bluuebunny/crossref_metadata_2025 huggingface dataset:
The Trip Scheduling Problem
Authors: Archetti Claudia , Savelsbergh Martin
Published: September 2009

The hours of service (HOS) regulations of the department of transportation severely restrict the set of feasible driver schedules. So much so that establishing whether a sequence of full truckload transportation requests, each with a dispatch window at the origin, can feasibly be executed by a driver is no longer a matter of simple forward simulation. We consider this problem and prove that the feasibility of a driver schedule can be checked in polynomial time by providing an O(n3) algorithm for establishing whether a sequence of full truckload transportation requests, each with a dispatch window at the origin, can be executed by a driver.
Women's Experiences with Anal Sex: Motivations and Implications for STD Prevention
Authors: Maynard Emily , Carballo‐Diéguez Alex , Ventuneac Ana , Exner Theresa , Mayer Kenneth
Published: September 2009

CONTEXT:Heterosexual anal intercourse is a highly efficient mode of HIV transmission, yet little is known about the contexts in which women engage in it, or when and with whom they use condoms. Similarly, sexuality and reproductive health research has paid little attention to female desire and pleasure‐seeking.

METHODS:In‐depth interviews were conducted in Boston in 2006 with 28 women who reported having had unprotected anal intercourse in the last year with a man who was HIV‐positive or whose serostatus was unknown. Sexual scripting theory guided analyses of their experiences with and motivations to practice anal intercourse.

RESULTS:Participants engaged in anal intercourse for a wide variety of reasons: to experience physical pleasure, enhance emotional intimacy, please their male partners or avoid violence. Male partners usually initiated anal sex. Anal intercourse often occurred in the context of vaginal and oral sex. Among reasons women cited for not using condoms were familiarity with their partner and feeling that condoms made anal sex less pleasurable. Knowledge of HIV and STD risks did not appear to encourage condom use.

CONCLUSIONS:Women who perceive condom use during anal sex as limiting their pleasure or intimacy may be at increased risk for acquiring HIV. Consequently, interventions to promote safer anal intercourse must find a way to increase the use of barrier methods without decreasing pleasure or perceived intimacy between sexual partners.
An Illusion of Power: Qualitative Perspectives On Abortion Decision‐Making Among Teenage Women In Sweden
Authors: Ekstrand Maria , Tydén Tanja , Darj Elisabeth , Larsson Margareta
Published: September 2009

CONTEXT: Swedish law permits abortion at the request of a pregnant woman until the 18th week of gestation. However, the extent to which the decision is truly the woman's own is subject to debate; women are often influenced, directly or indirectly, by the attitudes of their partners, family and friends or by social norms.

METHODS: Individual in‐depth interviews about the pregnancy and the abortion decision were conducted 3–4 weeks postabortion with 25 women aged 16–20 at different periods in 2003, 2005 and 2007. Interviews were audio‐taped, transcribed verbatim and analyzed using latent content analysis.

RESULTS: The main reasons for unplanned pregnancy were underestimation of pregnancy risk and inconsistent contraceptive use. Pregnancy prevention was perceived as the woman's responsibility. The abortion decision was accompanied by mixed emotions, and was seen as a natural yet difficult choice. Social norms and the negative attitudes of family and friends strongly influenced the decision. Partners and parents were regarded as the most important sources of support. After the abortion, the women felt pressured by contraceptive counselors to use highly effective contraceptives despite their previous negative experiences or worries about side effects.

CONCLUSIONS: Swedish teenagers' basic right to decide whether to have an abortion may be limited by societal norms and disapproval of teenage childbearing. Given the perception that women are responsible for contraception, programs need to emphasize that pregnancy prevention is a shared responsibility; greater efforts to include males in prevention practices are needed.
Relationship Dynamics and Consistency of Condom Use Among Adolescents
Authors: Manning Wendy D. , Flanigan Christine M. , Giordano Peggy C. , Longmore Monica A.
Published: September 2009

CONTEXT: Research on adolescent condom use often focuses on the influence of parents, peers and environmental factors. Although most sexually active teenagers have sex within dating relationships, little is known about associations between the characteristics of these relationships and consistency of condom use.

METHODS: Data on 269 participants in Wave 1 of the Toledo Adolescent Relationships Study who had had sex in their current or most recent dating relationship were analyzed in logistic regression models to examine how positive and negative relationship qualities are associated with consistent condom use.

RESULTS: Among teenagers who had had sex with their dating partner, both negative relationship dynamics (conflict, partner's controlling behavior, mistrust, jealousy, perceived partner inferiority) and positive qualities (love, enmeshment, salience, self‐disclosure) were negatively associated with consistent condom use (odds ratios, 0.7–0.9). Asymmetries in partners' age, race and school were not related to consistent condom use. Relationship duration was negatively associated with consistency (0.98–0.99), but the association was explained by feelings of relationship importance. Findings for relationship qualities were similar for males and females, with the exception of conflict, which was positively associated with consistent condom use among females but not males.

CONCLUSIONS: Although the relationship processes associated with consistent condom use are complex, such processes appeared to be more strongly associated with consistent condom use than were social and demographic characteristics. Programs should focus on relationship qualities and dynamics, recognizing that both negative and positive relationship features are associated with consistent condom use.
Use and abuse of cesarean section – a transatlantic evaluation
Authors: Schmidt Stephan
Published: September 2009

No abstract available
Prevention of intrauterine growth restriction: are there no effective methods available?
Authors: Mandruzzato Giampaolo
Published: September 2009

No abstract available
The death of Prof. Albert Huch
Authors: Dudenhausen Joachim W.
Published: September 2009

No abstract available
An Investigation of Factors Impacting Nitinol Wire Fatigue Life
Authors: Wong S. , Lin Z. C. , Tahran A. , Boylan J. , Pike K. , Kramer-Brown P.
Published: September 2009

The purpose of this study is to identify factors that affect superelastic Nitinol fatigue resistance using a commercially available wire specimen. The study reveals the fatigue resistance of Nitinol wire as functions of surface finish, inclusions, processing, and applied stress applied. Nitinol wires were fatigue tested using the rotating beam fatigue method. The sample strains were verified using a direct strain-measurement method. Wires with outer diameters ranging from 0.127 to 0.343 mm processed with a mechanical and/or electropolished surface finish were compared to one another.
Influence of Test Machine Control Method on Flexural Performance of Fiber Reinforced Concrete Beams
Authors: Bernard E. S.
Published: September 2009

Flexural testing of fiber reinforced concrete (FRC) and shotcrete using beams has undergone a steady evolution over the past 30 years to the point where complex servo-controlled test machines are now required to undertake these tests. These machines have been found necessary in order to impose stable and reproducible test conditions on beams. Servo-controlled machines utilize closed-loop strain feedback mechanisms in an attempt to maintain stability throughout the post-crack deformation history of a brittle FRC specimen. However, some standard test methods for flexural performance assessment of FRC require displacement-control of the loading piston rather than strain-control based on the measured deformation of the beam. Displacement-control has frequently been found to result in unstable unloading of brittle FRC. Anecdotal evidence suggests that differences in the method of machine control may lead to changes in the apparent performance of specimens. An investigation was therefore instigated to examine the apparent performance of FRC beams tested using strain-controlled loading compared to displacement-control.
A Sensitivity Study on a Normalization Procedure
Authors: Van Der Sluys WA , Young BA
Published: September 2009

Various committees within ASTM E08 are considering the possibility of making normalization a part of current standards or new standards in development. In these applications normalization would be used to determine crack lengths from the load displacement data obtained during a fracture test. Normalization assumes a continuous coupling between the three variables: load, load line displacement, and crack length. Given continuous information about any two of the variables and the boundary conditions on the third, the information between the boundary conditions can be resolved. An application for normalization would be to obtain a J-R curve from the continuous variables load and the load-line displacement with known boundary conditions of the initial and final physically measured crack lengths. The objective of this study was to determine the sensitivity of the output variables to the variability of the input parameters. Input parameters such as physically measured crack lengths, data spacing on the load COD graph, goodness of fit in the regression analysis, deviation allowance from the data to the fitted curve, and data cut off for normalized plastic displacement were varied in this study. The output variables to determine sensitivity were the JIC value and the J-R curve coefficients.
Separability Property and Load Normalization in AA 6061-T6 Aluminum Alloy
Authors: Cassanelli AN , Ortiz H , Wainstein JE , deVedia LA
Published: September 2009

In the present work, a study of the separability property, experimental ηpl factor determination, and load normalization AA 6061-T6 aluminum alloy is described. The separability property has been studied using the Sij parameter with Standard ASTM E 1820-96 SE(B) blunt notch specimens with 8 and 24% side grooving.

The deformation property function H, from variable separability property, was written in terms of plastic and total displacement. The ηpl factor was determined using the Sharobeam and Landes methodology with two side grooves and the two H functions. The ηpl factor values obtained with the H function evaluated in terms of the total and plastic displacement differed by less than 1.4%. The values obtained were close to that suggested in ASTM E 1820-96.

In order to estimate crack length from the test record, the unloading and normalization load methodologies were used. Special attention was paid to the point where the domain of definition of the separability property in plastic displacement started and the influence it had on the estimated crack length. The normalization load was described by means of a standard and a modified power law, and calibration curves were obtained for blunt notched and fatigue precracked specimens.

The degree of restraint introduced by different side-grooving ratios had an influence on the resulting J-R curve, and the three methods employed were sensitive to this change. The toughness obtained with the geometry, dimensions, constraints, test conditions, and material used in this work with different estimation methodologies were in relatively good agreement.
Scanning Atomic-Force Microscopy on Initiation and Growth Behavior of Fatigue Slip-Bands in α-Brass
Authors: Nakai Y , Kusukawa T , Hayashi N
Published: September 2009

Slip-band formation and fatigue crack-initiation processes in α-brass were observed by means of atomic force microscopy (AFM), and the effects of the grain size and the stress amplitude were discussed. In a fine grain material, fatigue cracks were initiated only from slip-bands. In a coarse grain material, however, they were initiated either from slip-bands or grain boundaries. The depth of an intrusion drastically increased with its outgrowth to a crack, and with coalescence of cracks, the width of cracks increased rapidly.

The depth of an intrusion increased with the number of loading cycles, and when the depth reaches a critical value, a transgranular crack was initiated from the intrusion. The critical value was given as a function of the slip-band angle relative to the stress axis. From the AFM observations, it was found that the critical value of the slip distance was independent of the slip-band angle relative to the stress axis, the stress amplitude, and the grain-size. For crack-initiations from grain boundaries, however, the value of the grain boundary depth at the crack initiation was not a unique function of the grain boundary angle relative to the stress axis.
Creep Crack Growth in X20CrMoV 12 1 Steel Weld Joints
Authors: Kim KS , Lee NW , Chung YK , Park JJ
Published: September 2009

This paper investigated creep crack growth in X20CrMoV 12 1 steel weld joints. Crack growth tests were carried out at 545°C on side-grooved 1/2T CT specimens under static loads. A material with simulated intercritical HAZ properties, along which creep crack growth normally occurs, was produced for this study. Constitutive properties were obtained for the simulated HAZ material as well as for the base metal and weld metal. Finite element analyses of crack growth were performed on the models with and without a HAZ layer, using the experimental crack length-time history. The inclusion of a HAZ layer increased the load line velocities significantly. The crack growth rates were correlated reasonably well with C*(t). The minimum crack extension for validity of C*(t) was found much smaller than the ASTM minimum size, 0.5 mm, for IT CT specimens of creep-ductile materials.
Three-Dimensional Analyses of Crack-Tip-Opening Angles and δ5-Resistance Curves for 2024-T351 Aluminum Alloy
Authors: James MA , Newman JC , Johnston WM
Published: September 2009

The objective of this paper was to investigate the fracture behavior of compact and middle-crack tension specimens made of 6.35 mm thick 2024-T351 aluminum alloy. Tests were conducted on compact tension, C(T), specimens ranging in width from 51 to 152 mm and on middle-crack tension, M(T), specimens ranging in width from 76 to 1016 mm. Most of the M(T) specimens were allowed to buckle during the fracture tests. Three-dimensional, elastic-plastic, finite-element analyses (FEA) using the WARP3D code with straight-front cracks were used to show transferability of the critical crack-tip-opening angle (CTOA) fracture criterion from small laboratory specimens, such as the C(T) specimen to large M(T) specimens. A single value of critical CTOA (Ψc = 6.35°) was determined from the FEA (with a straight-crack front) by matching the average failure load for the 152 mm C(T) specimens. CTOA analyses were then conducted on the various width C(T) and M(T) specimens. The WARP3D analyses with the critical CTOA predicted the experimental failure loads within ±3% for all specimens. The δ5-resistance curves from the analyses of the C(T) and M(T) specimens were nearly identical up to the maximum load. Beyond maximum load, the δ5-resistance curves for the C(T) specimens began to deviate rapidly; whereas, the δ5-resistance curves for the M(T) specimens only deviated slightly.
Standard Reference Material 2100: Fracture Toughness of Ceramics
Authors: Quinn GD , Xu K , Gettings R , Salem JA , Swab JJ
Published: September 2009

New Standard Reference Material (SRM) 2100 is the first reference material in the world for the property fracture toughness for any class material. The SRM is for fracture toughness of ceramics and may be used with any ceramic fracture toughness test method, but is optimized for methods that use beams in bending. The SRM complements the new ASTM Test Method for Determination of Fracture Toughness of Advanced Ceramics at Ambient Temperature (C 1421) as well as three International Standards Organization (ISO) draft standards now under development. This SRM, for which the fracture toughness is known with a high accuracy and high precision, should dramatically improve fracture toughness testing and enhance data quality around the world. This paper describes SRM 2100 and its creation.
An X-Specimen Test for Determination of Thin-Walled Tube Fracture Toughness
Authors: Hsu HH , Chien KF , Chu HC , Kuo RC , Liaw PK
Published: September 2009

A new fracture toughness measurement method, named an X-specimen test that is based on the curved compact-tension test, was proposed to assess the fracture toughness of thin-walled tubing materials like Zircaloy fuel cladding. This technique offers applications of fracture mechanics for testing thin-walled tubes, which do not meet the requirements of the American Society for Testing and Materials standards in terms of the specimen configuration and loading state. The finite-element analysis was conducted to evaluate the feasibility of applying the X-specimen test to the measurement of cladding fracture toughness and to develop a relationship between the stress intensity factor and crack extension. Then fracture and fatigue tests were performed employing a hydraulic mechanical testing machine. The J-integral value was evaluated using the experimental results of the applied load, loadline displacement, and crack extension.

By means of a backtracking method, the stress intensity solutions were computed using fatigue results. A J-integral value of about 82 kN/m was obtained for Zircaloy fuel cladding. A comparison of the present test results and literature data shows that the X-specimen test is suitable for a quantitative evaluation of the fracture behavior of thin-walled tubing materials.
Fatigue and Fracture Mechanics: 32nd Volume
Authors: Chona R
Published: September 2009

Description

23 peer-reviewed papers detail the latest advances in all aspects of fatigue and fracture mechanics, related technologies, and innovative applications. Topics range from:

• New analytical approaches to applications for tried and true methods

• Life assessment issues facing critical engineering components and structures

• Fracture behavior under dynamic loading

• Failure mechanics in ceramics and composites.
Effects of Radiation on Materials: 23rd International Symposium
Authors: Lott Randy G. , Busby Jeremy T.
Published: September 2009

Description

Eighteen peer-reviewed papers focus on the irradiation embrittlement of reactor pressure vessel steels. This new publication provides a broad perspective on the development and application of trend curves used to predict fracture toughness transition temperatures in irradiated reactor pressure vessel steels. Papers cover materials ranging from erbium-tritide films to oxide dispersion strengthened (ODS) ferritic steels.
Control of Interferences Caused by Acids and Salts in the Flame Photometric Determination of Sodium and Potassium
Authors: Eggertsen FT , Wyld G , Lykken L
Published: September 2009

In the determination of sodium and potassium by flame photometry, substantial negative errors are produced by moderate concentrations of common acids and salts in the test solution when the instrument operates on a mist produced in a spray chamber and is used without an internal standard. Our work indicates that these errors are primarily caused by the decrease in the amount of evaporation that occurs between the time the mist droplets form and enter the flame. It appears that the presence of acids or salts in the mist droplets hinders evaporation of the droplets and that the resulting increased amount of water carried into the flame results in a lowered radiation intensity produced in the flame by the test element. Interference from this source can be virtually eliminated by adding a high concentration of a salt or acid, as a buffer, to both the test solution and comparison standards. Lithium chloride is an exceptionally good buffer because, in addition to eliminating errors produced by acids and salts, it serves also as a radiation buffer to reduce interference by mutual excitation.
Transverse Strength of Masonry Walls
Authors: Monk CB
Published: September 2009

Transverse strength of brick masonry walls is usually not directly recognized by most building codes. Indirectly, the transverse or flexural resistance of masonry walls is controlled by the height-to-thickness limitations imposed by nearly all codes. However, allowable extreme fiber stresses that would permit rational analysis is indeed lacking. The American Standard Building Code Requirements for Masonry make no provision for tension in masonry; however, through rules such as wall thickness-height ratios and lateral support requirements, ample lateral resistance is indirectly obtained. The Uniform Building Code is the only major code in this country that recognizes an allowable tensile stress in masonry subject to flexural loads. Therefore, the interest in the following series of tests was occasioned by the meager code basis on which to rationally design unreinforced masonry to meet lateral force requirements.
Fire Tests of Building Structures and Materials and their Utilization in Building Code Requirements
Authors: Steiner AJ
Published: September 2009

Fundamentally, the purpose of fire tests for building materials and structures is to provide a basis for comparison of the behavior of different building elements under fire exposure conditions. These tests must be standardized and be of a kind which provides a means of classification for their utilization in building codes. If this is not accomplished, confusion is the result and fire disaster follows.
Lateral Tests on Full-Scale Lumber- and Plywood-Sheathed Roof Diaphragms
Authors: Stillinger JR
Published: September 2009

During 1952 and 1953, the Timber Mechanics Section of the Oregon Forest Products Laboratory built and tested eight lumber-sheathed and two plywood-sheathed roof diaphragms 20 by 60-ft in size, in order to determine the strength and stiffness at various load levels when the following structural elements were investigated: (1) ⅜-in. plywood sheathing; (2) 1.-in. lumber sheathing used green and dry and applied in a longitudinal or diagonal orientation; (3) different nailing patterns; (4) variations in boundary member construction; (5) presence or absence of bridging and blocking; (6) different corner connections; (7) use of metal corrugated fasteners; and (8) presence or absence of skylight openings.

A pin-connected steel-and-timber truss was used in testing the diaphragms. Loads were applied by two 30-ton hydraulic jacks connected in unison. The load was applied in steps to a predetermined level, then released to a zero load; the same procedure was followed for each new load level. In some of the diaphragms, a repetitive loading procedure was employed to determine the load level where permanent set occurred.

In addition to deflection readings, buckling in the framing members, sheathing movement, and strains across joints and within members of the tension chord and endposts were measured.

The summary of test results indicates that the strength and stiffness of roof diaphragms can be appreciably influenced by altering any of the test variables included in this testing program.
A Review of Pozzolanic Materials and Their Use in Concretes
Authors: Davis RE
Published: September 2009

Long ago it was discovered that certain finely divided siliceous materials when mixed with lime produced cements having hydraulic properties. The use of such cements certainly dates back to the days of ancient Rome, when they were employed in the masonry construction of aqueducts, arch bridges, retaining walls, and buildings. One such material was a consolidated volcanic ash or tuff found near Pozzuoli, Italy. This came to be designated as Pozzuolana, a general term covering similar materials of volcanic origin found in other deposits in Italy, France, and Spain. Later the term was employed throughout Europe to designate any material, regardless of its geologic origin, which possessed similar properties. Though not to be found in the dictionary, among technical men in this country the present preferred spelling of the word is “pozzolan.” Until the development of natural cements, less than two centuries ago, the only hydraulic cements were those composed of a mixture of pozzolan and lime.
Effect of Calcination on Natural Pozzolans
Authors: Mielenz RC , Witte LP , Glantz OJ
Published: September 2009

Calcination will improve the quality of some pozzolans, reduce the quality of others, and induce pozzolanic properties in some otherwise essentially non-reactive-substances. Natural pozzolans or natural materials in which pozzolanic properties can be induced by calcination at temperatures less than 2000 F. owe their activity to One or more of five kinds of substances. Consequently, natural pozzolans can be classified by their essential active ingredient as follows: Activity type Essential active constituent 1....................:...............Volcanic glass 2....................... Opal 3a...................................Kaolinite-type clay 3b...................................Montmorillonite-type clay 3c...................................Illite-type clay 3d...................................Mixed clay with vermiculite 4....................................Zeolites 5....................................Hydrated oxides of aluminum 6....................................Nonpozzolan

Water requirement, setting time of lime-pozzolan paste, strength development of portland-pozzolan mortar, and control of alkali-aggregate reaction are affected significantly by calcination at temperatures up to 2000 F. Calcination of clayey materials, activity type 3, is essential to develop satisfactory pozzolanic activity. The quality of activity types 1, 2, and 4 frequently can be improved considerably by calcination. No materials of activity type 5 were included in the investigations.

Pozzolans of activity types 1, 2, 3a, and 3b are the most promising from the standpoints of strength development and control of alkali-aggregate reaction in mortar and concrete, opaline cherts of activity type 2 being superior to all others. For these materials, calcination in the range from 1200 F. to 1600 F. will induce optimum activity.
The Effect of the Use of Diatomite Treated With Air-Entraining Agents Upon the Properties of Concrete
Authors: Davis RE , Klein A
Published: September 2009

Early investigations demonstrated the usefulness of small additions of diatomite [or diatomaceous] earth in increasing the plasticity and decreasing the tendency towards segregation of concrete mixes. As a result of these findings and field experience, diatomaceous earth was processed by a number of manufacturers and came to be widely used as a concrete ad-mixture. The raw earth, after being dried, was usually pulverized in impact mills; and the product, though fine as compared with portland cement, was still largely composed of unfractured or partly fractured skeletons of diatoms and was therefore highly absorptive. Its unit weight was of the order of 10 lb. per cu. ft. It was generally believed that there was an advantage in this high absorption and low unit weight, though additions in excess of 2 or 3 per cent of the weight of the cement significantly increased the water requirement to produce concrete of a given consistency, and significantly increased the yield.
Studies of Some Methods of Avoiding The Expansion and Pattern Cracking Associated with The Alkali-Aggregate Reaction
Authors: Leech W
Published: September 2009

The chemical interaction of certain siliceous mineral constituents of aggregates with the alkalies in portland cement is known to be a cause of abnormal expansion and pattern cracking in some concrete structures. The most practical and most certain method of preventing this type of expansion and pattern cracking is to select a non-reactive aggregate. When the use of a reactive aggregate is unavoidable, control of the alkali content of the cement may be considered after thorough tests justify it, or the use qf certain proved pozzolanic materials may provide protection. This paper describes progress made toward the development of various methods for gaging the presence of reactive minerals in the aggregates, and discusses the procedure for limiting the alkali content of the cement and the use of proved pozzolanic admixtures as alternate methods of minimizing the expansion and pattern cracking associated with the alkali-aggregate reaction, as shown by field experience and results of laboratory tests available to date.
Oxygen Determinations Using a Platinum Bath and Capillary Trap
Authors: Smiley William G.
Published: September 2009

Although it was developed primarily for the analysis of fissionable materials, the capillary trap method for oxygen in metals should have wide usefulness. As in vacuum fusion, the sample is fused in a graphite crucible with a flux, but a stream of argon at atmospheric pressure is used in place of high vacuum. Carbon monoxide is converted by Schütze's reagent to carbon dioxide, which is condensed in a capillary trap and measured with a capillary manometer. Most determinations require only 12 min. Platinum is preferred as a flux because it has a very low vapor pressure and dissolves only a moderate amount of carbon, avoiding the “solidification” which occurs with iron. Platinum is not an effective flux for the refractory metals such as tantalum and tungsten; platinum-cobalt and platinum-iron alloys dissolve these metals but give somewhat low results on known samples. The platinum bath gave a standard deviation of 7 ppm on 50-mg plutonium samples, and samples with added oxygen gave correct results within 2 per cent of the total oxygen. Twenty-two elements and numerous alloys have been analyzed. The method is especially recommended for rapid routine determinations.
Ammonia and Mercury Stress-cracking Tests for Brass
Authors: Edmunds Gerald , Anderson E. A. , Waring R. K.
Published: September 2009

Brass is liable to failure under the combined influence of stress, certain corrosion media, and time, a phenomenon commonly termed season cracking or stress-corrosion cracking. The consequences of this are serious in applications of brass generally, including the important field of cartridge cases. Cartridge cases (70 Cu:3o Zn) that fail from this cause may allow the escape of gas from the gun breech, a hazard to the shooter, and may not eject, thus temporarily putting the gun out of action. In loaded cartridge cases, the stress present is partly residual from the drawing and necking operations and partly applied by the insertion of the projectile. Ammonia, present as a decomposition product of smokeless powder, air and moisture constitute corrosive media.
Stress-Corrosion Testing of Copper-Base Alloys
Authors: Bulow C. L.
Published: September 2009

In this discussion of stress-corrosion cracking of widely used copper-base alloys, no attempt has been made to prepare an extensive review or bibliography since this has been quite ably covered by other investigators. An excellent bibliography was published by H. P. Croft (1) in connection with his studies of stress-corrosion cracking in mercurous nitrate solutions and his analyses of the magnitude and distribution of stresses in brass parts. We are reporting on a few of the results which have been obtained to date in connection with an ammonia vapor test and an alternate immersion test. These are accelerated corrosion tests for determining the susceptibility of materials to failure from season or stress-corrosion cracking due to the presence of moist ammonia and oxygen so prevalent in nature. Our experiences with the ammonia test seem to indicate that it is a more searching test than the mercurous nitrate test.
Aqua Ammonia Test
Authors: Jamieson A. L. , Rosenthal H.
Published: September 2009

Stress-corrosion cracking of copper-base alloys is of considerable importance and has been the subject of many investigations which employed various accelerated tests and long-time service tests. The outstanding accelerated tests used are variations of either the mercury cracking test reported by Rogers in 1905(1) or the ammonia test reported in 1910(2). The ease of application of the mercury test is probably the reason industry adopted it. Subsequent investigation of this test(3,4) revealed that a minimum threshold stress was necessary before mercury cracking could develop.
The Stress-Corrosion Properties of Some Non-Ferrous Sheet Metals
Authors: Gohn G. R. , Arnold S. M.
Published: September 2009

The results of stress-corrosion tests upon several non-ferrous sheet metals are presented in this paper. The metals include tough pitch copper, five binary brasses, two leaded brasses, one copper-silicon alloy, two tin bronzes, and two nickel-silver alloys.
Effect on Season Cracking of Alloy Additions to Cartridge Brass
Authors: Wilson T. C. , Edmunds Gerald , Anderson E. A. , Peirce W. M.
Published: September 2009

Thirty-six elements have been alloyed singly with cartridge brass. Ammonia and mercury stress-cracking tests have been conducted on the as-rolled and recrystallized strip. Ultra high purity cartridge brass has also been tested. Silicon improves stress-cracking behavior. High silicon (1 per cent) cartridge brass quenched from high temperature (for example, 800 C.) annealing is exceptionally resistant to ammonia stress cracking. This improvement is not lost by subsequent cold working, but is greatly reduced by subsequent low temperature annealing. Phosphorus, arsenic, barium, cerium, magnesium, tellurium, tin, beryllium, and manganese benefit stress-corrosion resistance under some circumstances, but not others. The other alloying additions tried had no large effect on stress-cracking resistance. None of the elements added accelerated stress cracking. The impurities in commercial brass are not responsible for season cracking.
Stress-Corrosion Testing of Magnesium Alloys
Authors: Loose W. S. , Barbian H. A.
Published: September 2009

Tests to evaluate correctly the stress-corrosion sensitivity of magnesium alloys have been recently carried out in this country. In Germany, Siebel(1)2 studied the stress cracking of Electron AZM alloy, but concluded that despite its sensitivity in laboratory tests, actual service data had shown it to be a very satisfactory material. As an example, he cites the results of quarterly inspections over a period of 6 yr. of magnesium subassemblies used on two airplanes. A satisfactory condition of all parts was maintained. Beck(2), Graff(3), and others have reported extensive research that has been conducted in Germany throughout the past 10 yr. on the stress-corrosion resistance of a variety of magnesium alloys.
Stress-Corrosion Tests on Cast Aluminum Alloys
Authors: Brown Hiram
Published: September 2009

The problem of stress corrosion has been discussed a great deal recently, but many factors have as yet not been clarified. There are many interpretations of the definition of the word, different corrosive media are used, and numerous methods of stressing are utilized. Some quarters believe that the inherent strength of the material under test is the determining factor of its resistance to stress corrosion, while others think that the natural corrosion resistance of the material is the determining factor. This paper is intended merely to set forth the limited experience we have had and to discuss some of the other stress-corrosion tests which have been made with light alloys.
A Generalized Theory of Stress Corrosion of Alloys
Authors: Mears R. B. , Brown R. H. , Dix E. H.
Published: September 2009

In the Institute of Metals Division Lecture of 1940, E. H. Dix, Jr.(1) discussed the acceleration of the rate of corrosion by high constant stresses. Experimental data obtained on this subject at the Aluminum Research Laboratories and a theory compatible with these facts were included in that lecture. The present paper contains data and ideas subsequently developed at the Aluminum Research Laboratories.
Some Observations of Stress-Corrosion Cracking in Austenitic Stainless Alloys
Authors: Scheil M. A.
Published: September 2009

Austenitic stainless alloys are susceptible to stress-corrosion cracking which may occur under certain corrosion environments irrespective of their susceptibility to intergranular corrosion.

Test samples are described for investigating stress-corrosion susceptibility of alloys for industrial equipment.

A laboratory test using a solution of magnesium chloride boiling at 309 F. was found to produce transgranular cracks in several alloys investigated and in types 347 and 316 stainless steel tubing a residual stress of the order of 10,000 psi. was observed to initiate cracking.

The susceptibility to stress-corrosion cracking as judged by the boiling magnesium chloride test indicates that alloys may be selected which will withstand a high stress in service.

Stressed specimens of stainless alloys included in a corrosion testing program will aid in determining the acceptibility of these fabricated alloys, when stressed, to the service conditions.
Stress-Corrosion Cracking of Nickel and Some Nickel Alloys
Authors: Feaser O. B. J.
Published: September 2009

Stress-corrosion cracking of nickel andhigh nickel alloys is rare but not unknown.As with other metals and alloys thisphenomenon, in the high nickel materials,is highly specific; it has occurred onlyunder exposure to certain fairly welldefined corrosive conditions and is not afunction of corrosion rate. It is not aserious hazard; the cases to be recountedare actually only isolated instances in theexperience of many years' use of manymillions of pounds of the high nickelmaterials in the services in which theisolated instances have occurred. Therehave been no cases in the experience ofthe major producer of nickel of spontaneouscracking of stressed material under atmosphericexposure, such as occurs withcertain copper-zinc alloys.
Field Loading Tests for the Evaluation of the Wheel-Load Capacities of Airport Pavements
Authors: Palmer L. A.
Published: September 2009

The Bureau of Yards and Docks and the Bureau of Aeronautics of the Navy Department jointly sponsored an extensive investigation of concrete and bituminous-surfaced airfield pavements at more than 40 Naval and Marine Corps Air stations. This involved making more than 3000 plate loading tests ranging up to 75,000 lb. maximum loads, also taking and testing an approximately equal number of samples of subgrades and pavement components.

The objectives of this investigation were: (a) to obtain directly the maximum safe wheel-load capacities of the pavements at the specific fields, (b) to obtain basic information of value in estimating the wheel-load capacities of pavements at other fields not included in the study, and (c) to obtain basic information of value in checking current design procedures and possibly developing new design procedures and methods of construction.

This paper is primarily concerned with one phase of the project, namely, field loading tests and factors which influence the loading test data.

The general procedure for evaluating the wheel-load bearing capacities of flexible types of pavements at Naval Air stations is described. The procedure includes plate loading tests, both on the pavement surface and on the subgrade, and in-place density and moisture tests of base course, sub-base and subgrade materials. Laboratory tests include triaxial tests on undisturbed subgrade samples and for both base course, sub-base and subgrade materials, density and moisture relations, Atterburg limits, and grain size. Asphalt stability and other tests are made with the surfacing materials. Comparisons are made between the in-place densities and moisture percentages of subgrade soils and the laboratory compacted maximum densities and optimum moistures of the same soils. The limitations and applicability of theory are being studied. Data indicate the relationship between bearing capacity and tire pressure and also the relationships between pavement thickness and subgrade properties on the bearing value of both the pavement and the subgrade.
Methods of Testing Soils for Runways and Foundations
Authors: Seelye Elwyn E. , Bailey W. D. , Teetor S. D.
Published: September 2009

This paper includes a discussion of the testing of soil from the point of view of the spread foundations of structures and foundations for air strip runways, with particular reference to the use of load tests since this is the primary purpose of the present symposium. Load tests are also applied to pile foundations but this type of load test is somewhat outside of the scope of the symposium and accordingly the subject is not treated in this paper.
Mechanical Polishing of Metallographic Specimens
Authors: Link Harold S
Published: September 2009

The primary purpose of metallographic polishing is to produce an optically flat surface suitably free of polishing defects for subsequent microscopic examination. How this suitable surface is obtained is of secondary importance.

With such modern aids as automatic polishing machines and electropolishers, a technician with only a small amount of training can generally prepare satisfactory specimens in a relatively short time. However, this type of advanced equipment is not essential except in special cases. Examples are shown of the type of work that experienced metallographers can accomplish with polishing wheels that are much the same as those used since the earliest days of metallography.
Use of Diamond Abrasives in Metallographic Problems
Authors: Olden E C
Published: September 2009

A polishing procedure incorporating the use of diamond abrasives was developed for assignments representing the three major problem areas in metallographic preparation of ferrous and non-ferrous alloys, namely, loss of non-metallic inclusions, surface distortion, and insufficient flatness of field. Efforts were made to keep the metallographic technique simple and suitable for use even by relatively inexperienced personnel.

Results of the study indicated that the utilization of diamond abrasives minimized, to a large degree, polishing difficulties ordinarily experienced in the above mentioned problem areas. In addition, it was found that by using this polishing medium, one basic procedure could be used, thus avoiding the need of specialized techniques and experience often required when only conventional abrasives were employed.

Use of diamond abrasives was recommended in metallographic work wherein retention of nonmetallic inclusions, surface distortion, or flatness of field constitute a problem.
Present Methods of Metallographic Specimen Preparation for Retention and Identification of Inclusions in Steel
Authors: Brandenburg C F
Published: September 2009

The procedures used by five bearing companies, three steel companies, and one aircraft engine builder were examined and studied for the establishment of the most useful metallographic specimen preparation for retention and identification of inclusions in steel.

An attempt was made to incorporate and correlate the various techniques into four basic methods, all referring to the procedure specified in ASTM Recommended Practice E 45.2 No attempt was made to determine the economics of one method as compared to another, but rather to point out the various techniques used to produce satisfactory metallographic specimens for determination and identification of inclusions in steel when compared to the readings specified on the Jernkontoret chart.

Each laboratory procedure was studied and categorized in accordance with the seven basic stages of specimen preparation. The metallographic examination and procedure for identification of nonmetallic inclusions is presented. From the suggestions and recommendations contained in this paper, laboratories may attempt to improve their present method and reach a more common over-all method in preparing metallographic specimens.
The Automatic Polishing of Metallographic Specimens
Authors: Anderson R L
Published: September 2009

Automatic polishers and automated methods for the preparation of metallographic specimens are discussed, as well as the theories and mechanism of specimen polishing. Currently available automatic polishing equipment is described and, where available, techniques for their use are presented. Representative results from some of these polishers are shown. The arrangement of automatic polishers currently in use at the Westinghouse Research Laboratories is described.
Techniques for Controlling Surface Pitting in Polishing Ceramic Materials
Authors: Snow R B
Published: September 2009

One of the greatest difficulties in the preparation of polished sections of ceramic materials has been the severe pitting during the primary and intermediate grinding operation. In hard minerals the deeper the pits the greater the time required for their removal. Therefore, techniques and procedures based on the approximate hardness of the minerals present are given so that in 2 to 10 min, specimens of ceramic materials can be prepared for final polishing with a minimum amount of pitting. A final polishing with gamma alumina on a wool cloth produces sufficient relief to differentiate among minerals.
The Effect of Mean Stress on Fatigue Strength of Plain and Notched Stainless Steel Sheet in the Range From 10 to 107 Cycles
Authors: Bell W. J. , Benham P. P.
Published: September 2009

Stainless steel sheet (18Cr-9Ni) was tested in fatigue under axial-load cycling in plain and notched conditions. Various stress ratios were used ranging from R = −1.0 to +0.91, and endurances (see Definitions) from 10 to 107 cycles were covered using testing frequencies of 5 to 15 cpm and 3000 cpm.

The effect of mean stress on notch fatigue strength could not be predicted empirically solely from unnotched material data; at least one notched fatigue curve would be required.

A fatigue strength reduction factor based on maximum stress for a particular mean stress and endurance provided the most reliable correlation between unnotched and notched data.

Low-cycle and high-cycle fatigue curves matched up only to a limited extent at the overlap, but there was generally strength reduction at low frequency. Under certain conditions of mean stress and stress ratio a cyclic creep or ratchetting mechanism leading to ductile rupture was obtained at low endurances.

Simple functions existed in the low-cycle region between stress range and plastic strain range and total energy and cycles to fracture, both of which were largely independent of stress ratio.
Low-Cycle Fatigue of Ti-6Al-4V at −423 F
Authors: Hilsen R. R. , Yen C. S. , Whiteson B. V.
Published: September 2009

To determine the effects of various factors on low-cycle fatigue phenomena in connection with space vehicle design, axial tension fatigue tests up to 2000 cycles were conducted on titanium alloy, Ti-6Al-4V, at −423 F. The effects of changing the minimum-to-maximum load ratio and cycling speed for the range tested were slight. The fatigue strength of pressure-welded specimens was within 1 per cent of that of the base metal. Fatigue strengths at −423 F were 65 to 68 per cent higher than those at room temperature.

Two types of fractures were observed, depending on the fatigue life. A transition in the fracture appearance occurred between 700 and 2000 cycles in which the fracture changed from a cup-and-cone to a more typical surface-initiated fatigue fracture. Cycling below the ultimate tensile strength tended to raise the fatigue strength above the static tensile strength. Possible mechanisms are discussed.