bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ultrasonic Wave Measurements of Elastic Moduli E, G, and μ for Product Development and Design Calculations
Authors: Papadakis EP 
Published: May 2009

Abstract
A technique is presented to measure the isotropic elastic constants of small specimens using instrumentation designed for the ultrasonic measurement of thickness. Specimens as small as 5 mm × 5 mm × 0.5 mm can be measured. Shape is not critical as long as the major faces are plane and parallel. Young's modulus E, the shear (stiffness) modulus G, and Poisson's ratio μ are calculated from measurements of density and ultrasonic shear and longitudinal wave velocities. Samples of automotive valve train materials and of brake drum materials were machined from components, measured, and analyzed. Specimens included gray cast iron during stages of a development process, chill cast iron, hardened cast iron, low alloy steel, tool steel, stainless steel, a nickel-based superalloy, and a powder metal alloy. The magnitudes of the measured values of the elastic constants are reasonable when compared with published values available for some materials. The measurement error for each of the constants is estimated to be less than 1%.
Moduli determined by this method can be used in finite element analysis to improve design. When material properties are different near the surface, elastic constants characteristic of the surface layer can be measured. The development of new fabrication, alloying, or treatment processes can be monitored to assure the production of the desired material properties if modulus or some property correlated with modulus is desired. When the material properties are a function of the fabrication process, e.g., small castings or powder metal components, reliable elastic constants can be found. “Small” is relative to the practicality of cutting tension bars and torsion rings from parts, so “Small” may seem rather large in some cases. Metal stampings can be analyzed in a through-thickness direction. The elastic properties of nonmetallics—ceramics, glasses, and plastics—can also be measured.
On the Determination of Fracture Energy Using the Peel Test
Authors: Moidu AK , Sinclair AN , Spelt JK 
Published: May 2009

Abstract
This paper presents an improved model for the prediction of the adherend plastic dissipation in the peel test, thereby allowing the determination of the critical fracture eaergy. The model, which is based on earlier work, takes into account the effects of adhesive shear stresses, and a bilinear stress-strain response for the flexible adherend. Treating the flexible adherend as a beam-on-elastic foundation, expressions for the normal and shear foundation constants due to the compliance at the root of the adherend under elastic-plastic loading are derived using the deformation theory of plasticity. Application of the model to experimental peel data shows that it gives an improved estimate of the critical fracture energy.
Piezo-Actuated Microtensile Test Apparatus
Authors: Read DT 
Published: May 2009

Abstract
The design and performance of a microtensile test device designed for measuring the mechanical properties of thin films are reported. The moving grip is cantilevered to avoid friction. Piezoelectric actuation allows precise control of the applied tension. Force is measured indirectly using an eddy-current sensor near a flexible measuring beam, and grip displacement is measured using two similar displacement sensors. The apparatus is constructed for use with specially designed specimen assemblies in which the thin film to be tested is suspended across a silicon frame. The apparatus is rigid enough that the frames can be cut without applying tension to the thin-film tensile specimen. The tester is run in closed-loop control through a laboratory computer, which records force, displacement, and other parameters 5 times per second. Key capabilities are: stroke, 50 μm; maximum force, 1 N; minimum cycle time, 2 s; displacement resolution, ± 20 nm; and force resolution, ± 200 μN.
Influence of Corrosion on the Fatigue Properties of Al 7075-T6
Authors: Du ML , Chiang FP , Kagwade SV , Clayton CR 
Published: May 2009

AbstractChloride ion attack on Al 7075-T6 in aqueous hydrochloric acid leads to localized corrosion and subsequent initiation of fatigue cracks on the surface. Pitting is observed when the specimen is exposed to a corrosive environment. Microcracks, voids, extrusions, and intrusions are then formed during the fatigue process. From a global viewpoint, all of the corrosion and fatigue damage appears to be randomly oriented, resulting in a change in the surface roughness. The Laser Speckle Sensor technique is used to detect the minute surface texture change, associated with the damage caused by corrosion and fatigue. Nonuniform surface roughness is observed due to corrosion. The corrosion pits tend to coalesce along the rolling direction. The change in surface roughness is significant around the crack tip during the fatigue process. As a result there are synergistic activities; the surface roughness caused by corrosion and fatigue leads to crack initiation, and the crack growth further increases surface roughness.
Investigation of Welding Effect on Rebars Using Neural Networks
Authors: Mo YL , Koan KJ 
Published: May 2009

Abstract
Typically material modeling has involved the development of mathematical models of material behavior derived from human observation of experimental data. An alternative procedure, discussed in this paper, is to use of computation and knowledge representation paradigm, called a neural network, to model material behavior. The main benefits in using a neural network approach are that all behavior can be represented within the unified environment of a neural network and that the network is built directly from experimental data using the self-organizing capabilities of the neural network, meaning that the network is presented with the experimental data and learns the relationships between stresses and Strains. Such a modeling strategy has important implications for modeling the behavior of complex materials. In this paper, the mechanical behavior of rebars affected by welds is modeled with a back-propagation neural network. The results of using networks to study the effect of welds on rebars look very promising.
Establishing Mechanical Property Allowables for Metals
Authors: McLellan DL , McLellan MM 
Published: May 2009

Abstract
Allowable mechanical property development for structural design of metallic aerospace vehicles requires an approved method for statistically analyzing empirical test data. When sufficient test data have been analyzed, the resulting allowables are presented to members of the metal-producing industry, airframers, and regulatory agencies for approval. Upon approval, these properties are published by the government for unrestricted use. However, even though sufficient data are made available, the analysis process is not always straightforward. When data do not conform to acceptable distributions, the process cannot be completed: The purpose of this paper is to promote a better understanding of this type of problem, and a possible rationale to overcome such events without increasing the amount of test data.
Design and Development of a High-Speed Bearing Test Apparatus
Authors: Kim K 
Published: May 2009

Abstract
A bearing test apparatus was developed to test high-speed rolling element bearings such as the main-shaft bearings of gas turbine engines. The apparatus design was focused on the evaluation of the lubrication characteristics of bearings in an environment similar to that of gas turbine engines, such as the same bearing support structure, the lubrication method, the squeeze film damper, and the operating conditions. Using the module design of the system, both ball and roller bearings can be tested, and the bearings can be tested up to 42 000 rpm and 19 600 N axial and 1960 N radial load. The testing was successively carried out with the bearings up to 30 000 rpm.
Eddy Current Decay and Resistivity Measurements on Longitudinally Grooved High-Purity Aluminum Bars
Authors: Gillenwater MW , Hartwig KT , Hua CY 
Published: May 2009

Abstract
The eddy current decay (ECD) method for determining electrical resistivity uses a relationship between the time constant of magnetic flux diffusion and resistivity. This method is shown to be valid for determining the resistivity of solid high-purity aluminum cylinders with eight equally spaced longitudinal grooves machined into the surface. The effects of changes in groove dimensions for a 25.4-mm-diameter, superconducting magnetic energy storage (SMES) conductor stabilizer are reported. Observations of machining, heat treatment, and material inhomogeneity effects are discussed. It is found that the ECD time constant is dependent primarily on groove depth and that groove width has only a minor influence. An empirical equation relating groove dimensions with the time constant and with resistivity is presented.
Variation of Resilient Modulus of Aggregate Base and Its Influence on Pavement Performance
Authors: Tian P , Zaman MM , Laguros JG 
Published: May 2009

Abstract
Resilient modulus (MR), which properly characterizes the load-deformation response of pavement materials under traffic loading, is evaluated. The MR variations due to three different gradations and three different moisture contents were investigated for Richard Spur (RS) aggregate, which is commonly used in Oklahoma as the base material of roadway pavements. The three gradations selected are finer limit, median, and coarser limit, as specified by the Oklahoma Department of Transportation (ODOT) for Type A aggregate. The three moisture contents selected are optimum moisture content (OMC), 2% below and 2% above the OMC. Six duplicate MR tests under identical conditions were conducted for each case by using the AASHTO designation T 294-94. The variabilities of MR values due to the three different gradations and three different moisture contents were found to be within 10 to 50% and 10 to 20%, respectively. Furthermore, the material model coefficients K1 and K2 were calculated, and a multiple linear regression model for predicting the MR values of the aggregate was established in this study. Finally, the effect of MR variation on pavement performance was demonstrated by using one pavement design example.
Pin-on-Disk Corrosion-Wear Test
Authors: Friedersdorf FJ , Holcomb GR 
Published: May 2009

Abstract
An electrochemical pin-on-disk corrosion-wear apparatus was developed at the Albany Research Center of the U.S. Department of Energy. The instrument was qualified on a low-alloy T1 tool steel [ASTM A 514] and a 304 stainless steel (Type 304). The apparatus incorporates simple specimen and counterface geometry and is instrumented for simultaneous corrosion and wear testing. The electrochemical and wear parameters of potential, current, charge, sliding speed, frictional force, and normal acceleration can be continuously displayed and recorded. After a break-in period, the electrochemical pin-on-disk produced constant wear rates independent of path length for both ASTM A 514 steel and 304 stainless steel. Results for 304 stainless steel in sulfate solutions show that abrasive wear causes the corrosion potential to shift by 0.4 V in the active direction and the passive current density to increase by three orders of magnitude, compound with the condition of no wear. Current density was a linear function of the sliding speed at a constant applied anodic potential. The open circuit corrosion potential exhibits a decay function behavior with respect to the sliding speed. Volume loss and corrosion measurements showed that mechanical removal of material was responsible for 95% of the corrosion-wear losses for 304 stainless steel. Continual corrosion exposure, however, increased the mechanical removal of material by 35 to 48%.
Stress-State Permeability Relationships for Clays with Coarse Fraction
Authors: Pandian NS , Narasimha Raju PSR , Nagaraj TS 
Published: May 2009

Abstract
In standard laboratory consolidation tests, only the fraction of soil passing through a particular size of the sieve, called the matrix material, is used. This size is usually restricted to 110 of the height of the consolidation ring. Particles larger than this size that are removed before the test may consist of gravel, fragments of sock, or other coarse materials. Hence, it is not possible to estimate the compressibility and permeability of the total material based on the compressibility and permeability behavior obtained from laboratory consolidation tests on the matrix material. In the present investigation an attempt has been made to estimate the compressibility and permeability behavior of the total material based on the compressibility and permeability behavior of the matrix material. The results indicate that the presence of coarse particles will reduce the compressibility of the soil in proportion to the coarse fraction present in the whole soil and will not affect the permeability of the soil for the range investigated. If the coarse fraction exceeds the limiting percentage, the void ratiovertical effective stress path will also start to deviate from the predicted path. An expression has been developed to estimate approximately the deviating pressure, and it is found to depend on the soil type as well as the percent clay fraction.
Adhesively Bonded Strain Gages for Extended Use at 315°C on Polymers
Authors: Rabzak C , Pereira JM , Roberts GD 
Published: May 2009

Abstract
A unique strain gage and adhesive system was developed for mechanical property measurement of polymers and polymer composites at elevated temperatures. This system overcomes some of the problems encountered in using commercial strain gages and adhesives. An important limitation with typical commercial strain gage adhesives is that they require a post-cure at temperatures substantially higher than the maximum test temperature. The exposure of the specimen to this temperature may affect subsequent results, and in some cases may be higher than the glass transition temperature of the polymer. In addition, while typical commercial strain gages can be used for short times at temperatures up to 370°C, their long-term use is limited to 230°C. This precludes their use for testing some high-temperature polyimides near their maximum-temperature capability. The system that was developed consists of a nonencapsulated, unbacked gage grid that is bonded directly to the polymer using a specially formulated adhesive. The gage is applied after the specimen has been cured, but prior to the normal post-cure cycle. The adhesive was formulated to cure under the specimen post-cure conditions. Special handling, mounting, and electrical connection procedures were developed, and a fixture was designed to calibrate each strain gage after application on the specimen. A variety of tests was conducted to determine the performance characteristics of the gages at elevated temperatures on PMR-15 neat resin and titanium specimens. These tests included static tension, thermal exposure, and creep tests. The gage and adhesive system performed within normal strain gage specifications at 315°C under these conditions.
A Procedure for Fracture Toughness Testing Using a Chevron-Notched Crack-Arrest Specimen
Authors: Bonenberger RJ , Dally JW , Fourney WL 
Published: May 2009

AbstractA new chevron-notched crack-arrest (CNCA) specimen has been developed for determining the fracture toughness of metals in a more cost-effective manner. The specimen is a hybrid design that incorporates features from the standard KIc and KIc specimens. Details of the specimen geometry and associated test procedures are described. Strain gages record the stress state in the specimen, and a clip gage measures the crack mouth opening displacement. The method for extracting arrest and initiation toughness from the measured data is presented. Fracture experiments using the CNCA specimen ware conducted to determine Ka and Kc for A533-B reactor grade steel at 23°C. The Ka and Kc results from this study were consistent with similar data established for the same material by other-researchers. A fractographic analysis identified cleavage as the dominant failure mode during crack propagation, with a conversion to ductile tearing just before arrest.
A Strategy for Mimicking Voids in Historic Masonry
Authors: Sickels-Taves LB , Sheehan MS 
Published: May 2009

Abstract
This paper examines the issue of voids in historic masonry. Tabby, an historic, concrete-like substance composed of lime, sand, oyster shell, and water, was selected as the masonry to examine. This study had a two-fold purpose: to develop a strategy for mimicking voids using tabby as a test bed for employment in other masonry contexts, and to replicate the appearance of historic tabby while eliminating the liabilities associated with opea voids in the Masonry matrix. To this end, glass beads were introduced into the tabby mix. The desired result was a product that appeared to have voids, but in fact did not. Test results indicated that the visual appearance of original tabby is mimicked due to the translucent quality of glass, and the structural instability factor is reduced by effectively filling the voids without altering the physical characteristics or producing additional liabilities.
Results from a Round Robin on a Standard Method for Measurement of Fracture Toughness
Authors: Landes JD , Brown K 
Published: May 2009

Abstract
A paper round robin was conducted to evaluate the workability and reproducibility of a unified draft fracture toughness test standard titled “Standard Method for Measurement of Fracture Toughness.” The paper round robin consisted of 19 records from fracture toughness tests conducted separately from this round-robin exercise. These test records were given to the participants with the requirement that they use the draft standard to evaluate the fracture toughness values from the tests. The round robin was conducted between February 1991 and June 1992. Originally more than 30 organizations were invited to participate; however, only five finally responded with complete analyses of all of the test records. The five participants were all experienced in fracture testing and analyses. To subject the method to an evaluation by persons with less experience, some of the test records were analyzed by graduate students whose only experience with fracture testing and analyses was a course on fracture mechanics.
The round robin was conducted on Draft 10 of the proposed standard: “Standard Method for Measurement of Fracture Toughness” This paper contains a brief description of the draft test method, a discussion of the specimens and test records supplied, a brief summary of results, and a discussion of the changes made to the test method as a result of the round-robin exercise. All tests and analyses were conducted using English units; therefore, to accurately transmit the results, English rather than SI are used as the primary units of this report.
The Dynamic Behavior and Vibration Monitoring of Reinforced Concrete Beams
Authors: Wang Z , Man XTC , Finch RD , Jansen BH 
Published: May 2009

Abstract
The dynamic behavior of a reinforced concrete beam was studied theoretically and experimentally. A relationship between the resonance frequency of the beam and the applied bending moment was established. A frequency criterion corresponding to the crack control criterion in the ACI Building Code was developed. It was found that resonance frequencies and damping will change rapidly when cracks are initialized and growing. The resonance frequency shift could be as large as 20 to 25% of the original value, and the decay rate could change by a factor of 4. The applied bending moment not only determines the number and the size of cracks but also determines the crack opening or closing condition that affects both resonance frequency and damping. To accurately estimate the frequency and damping of a cracked-reinforced concrete beam, empirical formulas are proposed based on a small number of experiments. The technique has promise for global nondestructive evaluation of reinforced concrete structures such as highway bridges.
Experimental Justification for Proposed Changes to the Measurement of KIc Using ASTM E 399
Authors: Joyce JA 
Published: May 2009

Abstract
During the past five years considerable effort has been devoted to developing a fracture toughness measurement standard that combines the linear elastic stress intensity factor at the onset of crack extension, KIc, and the elastic-plastic fracture toughness measurement quantities, namely, JIc, the J resistance curve (J-R curve), and the corresponding crack tip opening displacement resistance curve (CTOD-R curve). The objective of this effort was to allow the engineer to start with one specimen geometry, conduct a specified test, develop either a KQ or a JQ−R curve, and then, after application of the relevant size requirements, obtain a valid fracture toughness result. At present, different specimens are required by E 399 and E 1737 (the combination and replacement of E 813 and E 1152), and if the engineer uses the E 399 specimen geometry and test procedure and subsequently finds that the measured KQ fails the E 399 size requirements, new specimens must be machined and tested according to E 1737 to obtain valid fracture toughness measurements.
This paper describes experimental tests that have been conducted in parallel with the development of the new ASTM Standard E 1820-97, a combined fracture toughness test standard that is intended to address this problem. These experimental results show that the standard J integral specimen, incorporating load line crack mouth opening displacement measurements and side grooves, can be used to obtain KIc as presently defined by ASTM E 399. The use of larger a∕W ranges is also supported by these results as long as the basic size requirements of E 399 are met and applied to both the specimen crack length and remaining ligament as well as to the specimen gross thickness.
Role of Filter Paper Separators on the Response of Clays Under Long-Duration Sustained Loading
Authors: Robinson RG , Allam MM 
Published: May 2009

Abstract
In a one-dimensional consolidation test, a sustained load duration in excess of 104 min is rarely used for evaluation of the coefficient of secondary compression even for very plastic clays. However, there are instances in the literature where load durations have exceeded 105 min. The clogging of porous stones by migration of soil fines is conventionally prevented by interposing filter paper separators between the porous stones and the soil specimen. The present study examines the effect of filter paper separators on the secondary compression and swelling characteristics of a bentonite-sand mixture. In longterm volume change tests, use of filter paper separators results in increased deformation when the soil is undergoing drained creep in consolidation tests. When the soil undergoes swelling over a long period of time, some collapse occurs due to the decay of the filter paper separators. The observations of a long-duration drained creep test on this soil are used to explain the reported secondary compression behavior of some natural soils. The results of the study bring out the need to develop nondegradable separators for long-duration tests to protect porous stones from clogging with soil fines.