at various levels of the mean static transverse tensile strength using predominantly an R ratio of 0.1 and a frequency of 20 Hz. A great deal of scatter was seen in the data. The majority of specimens failed near the center loading roller. To determine whether the scatter in the fatigue data is due to variability in raw material and/or the manufacturing process, additional testing should be performed on panels manufactured from different sources.
Life Prediction Tool for Ceramic Matrix Composites at Elevated Temperatures
Authors: Case S , Iyengar N , Reifsnider K
Published: March 2009

A life prediction method for ceramic matrix composites is developed. This model is based upon damage mechanics concepts included in the framework of the critical element model. One unique feature of the model is its ability to include general variations of temperature and applied loads as functions of time. A detailed description of application of the model to elevated temperature fatigue is given. In addition, a validation example is presented that includes the combined effects of rupture and fatigue. The comparison with the experimental data is shown to be good, although the result does appear to be dominated by the rupture effect.
The Effects of Stress and Temperature on the Open-Hole Tension Fatigue Behavior of a Graphite/Bismaleimide Composite
Authors: Johnston WM , Gates TS
Published: March 2009

An experimental investigation was performed to determine the behavior of an open-hole tension (OHT) graphite/bismaleimide composite specimen loaded in tension-tension fatigue under isothermal, fixed-frequency conditions. A range of stress levels and temperature levels was chosen to assess performance. These loads and elevated temperatures ranged from relatively benign conditions (low stress, room temperature) up through aggressive conditions (high stress, high temperature). Measurements were made of stiffness, edge crack density, residual strength, weight loss, and changes in glass transition temperature (Tg).

Results from this work will help explain the roles of aging and fatigue damage in the performance of graphite/bismaleimide OHT specimens as well as providing insights into the individual and synergistic contributions of each of these processes. Contributions of aging and microcrack formation during elevated temperature fatigue of OHT specimens may result in a net stiffness increase in the gage section and a decrease in residual strength. The magnitude of changes in stiffness or strength is determined by the time at temperature and the chosen stress level.
Comparison of Two Accelerated Hot-Wet Aging Conditions of a Glass-Reinforced Epoxy Resin
Authors: Zaffaroni G , Cappelletti C , Rigamonti M , Fambri L , Pegoretti A
Published: March 2009

Two accelerated hot-wet aging tests of glass-reinforced epoxy resin were performed at 45 and 70°C at the same level of relative humidity (RH = 84%). Mechanical and physical properties of “dry” and differently saturated composites are compared. It has been found that the higher the conditioning temperature, the higher the equilibrium moisture content. The glass transition temperature decreases from 138°C (dry) to 108 to 111°C (for both moisture saturated cases). Moreover, it has been found that moisture absorption reduces the static properties while not modifying the endurance in fatigue tests.
Differences in the Impact Response Mechanisms of Graphite/Epoxy Composite Cylinders
Authors: Patterson JE
Published: March 2009

Impact damage to composites has been identified as a major limiting factor in the wider use of composite materials as structural components. Graphite fiber is often selected as a structural fiber due to its low density and high strength, both desirable properties in rocket motorcase and launch tube design. An understanding of the damage mechanisms involved is critical in the determination of composite structural integrity and for the development of damage models and design codes. To this end, a test program was conducted to characterize the impact response of graphite/epoxy structures. Overall design of the test article utilized for this program was directed towards a generic thin-walled structure applicable for use as either a rocket motorcase or launch tube. Low-energy impacts between 1.25 and 7.75 J (0.9 and 5.6 ft-lb) were imparted to empty cylinders and to cylinders whose casewalls were strengthened to simulate launch tube and rocket motorcase configurations. Significant differences between the test configurations were identified with regard to visual damage, impact loads, absorbed energy, and casewall deflection. However, with all the readily apparent differences noted, the post-impact residual strength capability was quite similar. The data indicate that significant strength losses can be expected at impact energies as low as 1.3 J (0.94 ft-lb).
Residual Strength Prediction of Impact-Damaged Composite Structures by Optical and Acoustical Computer Sensing with Neural Network Techniques
Authors: Lansing MD , Walker JL , Russell SS
Published: March 2009

The proliferation of composites as a structural material has increased the necessity for detection and characterization of impact damage. Impact damage, due either to mishandling or in-service environment, in the form of delaminations, matrix cracking, and fiber chopping, may be sufficient to reduce the load-bearing ability of the structure below safety limits and may still not be visible to the unaided observer. Such damage may exist on the surface of an internal cavity, which may prevent it from being viewed, or it may exist within the thickness of the structure and not be visible from either side of the laminate. Impact damage that is partially visible often extends further along and through the material than that which can be seen. Computerized methods for damage detection offer greater assessment capabilities than visual inspections and are capable of detecting subsurface or internal flaws. For these reasons, as well as the declining cost of more powerful hardware, computer sensing methods for nondestructive evaluation (NDE) have grown increasingly popular in recent years.

A disadvantage of some computerized NDE methods is that vast amounts of data are generally obtained from any given test, and often it is up to the inspection conductor to interpret these results subjectively based upon prior experience. An alternative is to train the computer sensing system to analyze the huge data arrays, which it can digest more easily than can its human counterpart, and to provide objective interpretations. This paper presents the results of an experimental study in which two computer sensing techniques were used to monitor filament-wound pressure vessels during pressurization. Acoustic emission registers the sound generated by microscopic damage propagation. Video image correlation is a noncontact computer vision technique that simultaneously measures full-field in-plane surface displacements and strains, both linear and angular, with subpixel accuracy. Neural networks were used to predict the burst pressures of impacted pressure vessels based upon data obtained at less than approximately one third of the expected burst pressure for an undamaged specimen.
Fatigue and Fracture of Art Made from Composite Materials
Authors: Reilly JK
Published: March 2009

Art, in the form of sculpture and masonry murals, has been and is often made from composite materials. Natural fiber materials are used often for sculpture and murals. Examples of art are discussed in relation to most of the important topics of the symposium: fracture by impact; thermal fatigue and fracture; multiaxial loading failure; new composite materials for art; and the monitoring of damage growth. Fracture of art can be caused by centuries of stress fatigue, pollution, seismic activity, and dynamic impact due to theft or bad custodial care. Modern designers should consider structural design and composite material in the selection process to ensure longevity of the art.
A Probabilistic Interpretation of the Quotient Method for Characterizing and Managing Risk to Ecological Receptors
Authors: Burns TP , Cornaby BW , Mitz SV , Hadden CT
Published: March 2009

Hazard or ‘risk’ quotients are commonly used to characterize the risk to ecological receptors at Superfund sites. A risk quotient is the ratio of an estimated exposure level (concentration or dose) to an effects threshold level (concentration or dose). Ecological hazard quotients can be formulated and interpreted in probabilistic terms. The numerator of the ratio is the exposure corresponding to the maximum allowable risk to the receptor at the site. Given a distribution of exposures at a site, the specified exposure level defines the maximum acceptable probability that a receptor experiences unacceptable harm, i.e., maximum acceptable risk. The exposure level at Superfund sites is frequently specified by regulators to be that corresponding to the upper 95th confidence limit on the mean concentration. The denominator of the ratio is the exposure corresponding to the dose causing the maximum allowable adverse effect on the receptor. Given a distribution of exposures at a site, the effects threshold defines the actual probability that the receptor is exposed to levels greater than the threshold, i.e., actual risk. The effects threshold at Superfund sites is frequently required by regulators to be that corresponding to the no effect level. This formulation of ecological hazard quotients clarifies the meaning of the quotient and highlights the importance of the exposure level and effects thresholds specified by regulators. This paper also discusses the relationship between this probabilistic interpretation of risk quotients and probabilistic exposure modeling, e.g., Monte Carlo simulation.
Stormwater Runoff Water Quality Evaluation and Management Program for Hazardous Chemical Sites: Development Issues
Authors: Lee GF , Jones-Lee A
Published: March 2009

The deficiencies in the typical stormwater runoff water quality monitoring from hazardous chemical sites and an alternative approach (Evaluation Monitoring) for monitoring that shifts the monitoring program from periodic sampling and analysis of stormwater runoff for a suite of chemical parameters to examining the receiving waters to determine what, if any, water quality use impairments are occurring due to the runoff-associated constituents is presented in this paper. Rather than measuring potentially toxic constituents such as heavy metals in runoff, the monitoring program determines whether there is aquatic life toxicity in the receiving waters associated with the stormwater runoff. If toxicity is found, its cause is determined and the source of the constituents causing the toxicity is identified through forensic analysis. Based on this information, site-specific, technically valid stormwater runoff management programs can be developed that will control real water quality impacts caused by stormwater runoff-associated constituents.
Evaluation of the Performance of Statistical Tests Used in Making Cleanup Decisions at Superfund Sites. Part 1: Choosing an Appropriate Statistical Test
Authors: Berman DW , Allen BC , Van Landingham CB
Published: March 2009

The decision rules commonly employed to determine the need for cleanup (including those cited in recent guidance) are evaluated below both to identify conditions under which they lead to erroneous conclusions and to quantify the rate that such errors occur. Their performance is also compared with that of other applicable decision rules.

We based the evaluation of decision rules on simulations. Results are presented as power curves. These curves demonstrate that the degree of statistical control achieved is independent of the form of the null hypothesis. The loss of statistical control that occurs when a decision rule is applied to a data set that does not satisfy the rule's validity criteria is also clearly demonstrated. Some of the rules evaluated do not offer the formal statistical control that is an inherent design feature of other rules. Nevertheless, results indicate that such “informal” decision rules may provide superior overall control of error rates, when their application is restricted to data exhibiting particular characteristics.

The results reported here are limited to decision rules applied to uncensored and lognormally distributed data. To optimize decision rules, it is necessary to evaluate their behavior when applied to data exhibiting a range of characteristics that bracket those common to field data. The performance of decision rules applied to data sets exhibiting a broader range of characteristics is reported in the second paper of this study.
Towards Standardization of Service Life Prediction of Roofing Membranes
Authors: Lounis Z , Lacasse MA , Vanier DJ , Kyle BR
Published: March 2009

A service life prediction approach for roofing membranes and systems is proposed based on a probabilistic modeling of the time-dependent performance. The membrane performance is modeled using a discrete Markov chain that evaluates the change of performance over time as a result of deterioration or repair. This stochastic model will be developed using in-field performance data collected during roof inspections, considering the roofing system type, membrane type, age group, exposure conditions, and maintenance level. The use of in-field performance data captures the interaction between roofing components, as well as the synergism of the various degradation factors. The probabilistic modeling accounts for the uncertainty and variability of material properties, degradation factors, and quality of workmanship and maintenance. The service life is determined considering both the technical and economical performances, in addition to the risk of failure; this constitutes the first step towards the standardization of service life prediction of roofing membranes and systems.