bluuebunny/crossref_metadata_2025 huggingface dataset:
An Expert Infobase System for Tracing Hazardous Materials in Engineering Documents and System Requirements for Materials Information Standardization
Authors: Aung SU , Barbara T
Published: February 2009

The Hazardous Waste Minimization (HAZMIN) Infobase has a Navy Aviation Depot's maintenance directives and processing procedures in digitized text and graphics files. It is important that all chemicals that are restricted in some manner by state and federal environmental and safety regulations are identified in the materials that are specified within the processing documents, by shop (work area), and to the level of the ingredients that make up the materials in use. Described will be how, by using the HyGEN Expert Infobase System technology and appropriate methodology, an audit trail for state and federal safety- and environmentally-restricted materials can be established against engineering and material documentations. The Expert Infobase system is an integration of infobase, database, and rule-based expert systems. HyGEN software can synergistically integrate a select set of off-the-shelf PC software and can provide the system with relational capabilities such as database to text and vice versa, in addition to the common database to database. Also, there are database or text to graphics cross-relating capabilities. The system can possess similar properties as those of the object-oriented programming technology. These capabilities can furthermore be synergized to successfully design and automatically manage complex information structures such as with repeating data groups nesting within another level of repeating data group. Also described will be the organizing approaches for viewing information from several perspectives yet using the same basic information set.
Material Specifications of Advanced Ceramics and Other Issues in the Use of Property Databases with Corrosion Analysis Models
Authors: Munro RG
Published: February 2009

The growing interest in linking analysis models with distributed materials property databases gives rise to new database design requirements. This paper discusses the conditions encountered in the modeling of the corrosion of a ceramic material as a time-dependent phenomenon. In the corrosion of ceramics, numerous distinct contributing processes occur in different regions of the specimen simultaneously. These different regions usually have different compositions, native microstructures, and environmentally intrusive agents. Both predictive modeling efforts and post-test diagnostic analyses, therefore, require chemical and physical property data that are related to the specific material substructures. There are significant problems in the practice of representing such information in general-purpose materials property databases. The essential issues pertain to the form of the representation, the accessibility of the data, and the uniqueness of the value set. This paper addresses these issues in the context of a multipurpose database into which access is needed by an automated, external, analysis program. The corrosion of silicon carbide is used as a prototypic case in discussing the standards for the database, the expectations of the user, and the implications of the practical design of the property database. It is concluded that the required analysis tools include the model with constraints on the material and the environment, a property database that distinguishes the material's substructure types and locations, a reactions database for all significantly reacting species in the system, and an expert system interface to assess the performance level options available by means of the property data.
Residual Stresses in Plastic Pipes by Laser Speckle Technique
Authors: Seif MA , Kishawy HA , Hassan MA
Published: February 2009

Laser speckle technique has been employed as a sensitive noncontact quantitative tool to measure the residual stress distribution developed in plastic pipes due to manufacturing processes. Pipes are classified into two main categories: thin-walled and thick-walled pipes. In thick-walled pipes, the laser technique has been combined with the layer removal method to describe accurately the stress distribution along the pipe thickness. A merit of the present investigation is the development of an empirical formula to assist the laser measurement in obtaining a more reliable stress distribution. Therefore, the need for the layer removal method has been eliminated, and the usual inaccuracy patterns resulting from excessive machining have been avoided. Since the results obtained are compared favorably with different techniques such as strain gages, ring slitting, and layer removal techniques, the proposed work possesses different advantages with respect to simplicity, practicality, and sensitivity.
Fatigue Testing of Microspecimens from a Weldment
Authors: Yuan B , Sharpe WN
Published: February 2009

This paper describes a technique for measuring the strain-controlled cyclic stress-strain behavior of microspecimens taken from a steel weldment. The specimens have a cross-section 0.3 by 0.3 mm with a gage section approximately 1.4-mm long and are believed to be the smallest specimens that have ever been tested in fully-reversed axially-loaded fatigue tests. The microsample fatigue test system developed allows both strain and stress control. The key feature is the ability to measure strain directly using a laser-based strain gage that measures the relative displacement between two tiny reflective indentations in the specimen surface.
Effect of Specimen Thickness on the Long-Life Fatigue Performance of a Randomly-Oriented Continuous-Strand Glass-Mat-Reinforced Polypropylene Composite
Authors: Little RE
Published: February 2009

This paper summarizes an experimental study of how three specimen thicknesses—⅛, 3/16, and ¼ in. (3.18, 4.76, and 6.35 mm)—affect the long-life fatigue performance of a thermoplastic composite material with 40% randomly-oriented continuous-strand glass in a polypropylene matrix (Azdel). Axial-load and four-point-bending fatigue tests were conducted to compare (1) the respective median logarithmic fatigue lives for a common alternating stress amplitude and (2) the respective estimated median fatigue strengths at 107 stress cycles. Both the median logarithmic fatigue life and the median fatigue strength decreased markedly when the specimen thickness was increased from ⅛ to 3/16 in. (from 3.18 to 4.76 mm). However, in each case, no further decrease was statistically evident when the specimen thickness was increased from 3/16 to ¼ in. (from 4.76 to 6.35 mm).
Ultrasonic Stress Evaluation in a Compressor Rotor
Authors: Bray DE , Tang W , Grewal DS
Published: February 2009

The run-out report for a compressor rotor showed an almost continuous bow between the two bearings. The maximum run-out of 0.03 mm (0.0012 in.) occurred at the inlet to the fourth stage impeller. The steel compressor rotor was just over 3 m in length. It had been removed from service for maintenance. Each of the seven compressor stages was mounted on the rotor at the time of the stress measurement. An evaluation of the residual stress at the inlet locations in the shaft using critically refracted longitudinal, LCR, ultrasonic waves showed compressive stress on the bowed side of the rotor, supporting the conclusion that residual stress is the cause of the bow.
An Ultrasonic Technique for Monitoring Automotive Components
Authors: Lopes R , Mazzeranghi A , Ronchiato G , Vangi D
Published: February 2009

Early and reliable damage location is a key element for the quality and quantity of the data that can be acquired from a fatigue test on automotive components and from mechanical components subjected to road-simulated endurance testing. This paper describes an acousto-ultrasonic methodology for monitoring structures or mechanical components. The technique has been developed gradually by applying it first to simple elements, such as spot-welded steel panels, sections, etc., then to individual body nodes, and finally to a complete car body. The results of a road simulated endurance test carried out on a car body are presented. This technique makes it possible to reduce to the minimum, or eliminate altogether, visual checks, and to identify fatigue cracks at their earliest initiation stages and spot weld failure, without having to wait until a defect grows to the point of modifying the overall mechanical properties of the element being tested.
Transverse Vibration of a Simply Supported Beam with Symmetric Overhang of Arbitrary Length
Authors: Murphy JF
Published: February 2009

The numerical solution to the frequency equation for the transverse vibration of a simple beam with symmetric overhang is found. The numerical results converge to the analytical solutions for the two limiting cases of a beam with no overhang and a beam with no span and agree with the case in which the supports are at the nodal points of a freely vibrating beam. An approximation to the solution of the frequency equation for beams with small overhang is presented and compared to the numerical solution. This simple yet accurate approximation is most useful to determine a beam's flexural stiffness, EI, or modulus of elasticity, E, by freely vibrating a simply supported beam.
A Preliminary Examination of the Laboratory Sheen Test
Authors: Jones M
Published: February 2009

A proposed test procedure for detecting “free oil” in discharges of drilling fluids and cuttings from offshore oil and gas wells has been evaluated by the Environmental Protection Agency (EPA) and independently. Several preliminary examinations with small numbers of observers were performed, and later expanded by testing with 26 observers. The procedure, including recent modifications, appears to be relatively sensitive but of questionable usefulness as a monitoring tool. Results are highly variable, depending on the type of drilling mud, presence of interfering compounds, and sample size. Other factors (i.e., vibration, angle and type of light, sample age, and sample preparations) may also cause variable results and will need to be more carefully evaluated. The definition of sheen is expanded in the most recently proposed version of the procedure, causing more samples to fail than with previous definitions. It is suggested that the procedure be further evaluated.
Fatigue Crack Growth Threshold and Crack Opening of a Mild Steel
Authors: Yu MT , Topper TH , DuQuesnay DL , Pompetzki MA
Published: February 2009

The effects of stress ratio, compressive peak stress, and cold rolling on the threshold stress intensity and crack closure level of a mild steel (SAE 1010) were investigated. As the stress ratio and the magnitude of the compressive peak stress were increased, the threshold level decreased linearly. The threshold stress intensity also decreased linearly as the yield strength was increased by cold rolling. Crack opening measurements showed that the measured threshold is composed of two parts: an intrinsic threshold stress intensity range, ΔKin, and an opening stress intensity, ΔKop. The opening stress intensity decreased with increasing magnitude of the compressive peak stress. The intrinsic threshold stress intensity range was not significantly affected by the compressive peak stress. Severe cold rolling decreased the opening stress in the near threshold region to near zero. In a constant amplitude load-controlled test, the ratio of the opening stress intensity to the maximum stress intensity decreased as the maximum stress intensity (crack length) increased, and no crack closure could be observed when the net stress approached the yield strength of the material.
Chromium Conservation in Stainless Steel
Authors: Heger JJ
Published: February 2009

A critical review of published literature, and personal contacts with industries and individuals, were made to determine the possibilities for chromium conservation in stainless steels. The information obtained indicates that no low- or non-chromium substitute will be universally satisfactory. However, substitutes are possible in many specific applications, although the substitute probably will differ for each application. Examples are given.
Fracture Toughness of Unalloyed Austempered Ductile Cast Iron (ADI)
Authors: Putatunda SK , Singh I
Published: February 2009

The influence of microstructure on the tensile properties and the plane strain fracture toughness (KIc) of unalloyed austempered ductile cast iron (ADI) was examined in room temperature ambient atmosphere. The crack growth mechanism during fracture toughness tests was determined through detailed fractographic studies. Compact tension and round cylindrical specimens were prepared from unalloyed ADI and were given four different austempering heat treatments to produce four different microstructures. Tensile properties and fracture toughness of these four differently heat-treated materials as well as cast materials were determined as per relevant ASTM standards.

The results of the present investigation demonstrate that the fracture toughness of unalloyed ADI increases with increase in volume fraction of ferrite in the matrix and reaches a peak when the ferrite content of the matrix is around 65%. Both yield and ultimate tensile strength of the unalloyed ADI was found to increase with increase in volume fraction of ferrite in the matrix. The ductility of ADI, on the other hand, was found to increase with increase in volume fraction of austenite in the matrix. The crack growth mechanism was found to be predominantly by the microvoid coalescence. The crack path appears to connect the graphite nodules along the way.
Mixed Mode Stress Intensity Calibrations for an Angled Crack Bend Specimen
Authors: Yates JR , Ho KF , Goldthorpe MR
Published: February 2009

Test specimens with angled or inclined cracks are frequently used to investigate mixed mode fatigue and fracture properties. A full three-dimensional (3-D) linear elastic finite element stress analysis has been performed for a beam with an angled single edge crack subjected to three-point bend loading. Crack angles of 45°, 60°, 75°, and 90° to the longitudinal axis of the beam have been considered. The resulting geometric correction terms to the linear elastic fracture mechanics (LEFM) mode I, II, and III stress intensity factors are presented.
Development of a Dynamic Load-Deflection Apparatus for Elastomeric Materials
Authors: Vallee GE , Shukla A
Published: February 2009

A method of experimentally determining the dynamic load-deflection behavior of elastomeric impact absorbers is developed. Particular attention was given to impact absorbers (bumpers) used in pneumatic fastening tools, and the dynamic load-deflection apparatus developed here closely replicated actual service conditions. Cylindrical specimens and actual bumpers were fabricated from epichlorohydrin and nitrile elastomers, two materials commonly used in the bumper application. The dynamic behavior of thin circular disks is also studied and brief comparison with the Split Hopkinson Pressure Bar technique is given.
Durability Design Process of a Vehicle Suspension Component
Authors: Lee Y-L , Raymond MN , Villaire MA
Published: February 2009

An improved methodology to quantitatively assess fatigue lives of automotive structures and to identify critical and non-damaging areas for design enhancement and weight reduction is presented. The methodology of automated fatigue assessment, called CAE-FATIGUE (Computer Aided Engineering in Fatigue), combines a load-time history file with the result file from an elastic finite element analysis to estimate fatigue lives (damage contours). The CAE-FATIGUE methodology is of particular value when it is used as a proactive tool in the early design stage to reduce design iterations and prototype costs.

CAE-FATIGUE is applicable to elastic finite element analysis results because the Glinka energy density method (plasticity correction approach) is used to approximate true stresses and strains from the elastic stresses. CAE-FATIGUE cannot be applied to cases where loading frequency is of importance, since the elastic stress components from all loading channels are superimposed to the resultant stresses at the same specific time. CAE-FATIGUE calculates fatigue lives based on the maximum normal stress and strain range on a critical plane on which maximum principal stresses for the entire loading history are maximized. Also, CAE-FATIGUE can generate life/damage contour plots to identify critical and nondamaging areas for design enforcement and weight reduction.

This report focuses on practical aspects of designing automotive suspension components to avoid fatigue failure. The design process for a proposed front suspension knuckle is presented for illustration purposes. Critical planes highlighted with damage contours can also be used to develop “smart” and efficient prototype tests. Emphasis is placed on how to optimize the component to meet the durability criteria through mechanical life test procedure and test field endurance schedules.
Structure and Outliers in Interlaboratory Studies
Authors: Mandel J
Published: February 2009

The current statistical analysis of interlaboratory test data involves tests of significance for outliers. In this paper we show that the use of tests of significance is faulty and we propose instead an analysis according to a row-linear model. This approach involves an examination of straight lines fitted by least squares for all laboratories against the averages over all laboratories for each level in the two-way table. By this method, a laboratory can be judged both in terms of the position of its response line when compared to other laboratories, as well as in terms of the residuals of the observed measurements from the fitted line.
Elastic Strain, Creep, and Recovery in Mortars: Additional Analysis
Authors: Sickels Taves LB
Published: February 2009

This paper examines the subject of elastic strain, creep, and their recoveries in mortars. An experimental program, outlined in an earlier issue of this journal, was undertaken to study the behaviors of mortars alone. Results indicated that the lime component directly and favorably affects movement in mortars. The obtained data were studied further, particularly the early minutes under compression, to determine if prior conclusions held firm and to continue to add to existing knowledge of mortars and their properties.
A Multistep Shear Test for Bond Strength of Claddings
Authors: Blickensderfer R , Burrus JM
Published: February 2009

A test for determining the bonding shear strength of a clad metal and the fixture for performing the test are described. The test specimen, which is relatively easy to machine, has approximately nine shear steps ranging in depth from shallower than the cladding to deeper than the cladding. Thus, at least one of the shear lips gives the shear strength very near the interface between the cladding and the base metal. Test results on a variety of bimetals are presented. Results are compared with ASTM Specification for Corrosion-Resisting Chromium Steel Clad Plate, Sheet, and Strip (A 264) criteria. This work was conducted by the Bureau of Mines, U.S. Department of the Interior, as a part of its effort to develop vacuum rolled claddings to conserve strategic materials.
An Estimation of Hardness of Hardened Steels by X-Ray Diffraction Using a Gaussian Curve-Fitting Method
Authors: Kurita M , Hirayama H
Published: February 2009

A simplified equation for calculating rapidly a parameter of a Gaussian curve fitted to a diffraction line peak is proposed for use in the evaluation of the diffraction line width. An equation for calculating the standard deviation of the parameter, caused by counting statistics, is also given to evaluate the reproducibility of the parameter. The parameter together with its standard deviation can be calculated in only 0.8 s with an inexpensive microcomputer. The time required for the X-ray intensity measurement in determining the parameter is about one third of that required in the half-width determination. The line width represented by the parameter of various quenched and tempered steels increases with increasing hardness. Hence, the use of the parameter allows a rapid and nondestructive estimation of hardness of hardened steels.
Fourier Transform Infrared Spectroscopy of Polymers—Theory and Application
Authors: Fanconi BM
Published: February 2009

The Fourier transform infrared (FT-IR) technique is replacing conventional dispersive instruments in the acquisition of IR spectroscopic data. For standards organizations this implies that existing standard test methods involving IR spectral analysis need to be modified. In an FT-IR system all spectral information is contained in the interferogram produced by scanning the Michelson interferometer. The factors controlling spectral resolution and sensitivity are, therefore, different from those governing these properties of dispersive instruments. The FT-IR technique has the advantages of greater signal-to-noise ratio and digitized data that open up new areas of application as well as provide greater sensitivity in the more traditional uses of IR spectroscopy. A review of the field of vibrational spectroscopy of polymers identifies time-dependent phenomena and characterization of structural imperfections as two areas likely to see major advances as a result of FT-IR.

Examples of the use of FT-IR in polymer research are given to illustrate the potential of the technique. At the National Bureau of Standards FT-IR has been used to determine the role of chain scission in the mechanical degradation of polymers, to measure the extent of chemical reactions during processing polymer composites, and to characterize polymeric materials.
Advantages of Using Data from Fourier Transform Infrared Spectrophotometers for Process Control
Authors: Pike L
Published: February 2009

Significant advantages in using data from Fourier transform infrared (FTIR) spectrophotometers instead of conventional prism and grating spectrophotometers for process control measurements have been observed in the research laboratories of the Cryovac Division of W. R. Grace & Co. The advantages center around the ability to quantitate accurately and precisely very low intensity absorbances with the expenditure of significantly less technician time than the older equipment requires. An example of the advantages is illustrated using the measurement of the transvinylene absorbance near 966 cm−1 or 10.35 μm of polyethylene. Use of FTIR spectrophotometers results in a four- to five-fold improvement in precision (reproducibility) and a decrease of 75% in the technician time required to make the measurements. This paper contains the details involved in using the two types of equipment for the above stated measurement and some factors contributing to the advantages obtained by using FTIR.
Current and Potential Uses for Mining and Mineral Processing Wastes in Canada: Standards
Authors: Collings RK
Published: February 2009

Mining and mineral processing operations in Canada produce about 650 × 106 metric tons of mineral waste annually. This waste is composed of broken rock from open pits and underground mines, coarse mill rejects from screening and heavy media separation processes, and fine mill tailings from screening, magnetic separation, and flotation processes. Most wastes have limited potential for reuse because of their high impurity content or remote location. However, some are favorably located and of interest because of contained metals and minerals or inherent physical and chemical characteristics. Waste utilization is an attractive alternative to disposal because disposal costs and potential pollution problems are reduced or even eliminated and resources are conserved. Waste rock could be used as landfill, in roadbed and dam construction, as railroad ballast, as aggregate in concrete and asphalt mixes, and, for the finer sizes of waste, as construction sand, as an additive to concrete and asphalt mixes, in brick and block manufacture, in the manufacture of thermal insulation, for the recovery of valuable metals or minerals, and as mineral fillers. Examples of the commercial utilization of a number of such wastes are noted.
An Analysis of Hot Mix Asphalt Mat Density Measurements
Authors: Parker F , Hossain MS
Published: February 2009

Hot mix asphalt mat density data collected during the 1990–1993 implementation of a quality control and quality assurance (QC/QA) program for pavement construction by the Alabama Highway Department (AHD) were analyzed. The influence of different measuring agencies (buyer and seller), mix type, application rate, and overlay interface conditions on the variability of nuclear gage and core density measurements was studied. The data were also used to study the influence of the several measurement variables on the ability to achieve target density. Variability and the ability to achieve target density improved as the QC/QA program was implemented, but there remained a consistent inability to achieve the target compaction level. Analysis of the significance of differences between AHD and contractor measurements was inconclusive, but AHD density measurements were consistently lower. Thicker binder mix layers had lower variability than thinner surface mix layers, but the level of compaction achieved was greater for surface mixes. Milling of the surfaces of old pavements significantly reduced the variability of density in overlay mats.
A Servo-Control System for the Universal Panel Tester
Authors: Hsu TTC , Zhang L-X , Gomez T
Published: February 2009

A servo-control system has been successfully installed on the universal panel tester to study the behavior of full-size reinforced concrete panel elements. In addition to the load-control procedure, this unique testing facility is now capable of testing panels using deformation-control procedure. This servo-control system controls up to ten different servo valves with independent programming capabilities and is thus suitable for many complex applications. By using this new servo control system we were able to determine, for the first time, some material properties of reinforced concrete, including Poisson ratios, the descending branch of compression stress-strain curves, as well as the characteristics of the compressive stress-strain curves of concrete in panels with 45° steel bars.
Specimen Size Effects on the Diametrical Mechanical Testing of Cylindrical Asphalt Mixes
Authors: Lim C-T , Tan S-A , Fwa T-F
Published: February 2009

Specimens, 4-in. (101.6 mm), 5-in. (127.0 mm), and 6-in. (152.4 mm) in diameter, of asphalt mixtures were prepared in the laboratory to test for the specimen size effect on the resilient modulus test, the indirect tension test, and the Marshall test. Four asphalt mixtures with different top stone sizes ranging from 15.8 to 31.5 mm were used. They are B1 mix (base course), Airport, W3, and W6 mixes (wearing course).

Specimens, 5-in. (127.0 mm) in size, were prepared using the same compaction equipment as 6-in. (152.4-mm) specimens, designed as by Kandhal, P. S. (“Large Stone Asphalt Mixes: Design and Construction,” Proceedings of the Association of Asphalt Paving Technologists, 1990). The height of the 5-in. (127.0-mm) diameter specimen was calculated based on the diameter over the height ratios for the 4- and 6-in. (101.6- and 152.4-mm) specimens. The compaction level required was based on the energy per unit volume ratio of 4- and 6-in. (101.6- and 152.4 mm) diameter specimens. Similar measured densities of the 5-in. (127.0-mm) specimens compared with the densities of the 4- and 6-in. (101.6- and 152.4-mm) specimens indicate that the same level of compaction has been achieved.

The stability ratios (stability of 6-in./5-in. specimen, stability of 6-in./4-in. specimen and stability of 5-in./4-in.) were also analyzed. They were found to be close to the theoretical values reported by Kandhal, P. S. (“Large Stone Asphalt Mixes: Design and Construction,” Proceedings of the Association of Asphalt Paving Technologists, 1990). Detailed comparison of flow values for the W3 and B1 mixes were made. The B1 mix gave an unacceptable flow/diameter ratio caused by the effect of large stones. The value was too low in the case of the 4-in. (101.6-mm) specimen for the B1 mix. However, acceptable values were found for all sizes tested using the W3 mix, which had a top stone size less than 1-in. Hence, large stones (stones with diameter greater than 1-in.) in 4-in. specimens tend to produce lower deformation under loading, which also accounts for the higher modulus measured in the resilient modulus test.

The influence of the ratios of the diameter of specimens to top stone size were determined for the resilient modulus and the indirect tension test. A general trend of reduction in resilient modulus and indirect tensile strength was observed. The trend suggested that 5- and 6-in. diameter specimens would give more realistic values of tensile strength and stiffness for mixes using large stones (larger than 1-in.). When larger diameter specimens are used, the results obtained from the resilient modulus and the indirect tension test are more representative of the behavior of the mixtures.
Measurement and Analysis of the Overnight Small Package Shipping Environment for Federal Express and United Parcel Service
Authors: Singh PS , Cheema A
Published: February 2009

The purpose of this study was to measure and characterize the various impacts (free fall drops, lateral kicks, and tosses) received by packages in the overnight small parcel environments found at Federal Express and United Parcel Service. Packages instrumented with tri-axial shock data recorders were repeatedly sent through UPS “Next Day Air” and Federal Express “Priority Overnight” services and shipped from East Lansing, MI to five destinations: Monterey, CA; Atlanta, GA; Rochester, NY; Portland, OR; and Memphis, TN. A total of 100 trips were monitored and 2394 impact events recorded that measured over the trigger threshold level of 10 G. The data show that a package encounters an average of 24 shock events throughout a one-way trip consisting of 31% drops, 43.6% kicks, and 25.4% tosses. The highest free-fall drop height measured was 1.97 m (77.8 in.). The maximum kick level was 5.91 m/s (233 in./s), and the highest equivalent drop height in a toss was 0.79 m (31.4 in.).

The results indicate that 95% of all drops were from less than 0.40 m (16 in.), 95% of all kicks were from less than 3.42 m/sec (135 in./s), and 95% of all tosses were from less than 0.26 m (10.5 in.) equivalent drop height. The packages received 51.1% of total impacts on edges, 42% on corners, and only 6.9% on the six flat faces. Erratum to this paper appears in 24(6).
Creep Lifetime Under Constant Load and Constant Stress: Theory and Experiment
Authors: Aktaa J , Schinke B
Published: February 2009

Creep tests are usually performed under constant load. The remarkable reduction of time to rupture due to the increase of true stress with the elongation of the specimen and with necking is estimated on the basis of the theories by Hoff, Brooklyn, and Kachanov. The influence of necking in tests under constant load and constant stress is investigated using the finite element method (FEM) with specimens containing an initial geometric imperfection. Results of the two types of tests show specimens have different sensitivities to these imperfections.

To verify the theoretical statements, two types of creep tests under constant stress were performed in which the behavior of the AISI 316 L(N) austenitic steel at 700°C was investigated. In the first type, tests under constant homogenized stress, necking of the specimen was ignored. In the second type, tests under constant true stress, the mean axial stress in the minimal cross-section was held constant. To perform this type of test, an optical measuring technique was employed to determine the minimal diameter of the specimen during the test. The observed data, in particular the time to rupture, are compared with those from creep tests performed under constant load. Remarkable differences are observed.

Theory and experiments confirm that problems arise if creep tests under constant load on ductile materials yielding too conservative data are interpreted with lifetime rules or continuum damage models.
Initial Deformation During Small Punch Testing
Authors: Cheon JS , Kim IS
Published: February 2009

Initial deformation behavior during small punch (SP) testing was investigated in order to estimate yield stress using two sizes of SP specimens, 10 by 10 by 0.5 mm3 and 10 by 10 by 0.25 mm3 by finite element (FE) analysis and by experiments with heattreated SA508 and 12Cr steels. The increase of thickness resulted in a deviation from the initial linearity of the load-displacement curve at higher loads. The deviation was attributed to different causes, namely loss of the constraint by the surrounding material and radial propagation of plastic bending deformation for 0.5 and 0.25-mm specimens, respectively. The causes for the transition of deformation mode were identical irrespective of material strength and work-hardening rate in the range of yield stress about 400 to 900 MPa. Based on the invariance of the deformation mode, a distinct linear relationship between the load at the breakaway from initial linearity and the yield stress was predicted by the FE analysis and compared with the experimental results.
Fatigue Under Stress Cycling With Nonzero Means
Authors: Gong Y , Norton MP
Published: February 2009

Several models are available for mean stress correction on fatigue life when nonzero means are applied. Mean value adjustment may be necessary in some cases when maximum/minimum stress causes plastic deformation. Strain-cycled fatigue tests conducted for a mild steel suggest that there may be some strain ranges where the effect of mean strain/stress is contrary to the prediction of existing models. In this study, mild steel specimens have been stress-cycled under various combinations of stress amplitudes and nonzero mean stresses. The stress amplitudes are chosen to be equivalent to the ones applied in the strain-cycled tests in a sense that the strain response is in the elastic range during the first portion of life and subsequently develops into the plastic range. Experimental results confirm observations in the study where strain cycles were applied. The cyclic softening and cycle-dependent creep process have also been studied. Possible modifications to the existing models have been suggested for the stress ranges investigated.
High-Resolution Force Plate Analysis of Utilized Slip Resistance in Human Walking
Authors: Buczek FL , Banks SA
Published: February 2009

Little controversy exists regarding the costs to society, both financial and in terms of human pain and suffering, associated with slip and fall injuries. Yet, for all the very valuable research published to date in the United States and abroad, controversy still exists regarding the biomechanics of initial foot-to-ground contact (that is, footstrike). Studies of foot kinetics have been limited by the use of force plate sensitivities chosen to capture the entire stance phase, rather than footstrike alone, necessitating the use of calculation thresholds. The present study of young adults (2 male, 2 female; 8 foot contacts each) was conducted to address these limitations. Two strain gage force plates, with sensitivities set to optimize amplitude resolution at footstrike (+100 ms), were sampled at 1000 Hz. A net shear force Fs was calculated as the vector sum of medio-lateral Fy and anteroposterior Fx shear forces. Since Fx predominantly affected the direction of impending slip, a novel shear force Fs′ was given the amplitude of Fs and the sign of Fx. In this way, impending slips could be identified as predominantly forward or backward. Utilized slip resistance μsr was calculated for each sampled instant as the ratio of Fs′ to the normal force Fz. For comparison purposes, a geometric approximation of μsr was calculated using leg length and half step length (from force plate center-of-pressure data) to derive the tangent of an “apex angle.” Results showed two distinct patterns for μsr over the first 100 ms of foot contact. Pattern 1 began with an initial backward slip tendency, with peak μsr values near −0.4 occurring at approximately 10 ms. This was followed by a forward slip tendency peaking between 0.2 and 0.3, at approximately 45 ms. Pattern 1 did not seem to put the subjects at risk for slipping. Pattern 2 began with a profound forward slip tendency, with μsr values above 1.0 occurring during the first 20 ms. This was followed by a brief period of backward slip tendency (|μsr| < 0.3), and a second forward slip tendency (0.2 < μsr < 0.3) for the remainder of the 100 ms sampling interval. Pattern 2 did seem to put the subjects at risk for an initial forward slip, though none were reported. The geometric approximations for μsr, typically had magnitudes near 0.4 and always predicted forward slips. We concluded that variations can be expected in foot contact patterns among normal adults. Although Patterns 1 and 2 were divided according to sex here, this may have been a coincidental finding confounded by small sample sizes, more related to shoe construction or preferred gait kinematics than to sex. Finally, geometric approximations for μsr grossly oversimplified initial foot contact, and should be discontinued in favor of more accurate methodology.
Slip Resistance Characteristics of Footwear Solings Assessed Using the SATRA Friction Tester
Authors: Wilson M
Published: February 2009

The development of the SATRA Friction Tester was described in ASTM STP 1103-1990. Since then the tester has been used in regular service and research work, testing and evaluating a wide range of footwear types and soling materials. This paper reviews some of the experience gained and presents data on the ranges of friction values associated with different types of commercially used soling materials. The data presented correlate well with industry experience, validating the test method. The findings of some additional complementary research is also reported including results of studies on the relationship between soling material hardness and measured friction. For example, on a dry surface, smooth PVC soling friction decreases with increasing hardness and wet friction increases up to a certain hardness level. A tread pattern, however, reverses the hardness effect on the wet surface, giving results comparable with smooth PVC in the dry. Other results show the significant effects of abrasion of solings and floor surfaces on slip resistance and the key contribution of surface roughness to wet friction. Finally, some of the problems surrounding standards development and the setting of pass levels are discussed. A number of areas for future research are identified and it is suggested that future studies look at the shoe, floor, and surface contamination as interactive components of a single system in which solings and floorings need to have complementary properties to optimize slip resistance.
A New Approach to Measuring Transverse Properties of Structural Tubing by a Ring Test
Authors: Arsene S , Bai J
Published: February 2009

A new approach to the ring test is presented in this paper. Three-dimensional elastoplastic finite element modeling with contact has been performed to analyze the stress and strain distribution in the ring, to optimize the ring testing system, and to investigate the effect of friction between the ring specimen and the fixture. Based on the numerical results, a new design of a holding device that creates a uniaxially stressed zone is proposed in order to determine transverse behavior of tubular products, such as the modulus and the stress-strain curve. A case study is presented on nuclear cladding tubes in Zircaloy. The approach shows promise for testing various kinds of materials in structural tubing, including ductile or brittle materials, metals, composites, or polymers.
Repeatability and Reproducibility for Pass/Fail Data
Authors: Mandel J
Published: February 2009

A distribution-free method is presented for the evaluation of the reproducibility standard deviation in interlaboratory studies. The method is especially useful in the analysis of pass/fail interlaboratory data.
Low-Temperature Aging Kinetics in Cast Duplex Stainless Steels: Experimental Characterization
Authors: González JJ , Gutiérrez-Solana F , Sánchez L , Setién J
Published: February 2009

Low-temperature aging (280 to 300°C) of duplex (austenite-ferrite) stainless steels and their resulting long-term loss of toughness is a well-known problem in the energy-producing as well as in other industrial sectors. In order to analyze the problem, the phenomenon was assumed to be thermally activated, accelerated aging at higher temperatures (350 to 400°C) was planned, and the activation energy was estimated. Assuming that the cause of brittleness is the ferrite's spinodal decomposition into the α and α' phases, the present work analyzes the aging kinetics at three temperatures (280, 350, and 400°C) by means of microhardness measurements of the ferritic phase taken in three different duplex stainless steels named after their ferrite content, 12F, 18F and 22F. In view of the microhardness results, an exponential law is proposed to represent the temporal evolution for each of the steels, with three parameters, of which one varies with aging temperature. It should be noted that there is no unique value for the activation energy in all the 280 to 400°C range. This should be divided into smaller subranges for more precision, and here it is shown that in all cases the extrapolation to the service temperature (280°C) of the results obtained in the 350 to 400°C range produces non-conservative results. These results are discussed considering the effect of the G-phase precipitation on the spinodal decomposition kinetics. For assessment applications a mathematical law is proposed that represents the aging kinetics of these steels and that provides reliable results for their service temperature (280°C).
Evaluation of Overhead and In-Ground Vehicle Detector Technologies for Traffic Flow Measurement
Authors: Klein LA , Kelley MR , Mills MK
Published: February 2009

As part of the U.S. FHWA-sponsored Detection Technology for IVHS program, ultrasonic, microwave radar, infrared laser radar, nonimaging passive infrared, video image processing with visible and infrared spectrum imagery, acoustic array, high sampling rate inductive loop, conventional inductive loop, microloop, and magnetometer detector technologies were evaluated at freeway and surface street arterial sites in Minnesota, Florida, and Arizona. These states were chosen because they exhibited a wide range of climatic conditions. The criteria for selecting the detector evaluation sites included searching for roadways with high traffic density and suitable structures for mounting the overhead detectors. Approximately 5.9 Gbytes of digital and analog vehicle detection and signature data and more than 300 video tapes of the corresponding traffic flow were recorded.

The detector outputs were time tagged and recorded on 88 Mbyte magnetic cartridges by using a data logger specifically designed and built for this project. Detectors with serial RS-232 outputs required interface software to be written for each unique data structure. Data analysis software was also written to convert the raw data into an easily accessible Paradox database format compatible with a Windows personal computer operating system. Traffic volume ground truth data, obtained by counting vehicles from the recorded video imagery, were compared with the counts from the detector outputs. Speed ground truth data, obtained by driving probe vehicles through the field of view of the detectors and noting their speed as measured by the vehicle's speedometer, were compared with the speed measurement from the detectors. Several types of detectors were found to satisfy current traffic management requirements. However, improved accuracies and new types of information, such as queue length and vehicle turning or erratic movements, may be required from detectors for future traffic management applications.
Needs and Challenges in Precision Wear Measurement
Authors: Blau PJ
Published: February 2009

Accurate and precise wear measurements are a key element in solving both current wear problems and in facilitating basic wear research. Applications range from assessing the durability of micro-scale components to the accurate screening of surface treatments and thin solid films. The need to distinguish small differences in wear rate presents problems for those who are developing new materials and surface treatments. The sensitivities of methods for measuring wear in ASTM standard test methods are discussed. Errors associated with using alternate methods of wear measurement on the same test specimen are described. Human judgmental factors are a concern in common methods for wear measurement, and the results of an experiment involving measurement of a simulated wear scar by ten different people are described. Precision in wear measurement is limited by both the capabilities of the measuring instruments and by the nonuniformity of wear processes. The advantages and disadvantages of measuring wear using micro- and nano-scale indentations is discussed. The current and future prospects for incorporating advanced, higher-precision wear measurement methods into standards must be evaluated.
The Nonvibrating Kelvin Probe and Its Application for Monitoring Surface Wear
Authors: Zanoria ES , Hamall K , Danyluk S , Zharin AL
Published: February 2009

This paper reports on the design and development of the nonvibrating Kelvin probe that could be used as a noncontact sensor for tribological damage. This device detects surface charge through temporal variation in the electron work function of a material. Experiments are performed to demonstrate the operation of the probe on a rotating aluminum shaft. The probe, made of lead, is placed adjacent (<0.5-mm distance) to the shaft. The two surfaces, which are electrically connected, form a capacitor. Benchmark experiments on the variation of the work function with changes in surface chemistry were performed by coating a segment along the shaft circumference with a colloidal silver paint. As the shaft rotated, the probe senses changes in the contact potential difference with the shaft surface, due to the compositional variation. The temporal variation in the contact potential difference induces a current in an external electrical circuit. This current is amplified and converted to a voltage signal. The magnitude of the signal decreases asymptotically with the electrode-shaft distance and increases linearly with the rotational frequency, as expected. These results are consistent with the theoretical. Preliminary tests to detect mechanical surface damage, using the probe, were also done. These results show that the Kelvin probe can distinguish geometrical features on the surface.