bluuebunny/crossref_metadata_2025 huggingface dataset:
Elastic Compliance of the Compact Tension Specimen Comprising Two Linear-Elastic Materials Bonded with a Thin Layer
Authors: McNaney JM , Havens R , Ritchie RO
Published: February 2009

Although the compact-tension C(T) specimen is widely used in conventional fracture mechanics testing, its application to the fracture behavior of layered structures, in the assessment of the toughness and fatigue crack growth behavior of bimaterial interfaces, for example, has been limited due to problems in identifying the crack length. Accordingly, to provide a basis for crack-length monitoring in the sandwich C(T) specimen, comprising two materials bonded with a thin layer under linear-elastic conditions, the linear-elastic compliance based on back-face strain, crack-opening displacement and load-line displacement has been determined for a wide range of substrate/layer material combinations using finite-element analyses. Calculations for sandwich systems, with elastic moduli ratios varying from 0.2 to 5 and with joining layer thicknesses between 0.4 and 2% of the specimen width, show that for crack sizes between 0.25 to 0.75 of the specimen width, the compliance is significantly different from that of the bulk substrates, except when the layer is very thin and the modulus ratio approaches unity. It is concluded that crack-opening displacements are preferable for the monitoring and detection of interfacial and near-interfacial cracks in this specimen geometry, as the compliance based on these displacements is the least sensitive to errors from either measurement site or crack location.
Experimental Determination of the Cooling Curve for Production of Continuous-Cast Steel Billets
Authors: Bailey WH
Published: February 2009

Temperature measurements of 20-cm round, 10-m long, continuous-cast steel billets in the cooling stages of production were made using a contact thermocouple. Temperatures were measured from the time they reached the cross transfer on the cooling bed to a holding area across the street from the facility. A cooling curve derived from temperatures measured on the end of the billet was generated with the equation T = 467.29e−.0001t
The Relationship Between Porosity and Air Permeability of Woven Textile Fabrics
Authors: Epps HH , Leonas KK
Published: February 2009

Based on a comprehensive review of the literature on textile fabric porosity, air permeability, and related research on fabric geometry, a study of the relationships between air permeability measurements and fabric pore size was undertaken using liquid porosimetry. Experiments were conducted on ten woven textile fabrics. Air permeability was most highly correlated with minimum pore size, but was also significantly correlated with mean flow pore size measurements and with calculated values of theoretical porosity and fabric cover factor.
Kinematic Methods for Quantifying Loss of Balance While Negotiating a Curved Path on a Slippery Surface
Authors: Wang B , Bhattacharya A , Bagchee A , Wang W , Succop PA
Published: February 2009

Ten healthy industrial workers were recruited to perform a gait test for this study. The workers were required to negotiate straight and turning paths on dry and very slippery surfaces. Seven variables that quantify loss of balance during single stance were used to assess the potential of loss of balance when negotiating the different paths on slippery surfaces. These variables included measure of the distance of the whole body center of gravity (COG) deviated from the supporting base, slide distance, slide direction, and turning radius. Using these variables, it was possible to biomechanically conclude that negotiating a curved path on a slippery surface was the most difficult task, with the highest potential of loss of balance and fall. The direction most subjects' feet slid was 52 to 60° in the lateral direction. This study provides range of COF values in the lateral direction between the shoe-floor interface for preventing slip when negotiating a curved path.
Effect of Preloading on the Strength of Soda-Lime Glass
Authors: Chen X , Matsumura M
Published: February 2009

Static fatigue and bending experiments were carried out on as-cut soda-lime glass to investigate the effect of preloading on the residual strength. Ambient air or semi-controlled dry air was used for the preloading. The results show that preloading increases both the static fatigue life and bending strength. The static fatigue life increases with preloading load, and is longer after preloading in air than in dry air. In bending tests, the bending strength increases with preloading time. The improvements of the strength of glass by preloading are interpreted as stress enhanced aging. Two dominant mechanisms for aging, the crack blunting model and stress release model, were examined by using the present experimental results.
Relating Triaxial Test Properties of Asphalt Mixtures to Mix Parameters Determined by Marshall Stability Test
Authors: Fwa TF , Tan SA , Low BH
Published: February 2009

The conventional method of asphalt mix design based on the Marshall stability test cannot be used directly for pavement thickness design and performance analysis. On the other hand, the triaxial test that measures fundamental engineering properties of friction-cohesive materials is a well understood and established test in civil engineering, and the authors have reported in an earlier paper that triaxial test properties of asphalt mixtures can be used to study analytically the response of the mixtures under loads. In an effort to establish a link between the two tests, this paper illustrates that the three triaxial test-determined properties of an asphalt mixture, namely cohesion c, angle of friction φ and elastic modulus Ep, are statistically correlated with Marshall stability test properties of the asphalt mixture. The statistical analyses furnish useful information on the trends of variation of various material parameters as a function of mix properties. Potentially useful statistical regression predictive models are derived for predicting material parameters of the Marshall stability tests using the triaxial test properties, and vice versa. Such models make it possible to analyze pavement performance under loads for those pavements constructed based on Marshall mix design.
Effects of Laundering and Exposure to Light on Environmentally-Improved Fabrics
Authors: Leimer S , Moore MA , Goldsmith E
Published: February 2009

This study evaluated the performance of four environmentally-improved fabrics after laundering or exposure to light. Specific objectives were to evaluate and compare the breaking strength, breaking elongation, and color change of the experimental fabrics after laundering or exposure to light. Results of the data analyses revealed a significant difference in the percentage of change in breaking strength and breaking elongation among the environmentally-improved fabrics as a result of laundering or exposure to light. Also, there were significant correlations between the percentage change in breaking strength, percentage change in breaking elongation, and color change due to the accelerated treatments of laundering or exposure to light.
Factors Affecting Results of Chemotaxis Inhibition Tests with Protozoa
Authors: Berk SG , Mills BA
Published: February 2009

Several factors were examined with respect to their influence on the attraction of protozoa towards yeast extract and on the inhibitory effect of cadmium on chemoattraction. These included: density of protozoa (numbers per volume), age of cultures, axenic and bacterized cultures, and starvation period before testing. A marine species, Miamiensis avidus, and a strain of Tetrahymena isolated from a local river, were tested separately. Two-fold increases in density of Miamiensis resulted in a three-fold increase in numbers attracted, whereas Tetrahymena resulted in a two-fold decrease in numbers attracted. However, inhibition by cadmium was not altered by using different densities. At 250 and 500 protozoa/25 μL, Tetrahymena was inhibited 87.8 ± 5.2 (average of four replicates ± 1 SD) and 89.0 ± 2.6%, respectively; at 117 and < 1 protozoa/25 μL, Miamiensis was inhibited 76.0 ± 4.4 and 67.5 ± 10.0%, respectively. Age of culture had an effect on cadmium sensitivity of Miamiensis but not of Tetrahymena. Older cultures of Miamiensis were more inhibited by cadmium (77.0 ± 2.0%) than younger cultures (57.3 ± 8.4%). Protozoa from axenic and bacterized cultures of Tetrahymena were equally affected by cadmium. This aspect was not tested for Miamiensis, since we did not have axenic cultures of this species. For both species, the starvation period clearly affected the numbers of protozoa attracted to yeast extract. Longer starvation periods resulted in greater attraction, yet their sensitivity to the metal did not change. After 1 and 72 h of starvation Tetrahymena was inhibited 79.0 ± 7.4 and 80.7 ± 10.8%, respectively, and Miamiensis was inhibited 78.5 ± 10.0 and 78.5 ± 5.0%, respectively. These results should provide suggestions for better standardization of behavioral tests using protozoa.
A Personal Computer Based Thermal-Mechanical Fatigue Test System
Authors: Elzey DM , Henry AT , Anderson AF
Published: February 2009

A materials testing apparatus is described which employs two closed feedback control loops simultaneously; one loop controls thermal cycling (i.e., specimen temperature cycling), while the other controls mechanical cycling (i.e., strain cycling). Although numerous variations of TMF (thermal-mechanical fatigue) test stations have been reported previously, several unique features justify a description of the current system: (1) thermal and mechanical control cycles are individually controlled using remotely programmable, arbitrary waveform function generators; (2) a personal computer is used to coordinate data acquisition and monitoring of critical test parameters; and (3) a method of real-time separation of temperature induced strain and mechanically induced strain has been incorporated. The system is currently being used to simulate actual operating conditions to which turbine engineering alloys are exposed during start-up and steady-state operation.
Effect of Bearing Plate Properties on the Behavior of Block Masonry Prisms under Axial Compression
Authors: Hamid AA , Chukwunenye AO
Published: February 2009

An analytical investigation using a three-dimensional finite element model was conducted to study the effect of bearing plate thickness and stiffness on the behavior of axially loaded hollow block masonry prisms. Faceshell and full mortar bedding of prisms were considered. Detailed vertical and lateral stress distributions for different bearing plates were determined which help in understanding the impact of bearing plate properties on the behavior of the prism. The results show that a 51 mm (2 in.) thick steel bearing plate for a 203 mm (8 in.) block prism is inadequate and leads to a nonuniform state of strain. It is concluded that plate stiffness rather than plate thickness is the most appropriate factor to be considered when selecting bearing plate size. A 102 mm (4 in.) steel plate is recommended for testing 203 mm (8 in.) block prisms under axial compression.
Measurement of Granule Coverage on Bituminous Roofing Surfaces
Authors: Dutt O
Published: February 2009

Methods were developed to measure the exposed area of bitumen on a granule-covered roofing surface. They included traverse microscopical examination, image analysis technique, and photometric measurements. Three specially prepared samples were tested for granule coverage. One of the samples was further tested for the exposed area of bitumen after progressively removing granules from its surface. The study showed that the exposure of bitumen could be related to the loss of granules.
Development of a New Accelerated Adhesion Test for Silicone Sealants
Authors: Cerra AP
Published: February 2009

Existing accelerated laboratory adhesion tests for silicone sealants are shown to lack the discrimination necessary to assess relative adhesive behavior. A novel test protocol is offered that enables improved discrimination by more precisely quantifying the adhesive strength of the sealant/substrate system. The method is based on the simultaneous application of both mechanical and environmental stress, in order to promote adhesive failure at loads below the cohesive strength of the bulk sealant.
Material Specifications of Advanced Ceramics in Corrosion Studies
Authors: Munro RG
Published: February 2009

Chemical and physical data are often reported independently in materials property databases. However, when specific applications of these data are considered, it is easily recognized that such specifications have limited utility unless the interdependence of the chemical and physical information is also reported. In this paper, the chemical and physical specification of silicon carbide, with an anticipated application to corrosion, is used as a prototypic case study of the database design requirements. With respect to corrosion, the chemical data are needed in the context of the structural information; i.e., the chemical compositions of the bulk material, the surface layers, the grain boundary regions, and regional interfaces must be distinguished. Standards for the database structure will be discussed in the context of the efficiency of the storage and retrieval system, the interdependence of chemical and physical characteristics, and the effective use of the information in subsequent applications.
A Study of the Variation of Neutron Skyshine Dose with Respect to Roof Thickness, Source Spectrum Distribution
Authors: Prabhakara Rao G , Sarkar PK
Published: February 2009

Sensitivities of neutron skyshine dose calculation from particle accelerators to certain parameters like roof thickness, distance of the neutron source from the roof, and fraction of the high-energy part of the neutron spectrum were evaluated using response surface methodology. The calculations were done for distances ranging from 100 to 2000 m for various nominal values of roof thickness and for 50- and 60-MeV α-induced neutron spectra on thick tantalum targets. Roof thickness is found to be the most sensitive parameter, and next is the high-energy part of the source neutron distribution, followed by the interaction term of the two variables.
An X-Ray Diffraction Analysis of Residual Stresses Induced by Sliding Wear of Copper-Aluminum Alloys
Authors: Wert JJ , Singerman SA , Quarles RA , Chaudhuri DK
Published: February 2009

Residual stresses induced during unlubricated sliding contact have been measured by the two-exposure technique as well as by peak shift analysis. The peak shift analysis provides the necessary information for the determination of the sum of the principal residual stresses and stacking fault probability. The results of the lattice parameter method suggested by Wagner are compared with those obtained via the conventional two-exposure X-ray technique. If the 222 and 400 reflections are of sufficient intensity, either method may be used to determine the state of stress. However, if the peaks are very diffuse because of strain hardening, the two-exposure technique yields the most reliable results.
A Simple Apparatus for Conducting In-Stream Toxicity Tests
Authors: Newbry BW , Lee GF
Published: February 2009

Because of the increasing importance of evaluating the actual impact of chemical discharges on fish in receiving waters the need for a suitable apparatus for conducting in situ toxicity tests has arisen. This paper describes a simple, inexpensive, easily handled fish cage that has proven to be quite suitable for conducting in situ toxicity tests with small fish. The cages are constructed of 10-cm plastic pipe.
Prediction of Creep Properties of Chipboard Used in Stressed-Skin Panels
Authors: Kliger IR , Pellicane PJ
Published: February 2009

In recent years, attention has been focused on structural stressed-skin panels (SSP) with lumber webs and sheet metal and chipboard panels as tension and compression flanges, respectively, at Chalmers University of Technology. In this study, certain mechanical and rheological properties of structural chipboard were evaluated as part of a larger project designed to predict the long-term behavior of SSP under load.

Several series of tests were conducted to evaluate short- and longterm properties of urea-formaldehyde bonded chipboard. From eight full-sized panels, specimens were fabricated for use in the determination of chipboard properties. Compressive strength and modulus of elasticity (MOE) were evaluated from short-term tests. Average strength and MOE values of 20 and 4100 MPa, respectively, were obtained. The MOE value was virtually identical to that obtained from initial deformations found in subsequent creep tests, indicating that test method had no effect on MOE.

Three series of long-term (11 000-h) tests were conducted under constant and similar environmental conditions and different combinations of stress-level and loading history. The results suggested that the magnitude of relative creep was greatest under lower stress levels. Two empirical models, a Clouser function without exponential terms and a power function with exponential terms (Clouser, W. S. “Creep of small wood beams under constant bending load,” FPL Report 2150, U.S. Forest Products Laboratory. Madison, WI., 1959), were evaluated as predictors of the deformation-time relationship for chipboard under constant loading. The power function with the exponential terms proved to be superior at extrapolating short-term results to long-term predictions. However, both functions were relatively similar with respect to describing the long-term behavior of chipboard as the compression flange in a SSP. Measuring methods and definition of the initial deformation were found to be important, especially for predicting the relative creep factor for chipboards under different load histories.
Water Leak Testing of Polyurethane Female Condoms
Authors: Neunaber LM , Boivin WS , Khatri ZH , Herman BA
Published: February 2009

This paper describes an apparatus and a technique for water leak testing of polyurethane female condoms. This test detects holes as effectively as other official FDA methods used to test barrier products such as latex male condoms and medical gloves. This rapid test simulates actual use conditions as much as possible without causing plastic deformation of the polyurethane material. Blind validation tests showed that the method detects a high percentage of holes 20 μm and larger over the entire surface of the condoms. Holes as small as 10 μm were detected with lower efficiency. Hole detection rate was highest in the bottom one third of the condom where the water pressure was greatest. The condom lubricant was shown to act as a surfactant when added to water.
Objective Assessment of Fabric Handle in Fabrics Treated with Flame Retardants
Authors: Kim JO , Slaten BL
Published: February 2009

Flame retardant finishes generally affect fabric handle, the tactile sensations resulting from fabric-skin contact. The subjectivity involved in the measurement of fabric handle has posed a major problem in the objective evaluation of the fabric's surface characteristics and comfort. This study investigated the effects of various flame-resistant (FR) finishes on changes in fabric handle utilizing a simple measurement technique. The nozzle extraction handle measurement method can be used as an effective objective measurement tool for textile and apparel industries to detect changes in the overall handle resulting from the processing of fibers, fabrics, or finishes. Peak handle force and slope near the peak force serve as variables to reflect overall handle. The relationships of fabric handle values to selective properties (weight, thickness, flexural rigidity, and drape coefficient) indicate that the fabric handle measured by the extraction method correlates most closely with the drape coefficient.
International Symposium on Slip Resistance: The Interface of Man, Footwear, and Walking Surfaces
Authors: Sacher A , Owens JM
Published: February 2009

The first four papers in this issue were presented at the International Symposium on Slip Resistance: The Interaction of Man, Footwear, and Walking Surfaces, held 30–31 October 1995 at the National Institute of Standards and Technology (NIST) in Gaithersburg, MD. Sponsored by Committee D 21 on Polishes and Subcommittee D 21.06 on Slip Resistance, this symposium represents the culmination of research initiated in the 1950s to determine the coefficient of friction of polished walkway surfaces. Extensive laboratory and field studies of methods and apparatus led to the development of the ASTM Test Method for Static Coefficient of Friction of Polish-Coated Floor Surfaces as Measured by the James Machine.
Color Change as a Predictor of Strength Loss in PFD Cover Fabrics
Authors: Epps HH , Leonas KK
Published: February 2009

The fabric covers of many wearable personal flotation devices (PFDs) currently on the market are subject to rapid fading and loss of strength when exposed to light. The result of this rapid degradation may be loss of flotation protection for the wearer. This research evaluates the relationship between color change and loss of breaking strength in six PFD cover fabrics and explores the possibility of using color change to predict strength loss of selected PFD covers. Regression models were developed for each fabric and the models were used to predict the level of color change at which the fabric would fail to meet the U. S. Coast Guard minimum strength requirement for covers of wearable PFDs.
Corrosiveness of Chromate Exposure to Steel Embedded in Soil or Concrete
Authors: Poston RW , Galitz CL , Yates JS
Published: February 2009

This paper presents findings from a one-year laboratory study conducted to assess the corrosion susceptibility of steel in concrete and in soil when exposed to chromates and other selected chemicals. The findings are based on electrical potential and resistance measurements taken for each of 16 corrosion cells, 8 of which were concrete and the remainder soil. A post-mortem inspection was conducted to visually confirm corrosion activity. For each medium, comparison and control cells were fabricated to relate the corrosion potential of chromium to other solutions, such as water, chlorine bleach, sodium hydroxide, and sodium chloride. Where appropriate, results were compared to previously reported research studies. Based on results of this study, it is concluded that chromate solutions are no more corrosive to reinforcing steel in soil and in concrete than is distilled water.
Creep Rupture Investigation of 63Sn-37Pb Solder by Experiments and Damage Mechanics
Authors: Ju S-H , Sandor B , Plesha ME
Published: February 2009

The main purpose of this paper is to investigate the crack growth path and creep rupture life of 63Sn-37Pb bulk solder experimentally by Moiré analysis and theoretically using continuum damage mechanics. In conventional fracture mechanics analysis, a crack growth path is assumed a priori. Fracture parameters such as the J-integral and stress intensity factor are subsequently calculated to predict the crack growth rate and structural life. However, it is often difficult to postulate the correct crack growth path for a complex structure that is subject to complex loading. Continuum damage mechanics is an alternative method that can be used to compute structural life with the important feature that the crack growth path is computed automatically. In this paper we develop a theory for partially reversible creep-fatigue damage. A finite element procedure incorporating this damage theory is developed and used to analyze the response of bulk solder plates with holes. The displacement fields obtained by finite element analysis are compared to the fringe patterns obtained from conventional Moiré experiments. Furthermore, the accuracy of the predicted crack growth paths was investigated by comparison between the maximum damage contours obtained by finite element simulation with the actual crack paths occurring in the laboratory specimens. These comparisons indicate the new continuum damage theory developed herein can adequately predict creep displacements, crack growth paths, and structural life.
Effects of Surface Geometry on Fabric Friction
Authors: Ajayi JO , Elder HM
Published: February 2009

The influence of yarn geometry on surface topography, friction, and smoothness of fabrics is reported. A systematic increase in fabric construction (threads per cm) increases frictional resistance but the fabric surface becomes smoother. This is attributed to the diminishing crown height as yarn sett increases. Similarly, an increase in yarn linear density (diameter) also increases the frictional resistance and surface roughness. The increase in surface roughness is ascribed to an increase in mechanical interlocking of yarn crowns.
Relationship Between Statistical Distributions of Traffic Loads and Pavement Responses
Authors: Newcomb DE , Chadbourn BA , Van Deusen DA
Published: February 2009

Mechanistic-empirical design approaches have been developed to predict flexible pavement responses based on vehicle loads and elastic material parameters, but little is known about vehicle load distributions and seasonal changes in these parameters. Analysis of vehicle load and transverse strain distributions suggest a relationship between wheel loads and temperature-corrected strains. It appears that the wheel load distributions and corresponding temperature-corrected strain distributions are normal and lognormal, respectively. Plotting the 25th, 50th, 75th, and 99th percentile values from the load distribution against the corresponding percentiles from the strain distributions suggests a linear relationship between wheel load and temperature-corrected strain. This indicates that a probabilistic approach to traffic loadings may be incorporated into mechanistic-empirical design procedures for flexible pavements.
Precision Profilometry of Wear Scars on Curved Surfaces
Authors: Yust CS , Blau PJ
Published: February 2009

Wear scars less than 1 μm in depth are a challenge to measure accurately by surface profilometry, particularly if they are formed on a curved surface. The resultant curved traces limit the use of the vertical scale enlargements necessary for the detection and measurement of minimal wear scars. Profilometer traces on the surface of an internal combustion engine cylinder, for example, commonly yield curved traces even when the stylus moves parallel to the cylinder axis because of (a) the difficulty in orienting the profilometer trace precisely along an element of the cylindrical surface and (b) small departures from a true cylindrical form in most manufactured cylinders. A simple procedure has been devised that permits a curved trace to be “straightened” and scaled to facilitate the determination of wear scar depths and cross sections in the sub-micron range. In some cases, wear scars within the original surface roughness can be detected and measured. The procedure will be illustrated on wear scar depths of 1 μm and less in cylindrical surfaces.
A Low-Cost, Computer-Controlled Adiabatic Calorimeter for Determining the Heat of Hydration of Concrete
Authors: Gibbon GJ , Ballim Y , Grieve GRH
Published: February 2009

An understanding of the rate and amount of heat generated during the early stages of hydration of concrete mixes is essential in the prediction of the thermal behavior of concrete structures. This paper describes the design and operation of a low-cost, computer-controlled adiabatic calorimeter used for the determination of the heat of hydration of concrete mixes using small samples of the concrete. Heat measurements are started approximately 10 min after water is added to the concrete and a continuous plot of the rate of heat generation is obtained. Furthermore, the use of the calorimeter for temperature-matched curing tests on concrete is also discussed.
A Study on the Prediction of Roundness Variation in Honing Using Hone Dynamics
Authors: Kim J-D , Choi M-S
Published: February 2009

This paper describes the simulation for estimating roundness variation according to the process variables in the honing process based on hone dynamics. Honing experiments were carried out to confirm the simulation results. The mandrel rotation speed and the workpiece stroke speed were treated as the main parameters in the simulation and the experiment. The honing force, which varies dynamically in the contact between the honing tool and workpiece, is the main cause of roundness variation. Honing tool and workpiece were assumed as a second-order system, i.e., a spring, mass and damper system in the modeling and analysis.
Determination of Tensile Properties at Increased Strain Rates and Various Temperatures
Authors: Schindler HJ , Veidt M
Published: February 2009

This paper reports on the development and first application of a low-cost dynamic tension testing method which makes testing at strain rates in the range of 100/s to 500/s and various temperatures as simple as an instrumented Charpy test. The kinematical and kinetic analysis of the newly introduced, reusable clamping device allows the determination of the stress-strain curve from the measured force history during the tearing process. The first results show that the new technique is very promising to determine the influence of loading rate and temperature on the mechanical properties of structural materials, since the measured dynamic tensile properties compare well in absolute value as well as accuracy and reproducibility with those obtained using conventional high-speed tension testing facilities.
Local Versus Global Strain Measurement of a Polymeric Geogrid
Authors: Perkins SW , Schulz JL , Lapeyre JA
Published: February 2009

Polymeric geogrids, which consist of a planar polymeric material with a grid-like configuration, have become increasingly popular as a reinforcement inclusion in soil structures. As the use of geogrid materials has increased, so has the need to quantify both the in-air and in-soil mechanical behavior. Bonded resistance strain gages have been used to quantify the strain response of geogrids. Problems associated with gage mounting, bonding, and environmental protection must be addressed. The relationship between the local measured strain and the global strain must be established. In this paper, these issues have been addressed by conducting in-air tension tests on a particular geogrid. In general, it has been found that strain gages can be successfully bonded to the ribs of geogrids such that strains up to 7% can be recorded. These gages were successfully protected and used in a field application for a period of five months. Strains measured along the ribs of the geogrids were seen in this study to be 1.25 to 1.6 times the average strain applied across the specimen for monotonic loading. The two strains correspond nearly one-for-one for cyclic loading. The presence of the strain gage and accompanying cement appears to have little effect on the strain response.
Preface to “Dynamic Young's Modulus Measurements in Metallic Materials: Results of an Interlaboratory Testing Program”
Authors: Papadakis EP
Published: February 2009

A round-robin study usually attempts to have several laboratories measure identical materials by the methods used in each laboratory. Similarly, the methods usually are expected to produce comparable absolute errors if used properly. Round-robins then have the facility to detect gross errors in one operation vis-à-vis the mean and standard deviation of the remainder of the set.
Effects of the Average Increment ΔC on the Scatter in da/dN Data and Mean Life Cycles in HY-80 Steel Plate
Authors: Betancourt TK , Matthews JR
Published: February 2009

This paper analyzes the effects of the data averaging increment (ΔC) on the prediction of mean life cycles in 25-mm. (1-in.)-thick HY-80 steel plate using CT test specimens. The analysis shows that the crack propagation in this steel plate is not uniform; the crack rate randomly oscillates along the crack at variable amplitude. The frequency of crack rate variation was found to have the characteristics of a normal distribution curve and was therefore characterized by mean and variance. The mean crack behavior, including mean crack propagation rates and mean life cycles, was determined for crack propagation data obtained at different ΔC and statistically compared. It was found that the same raw a and N data averaged over different ΔC yielded significantly different mean crack rates and mean life cycles.

The 95% confidence limits that were assigned to the mean life cycles (N ± 1.96 √σ/n) were also different and affected by ΔC. This becomes extremely important in engineering design when trying to determine the expected confidence in a life prediction or a safe inspection interval. To use the scatter in da/dN data to generate the design confidence limit, it is essential that the same ΔC be used in the numerical integration that was used to generate the data.
Characterization of Fracture Behavior in Small Punch Test by Combined Recrystallization-Etch Method and Rigid Plastic Analysis
Authors: Mao X , Shoji T , Takahashi H
Published: February 2009

The purpose of this investigation is to understand the deformation process of the small punch test and to use it to characterize the fracture properties of materials. By comparisons between recrystallization-etch results and perfect-rigid plastic analysis, the deformation process of the small punch test has been clearly divided into three regions. Equivalent fracture strain under biaxial stress state has been obtained from 10 by 10 by 0.5 mm thin sheet samples using both a recrystallization-etch technique and a semi-analytical method to characterize the fracture property of the material. The results of biaxial equivalent fracture strain can be related almost linearly to fracture toughness (JIc) for elastic-plastic behavior.
Life Expectancy for Fossil Steam Turbine Casings after 1000 000 Hours
Authors: Coulon PA , Saisse H , Thauvin G
Published: February 2009

Today with the rapid development of nuclear electricity generation on a large scale, there arises the problem of maintaining fossil fuel generating stations that have been in operation for some 100 000 h or more. Operators usually hope to prolong the service life of units where safety margins permit, with objectives attaining beyond 150 000 h. This is an extremely ambitious program that is thwarted by the very nature of the work demanded from this type of thermal generating station: namely fulfillment of the needs of daily and seasonal peak periods, which increase the number of severe thermal operating transients.

This paper examines the question of metallurgical studies carried out by Alsthom-Atlantique on stator steel castings with a view to estimating their expectation of life potential. This work constitutes the second part of a study entitled “Quenching, Tempering, and Aging of Chromium-Molybdenum-Vanadium Cast Steels” in the Journal of Evaluation and Testing, Vol. 9, No. 2, March 1981.
A Summary of Fracture Mechanics Concepts
Authors: Irwin GR , de Wit R
Published: February 2009

The basic concepts of fracture mechanics are presented in a logical sequence. Each concept is given in a concise definition-like paragraph. The concepts of toughness, process zone, crack, and linear-elastic fracture mechanics are first introduced. The crack-tip characterizations, that is, stress-intensity factor, crack extension force, J integral, and crack-tip opening displacement are then discussed. The constraints in plane stress, plane strain, and three dimensions are pointed out. Various methods of evaluating the crack-tip characterizations are explained. The concept of fracture toughness is presented in relation to resistance curves, dynamics, constraints, and fast-stable crack growth. Some practical empirical fracture toughness relations are given. Then slow-stable crack growth is discussed, that is, stress corrosion cracking, fatigue cracking, corrosion fatigue, and viscous (creep) cracking. The summary concludes with the concept of fracture control plans.
Determination of Stress Relaxation by Damping Measurements
Authors: Weissmann GF
Published: February 2009

The conventional determination of the stress relaxation properties of metals and their alloys is tedious and time-consuming. The method of predicting stress relaxation in metal strips subjected to uniform bending is based on the work per cycle required to maintain a constant strain energy level for the specimen. The change of the work per cycle with time or the number of cycles has been considered. The data obtained by damping measurements agree very well with a limited number of static stress relaxation measurements. The proposed method of predicting stress relaxation by damping measurements is simple and fast and should be particularly useful for data recorded at or close to room temperature.
Structural Integrity in Aircraft
Authors: Hardrath HF
Published: February 2009

The paper reviews briefly the current design philosophies for achieving long, efficient, and reliable service in aircraft structures. The strengths and weaknesses of these design philosophies and their demonstrated records of success are discussed. The state of the art has not been developed to the point where designing can be done without major test inspection and maintenance programs.

A broad program of research is proposed through which a viable computerized design scheme will be provided during the next decade. The program will organize and correlate existing knowledge on fatigue and fracture behavior, identify gaps in this knowledge, and guide specific research to upgrade design capabilities. An early application of the scheme leads to an objective choice of materials to provide maximum reliability between inspections. An analytical tool has been developed that assesses the resistance of a structural configuration to fatigue and static crack propagation.
Direct Nondestructive Prediction of Engineering Properties
Authors: Zurbrick JR
Published: February 2009

Quantitative nondestructive evaluation provides the means for directly predicting engineering properties of materials on individual components. Through proper problem definitions, the working concept of material ↔ energy interaction, and multifunctional/multivariable relationships, a complex material system can now be characterized in terms of both bulk and constituent properties as they actually exist in the finished product. In fiber-reinforced composite materials, properties such as in-plane tension/compression elastic modulus, at any polar angle, or in the thickness direction; shear modulus; poisson's ratio; density; volume fractions of fiber, matrix and porosity; and fiber elastic modulus may be pinpointed. In adhesively bonded joints, where failure mode is brittle fracture at or near the interface, bond adhesive strength may be predicted from nondestructive measurements of substrate surface free energy, contact angle, and bondline thickness, when the reference liquid surface free energy, effective strain, and stress-strain integral are known.
The Membrane Effect in Triaxial Testing of Granular Soils
Authors: Frydman S , Zeitlen JG , Alpan I
Published: February 2009

The volume change measurements of granular soils in triaxial testing are generally affected by penetration of the membrane enclosing the soil into the voids between the particles. The major factor influencing this penetration has been shown to be the particle size of the soil being tested. On the basis of the results of previous investigations and the present study, a relationship has been found between the membrane penetration and particle size. This relationship may be used to estimate the membrane effect for any granular soil.
Room Temperature Creep Behavior of Superplastic Zn-22Al under Bending and Plane Conditions
Authors: Mulvania LE
Published: February 2009

Machine covers and other structural components made of superplastic Zn-22Al can easily and economically be formed by techniques commonly used in the polymeric field. This alloy, however, has a tendency to creep under sustained loads at room temperature. The primary objective of this program was to characterize the behavior of superplastic Zn-22Al under stress conditions experienced by fabricated structures so designers can predict the total strain or deflection over the life of a machine. Creep tests were conducted with simple supported beams and with fixed edge plates. Creep behavior under these bending and biaxial stress conditions was studied and related to the more comprehensive uniaxial tensile creep studies with Zn-22Al. It was concluded that the uniaxial tensile data is conservative when those creep rates are used for the maximum principal stresses in simple or plane bending applications. Included in the report are creep curves for bending of beams and plates, stress calculations and the consideration of several plastic flow theories for creep under combined stresses.
A DirectJ-RCurve Analysis of Fracture Toughness Tests
Authors: Herrera R , Landes JD
Published: February 2009

A method is proposed to evaluate fracture toughness in a J-R curve format directly from load displacement records without the need for automatic crack length measurement devices. This method uses the calibration curve in which the flow properties of a material for a stationary crack provide the relationships between load, displacement, and crack length. Crack growth is then evaluated by comparing load and displacement pairs for the growing crack case with this stationary crack curve. This is similar to the approach in which a common “key curve” was used to determine crack length; however, in this case, individual calibration curves are developed for each specimen. The calibration curve is described by separate elastic and plastic components of displacement. The relationship between load and elastic displacement is described by a compliance function and between load and plastic displacement by a power term with constant coefficient and exponent. Three methods are suggested for evaluating the power term exponent and coefficient. The first assumes that the exponent coming from a fit of the true-stress true-strain tensile test results can be used, the second determines all information directly from the test record, and a third does the same but uses a plastic zone adjustment.

The method is applied to a set of results from an A508 steel in which the J-R curve had previously been determined using the elastic compliance method of crack length measurement. These tests were conducted on compact specimens with a range of sizes varying by a factor of 20 (10T to 1/2T). The method is also applied to a 4340 steel and stainless steel weld metal. The results show that second approach works best. Although further evaluation of the method is needed, it showed promise as a replacement for automatic crack length measurement techniques in the evaluation of J-R curves.
Changes in AISC Specification for High-Strength Steel Bolt Use
Authors:   American Iron and Steel Institute
Published: February 2009

Significant changes in the erection of structural steel for buildings and bridges, especially in steel-to-steel connections, are resulting from major revisions to AISC (American Institute of Steel Construction) Specification for Structural Joints Using ASTM A325 or A490 Bolts. The changes are altering decades-long practices in using these high-strength steel bolts. This article covers the key changes in installation, tensioning, tension calibrating devices and methods, inspections, storage and handling, painting, burr removal, and other factors. This note is of concern to all who use steel bolts or erect structural steel.
Fatigue Threshold Regime of a Low Alloy Ferritic Steel under Closure-Free Testing Conditions: Part I—Compliance Variations in the Threshold Regime
Authors: Vaidya WV
Published: February 2009

Compliance variations in the threshold regime of a high strength ferritic steel tested under closure-free conditions at room temperature and in air are reported. In contrast to the Paris regime, and irrespective of whether the data during load shedding, at threshold, or after post-threshold load increase are considered. it is found that compliance varies inconsistently in the threshold regime. Therefore a 1:1 correlation between the averaged optical crack length and that inferred from compliance was not observed. Possible reasons of this discrepancy are discussed, and the crack front lag inferred is explained in terms of the constraint.
Introduction to Symposium on the Use and Performance of Staples in the Human Body
Authors: Harvey JP
Published: February 2009

[The Symposium on the Use and Performance of staples in the Human Body, held in Atlantic City, New Jersey, on 8 May 1991, was sponsored by ASTM Committee F-4 on Medical and Surgical Materials and Devices. Three papers presented at the symposium are presented in this issue of Journal of Testing and Evaluation.—Editor]
Charpy Absorbed Energy and JIc as Measures of Cryogenic Fracture Toughness
Authors: Hwang IS , Morra MM , Ballinger RG , Nakajima H , Shimamoto S , Tobler RL
Published: February 2009

In this paper, we present experimental comparisons between the critical energy line integral (JIc) and Charpy absorbed energy (Cv) at 4 and 77 K for materials ranging from fully austenitic steels to ferritic steels. At 4 K the correlation between JIc and Cv is weak, indicating that Cv is a poor indicator of static fracture roughness at this temperature. At 77 K, a good correlation exists between JIc and Cv. A good correlation is also observed between JIc at 77 K and Cv at 4 K. The results are explained by the large temperature rise during the Charpy rest. Further evidence of the temperature rise is the marginal change in Cv between 4 and 77 K and the disparity in fracture modes between Charpy and fracture mechanics specimens. For c stainless steels, Cv changed little from 4 to 77 K whereas JIc increased significantly. For ferritic steels, Cv increased in proportion to JIc from 4 to 77 K. Especially in steels with low nickel contents, fracture surfaces of Charpy specimens revealed higher ductility than those of fracture mechanics test specimens. The results qualitatively support the predicted temperature rises to 130 and 150 K for crack initiation during Charpy tests at 4 and 77 K, respectively. Due to a wide variation in roughness response to temperature rise, the Cv-based regulatory criteria developed for one group of alloys will have no validity when applied to another group. Therefore the Charpy test near absolute zero should not be regarded as a measure of the static fracture resistance. Alternative simplified methods of cryogenic fracture toughness are suggested.
Magnetic Particle Testing of Turbine Blades Mounted on the Turbine Rotor Shaft
Authors: Imbert C , Rampersad K
Published: February 2009

Turbines constitute some of the most critical elements in such things as aircraft engines and power generating plants where breakdowns can be catastrophic. Preventive maintenance is therefore vital in such situations. Non-Destructive Evaluation (NDE) plays a significant role in such maintenance programmes. Turbine blade failure can occur without warning and with disastrous results. Such failures are, for the most part, caused by cracks or less frequently, by inclusions. Such defects are readily detected by NDE techniques such as magnetic particle inspection (MPI) if they are on or near the surface and accessible, which is the case in turbine blades.

This paper outlines the general technique of MPI of turbine blades mounted on the turbine rotor shaft with specific reference to the placement of the magectizing coils. Of the two practical techniques, the method of placing a preformed coil over a number of blades in one row is preferred to the method of wrapping the coil around the rotor shaft across an entire row of blades.