bluuebunny/crossref_metadata_2025 huggingface dataset:
Silicon Epitaxial Thickness Measurements: Why and How
Authors: Gardner EE
Published: February 2009

In the decade since the introduction of epitaxial layers for the fabrication of semiconductor devices, several techniques have been proposed for the measurement of the thicknesses of these layers. Three techniques, bevel and stain, stacking fault, and infrared fringes are discussed in detail. A brief history of the progress of these techniques to become ASTM tentatives or standards is reported.
Epitaxial Resistivity
Authors: Langer PH , Pearce CW
Published: February 2009

In order to intelligently specify epitaxial silicon starting material for semiconductor devices, such as, diodes, transistors and integrated circuits, a precise knowledge of the variation of impurity concentration with depth is usually needed. Also, in order to control the epitaxial process, an accurate knowledge of the resistivity must be available in a relatively short time. Innovative techniques that yield impurity concentration profiles will be discussed along with methods that give a rapid indication of the average slice resistivity. Relative merits and disadvantages of each method will be assessed along with the work of the ASTM Committee F-1, Subcommittee 6, Section 6.2, on Epitaxial Resistivity.
Obtainable Radiographic Equivalent Penetrameter Sensitivity
Authors: Splettstosser HR
Published: February 2009

Some of the properties of film and vision which affect radiographic sensitivity are discussed. Values of obtainable equivalent penetrameter sensitivity are given for some practical conditions when radiographing ¼- to 2-in.-thick steel with X-rays and 1- to 6-in.-thick steel with Co-60. Limitations to calculations of sensitivity for other conditions are given based on these results.
Test Facilities for Measuring the Thermal Response of Materials to the Fire Environment
Authors: Crowley DP , Tempesta FL , Castle GK , Belason EB , D'Avanzo LJ
Published: February 2009

Subscale fire test facilities have been developed for evaluating the thermal response of material test specimens exposed to a variety of fire conditions. One of the facilities was used in an investigation of the feasibility of using subscale fire testing as an aid in predetermining the thermal performance of materials exposed to a full scale E 119 fire environment. Environmental incident heat flux histories were obtained during an Underwriter's Laboratory development safe-column furnace test of a prototype plastic fire resistant material assembly. These same heat flux histories were recreated in the subscale fire test facility. A specimen of the prototype plastic material was tested in the recreated environment. A comparison of the thermal performance of the material tested in the full scale and recreated fire environments showed good agreement. This paper presents a description of the subscale facilities and the results of correlating the E 119 fire test with the subscale fire test.
Flow Test for Determination of Set-Time of Powdered Coatings
Authors: Worley AA , Zell JG
Published: February 2009

In the manufacture of torroidal core rings coated with epoxy powder coating material the smoothness of the coating is influenced by the flow and cure characteristics of the material. These characteristics of thermosetting powder coatings could not be evaluated with standard test procedures that were available for determining the properties of liquid coating materials.

Several test procedures were evaluated and a new spiral flow test was developed that indicated the relative performance of coating materials on the final product. The apparatus and procedure used are described in detail. Data are presented to demonstrate the reliability of the method and the effect of temperature and particle size on the results.
Multistage Triaxial Testing of Lightly Overconsolidated Clays
Authors: Parry RHG , Nadarajah V
Published: February 2009

A comparison has been made between consolidated undrained tests on separate soil specimens and multistage testing of a single specimen. Three series of samples were prepared, two of the series consisting of remolded kaolin in each of which the specimens were lightly overconsolidated under K0 conditions, and one series consisting of undisturbed specimens of soft silty clay from a site at Fulford near York in England. It is concluded from these tests that although some differences arise from the two methods, the results from multistage tests are adequate for practical purposes both in the prediction of failure conditions and in the prediction of deformations and pore pressure response under working loads. In view of the number of advantages accruing from multistage testing, it is recommended that this method should be used in the routine triaxial testing of soft lightly overconsolidated clays of low sensitivity.
Atomic Absorption Analysis of Portland Cement and Raw Mix Using a Lithium Metaborate Fusion
Authors: Crow RF , Connolly JD
Published: February 2009

A rapid and accurate atomic absorption method is described for the analysis of nine elements in portland cement and portland cement raw mix. These elements are aluminum, calcium, iron, magnesium, manganese, potassium, sodium, silicon, and strontium. Samples are fused with anhydrous lithium metaborate in a graphite crucible, and the molten melt is poured into a dilute acid solution.

Possible interferences and “matrix” effects are minimised by calibrating the instrument with standard solutions prepared from NBS standard cements.

Calcium and silicon determinations are made using a signal-averaging digital-readout device and a standard-unknown-standard bracketing technique,

The precision and accuracy for all of the elements determined is sufficient for control purposes.

The time required for the analysis of a single sample is approximately 1 1/2 h. When multiple samples are to be analyzed, time per sample is greatly reduced.
Fatigue Failure Predictions for Plates with Holes and Edge Notches
Authors: Raske DT
Published: February 2009

A means to determine the fatigue notch factor, Kf is devised by identifying the zone of metal at the notch root which is thought to govern the fatigue process. Corrections are then developed for the effects of the stress gradient and critical volume in this zone. The resulting equation for Kf embodies these corrections and the theoretical elastic stress concentration factor, Kt. Experimental verification is obtained by testing notched plate specimens and by utilizing data from the literature. Predictions of Kf over fatigue lives of from 102 to 106 cycles are within 4 percent of experimental values when calculated in terms of stress and within 9 percent in terms of strain.
Analytical Prediction of the Thermal Response of Decomposing Materials in Fire Environments
Authors: Castle GK , Alexander JG , Tempesta FL , Belason EB
Published: February 2009

An analytical model is presented which accurately predicts the thermal response of decomposing materials in fire environments. The model is the same one developed for the design of reentry and space vehicle heat shield materials including the Apollo heat shield. The analysis handles one dimensional transient thermal conduction with decomposition, surface reactions, and transpiration with a variety of surface boundary conditions. Both temperature and density dependent properties are utilized for proper characterization of the thermophysical behavior of a material. Basic details of the thermal processes involved are given as well as the scope of the model. Thermal analyses of three different types of materials exposed to two different fire environments are presented. Two materials, gypsum wall board and a spray-on fiber material, were tested in a controlled subscale fire at the Avco Laboratories, while the third, a reinforced plastic, was tested at Underwriters' Laboratories in a safe-column furnace.

Measured thermal properties used to make the predictions are presented along with the methods of measurement. The test environment is also discussed in terms of heat transfer rates, enthalpy, and nature of the gases. The behavior of plastics and their reaction to a fire environment is discussed and related to the model. Results given for the predictions made show excellent correlation with the measured temperatures and weight losses. Finally, the utility of the model is discussed relative to predicting the fire response of various materials without the aid of extensive testing.
Contributions of Selected Residual Elements to the Radiation Embrittlement Sensitivity of Steel Forgings
Authors: Hawthorne JR
Published: February 2009

Residual impurity element content has a major influence on the sensitivity of low alloy steels to radiation-induced embrittlement. The identification of phosphorus as highly detrimental to irradiation performance has made tin, arsenic, and antimony additional suspect elements.

The influence of tin, arsenic, and antimony on elevated temperature radiation embrittlement sensitivity was explored using a series of seven experimental NiCrMoV forgings. The forgings represented high and low phosphorus contents in addition to statistical variations of tin, arsenic, and antimony content. Assessments of relative radiation sensitivity involved the exposure of Charpy-V specimens at 550°F (288°C) to 3.1 × 1019 n/cm2 > 1 MeV.

Postirradiation observations indicate that tin, arsenic, and antimony do not contribute directly to radiation embrittlement sensitivity, either individually or in combination, for the composition range studied. In contrast, phosphorus (∼0.015 percent P) was observed to have a pronounced detrimental effect on radiation embrittlement resistance. Significantly, the contribution of phosphorus to radiation embrittlement sensitivity was found to be greatly reduced by a high (100–150 ppm) tin content. The phosphorus-tin interaction appears to be independent of both antimony and molybdenum content for the levels investigated but may be dependent on a high (∼150 ppm) arsenic content. Points of similarity and non-similarity in the influence of phosphorus and tin on radiation embrittlement and temper embrittlement behavior are described.

Postirradiation observations confirm that impurity restrictions have significant capability for improving the radiation embrittlement resistance of low alloy steel forgings.
Application of the Laser Beam Technique to the Improvement of Metal Strength
Authors: Hsu TR
Published: February 2009

The present work demonstrates the feasibility of increasing both the static and fatigue strength of metals by a new thermal shock process produced by a solid-state laser. Because of its simplicity and effectiveness, this process is considered to be suitable for mass production purposes.
Probabilistic Updating of Flaw Information
Authors: Tang WH
Published: February 2009

The prediction and control of flaws in welds occupy an important role in design against fatigue and fracture failure. However, the present NDT devices can detect only a fraction of the flaws and they do not give the actual size of flaws detected. Using Bayes Theorem, a framework is proposed whereby distributions of flaw size and density are updated from NDT inspection data and the level of repair. The concept is equivalent to a filtering process where the detectability function of the NDT device acts as the filter. The information derived will help planning of NDT inspection programs and consistent code specifications.
Thermomechanical Testing of Plastics for Environmental Resistance
Authors: McKague EL , Reynolds JD , Halkias JE
Published: February 2009

A thermomechanical analysis (TMA) technique has been developed for evaluating effects of moisture on mechanical behavior of plastic materials after short exposures to humidity environments. The key to shortening environmental conditioning time is the capability to test very thin, micro-size specimens which provide a high surface area to volume (S/V) ratio. The weight percentage of moisture absorbed by a material in a given time is directly proportional to the S/V ratio; therefore, thin specimens exhibit faster rates of bulk weight and, consequently, bulk property changes. The TMA method involves measurement of deflections in specimens loaded in three-point flexure while the temperature is increased at a constant rate. The technique is similar to that described in ASTM D 648 for determining temperatures at which arbitrary amounts of deflection have been reached. In addition to its sensitivity in detecting environmental effects on short term environmental exposure, the TMA method has other advantages over the D 648 procedure. These include faster and more uniform specimen heating and continuous recording of deflection versus temperature and time.
A Study of Currently Used Methods for Determining the Permeability of Bituminous Mixtures
Authors: Gilbert P , Hode Keyser J
Published: February 2009

This paper presents a review of 15 permeameters along with a study on the advantages, disadvantages, and limitations of the six most currently used methods. The precision of the latter and the relationships which exist between the methods were also investigated.

The review shows the need for selecting the type of permeameter according to the purpose of measurements taking into account their inherent limitations. It also shows the need for establishing a standard permeability unit.

Tests were made on laboratory molded specimens, on slab surfaces, and on cores extracted from slabs. Test results indicate that precision must be expressed in terms of percentage of the mean. For mixes containing more than 6 percent voids, there is a good correlation between: (a) permeability and voids; (b) field and laboratory tests; (c) air permeameters and water permeameters; (d) permeability and rate of flow. Greater values were obtained with permeameters using air and when tests were made on pavement surfaces.
One-Dimensional Consolidation of Retarded Plastic Concrete
Authors: Uzomaka OJ
Published: February 2009

A study of the one-dimensional consolidation of plastic concrete (that is, a concrete mix within the first few hours after mixing when it can still be remolded) is discussed with particular reference to the soil mechanics analogy which the author proposed for a wider study of some engineering properties of plastic concrete [2]. This property of the mix is discussed in terms of classical consolidation parameters used in soil mechanics, namely the coefficient of compressibility (mv) and the coefficient of consolidation (cv. It was desired to study the consolidation behavior of the material as it is just after mixing and, consequently, the mixes were retarded by the addition of small quantities of sugar to minimize the effect of hydration.

Theoretical equations are developed to express the dependence of these two quantities on the initial moisture content of the mix and the applied consolidation pressure.

A linear relationship, as predicted from theory, was obtained between mv and the initial moisture content from results of the laboratory study in which the Rowe's cell was used. Further empirical results showed that there is no apparent simple relationship between cv and initial moisture content. However, there is a linear relationship between cv and pressure increment. The mv values lie between 1.25 × 10−3 and 6.25 × 10−2 in.2/lb, while the cv values lie between 1.5 × 10−2 and 4.5 × 10−2 in.2/min. In general, the mixes tested behaved similarly to remolded clays.

The Darcy coefficient of permeability of the mixes, deduced from the consolidation data, is of the order of 10−8 cm/s.
Development of Cold Weather Paving Specifications
Authors: Maupin GW
Published: February 2009

Cold weather paving specifications were developed from work by Corlew and Dickson who used a computer solution to predict the cooling rate of bituminous concrete.

Virginia had previously used a minimum atmospheric temperature as a criterion; however, it was evident that other factors had a significant effect on the cooling of bituminous concrete, so the computer solution was considered as a possible basis for new specifications.

Although the solution had been checked by field measurements, it was decided to obtain further verification by plotting cooling ourves for freshly placed hot mix. The curves were developed by measuring the cooling rates of bituminous mats of varying thicknesses under a variety of weather conditions. The field measurements verified the computer solution, and it was used to develop new cold weather paving specifications.

The first specification, put into effect in 1970, was written in tabular form using the laydown temperature and mat thickness as criteria. This specification has been modified and now appears in the form of a simple nomograph.
Comparison of the Heat Treatment Responses of Three Commercial Titanium Alloys
Authors: Fopiano PJ , Hickey CF
Published: February 2009

The purpose of this paper is to show the similarity between the heat treatment responses of Ti-6Al-4V, Ti-6Al-6V-2Sn, and Ti-8Al-1Mo-1V. Two hardening mechanisms can account for most of the responses to heat treatment. The changes in strength as the result of heat treatment are correlated with the equilibrium alloy contents of the phases present at the solution temperature.
Shear Transfer in Concrete and Polymer Modified Concrete Members Subjected to Shearing Loads
Authors: Nawy EG , Ukadike MM
Published: February 2009

Experiments were conducted to evaluate the shear transfer capacity of polymer modified concrete (PMC). The experimental program was designed to verify the general theory of shear transfer mechanism for concrete and to evaluate the necessary constants of the theoretical expressions. The general theory presented covers structural members with (1) no shear reinforcement, (2) moderate shear reinforcement, and (3) high shear reinforcement. Four groups of specimens were tested. Group A specimens were used to investigate the relation between intrinsic bond shear transfer capacity and the strength of the composite materials (PMC and concrete). No transverse steel was used in these specimens. Group B specimens contained various amounts of shear reinforcement at the shear interface. Group C specimens were cast monolithically using ordinary concrete to serve as control specimens. Group D were control specimens made up of cast-in-place concrete over precast concrete. They were designed to evaluate the “apparent cohesion” of such elements, for the purpose of comparison with Group A specimens.
Experimental Analysis and Numerical Simulation of Marshall Method of Asphalt Concrete Mix Design
Authors: Mamlouk MS , Manolis GD
Published: February 2009

The results of a numerical simulation of the Marshall testing procedure used in asphalt concrete mix design are reported in this work. The numerical simulation uses the finite element method to model both the asphalt concrete specimen as well as the surrounding testing heads. Linear elastic material behavior and plane stress conditions are assumed to hold in the finite element analysis of the Marshall testing procedure. The elastic modulus required for this analysis is obtained from a separate unconfined compression test on long cylidrical specimens made of the same asphalt concrete mixture as that used in the Marshall test. Although the assumption of linear elastic material behavior is restrictive, a qualitative picture of the displacements and stresses developed in the specimen during the Marshall test emerges from this work.
The Most Probable Pore-Size Distribution in Fluid Filter Media I. Evidence of Such a Distribution from Results of Extended Bubble-Point Measurements
Authors: Johnston PR
Published: February 2009

This theoretical distribution addresses those filter media with a random arrangement of pores. It is based upon the concept of a smallest pore, the size of which is a function of the size of the building blocks making up the filter medium. The distribution is solely a function of the porosity (the ratio: void volume/bulk volume). The greater the porosity the wider the distribution of pore sizes.
The Most Probable Pore-Size Distribution in Fluid Filter Media II. Determining the Size of the Average Pore from Fluid Permeability Measurements
Authors: Johnston PR
Published: February 2009

This theoretical distribution, addressing those filter media with a random arrangement of pores, was given credence in Part I of this paper via results of extended bubble-point measurements. Here the distribution is given credence through showing that theoretical calculations of laminar flow permeability correspond to actual measurements. And, the meaning of the average size pore—deduced from permeability measurements—is explained in relation to the pore-size distribution.
Predicting Heat-Affected Zone Hardness by the Weld Test Method
Authors: Bibby MJ , Chong L-M , Goldak JA
Published: February 2009

The “weld test method” of predicting heat-affected zone (HAZ) hardness first suggested by Stout el al is further developed in this investigation. The contemporary heat flow analysis of Adams and Jhaveri et al, and conclusions from the recent particularly relevant hardness-heat flow investigation of Graville are incorporated into the model. A “welding hardness diagram” is suggested to represent the test data and to simplify the task of predicting HAZ hardness. Experimental hardness results are compared to predicted values for a relatively wide range of carbon-manganese and low alloy structural steels in support of the welding hardness diagram approach. The relative merits of this procedure compared to the recent mathematical methods suggested by Bastien et al and by Arata et al for predicting HAZ hardness are discussed.
A New Test Method for Determining Environmental Stress-Crack Resistance of Ethylene Based Plastics
Authors: Crissman JM
Published: February 2009

A new test method is proposed for the determination of the environmental stress-crack resistance of ethylene based plastics. The method incorporates features of both ASTM Test for Environmental Stress-Cracking of Ethylene Plastics (D 1693) and Test for Environmental Stress Rupture of Type III Polyethylenes Under Constant Tensile Load (D 2552). The specimen is constrained in a fixed geometry by bending it around a cylindrical metallic form, and it is subjected to a constant applied stress. Statistical data are presented which indicate that the coefficients of variation that can be expected from the new test are at least comparable to those reported earlier in round robin tests carried out using ASTM D 2552. The principle advantage of the proposed new test over both ASTM D 1693 and D 2552 is a substantial savings in the time required to collect the data.
Training the Security Screening Station Operator
Authors: Hunter JM
Published: February 2009

The Federal Aviation Administration's (FAA) involvement in the subject area is generally limited to establishment of training standards, production, and distribution of training aids, and monitoring ongoing training to assure that regulatory standards are met. The screener/passenger interface is critical not only in assuring the safety of the system, but in projecting the airline image. It is not coincidental that laws and regulations governing the screening process call for courteous and tactful deportment on the part of all screeners. Training requirements include a vigorous testing program conducted by FAA and the airlines. As new threats evolve, such as the use of flammable liquids by Cuban refugees, FAA's training materials are updated and sophisticated. Training records are maintained for every screener and are monitored closely by FAA to assure effectiveness of the system. The cornerstone of the security safeguards in place at U.S. airports is the screening system. Only through continuous training can we collectively have confidence in the safety and security of air transportation in the United States.
Reference Materials—What They Are and How They Should be Used
Authors: Taylor JK
Published: February 2009

The role of reference materials in monitoring the chemical measurement process is considered. Requirements for reliable reference materials are reviewed. The use of reference material data in estimating the uncertainties of the results of measurements on test samples is discussed.
A Modified Metallographic Method to Detect Sensitization in Type 316 Stainless Steel
Authors: Parvathavarthini N , Dayal RK , Gnanamoorthy JB
Published: February 2009

For detecting susceptibility to intergranular corrosion (IGC) in austenitic stainless steels, ASTM Recommended Practices for Detecting Susceptibility to Intergranular Attack in Austenitic Stainless Steels (A 262), Practice A (metallographic test), serves as a screening test. Alloys showing “step” or “dual” structures are considered to have passed the test. When a “ditch” structure is obtained, the material needs further testing by one of the immersion tests (Practices B, C, D, or E). It has been observed that the electro-etching parameters of Practice A are rather severe, leading to the development of “ditch” structures in nonsensitized materials which are not susceptible to IGC. A modified etching technique has been developed in which nonsensitized samples of Type 316 stainless steel as detected by Practice E show step structure or no structure at all; ditch structure is developed only in the cases of samples heat treated close to or within the sensitization range. Use of this technique could result in a reduction of the number of specimens that must be tested by one of the other practices in ASTM A 262.
Erosion of Phosphor Bronze under Cavitation Attack in a Mineral Oil
Authors: Rao BCS , Buckley DH
Published: February 2009

Experimental investigations on erosion of a copper alloy, phosphor bronze, under cavitation attack in a viscous mineral oil are presented. The details of pit formation and erosion were studied using scanning electron microscopy. The mean depth of penetration, the variations in surface roughness, and the changes in erosion pit size were studied. Cavitation pits formed initially over the grain boundaries while the surface grains were plastically deformed. Erosion of surface grains occurred largely by ductile fracture involving microcracking and removal in layers. The ratio h/a of the depth h to half width a of cavitation pits increased with test duration from 0.047 to 0.55.
Evaluation of the Effect of Contact-Time When Measuring Floor Slip Resistance
Authors: Irvine CH
Published: February 2009

To test the slip resistance of shoe and floor materials, the Horizontal pull Slipmeter (HPS) is normally placed on a smooth floor surface and then connected to a capstan which applies force to overcome friction. This normal procedure was compared with a laboratory modification of the normal HPS operation: the meter was placed on the floor at the same time the capstan began applying the lateral force. Results from 1360 measurements involving 17 shoe-sole materials and two floor materials, wet and dry, were as follows: (1) differences in time of contact between shoe sole and floor materials affected the slip resistance for some materials, and (2) dry leather materials were most consistently and substantially affected, whereas other affected materials showed relatively small differences. Previous researchers have shown dry leather to be generally less slip resistant than other shoe-sole materials. Results from this evaluation study may be used in support of these previous findings.
Erosion by Solid-Particle Impacts: A Testing Update
Authors: Wood FW
Published: February 2009

A workshop on erosion by solid particles focused attention on the status of applicable testing technologies. ASTM Standard G 76-83, in which erodent particles are entrained in gas jets, was reviewed, and procedural variations based on it were described and discussed. Among the factors considered were cratering, particle fluxes, particle feeding, and the characteristics of nozzles, specimen surfaces, and erodent particles. Many effects of the foregoing factors are not yet fully understood. Jet-type erosion tests such as ASTM G 76 cannot simulate all practical circumstances in which erosion by solid particles occurs. Therefore the development of additional standardized testing procedures is needed. Two alternatives, slinger-type testing and wind-tunnel testing, with potential for further development were described.
A Rapid Test for Asphalt Content of Bituminous Mixtures
Authors: Martinez Chavez JJ , Winslow DN
Published: February 2009

A simple test procedure has been developed that greatly speeds the determination of the asphalt content of hot-mix bituminous mixtures. It involves a brief but thorough mixing of standard quantities of a bituminous mixture and trichloroethylene. The transmittance of light by the asphalt-trichloroethylene solution is then measured and correlated with the asphalt content of the mixture. The method takes about 5 min and uses reasonably inexpensive equipment that is highly portable. Preliminary tests indicate that the new method is as accurate as existing methods.
An Empirical Model for Predicting Performance of Fire-Resistive Coatings in Wood Construction
Authors: White RH
Published: February 2009

Currently used fire-retardant coatings for wood products reduce flame spread; they are not designed specifically to provide fire resistance. Fire-resistive coatings designed for steel and foam plastics generally are not recommended for wood. However, these fire-resistive coatings have been tested for their ability to improve the fire resistance of plywood. We have developed an empirical model for predicting the fire-resistance performance of fire-resistive-coated wood based on these small nonload-bearing fire-resistance tests.

The equations in the model provide estimates for the times to reach either a temperature rise of 139°C or a temperature of 288°C. Using these equations, various applications for fire-resistive coatings in wood construction were examined. Applications considered include thermal barriers, walls, floors, large timber members, and doors.

Predictions using the model compared favorably with the very limited experimental data available in the literature. Additional research is needed before use of fire-resistive coatings in wood construction can be realized.
A Microcomputer-Based System for the High-Speed Compression Test by the Split Hopkinson Pressure Bar Technique
Authors: Yokoyama T , Kishida K
Published: February 2009

A microcomputer-based system has been developed for the high-speed compression test by the split Hopkinson pressure bar technique. The present test system enables one to obtain reliable dynamic stress-strain data for materials for a very short period. The range of strain rates achieved by the test system is approximately 102 to 2 × 103 s−1 depending on the strength of the material and the impact velocity of a striker bar. The accuracy of the entire test system is checked directly by comparing the static and dynamic test results for a strain-rate insensitive material. Test results are presented for tough pitch copper and two aluminum alloys.
Effect of Fiber Loss by Carding on Average Fiber Diameter of Core Samples of Grease Wool
Authors: Stobart RH , Morrison EJ
Published: February 2009

Sixty wool samples were obtained from a commercial testing laboratory to study the effects of fiber loss by carding on the average fiber diameter measurements of 12.7 mm core samples. No difference (P > 0.05) was found between operators or between carded and uncarded paired samples. The commercial laboratory had smaller (P < 0.05) coefficients of variation than the University of Wyoming Wool Measurement Laboratory. The correlation between fiber diameter and card fallout was 0.899, but did not change the mean fiber diameter of any samples.
Modified Lever System for Constant-Stress Compressive Creep Machine
Authors: Dobeš F , Zvěřina O , Čadek J
Published: February 2009

A simple mechanical system for keeping constant applied stress during the course of a creep test is proposed. The system uses the forced movement of load and is especially suitable for compressive creep testing. Verification in practical implementation has shown that the tolerance in the stress constancy is better than ±1.5% up to a strain of 30%.
Using an Impact Device with Sliding Drop Collar for In Situ Evaluation of Compressive Strength of Insulating Cellular Concrete
Authors: Reichverger Z
Published: February 2009

This paper describes the efforts of the Central Building Laboratory of the Standards Institute of Israel to develop a relatively simple method for in situ nondestructive evaluation of the compressive strength of lightweight cellular concrete used for thermal insulation of roofs. The idea of the developed impact device with sliding drop collar is similar in principal to the well-known soil test method of drop-weight penetration, ordinarily used for field determination of compacted soil density.

Test results show that the depth of penetration is influenced by two main parameters: compressive strength of the concrete and its density. If the unit weight of the cellular concrete is known or predetermined, its compressive strength can be estimated by means of the impact device with a sufficient degree of accuracy. Thus the drop-collar penetrometer may find useful application in in situ quality control of lightweight cellular insulating concretes.
Precision Testing of Standardized Microbiological Methods
Authors: Beckers HJ
Published: February 2009

Tests performed on identical materials in identical circumstances do not yield identical results. This is attributed to unavoidable random errors inherent in every test procedure. Repeatability and reproducibility have been found sufficient for describing the precision of a method. Examples of interlaboratory precision experiments in the field of food microbiology are presented, which also demonstrate the different types of reference material that can be used. With a fluid, microbiologically stabilized by freezing, repeatability of aerobic and Enterobacteriaceae plate counts (expressed in 10log-units) appeared to be 0.28; reproducibility was 0.37 for both plate counts. The repeatability of Staphylococcus aureus plate counts varied between 0.26 and 0.52, reproducibility between 0.31 and 0.84, depending on the method of enumeration and the testing procedure. It is concluded that microbiological methods should be evaluated by precision tests, carried out on an international scale.
Crack Length Measurement During Rapid Crack Growth Using an Alternating-Current Potential Difference Method
Authors: Joyce JA , Schneider CS
Published: February 2009

The object of this project has been to investigate the applicability of an alternating-current potential difference method of crack length estimation to rapid loading fracture mechanics tests in ferromagnetic materials. The more commonly used direct-current method has been demonstrated to be very sensitive to induced magnetization under rapid loadings. The resulting direct-current output signal is complex and not repeatable, and the component related to crack extension cannot be separated from the total response. The tests reported here show calibrations of a 10 kHz alternating-current system on an A533B material and application of the calibration to a static unloading compliance test and to rapid servohydraulic tests. A d-c component dependent on stress-induced magnetization is still present but can now be separated from the high frequency component using Fourier series methods.

The major conclusion is that an alternating-current technique with a properly chosen excitation frequency can be used to detect crack growth in rapidly loaded specimens. Additional comments on developing an improved system are presented.
Strain Measurement Technique for Elevated Temperature Tensile and Creep Testing of Foil-Gage Metals
Authors: Blackburn LB
Published: February 2009

A technique has been developed for elevated temperature tensile testing of foil-gage metals which employs a modified mechanical extensometer in conjunction with a displacement transducer. The extensometer has been modified by attachment of a counterbalance to reduce the axial load contribution due to the mass of the extensometer to the total maximum test load. In addition, the extensometer grip inserts have been modified to incorporate a conical tip/flat-edge design to minimize induced stresses in the specimen resulting from extensometer attachment.

A room temperature evaluation of the counterbalanced extensometer with modified grip inserts was conducted by comparing the elastic moduli and residuals for titanium alloy (Ti-6Al-4V) specimens determined using bonded, electrical resistance strain gages, to the elastic moduli and residuals determined using the counterbalanced extensometer. Results show the extensometer consistently indicates an elastic modulus within 2.5% of that indicated by the strain gages and an average residual of approximately 2.4 × 10−5 m/m (in./in.).

Demonstration of the counterbalance technique and associated strain measurement system at elevated temperature was accomplished by performing creep tests on 0.102 mm (0.004 in.) thick specimens of Ti-6Al-4V at temperatures of 427°C (800°F) and 538°C (1000°F) and at nominal applied stresses of 310.3 MPa (45 ksi) and 172.4 MPa (25 ksi), respectively. Examination of the resulting creep-curves suggested that the strain measurement system provided actual creep strain values with good accuracy. In addition, the counterbalance technique resulted in a load contribution from the extensometer of less than 0.40% of the applied load levels compared with a 2.21 to 4.48% contribution for specimens tested without a counterbalanced extensometer.
Strain Gage Analysis of Residual Stress in Plastic Pipes
Authors: Chaoui K , Moet A , Chudnovsky A
Published: February 2009

Residual stress distribution in medium density polyethylene (MDPE) 102 mm (4 in.) pipe with 11.1 mm wall thickness is evaluated using three different procedures. A modified layer removal procedure is employed to evaluate the residual stress component in the longitudinal direction as a function of the pipe wall thickness. On the other hand, the residual stress distribution in the circumferential direction is estimated using the conventional ring slitting method. A strain gage technique for direct residual strain measurements is described. The results obtained from the three procedures in a given direction are in qualitative agreements. A tensile residual stress dominates about 24% of the inner section of the pipe wall. The residual stress then becomes compressive reaching its maximum value at the outermost layer.

The stress values obtained from the first two techniques appear unrealistically excessive. On the other hand, those obtained from direct strain measurements appear reasonable as indicated by recent crack propagation studies in the specimens prepared from the same pipe sample.
Evaluation of Singular Intensity Factors in Elastic-Plastic Materials
Authors: Groth HL , Brottare I
Published: February 2009

A singular intensity factor was evaluated for a butt joint geometry with different adhesive material behavior. The finite element method (FEM) was used for the determination of the stresses and displacements in the joint. It was found that the singular nature of the stress field at the free edge at the intersection between the adhesive and the adherend could be well characterized by a singular intensity factor.

The size of the plastic zone at the bi-material interface was investigated and compared with a simple estimation. It was found that the plastic zone sizes from the numerical analysis were smaller than this estimated zone size, even for a rather large amount of plastic deformation.

The singular stress field, governed by the singular intensity factor, was found to be large compared with the plastic zone size for valid small-scale yielding. This indicates that a fracture criterion based on a critical value of the singular intensity factor may be applicable not only to linear elastic materials but also to non-linear plastic materials.
Effect of Prestrain on Fracture Toughness of Rolled Mild Steel with Significant Inclusion Content
Authors: Arora PR , Raghavan MR , Prasad YVRK
Published: February 2009

The basic method of JIc calculation using a single specimen is discussed. Dokouipil's approach for evaluating the JIc value is extended further and the effect of prestrain on rolled mild steel with significant inclusions is studied using this modified approach. Although this method does not give an accurate value of JIc, it is quite effective for a comparative study. While the fracture toughness of annealed and 7% prestrained materials are about the same, the fracture toughness of 3% prestrained material is significantly lower.
Fracture Toughness by Small Punch Testing
Authors: Foulds JR , Woytowitz PJ , Parnell TK , Jewett CW
Published: February 2009

The small punch test, currently being used to empirically estimate the material fracture appearance transition temperature (FATT) of a range of components in fossil power plant service, has been further developed for direct estimation of KIc and JIc in a manner that is analytical, material-independent, and requires no prior knowledge of material mechanical properties. The procedure follows an approach that is based on the continuum material toughness concept wherein the criterion for fracture is defined and measured via the continuum stress-strain deformation properties of the material. The procedure specifically involves computing the “local” strain energy density accumulated at the location and time of crack initiation in the small punch test specimen using large-strain finite element (FE) analysis. Since the procedure also includes estimation of the material uniaxial tensile stress-strain behavior from the small punch load-displacement curve, both the fracture toughness and the uniaxial tensile behavior are determined from a single test. The procedure has been developed in order to take advantage of the miniature sample removal techniques that can be applied “nondestructively” to operating components. Results are presented on a range of steels.
Dynamic Fracture Toughness (DFT) of Banded HSLA Steels
Authors: Shanmugam P , Jana B , Pathak SD
Published: February 2009

Dynamic fracture toughness (DFT) evaluation by instrumented impact analysis has been emerging as a time- and material-conservative technique. The present investigation attempts to assess DFT of a high strength low alloy (HSLA) steel showing alternate layers of ferrite and pearlite in microstructure. The banded microstructure has given rise to an irregular stable crack front which shows spikes and splits. Three approaches to evaluate DFT, namely, premaximum energy, compliance changing rate (CCR), and the low blow test method, have been analyzed and compared to assess applicability in the case of irregular crack front. The curve fitting analysis of data justifies the power law fit to give conservative DFT values. The effects of a/w and impact velocity have been investigated. Attempts have also been made to calculate dynamic CTOD from load-displacement curves. Single specimen CCR technique obviates the need for stable crack growth (Δa) measurements and predicts conservative DFT values comparable to DFT values obtained from the low blow test method. Erratum to this paper appears in 23(2).
A Universal Panel Tester
Authors: Hsu TTC , Belarbi A , Pang X
Published: February 2009

A universal panel tester was built at the University of Houston to test reinforced concrete panel elements subjected to any combination of in-plane and out-of-plane forces. The forces are applied by 40 in-plane hydraulic jacks of 250-kip (1120-kN) capacity each and 20 out-of-plane hydraulic jacks of 140-kip (630-kN) capacity. The sophisticated hydraulic system makes it possible to simulate any complex stress condition in a panel.
On the Nonuniform Distributions of Temperature and Thermal Stress in DTA Testing
Authors: Zhu YT , Devletian JH , Chen SJ , Manthiram A
Published: February 2009

A nonuniform distribution of temperature across the solid specimen during differential thermal analysis (DTA) can cause thermal stress. The effect of such thermal stress and the resulting thermal strain energy on the DTA results is theoretically analyzed. It is found that, for most solid metallic specimens, the temperature nonuniformity in the solid specimen is less than 0.18 °C during normal DTA operation. The thermal stress and thermal strain are usually very small due to the small size of the specimen, and they do not have a substantial effect on the DTA results.
A Consideration of Evaluation of Fatigue Crack Propagation Rate from Effective Stress Intensity Factor Range
Authors: Makabe C , Kaneshiro H , Nishida S , Sakihama H
Published: February 2009

The fatigue crack propagation law was investigated for the two cases of crack propagation in a region of welding residual stress and after overloading. In the former case, the crack propagation rate da/dN was found to depend on the stress ratio R defined by σmin/σmax where σmin, σmax are the minimum and maximum cyclic stresses. Due to the tensile residual stress, the crack propagation rate increased as the stress ratio decreased in the range −2 ≤ R ≤ 0. In the latter case, the crack propagation rate da/dN after overloading was higher than that for the constant stress amplitude test at first and then became lower. The crack propagation rate was thus affected by both the residual stress and the overloading. However, the crack propagation behavior correlated well with the crack closure behavior. Therefore, in the cases considered here, the crack propagation law can be reasonably evaluated from the effective stress intensity factor range ΔKeff.
Calibration of DC Potential Technique Using an Optical Image Processing System in LCF Testing
Authors: Merah N , Bui-Quoc T , Bernard M
Published: February 2009

The direct current electrical potential drop (DCPD) technique is applied to monitor fatigue crack growth in plate specimens with central circular holes at room and high temperatures. The application of the calibration curves obtained from replica specimens to both room and high-temperature fatigue testing conditions is studied. The actual fatigue crack length is measured using a video-camera with image processing to assess the reliability of the DCPD technique. The use of two pairs of DCPD probes across the hole and the introduction of a special reference voltage have eliminated the dependence of the potential drop on the hole size and shape as well as the material resistivity and the notch plastic zone size prior to crack initiation. At high temperature, however, the calibration curve should be corrected to take into account the shifting in the potential ratio due to the increases in crack tip plastic zone and crack opening displacement. The effect of the temperature difference between the different potential probes is also examined.

By analyzing the results given by the DCPD in connection with the image processing technique, a criterion is suggested to define the interface between the crack initiation and propagation periods.
Evaluation of the Hall Effect Sensor for Pavement Instrumentation
Authors: Sebaaly PE , Tabatabaee N , Kulakowski B
Published: February 2009

This research evaluates a new concept to measure the tensile strains at the bottom of the asphalt concrete layer in flexible pavements. The concept consists of using the Hall Effect sensor in an H-gage configuration to measure the dynamic strains in flexible pavements. The evaluation program included both laboratory and field experiments to evaluate the fundamental and operational properties of the recommended gage design. The laboratory experiment showed that the Hall Effect gage can withstand the temperature and moisture conditions that are encountered during the construction and operation stages of hot mixed asphalt concrete pavements. It also indicated that the dynamic characteristics of the gage are suitable for measuring pavement strains under moving vehicle loads.

The field experiment evaluated the in-service characteristics of the Hall Effect gage under a large number of combinations of vehicle speed, axle load, and tire pressure. The field data showed that the Hall Effect gage has good survivability and repeatability and it compares favorably with other strain gages that have been used in flexible pavements.