bluuebunny/crossref_metadata_2025 huggingface dataset:
Compaction of Asphalt Mixtures for Laboratory Testing: Evaluation Based on Density Profile
Authors: Fwa TF , Low BH , Tan SA
Published: February 2009

Cylindrical specimens are commonly used in laboratory testing of asphaltic paving mixtures. This paper describes a study that examined the influence of different compaction methods on the resulted density distributions of cylindrical specimens using a laboratory twin-probe nuclear density gage. Two common sizes of 102 mm (4 in.) cylindrical specimens, namely 64-mm (2.5-in.) high Marshall-size specimens, and 200-mm (7.87-in.) high triaxial test specimens, were considered in the test program. Four compaction methods were studied: drop-hammer compaction, kneading compactions, single-plunger compression, and double-plunger compression. In the case of 200-mm-tall specimens, the effect of compaction in layers was also examined. Test results show that, except for the kneading compaction method, the other three methods could all produce 64-mm-tall Marshall-size specimens of relatively uniform density distributions with density variation within 0.05 g/cm3. For 200-mm-tall specimens, only the double-plunger compression method was able to produce specimens with density distribution of similar uniformity.
A Fiber Optic Chemical Sensor for Measurement of Groundwater pH
Authors: Maher MH , Shahriari MR
Published: February 2009

A fiber optic chemical sensor was developed for measurement of pH in groundwater. The sensor consists of a porous polymeric film immobilized with pH indicator, housed in a porous probe. The optical spectral characteristics of the sensor showed very good sensitivity to changes in the pH levels tested when visible light (380 to 780 nm) was used. The sensor/probe system was tested in a laboratory environmental chamber and showed very-good stability and reversibility under various confining pressures and flow rates.
Dynamic Testing of the Strength of Helmet Chin Straps
Authors: Gilchrist A , Mills NJ
Published: February 2009

A dynamic test of-chin strap strength was introduced into the British Standard BS 2495 in 1980. This test has subsequently been adapted for bicycle and horse riding helmets without the same correlation between accident and test failures being established. The causes of force peaks and oscillations in the test traces have been identified, and a means was found of obtaining reliable chin strap force measurements. Recommendations are made for improving the test so that chain straps and buckles are adequately strong but not over-designed.
Development and Precision Testing of a Standard Test Method for Screening Fuels in Soils
Authors: Sorini SS , Schabron JF
Published: February 2009

The ASTM Standard Test Method for Screening Fuels in Soils (D-5831-95), uses low-toxicity chemicals and can be used to screen organic-rich soils. It is also fast, easy, and inexpessive to perform. This screening method calls for extracting a sample of soil with isopropyl alcohol following treatment with calcium oxide. The resulting extract is filtered, and the ultraviolet absorbance of the extract is measured at 254 nm.

A collaborative study was conducted to determine the reproducibility (between participants) and repeatability (within participant) precision of the method when it is applied to a sand and an organic soil spiked with various concentrations of diesel fuel. The data generated in this study are specific to the test materials used. However, these data provide information on the variability that can be expected when the screening method is used by one or more users. Information obtained from the collaborative study will help potential users assess the usefulness of the screening method for their proposed applications.
Shear Lap-Joint Testing with Rubber Substrate
Authors: Chang DJ , Hanna WD
Published: February 2009

A test method has been developed and demonstrated for the determination of shear strength in a lap joint with rubber-like material as a substrate. A testing fixture used a stiffened aluminum substrate with a load-transferring lip, combined with a clamp, that restrained the lateral movement of the rubber. This fixture successfully produced shear-type failures on two back-to-back single lap-joint specimens. The design of the fixture was based on the near-incompressible nature of the rubber materials. The experimental part of the task included two phases: a pathfinder test series; and the actual data generation test series. The former phase involved testing concept development, test fixture design and modification, optimization of test specimen configuration, and failure mode demonstration. This phase was conducted using specimens fabricated in-house by the Mechanics and Materials Technology Center at The Aerospace Corporation. In the second phase, actual shear failure data were generated using specimens that were machined from panels fabricated by the vendor, Elkton Division, Tactical Operations of the Thiokol Corporation.

Linear elastic finite element analyses were performed to assist in the optimization of test parameters. The results identified optimal dimensions for lap-joint length, transverse groove width, and bracket lip width for the specimen and fixture configuration. Sixteen tests were done on specimens machined from vendor-supplied carbon phenolic/Epon EA 934 NA/ethylene propylene diene monomer (EPDM) panels. The average failure stresses were 4.46, 3.39, and 3.32 MPa (0.56, 0.43, and 0.42 ksi) for the 7.62, 10.16, and 12.70-mm (0.3, 0.4, and 0.5 in.) long lap-joints. Some of the failures were initiated inside the adhesive whereas other failures occurred between the adhesive and the substrate.

This test method should be considered as a viable technique in determining shear strength of bond line with rubber-like material as a substrate. More refinement, however, is needed before an optimal test fixture design can be reached.
Strain-Controlled Cumulative Fatigue with Mean Strains and High-Cycle and Low-Cycle Interaction
Authors: Gong Y , Norton MP
Published: February 2009

This work reports on baseline fatigue and cumulative fangue damage results of mild steel under cyclic strain control All cumulative damage tests were conducted with a step loading in a decreasing order, from a high strain amplitude of 0.4 or 0.3% to a lower one of 0.2%. Different mean strain values of −0.2, 0, and 0.2% were applied in each strain amplitude level. Seven combinations of strain amplitude and mean strain were investigated. It was observed that cyclic softening in the second level was significantly stabilized by the presence of the first level, which accounts for approximately 20% of the total fatigue life. Mean stress relaxation in the second level depended upon the loading in the first level and was similar to that for single-level loading under certain strain amplitudes and mean strains. The damage summations in terms of cycle ratio (Miner's damage sum), both with and without mean strain correction, were calculated and discussed. For all of the cases investigated, the average damage summations were found to be in the range of 0.94 to 1.28. The degree of approximation and the deviation of each individual test from unity depends on whether mean strain correction was made. The competing effects of mean stresses induced and plastic deformation tended to overshadow the more classical loading sequence effects in terms of the damage summation. Fatigue damage accumulation has also been analyzed using Continuum Damage Mechanics modeling. The sources of the deviation of damage summation from unity and the nonlinear accumulation of damage are discussed.
Determination of Ductile-Brittle Transition Temperature (DBTT) in Dynamic Small Punch Test
Authors: Joo Y-H , Hashida T , Takahashi H
Published: February 2009

A dynamic small punch test technique is demonstrated for measuring the ductile-brittle transition temperature (DBTT) of aged Cr-Mo-V turbine rotor steels. Based on fracture energy measurements and fracture surface observations it is shown that the dynamic small punch test specimens exhibit a clear ductile-brittle transition behavior. The DBTT can be determined reliably by statistically analyzing the scatter in the fracture energy data and by defining the fracture appearance transition temperature. The measured values of DBTT are compared with those obtained from Charpy impact tests.
Finite Element Method (FEM) Analysis of Elastic-Linear-Hardening Materials and Comparison with Measurements on Commercial Materials
Authors: Murakami Y , Yuan LP
Published: February 2009

The Brinell hardness HB (kgf/mm2) of elastic-linear-hardening materials with various yield stresses σY (MPa) and hardening moduli H (MPa) is analyzed by a finite element method (FEM). The well known empirical formula for the ratio of tensile strength σB to HB, σB/HB ⋟ 3.5, does not hold for materals having a large relative strain hardening modulus H/σY, where H is defined by dσ/dε in the σ-ε curve. It is shown that the dimensionless stress-strain curves (σ/σY vs. ε) of elastic-linear-hardening materials and those of various commercial materials give the crucial measurement in determining the value of σB/HB. The ratio of σB/HB remains in the range of 3.2 to 3.8 if the relative strain hardening modulus H/σY at large strains is less than ∼2.5. Correlations between the stress-strain curve and indentation shape, plastic zone size, and residual stresses are also investigated.
Analysis of Gas-Fired Ceramic Radiant Tubes During Transient Heating: Part II—Thermoelastic Stress Analysis
Authors: Segall AE , Hellmann JR
Published: February 2009

Transient radial and axial temperature distributions based on measured external surface temperatures and finite-element calculations were used with temperature dependent elastic material properties to determine the thermoelastic stresses experienced by reaction-bonded and sintered-alpha silicon-carbide open ended radiant tubes during gas-combustion beating. The resulting stresses exhibited a dependence on the radial temperature difference and the curvature of the axial temperature distribution. A failure rate analysis using a two-parameter Weibull formulation with a polyaxial stress approximation, the calculated surface and volume principal stresses, and temperature-dependent surface and volume Weibull strength data indicated low failure rates and the viability of both materials for the transient heating conditions studied.
Hydrochlorofluorocarbon (HCFC) Blowing Agents for Foam Insulation of Launch Vehicle Cryogenic Propellant Tanks
Authors: Strauss EL , Bzik JW
Published: February 2009

Two polyurethane spray-on foam insulations (SOFI) were evaluated with five hydrochlorofluorocarbon (HCFC) blowing agents each (HCFC-141b, HCFC-123, and three blends). Foams were evaluated by measuring bond and flatwise tension strengths at four temperatures, compression at ambient temperature, and substrate strain compatibility at liquid helium temperature. Additionally, foams were characterized for density, closed-cell content, oxygen index, and ablation under radiant heating. Compression strengths of RDB-1-152 (polyether polyol) exceeded those of SS-1825 SOFI (polyester polyether, blend). Highest compression and tensile strengths were for foams sprayed with HCFC-141b and strengths decreased with increasing HCFC-123 content in the blowing agent. No foam failures occurred adhesively at the aluminum substrate, but a high incidence of premature failures occurred in the knitline between successive spray layers. Process optimization studies will be conducted with the two best SOFI systems, RDB-1-152/HCFC-141b and RDB-1-152/30% HCFC-123: 70% HCFC-141b.
Experimental Evaluation of a Laboratory Twin-Probe Nuclear Gage for Specimen Density Measurement
Authors: Fwa TF , Tan SA
Published: February 2009

This paper describes a series of tests conducted to establish the operating requirements of a laboratory twin-probe nuclear gage for density measurement of cylindrical specimens of homogeneous materials. The nuclear device is an adaptation of a direct transmission field gage for laboratory density measurement. It is shown in this evaluation program that three forms of analysis are required for the setting up of such an apparatus: calibration analysis, precision evaluation, and accuracy assessment. Three specimen diameters (75, 100, and 150 mm), three materials with densities from 0.8 to 2.7 g/cm3, and nuclear gage source-to-detector spacings ranging from 250 to 450 mm were included in the evaluation program.

It was found that density calibration based on radiation attenuation theory is valid, and that a diameter-count rate relationship can be established experimentally so that only a single set of density calibration using one specimen diameter is needed for routine testing. In the accuracy assessment, it was found that there exists a narrow range of source-to-detector spacings for unbiased density estimation. A spacing of 280 mm is recommended for the device studied. At this spacing, the density measurement precision at 95% confidence level, using four 1-min counts per test, is found to vary from 0.010 g/cm3 for 150-mm-diameter specimens to 0.017 g/cm3 for 75-mm-diameter specimens.
Introduction to Symposium on Radiation Shielding for the 21st Century
Authors: Volkman DE
Published: February 2009

The Symposium on Radiation Shielding for the 21st Century was held in Atlantic City, New Jersey, on 24 June 1991. The event was sponsored by ASTM Committee C-9 on Concrete and Concrete Aggregates and hosted by ASTM subcommittee C09.08.02 on Concrete for Radiation Shielding.
Comparison of Fine Particle Colemanite and Boron Frit in Concrete for Time-Strength Relationship
Authors: Volkman DE , Bussolini PL
Published: February 2009

The element boron, when added to concrete, has proved effective in shielding neutron particles by absorbing the neutron and emitting a low-energy gamma ray. The various boron additives used with concrete can severely retard the set time and strength gain. An advantage to using small particle size boron is that the smaller grain size provides better boron disbursement within the concrete matrix to absorb neutrons. However, boron additives of powder consistency are usually not used due to the greater potential of forming chemical solutions that act as a retarder in the concrete.

Research has shown that the amount of boron additives in concrete can be reduced significantly if fine grain particles can be successfully incorporated into the concrete matrix. The purpose of this study is to compare strength gain characteristics of concrete mixes containing various quantities of fine grain boron additive. The boron additive colemanite, a natural mineral, is compared with two brands of manufactured aggregate, boron frit. Concrete test cylinders are molded for testing the compressive strength of the mix after 4, 7, 28, and 56 days. Tested are five different quantities of colemanite as well as five comparable amounts of boron frit for each brand of the material. The test values are compared with a control concrete specimen containing no boron additive. Results of this study can be used to optimize the cost and effectiveness of boron additives in radiation shielding concrete.
An Apparatus for Biaxial Strength Testing of Standard Tensile Specimens
Authors: Mazachek KD , Faddis TN
Published: February 2009

A novel, low cost testing apparatus has been designed for the application of biaxial stress on standard tensile spectmens. The apparatus independently applies compressive loading perpendicular to a tensile load. The compressive load is transferred through a compression pad, applying hydrostatic pressure to the test section.

The experimental results of tests conducted on 6061-T6 aluminum have been analyzed and compared using the von Mises failure criterion. The results indicate that using this test apparatus with a polytetrafluoroethylene (PTFE) compression pad produces biaxial failures consistent with the failure envelope defined by the von Mises failure criterion.
Compression Testing of Lumber: A Comparison of Methods
Authors: Green DW , Evans JW
Published: February 2009

A study was conducted to compare compression strength values obtained using short segments cut from full-length lumber and tested in accordance with ASTM D 4761-87 with those values obtained using full-leagth specimens and tested in accordance with ASTM D 198-84. Tests were conducted on Southern Pine lumber conditioned to a target moisture content of 9%. To obtaim a short-segment compression strength estimate within a factor of about 1.05 of those obtained by testing full-length (3-m [10-ft]) specimens, it is necessary to select two of the apparent worst strength-reducing defects in the full-length specimen using ASTM D 245-84 sorting criteria.
Field Evaluation of Pavement Instrumentation Methods
Authors: Tabatabaee N , Al-Qadi IL , Sebaaly PE
Published: February 2009

Full-scale testing was conducted to compare the performance of different in situ instrumentations used in flexible pavement, including strain gages, pressure cells, geophones, and single-layer deflectometers. Two test sections were instrumented: one thin section (15.2 cm [6 in. thick]) and one thick section (25.4 cm [10 in. thick]). Each section is 15.2 m (50 ft) long. The testing variables included pavement structure, load, tire pressures, and speed. The criteria for evaluation of performance of the instruments included survivability, repeatability, reliability, the effect of test variables, ease of installation, and data processing. The measured response under different conditions was compared with the calculated response using a multi-layered elastic model. Falling weight deflectometer (FWD) testing was used to quantify the in situ material properties needed for the computer model.
Ultrasonic Technique for Residual Stress Measurement in Ductile Iron Continuous Cast Round Bars
Authors: Srinivasan MN , Chundu SN , Bray DE , Alagarsamy A
Published: February 2009

An ultrasonic technique using critically refracted longitudinal (LOR) waves was used to determine the residual stresses in ductile iron bars in the as-cast, annealed, normalized as well as quenched and tempered states. The results conform to expected trends based on differential cooling rate and phase transformation effects.
Notch Dimensions for Three-Point Bend Fracture Specimens Based on Compliance Analyses
Authors: Baratta FI , Underwood JH
Published: February 2009

Load-line compliance was calculated for various three-point bend specimens containing finite width notches and cutouts, using methods of engineering strength of materials and elastic superposition. Comparison of compliance results for notched specimens with results for the ideal zero width crack was used to propose two basic notch configurations for fracture testing. A relatively wide notch that could be produced by conventional manufacturing methods resulted in load-line compliance values 10% or more above those of the ideal crack case. A narrow notch that could be produced by electric-discharge machining resulted in compliance values much closer to those of the ideal crack case.
Superposition Theory Applied to Nail/Glue Joints in Wood: Part I—Strength Behavior
Authors: Pellicane PJ
Published: February 2009

A model was developed based on concepts involving superposition of nail and glue joint strength to predict the ultimate load of nail/glue joints in wood subjected to lateral loading. Four combinations of two wood species (lodgepole pine and hard maple) and two nail sizes (6d and 8d) were examined. One brand of commercially-available elastomeric construction adhesive was used. A total of 169 nail, glue, and nail/glue joints were tested to ultimate load. Theoretical predictions based on nail and glue joint strength were compared with experimental data from nail/glue joint tests. The results showed that mean joint strength was predicted to within 9% for three of the four combinations of nail size and wood species studied. Statistical analyses revealed that for these three data sets, mean experimental and theoretical values were indistinguishable at the 0.01 level. In addition, the presence of glue in a nailed joint accounted for a substantial increase in strength over joints without glue.
Crack Initiation and Total Fatigue Life of a Carbon Steel in Vacuum and Air
Authors: Kujawski D , Ellyin F
Published: February 2009

Fully-reversed strain-controlled test results of a carbon steel (ASTM A 516 Gr. 70) in an ambient atmosphere and in a vacuum of 0.1 mPa are compared. Vacuum data may be viewed as representing a “pure” (mechanical) fatigue damage. In the case of an air environment, the rate of fatigue damage accumulation increases due to the environmental contribution.

The test results are described in terms of the crack initiation and total lives. The crack initiation data are fairly well-correlated with the plastic strain energy per cycle. The significance of the environment condition on the life prediction procedures is discussed.
The Shear Stress-Strain Curve Determination from Torsion Test in the Large Strain Range
Authors: Wu HC , Xu Z , Wang PT
Published: February 2009

A modified Nadai's method is proposed to determine the shear stress-strain curve by use of a solid circular cylinder subjected to torsional load. The modification is accomplished by taking into account the axial length change of the specimen. The method is extended to give the shear stresses in tubular specimens.

A series of experiments on annealed isotropic high purity cast aluminum material was conducted under the pure torsion condition. Torque-twist and axial elongation-twist curves were recorded. The shear stress-strain curves obtained from tubular specimens of various wall-thicknesses and solid circular cylindrical specimens are compared by using different methods of data analysis. It is found that the present method is the most appropriate one among all methods considered. It is suggested that long gage-sectioned, thick-walled tubular specimens be used to determine the shear stress-strain curve in the large strain range.
Comparison of the Fracture Behavior of Conventional Class U Railway Wheels and an Experimental Alloy Wheel
Authors: Bowles CQ , Roland JR
Published: February 2009

The fracture properties of high and low carbon Class U railway wheels were compared with an experimental low carbon alloy wheel using tensile, Charpy impact, and KIc tests on specimens cut from the circumferential and transverse directions of wheel rim. The experimental alloy design was based on results of dynamometer tests and service experience that suggested a decrease in carbon content increased fracture resistance. Additional chromium was added to the experimental alloy to maintain pearlitic microstructure, thereby maintaining wear resistance. The low carbon wheels were found to have the highest fracture toughness, which was attributed to a continuous network of grain boundary ferrite that inhibited crack growth across grains. However, impact toughness was not significantly higher. Toughness of the experimental alloy was found to be similar to the high carbon wheels. However, a limited number of toughness tests coupled with a number of nonvalid tests make toughness results tentative. It was believed that the addition of chromium to produce a nearly pearlitic structure also eliminated the continuous network of proeutectoid ferrite necessary for good toughness.
Residual Stresses and Fatigue Precracking Techniques for Weldment Fracture Toughness Specimens
Authors: Reemsnyder HS , Pisarski HG , Dawes MG
Published: February 2009

This article examines the ability of the local compression, stepwise high R-ratio, and reverse bend weldment fatigue precracking techniques to remove the residual stresses in the uncracked ligaments of as-welded fracture mechanics test specimens. The stepwise high R-ratio and reverse bend techniques appeared to have no significant influence on the residual stresses in the ligament. This was demonstrated by the occurrence of nonuniform fatigue cracks when these techniques were followed by the standard fatigue precracking procedures. Specimens given these treatments, and other specimens fatigue precracked using the standard procedures, showed evidence of crack closure and initial compliances that were lower than normal for these specimen geometries. In contrast, local compression reduced the residual stresses in the uncracked ligaments to low, uniform levels. This was indicated by acceptable fatigue precrack front-straightness and normal specimen compliance. Therefore, of the three precracking techniques investigated, only the local compression technique is recommended.
Fatigue Crack Initiation in Nonferrous Materials: A Model Assessment
Authors: Azimi HR , Miller GA
Published: February 2009

Elastic stress concentration (Ktd approach), fracture mechanics, and local strain approaches were evaluated for predicting fatigue crack initiation for a 2024-T3 aluminum alloy, commeretally pure copper. 70–30 brass, and Cu-Be alloy 25 Blunt (keyhole) and sharp (V-notched) compact tension specimens were subjected to cyclic loading in ambient laboratory air to produce crack initiation in the range 104 to 106 cycles.

The results show that the best initiation model. Ktd approach is based on computed estimates of strain at some distance ahead the notch root. This distance was shown to be inversely related to the material's strength. This model properly described the influence of both material and geometry over the full range of initiation cycles. Ni. Local strain and fracture mechanics models were less sensitive and exhibited greater variability.
Slice Synthesis Technique for an Embedded Crack in Residual Stress Fields
Authors: Nishimura T
Published: February 2009

Stress intensity factors are obtained for an embedded elliptical crack in a plate subjected to remote tensile and welding induced residual stresses. The three-dimensional crack configuration is reduced to a system of two-dimensional configurations in the crack depth and in crack length directions by using the slice synthesis technique. The algebraic equations on crack face displacements are formulated in terms of unknown coupled tractions acting on the slices. These equations are solved using a multiple linear regression scheme, and the unknown tractions and stress intensity factors are calculated. The accuracy of stress intensity factors is compared with known results from the literature for an embedded elliptical crack in tension and for an embedded penny-shaped crack subjected to welding residual stress. The stress intensity factors are presented for various elliptically shaped cracks embedded in an infinite plate and subjected to three different types of welding residual stresses.
Optimization of Test Parameters for Quantitative Stress Measurements Using the Miniaturized Disk-Bend Test
Authors: Meyers DE , Chen FC , Zhang J , Ardell AJ
Published: February 2009

A recently-developed miniaturized disk-bend test (MDBT) has been successfully used to evaluate the mechanical properties of a variety of materials, using specimens 3 mm in diameter. The load is applied either by a solid ball (the ball-on-ring (BOR) mode), or by a hollow cylinder (the ring-on-ring (ROR) mode). We have reproduced the yield stresses of ordered intermetallic compounds and the fracture toughnesses of several ceramics using analytical solutions to the equations of elasticity theory. Despite this success there are several curious features involved in the analysis of data, for example, in previous tests conducted in the BOR mode correct values of the yield stress were obtained using the equations appropriate to clamped specimens, whether or not they were actually clamped in the test fixture. We show that this is ubiquitous to tests in the BOR mode, and does not arise because of frictional constraints at the supporting ring. We have also completed a thorough evaluation of testing in the ROR mode, in which the yield stresses of cold-rolled or annealed AISI type 302 stainless steel were measured using various combinations of specimen thickness and radii of the loading and supporting rings, and compared to those of tensile specimens machined from the same material. The most accurate and reproducible measurements of the yield strength were obtained for specific combinations of specimen thickness and geometry of the apparatus. We describe these conditions and demonstrate that they provide values that are always within 10% of the tensile results. The errors induced by potential misalignments in the MDBT are also discussed, and are shown to cause no more than a 5% deviation in the measured yield stress.
A Novel Method for Imaging the Damage Pattern in Laminated Plastic Materials Subjected to Ballistic Impact
Authors: Sivakumar K , Ramakrishna YV , Ramanjaneyulu K , Balakrishna Bhat T
Published: February 2009

A new method for assessing the damage in laminated composites upon ballistic impact has been suggested. The proposed method, called infiltration radiography, consists of impregnating a semisolid lubricant mixed with fine metallic powder deep into the damage caused by bullets. The effect of metal content on the quality of image has been studied to determine the minimum required amount of metal powder. The influence of radiographic parameters such as voltage, current, and exposure time has also been studied.
Density Measurement of Cylindrical Specimens Within a Mold by Gamma-Rays
Authors: Tan S-A , Fwa T-F
Published: February 2009

This paper describes a series of tests used to establish a method of nondestructive density measurements of cylindrical specimens contained within a mold by using a twin-probe gamma-ray density gage. Cylindrical specimens within molds are common occurrence in civil engineering practice; examples are soil, concrete, or bituminous cores obtained by in situ sampling or laboratory compaction. In several applications it may be desirable to determine the core densities without removal from the mold, and this can be achieved by the use of a gamma-ray density gage which is an adaptation of a twin-probe direct transmission field gage for laboratory density measurement. It is shown that linear calibration relationships can be obtained by two different procedures. The first case is to use the count ratio between the count rate of specimen with mold to count rate of air plotted against the composite density of the specimen and mold. The composite density is computed using the irradiated volumetric proportions of the specimen and mold. The other case is to use the count ratio between the count rate of specimen and mold to the count rate of mold only plotted against the density of the specimen. Experiments were conducted with three aluminum molds of 116, 119, and 124 mm external diameters and 102 mm internal diameter, for five specimens of 100 mm diameters with density froms 0.87 to 2.70 g/cm3. Based on the radiation attenuation law, a theoretical basis for the linear calibration in the two cases are established. Comparison of the theoretical slopes of the calibration lines with the experimental slopes showed excellent agreement, thus verifying the validity of the calibration procedures.
An Improved Moisture Permeability Measurement Method
Authors: Douglas JS , Kuehn TH , Ramsey JW
Published: February 2009

This paper describes the development of a new method for measuring water vapor transport through common building materials. The method represents an improvement in flexibility over the standard ASTM cup methods in terms of allowing inothermal and nonisothermal testing. The method also accounts for convective boundary layers on both sides of the test material. This paper contains preliminary test results using gypsum board materials. Future testing will attempt to gain transport data for these and other materials under likely operating environments.
Validation of a Corona Discharge Technique to Test Male Latex Condoms for Pinhole Defects
Authors: Herman BA , Carey RF
Published: February 2009

The Center for Devices and Radiological Health, Food and Drug Administration, evaluated a prototype device using novel technology to detect pinholes in male latex condoms. This device uses multiple electrodes, maintained at high positive voltage, which interrogate a latex condom placed on a conducting mandrel. An electric discharge occurs only when a small hole is present in the condom and is sensed by the device. The mandrel is rotated to map out the entire surface of the condom. Using latex condoms with laser-drilled holes ranging from approximately 1 to 30 µm in diameter, we examined the sensitivity of this device. The smallest holes were detected, and the overall false negative rate was 2%.
Cyclic Response and Fatigue of Steels Subjected to Strain Control with Non-Zero Means
Authors: Gong Y , Norton M
Published: February 2009

Baseline fatigue data are presented through a series of strain-controlled tension-compression-type fatigue tests on smooth specimens of a Type S1214 mild steel under various combinations of strain amplitudes and nonzero mean strains. The strain magnitudes were chosen in the upper limit of the elastic range, in the plastic range, or in the transition area between the elastic and the plastic range. Experimental results show that for strain amplitudes in the upper limit of the elastic range, positive mean strains prolong fatigue life and negative mean strains shorten fatigue life. The observations are explained by the analysis of the basic material properties associated with the material concerned. The cyclic response behavior of the materials, namely the Bauschinger effect, the cyclic softening, and the mean stress relaxation processes have been studied also to reveal the underlying fatigue mechanism. Several modified models have been proposed for life prediction under nonzero mean strain and/or mean stress based on experimental observations. The comparison of the experimental results with the predictions made from the proposed models and from an existing model are also presented.
The Influence of Irregularities in the Crack Shape on the Crack Extension Measurement by Means of the Direct-Current-Potential-Drop Method
Authors: Riemelmoser FO , Pippan R , Weinhandl H , Kolednik O
Published: February 2009

The equations used for calculating the crack extension from the change in the potential drop at a fracture mechanics specimen are generally derived for perfectly straight crack fronts. In the practice of fracture mechanics tests the crack, however, usually grows faster in the interior of the specimen than at the exterior, leading to a curved crack front. For such a case we calculate the potential drop by means of a finite difference scheme. It is shown that for curved cracks the usual procedure of the direct-current-potential-drop method underestimates the real crack extension. The same finite difference scheme is then used to account for conductive bars and bridges, which sometimes are left behind the crack front. Finally, the influence of side grooves on the potential drop is investigated.
Experimental System for Simulating Crack Propagation in Asphalt Pavements and Effectiveness of Geosynthetics in Crack Retardation
Authors: Goulias DG , Ishai I
Published: February 2009

This paper presents the pneumatic moving wheel experimental system and its usefulness in simulating the role of geosynthetics (geogrids) in limiting crack propagation. The simultaneous development of rutting through the experiment was studied as well. The performance of the developed loading system showed that: (1) the moving wheel loading device provides a compact, convenient, simple, and rational experimental tool for investigating the effect of pneumatic wheel loading on the mechanical dynamic behavior of asphaltic layers; (2) two of the failure modes of asphaltic pavements, fatigue cracking and permanent deformation, could be assessed and measured simultaneously; and (3) the relative effect of geosynthetics reinforcement on the retardation of the development of the above distresses during service life was successfully measured to verify quantitatively the contribution of interlayer reinforcement toward the reduction of permanent deformation (rutting) and the increase of asphaltic surface layer life by retarding crack propagation.
Data Supporting a Provisional American Society for Testing and Materials (ASTM) Method for Metalworking Fluids, Part 2: Preliminary Report of Evaluation of a Ternary Solvent Blend in a Provisional ASTM Method for Metalworking Fluids (P-42-97)
Authors: Glaser RA , Shulman S , Klinger P
Published: February 2009

Samples of straight, soluble, semi-synthetic, and synthetic metalworking fluids (MWF) were spiked onto polytetrafluoroethylene (PTFE) membrane filters, stored overnight, and analyzed using a provisional American Society for Testing and Materials (ASTM) method for metalworking fluids. That technique involves collection of aerosolized fluid on PTFE membrane filters and separation of the fluid from co-sampled particulate matter via extraction of the filter with a blend of dichloromethane: methanol:toluene. The extraction of all fluids from the filters was quantitative over the range 200 to 815 µg for the straight fluid, from 223 to 878 µg for the soluble fluid, from 51 to 189 µg for the semisynthetic fluid, and from 102 to 420 µg for the synthetic fluid. For those weights of all four fluids spiked at levels ⩾200 µg, the precision (%relative standard deviation or %RSD) was estimated to be 4% for the total weight procedure and 5% for the extraction procedure. Limits of quantitation, estimated from blanks carried through the entire analytical procedure, were 30 µg for the weighing technique and 60 µg for the extraction technique.
Ultrasonic Measurement of the Dynamic Elastic Moduli of Small Metal Samples
Authors: Slotwinski JA , Blessing GV
Published: February 2009

Ultrasonic velocity measurements were used to determine the dynamic elastic moduli of small metal samples to a 2σ measurement uncertainty of better than 1%. The samples were cylindrical in shape, possessing nominal diameters of 12 mm and thicknesses of 6 mm. Aluminum, titanium, and stainless steel compositions were examined. In the longitudinal wave measurements, a 20-MHz quartz piezoelectric element transducer was employed in pulse-echo mode using a tone-burst excitation. These longitudinal time-of-flight measurements were made with a repeatable 2σ measurement uncertainty of ≤1.0 ns. Shear time-of-flight measurements, using a 10-MHz contact ceramic piezoelectric element transducer subjected to tone-burst excitation, were made with a repeatable 2σ measurement uncertainty of ≈2.0 ns. NIST calibration facilities provided measurements for the density and lengths of these samples, as needed for the moduli calculations. Results indicate that the measurement uncertainties for elastic moduli measurements of this type can be kept quite small.
A Back-Faced Strain Compliance Expression for the Compact Tension Specimen
Authors: Riddell WT , Piascik RS
Published: February 2009

A numerically generated expression to determine crack length in a compact tension specimen from back-faced strain compliance is presented. The numerically generated back-faced strain expression is bounded by two experimentally determined expressions previously published in the literature. Additionally, stress intensity factor and crack-mouth opening expressions are determined. These expressions agree well with previously published results.
A Simple Catapult System for Studying the Small Projectile Impact Resistance of Various Glass Laminates
Authors: Grant PV , Cantwell WJ
Published: February 2009

A catapult arrangement capable of propelling small granite chippings at velocities of between 4 and 20 ms-1 at laminated glass structures similar to those used in car windscreens has been designed and manufactured. The results from a series of studies utilizing this equipment are presented, with the overall aim of reducing the weight of these constructions with no loss in impact resistance. The impact resistance of the laminates has been shown to depend strongly on the thickness of the outer glass layer, while the inner glass layer is of secondary, and in most cases, minor relevance. Tests in which the composition and thickness of the interlayer have been varied have revealed that this layer is of no consequence in terms of the impact resistance of the structure as a whole. Chemical strengthening of the outer glass layer has been carried out, and no improvement in performance is observed due to the nature of the stone geometry. Finally, tests on bilayer systems have been carried out, and these results indicate a potential weight saving for no loss in impact performance.
Water Management and Moisture Transport in Direct-Applied and EIFS Wall Assemblies
Authors: Tonyan TD , Moyer KW , Brown WC
Published: February 2009

An experimental program has been completed investigating water management and moisture transport in direct-applied finish system (DEFS) and exterior insulation and finish system (EIFS) wall assemblies. The first objective of the study was to understand and quantify drainage through water-managed DEFS and EIFS. A second objective was to understand moisture transport through the wall cladding under a variety of climatic conditions. A third objective was to better understand the role of the sheathing membrane on the moisture transport characteristics of the system. A drainage test has been developed, and a variety of water-managed DEFS and EIFS wall assemblies have been tested. Also, DEFS and EIFS wall assemblies have been tested in an environmental chamber using five different sets of climatic conditions to create a vapor drive through the wall. Results from the drainage and environmental chamber testing are presented, along with an evaluation of sheathing membranes with different performance characteristics.
Efficient Mitigation of Edge Effects in Nearest-Neighbor Analysis
Authors: Frost JD , Saussus DR
Published: February 2009

The properties of soils and other civil engineering construction materials are influenced by the microstructural arrangement of the particles. The characterization of the spatial arrangement and distribution of microstructural features are therefore of importance if the mechanical properties of materials commonly used in civil engineering are to be better understood. Numerous statistical methods have been developed to characterize the spatial arrangement of microstructural features. However, care must be taken in implementing these methods using automated imaging systems to analyze finite quantities of features so that bias due to edge effects and other factors is not introduced. A new method for mitigating edge effects when nearest-neighbor analysis is being performed is proposed in this paper. The method is validated using synthetic square and triangular patterns for which the spatial arrangement free of edge effects (unbiased) is already known. Use of the method to analyze a real dataset representing the peripheral packing arrangement of sand particles in triaxial specimens is described. The results indicate that the new method is able to mitigate edge effects and offer substantial savings in terms of efficiency of data collection and analysis.
Experimental and Numerical Study of Delamination Growth Induced by a Transverse Crack in Unidirectional Laminates Subjected to Bending Loads
Authors: Javidrad F
Published: February 2009

This paper presents the results of an experimental and numerical investigation into the mixed-mode delamination growth initiated from a transverse crack in unidirectional laminates under the three-point-bend test condition. The delamination growth was found to be stable both numerically and experimentally. Two data reduction methods, the compliance calibration and the finite element-based data reduction, were used to analyze test results. It was shown that the latter method gives better results. The finite element delamination growth modeling incorporating the linear growth criterion was also used to model the growth of delamination. Very good agreement between numerical and experimental results was achieved. This type of specimen has the advantage of being very easy to prepare. There is no need to implant an artificial delamination as required for most interlaminar tests. The data reduction method using finite element analysis is straightforward. Therefore, this type of test specimen can be used effectively for determination of mixed-mode fracture toughness of laminated composites.
Displacement Ductility of Steel Members under Axial Tension
Authors: Itani AM , Woodgate J
Published: February 2009

This paper discusses the results of an experimental investigation conducted on seven ASTM A 36 steel members subjected to axial tension. The members were chosen with various ratios of net cross-sectional area An to gross cross-sectional area Ag. The specimens were subjected to incremental axial displacement until fracture to determine the displacement ductility of each speci men. The results of this study showed that the displacement ductil ity is highly dependent on the ratio An/Ag and the geometrical shape of the member. It was also found if the ratio An/Ag is less than the specified yield stress to ultimate strength Fy/Fu, the displacement ductility will be close to 1, which means the member will fail in a brittle manner.
Measurement of Young's Moduli for Lead Zirconate Titanate (PZT) Ceramics
Authors: Fett T , Munz D
Published: February 2009

Knowledge of the Young's moduli is necessary for piezoelectric ceramics in order to separate the total deformation into an elastic and a plastic contribution. The methods for the determination of the Young's moduli, well known from conventional ceramics, are much more complicated due to the special electrical boundary conditions. The main aim of the report is to discuss the question in which mechanical tests the conditions of a constant electrical field are fulfilled and in which type of test constant dielectric displacements occur. It will be illustrated that the results from tests with homogeneous stress states are much more trustworthy than results from bending tests.
Stochastic Resonance in Acoustic Emission
Authors: Friesel M
Published: February 2009

Stochastic resonance allows below-threshold signals to be detected because of the presence of favorable background noise. In this paper the author describes stochastic resonance and anti-resonance and presents some examples to illustrate how these affect the detection rates of acoustic emission signals or ultrasonic pulses in low signal-to-noise environments. The author introduces the signal fraction, a measure for quantifying the fraction of detected events that contain a signal that appears to have advantages over the signal-to-noise ratio for certain kinds of data, and a formalism for calculating the probability of signal detection when the noise is a time-dependent sinusoid.
Precision of ASTM D 5821 Standard Test Method for Determining the Percentage of Fractured Particles in Coarse Aggregate
Authors: Hand AJ , Epps JA , Sebaaly PE
Published: February 2009

An interlaboratory study was conducted to develop a precision statement for ASTM D 5821-95, Standard Test Method for Determining the Percentage of Fractured Particles in Coarse Aggregate. The experimental design included ten laboratories, four materials, and three replicates per material per laboratory, resulting in 54 degrees of freedom. Outlier detection was given careful con sideration due to the subjective nature of the method, and resulted in exclusion of one laboratory's data, reducing the degrees of freedom to 48. The materials included three partially crushed gravel blends and one quarry stone blend.

As expected, multilaboratory variability was greater than singleoperator variability. There was also a greater level of variability associated with two or more fractured face determinations than with one or more fractured face determinations. Surprisingly, the greatest variability was observed for the quarry stone rather than for the crushed gravels. The results of the analysis were compared with other available data. The level of variability associated with this study was less than that observed in other studies, due most likely to the highly fractured nature of the materials used in the study.