bluuebunny/crossref_metadata_2025 huggingface dataset:
Measurement of Relative Surface Roughness at Particulate-Continuum Interfaces
Authors: DeJong JT , Frost JD , Saussus DR
Published: February 2009

The shearing behavior at particulate-continuum interfaces is influenced strongly by the continuum surface roughness. To date this surface has been characterized with absolute roughness parameters that represent various aspects of the spatial distribution of surface features. However, for particulate-continuum interfaces, the effect of continuum surface roughness on interface behavior is itself dependent on the particulate material characteristics. This interaction suggests that the surface roughness be characterized in relation to the contacting particulate material. Filtering algorithms such as low-pass and high-pass filters are frequently used to isolate components of a surface profile such as waviness and roughness. However, these filters consider peaks and valleys of a surface profile equally and hence implicitly assume each feature has the same effect on the interface behavior. An extensive analysis that traces the centroids of different diameter particles as they traverse across surfaces is presented herein. The resulting observations include: (1) peaks and valleys on a surface affect particulate-continuum interactions differently; (2) conventional surface roughness parameters do not account adequately for the characteristics of the contacting particulate material; and (3) conventional filters incorrectly isolate surface features of interest in particulate continuum interfaces. A framework that allows for these issues to be considered in evaluating the relative roughness of surfaces is presented.
Flexural Characteristics of Sunlight-Aged Polyester Composites: Influence of Processing Variables
Authors: López FS , Ferrer C , Salvador MD , Amigo V
Published: February 2009

This work presents the results of flexural tests carried out on samples aged for different periods of time in a UV-Visible light chamber. The processing variables studied were the type of reinforcing fabric, the resin type, and the cure conditions. The evolution of flexural characteristics with time exposure adjusts to a mathematical model that corresponds to a damped exponential curve. The aging degree varies between 16 and 41%, depending on the preparation of the composites and the mechanical characteristics of the material. The aged material featured losses of its mechanical properties, and more on toughness than on strength properties. The kind of unsaturated o-phthalic polyester resin used showed no influence on the loss of mechanical properties. High cure temperatures decreased the loss of toughness to a higher degree than that observed for the loss of strength. The configuration of the reinforced fabrics used also influenced the mechanical properties: a mixed taffeta-multiaxial reinforced configuration leads to a high loss index on toughness properties and modulus of the composite.
Verification of Thin-Wall Ductile Iron Test Methodology
Authors: Schrems KK , Doğan ÖN , Hawk JA
Published: February 2009

Modifications need to be made to standard test procedures to determine the actual properties of thin-walled ductile iron castings. A series of experiments was performed on test bars to examine the effects of surface finish, elongation measurement techniques, and the amount of material removed during grinding. A paired t-test was used to show that strength and ductility increased as a result of removing the as-received (as-cast) surface. This is attributed to inaccuracies in measuring the cross section area of the rough surface as well as an actual increase in strain through removal of surface effects. A nontraditional method of measuring elongation (to retain the fracture surface) was compared to the standard ASTM method. The nontraditional method was found to be a conservative measure of elongation that is highly correlated with plastic strain as measured by the stress-strain curve. The amount of surface removed during grinding was found not to affect the mechanical properties with the exception of hardness, a surface measurement. It is suggested that thin-walled castings be tested in the condition the casting will be used, i.e., if the casting will be used with the as-cast surface, testing with the as cast surface will accurately reproduce the decrease in strain caused by the surface effects. If the casting will be ground before use, any amount of surface can be removed to make the testing convenient.
Effect of the Aging of the “Product/Package” System on the Mechanical Properties of Plastic Packaging
Authors: Ayad R , Safa L , Bureau G , Marull S
Published: February 2009

The influence of aging of four cosmetic formulations on the mechanical properties of plastic packaging is studied. Four thermoplastic materials in the form of bottles were used: polyethylene, polypropylene, polyethylene terephthalate, and polyethylene terephthalate glycol copolymer. Bottles were filled with cosmetic formulations and put into a steam room at 42°C for 15 days, 1 month, 2 months, and 3 months. Periodically, bottles were emptied, and mechanical properties and performances (tensile test, compression, and under-pressure tests) were studied as well as the wall thickness, the glass transition temperature (Tg), the crystallinity, and the kinetic sorption by Fourier transform infrared spectrometry. A significant change of mechanical properties was observed after the sorption of cosmetic components into the materials: this change depending on the type of material (especially for polyethylene and polypropylene) and on the cosmetic formulation. These changes must be minimized, particularly in the light of reducing packaging weight. This work leads to a new optimization methodology permitting the anticipation of packaging design.
Using X-ray Computerized Tomography for Characterization of Defects in Cartridge Filters
Authors: Maschio C , de Arruda ACF
Published: February 2009

Cartridge filter manufacturers conventionally use air permeability and bubble point tests for the evaluation of integrity and filtration rating of their filter elements. These tests reveal information only upstream and downstream of the filters. If a region of low density and a region of high density (compared to the mean density of the filter) exist in the interior of the element, these two regions may be superimposed and the results of the test may cause acceptance of an imperfect filter. The present paper shows the use of an X-ray computerized tomography scanner for visualization of internal defects in the cartridge filter elements used in industrial and domestic applications. Tomographic images with good contrast were obtained. The images clearly revealed cracks in the activated carbon filter and regions of high density in the fibrous filter (meltblown type). Finally, the main objective of this paper is to show that X-ray computerized tomography can be used successfully within the filter industries as a potential tool in the evaluation of existing products, and as a support in new product development.
Evaluation of an Accelerated Pavement Testing Facility and Development of its Load Equivalence Factors
Authors: Chen J-S , Lin K-Y
Published: February 2009

An accelerated pavement testing facility (APTF) was used to simulate the effect of traffic on pavement performance. An enhanced procedure was developed in this study to calculate the load equivalence factors (LEF) for APTF. Results indicated that this procedure is feasible to evaluate the effect of heavy axle loadings on pavement performance under an accelerated rate. The pavement performance after APTF followed the trend observed on full-scale test roads. Based on the present serviceability index loss of the APTF data, it was found that an eighth-power law existed for the APTF in contrast to the fourth-power law in full-scale test roads. This implied that the LEF for APTF single axle loads of the same configuration was equal to the ratio of the axle weights raised to the eighth power. This finding explained why pavements tested by the APTF failed much faster than regulated loading. Critical loads, however, appeared to be present for pavements tested by the APTF. Pavements tested with loads greater than the critical load might fail predominantly by traffic loading.
Fatigue Crack Growth in Cantilever Bending Under Displacement Control
Authors: Abd-Allah NM , Megahed MM , Eleiche AM
Published: February 2009

Fatigue crack growth (FCG) behavior of two martensitic steel grades was investigated using a single edge-notched bend specimen fixed beyond the notched section in cantilever bending under displacement control. This task was made possible by a new and original testing methodology developed on the basis of finite element analyses to define valid boundary conditions and the corresponding stress intensity factor K-expression for the test specimen. The behavior has been described including the nearthreshold zone and the second zone of relatively high FCG rates. Results for the two steel grades were found to correspond well with the empirical models reported in the literature. This confirms the validity of the methodology proposed in the present paper, which can be attributed to: (1) the accurate K-expression for the test specimen, (2) the proper definition of the boundary conditions adopted during testing, and (3) the validity of the adopted boundary conditions.
Correlating Permanent Deformation Characteristics of Hot Mix Asphalt with Aggregate Geometric Irregularities
Authors: Kuo C-Y
Published: February 2009

Regression analyses were performed to study the correlation between the permanent deformation characteristics of hot mix asphalt (HMA) mixtures and their aggregate geometric irregularities. Permanent deformation of HMA mixtures was characterized by permanent strain, creep modulus, and slope of the creep curve from unconfined repeated load deformation tests. The fine aggregate angularity (FAA) test was used to characterize fine aggregates while coarse aggregates were characterized with either the particle index (PI) test, the modified National Aggregate Association flow test (modified NAA), or image analysis. Regression analyses indicate strong correlation between the permanent deformation characteristics of HMA mixtures and the aggregate geometric irregularities. Use of imaging indices for characterizing coarse aggregates gives better coefficients of determination than do other coarse aggregate characteristics such as PI and modified NAA. The imaging indices have major potential in evaluating aggregate geometric irregularities for engineering analysis.
Scheduling of Pipelined Data Paths for On-line Testability
Authors: Ismaeel AA
Published: February 2009

This paper presents a time-constrained scheduling of a pipelined data path with the perspective of improving on-line testability. The testability is incorporated at the scheduling phase of the synthesis. Being a presynthesis method, the approach minimizes the area overhead. Operations of the same type are assigned to resources called functional units (FU). The on-line testing is carried out by capturing selective input and output variables of a circuit under test (CUT) in time frames called passes. The captured variables are shifted out to an external testing unit for verification. Each FU of the CUT is tested at least once in each pass. Minimizing the number of variables needed to test all FUs reduces the testing time. Thus, the scheduling is performed with the objective of improving on-line testability by minimizing the number of FUs and the number of variables needed to test all FUs. Promising results are obtained on benchmark examples.
Photoelastic Evaluation of Stress Fields and Fracture During Dynamic Splitting Experiments
Authors: Gomez JT , Shukla A , Sharma A
Published: February 2009

Dynamic tensile-splitting experiments were conducted on brittle polyester disks, manufactured from Homalite ®-100, to photoelastically visualize stress field development in the specimens and, ultimately, specimen fracture. A Split Hopkinson Pressure Bar (SHPB) was used to load the specimen dynamically and record load data as a function of time. Images of the stress field were captured with high-speed photography and interpreted using photoelastic analysis. The experiments determined that the specimens reached an equilibrium state relatively quickly, and remained in equilibrium until fracture. Fracture began with in-plane cracks forming on either side of the specimen. Transverse cracks emanated from the in-plane cracks, then propagated across the specimen mid-plane at velocities up to 60% of the shear wave velocity in the material. Contact loads calculated from photoelasticity agreed favorably with SHPB results. These experiments also allowed for the determination of the dynamic splitting strength of the Homalite ®-100 as a function of strain rate. The dynamic splitting strength of the material increased with the increasing strain rate, reaching a maximum value of about twice the static splitting strength.
Application of a Relativistic Conservation Equation to Crack Initiation
Authors: Ullrich G
Published: February 2009

Given the load versus deformation diagram, including the load maximum of a specimen with a known stress intensity factor, the initiation of stable crack growth can be calculated exactly from measurement results by introducing equations analogous to those found in the theory of general relativity. This can be done by means of the two-observer principle. A point on the plastic curve can be equivalently correlated to a given point on the elastic curve. In deriving the equivalence, it can be seen that the different geometrical configurations with respect to the loading direction and the crack plane have to be modified by the introduction of a factor. It was found that this factor is analogous to the Doppler effect (Lorentz transformation.) The agreement of the mathematical procedure using analytical functions with the experimental results (potential-drop technique) has been found to be excellent, using qualified steels. For those materials with significant deformation before crack initiation, the agreement between mathematical procedure and experiment is less good.
Influence of Hot-Mix Asphalt Parameters on the Correction Factors of the Ignition Oven Test
Authors: Sabaaly PE , Abdel-Magied O , Dunn M , Brinkmeyer W
Published: February 2009

The ignition oven method has been gaining popularity because of its applicability to both laboratory and field conditions, its nondependency on chemicals, and its ability to evaluate both binder content and aggregate gradations. However, the use of this method requires the careful determination of correction factors for both binder content and aggregate gradations. The need for such correction factors stems from the fact that most aggregates experience a certain level of weight loss as they are subjected to elevated temperatures. These weight losses must be accounted for in order to accurately determine the binder content and aggregate gradation of HMA mixtures. It is well accepted that the most important step of the ignition oven test is the determination of an accurate correction factor. The implementation of the ignition oven method requires the highway agency to assess the performance of the local materials with the test procedure and to identify the mixture parameters that significantly impact the determined correction factor. In preparation for the implementation of the ignition oven test, the Nevada Department of Transportation (NDOT) conducted an extensive laboratory testing program to assess the impact of the various mix parameters on the determination of the correction factors. The experiment included aggregate source, binder type, lime, and testing temperature. This paper analyzes the data generated from the NDOT experiment and evaluates the impact of each of the considered factors on the correction factor. In summary, the analysis of the data generated in the NDOT experiment showed that the aggregate source and the addition of lime have the most significant impact on the determined correction factor followed by the temperature and binder type. However, if during a field project the binder or the method of lime application changes, this change would not require the determination of a new correction factor. The data also showed that the blank aggregate method would generate correction factors that are less variable than the known asphalt content method.
Staged Compression-Immersion Direct Shear Test on Compacted Crushed Mudstone
Authors: Yoshida N , Enami K , Hosokawa K
Published: February 2009

This paper introduces a staged compression-immersion-direct shear test carried out in order to deal with compressive settlement phenomena of compacted crushed mudstone during staged filling and due to immersion from the viewpoints of not only deformation but also shear strength deterioration. The test apparatus and procedure are described, and as an example, compacted crushed Kobe mudstone samples are tested. It is shown that as expected, the crushed Kobe mudstone samples compacted with 95% degree of compaction exhibit larger compressive settlement than those compacted with 100% degree of compaction during staged loading, and that only the former samples show additional compression due to immersion. Shear strength decreases due to immersion being accompanied with volume decrease, and the shear strength decrease and volume change are larger in the samples compacted with 95% degree of compaction. It is also indicative that the shear strength of the aggregate itself has a significant influence on the shear strength of its compacted samples.
Measurement of Creep Damage by the Natural Frequency Method
Authors: Ling X , Tu S-t
Published: February 2009

The natural frequency method (NFM), a novel approach for the measurement of creep damage, is proposed in this paper. The technique, with instrument configuration and experimental procedure, is described in detail. The application of the approach has been made on 25Cr20Ni steel, widely used for furnace tubes. The measured results of creep damage show good agreement with theoretical predictions. The critical damage value ωcr of 25Cr20Ni also has been obtained by the proposed approach. Compared with the current density method and the loading and unloading method, NFM has many advantages, such as higher accuracy, simpler apparatus, and better repeatability. On the basis of NFM, an efficient approach can be given for life prediction and extension of high temperature components.
Experimental Evaluation of the Torsion Test for Determining Shear Strength of Structural Lumber
Authors: Gupta R , Heck LR , Miller TH
Published: February 2009

The torsion test was evaluated as a method for determining shear strength of full-size, structural lumber by length and depth studies. The length study consisted of fifty 38 by 89 mm specimens, ten each of lengths 0.5 m, 0.7 m, 0.8 m, 0.9 m, and 1.0 m, and ten shear blocks. The statistical analysis showed no evidence that length affected shear strength. The depth study consisted of 50 specimens, ten each of sizes 38 by 89 mm, 38 by 140 mm, 38 by 184 mm, 38 by 235 mm, and 38 by 286 mm, and 50 shear blocks. The statistical analysis did not show convincing evidence of a depth effect on shear strength, even after accounting for specific gravity and shear span as covariates. Failure modes were similar to shear failures observed in bending tests, and involved a longitudinal shear crack at the wide face, which propagated toward the ends of the specimens and through the cross section perpendicular to growth rings. Based on results of this study, the torsion test is the best practical method for determining pure shear strength of full-size, structural lumber.
Finite-Element Analysis of the Stress Distribution in a Torsion Test of Full-Size, Structural Lumber
Authors: Gupta R , Heck LR , Miller TH
Published: February 2009

Full-size structural lumber under torsion was analyzed using the finite-element method to determine stress distribution. A three-dimensional, homogeneous, orthotropic finite-element model was developed and analyzed using commercially available software, ANSYS®, to increase understanding of stress distribution and failure modes. Analyses revealed that uniform shear stress occurs within the shear span, which begins and ends at a distance of approximately two times the depth plus the grip distance away from each end of the specimen. In addition, finite-element analysis verified that the experimental shear-failure plane that occurs within the shear span is parallel to the grain. Shear slippage is also parallel to the grain, similar to the known shear-failure mode in specimens subjected to transverse loads. Based on results of this study, the torsion test is the best practical method to determine the pure shear strength of full-size, structural lumber.
Effect of Anisotropy on Compressive and Tensile Properties of Asphalt Mixtures
Authors: Mamlouk MS , Witczak MW , Kaloush KE , Ho Y-S
Published: February 2009

The research effort in this paper was part of the Superpave Support and Performance Models Management Project (Advanced Material Characterization) and was funded by the National Cooperative Highway Research Program Project 9–19. Anisotropy of hot mix asphalt materials greatly depends on specimen preparation, testing conditions, and test parameters under consideration. The objective of this study was to evaluate the anisotropy of selected test properties for specimens specially prepared with the Superpave gyratory compactor and cored in the vertical, horizontal, and diagnonal directions. The number of gyrations during compaction was adjusted on a trial-and-error basis to produce cores having air void contents of 4.0 ± 0.5% regardless of the direction of coring. Confined compression and tension tests were performed on the cored test specimens. The analysis included parameters such as the compressive / tensile strength, modulus of elasticity, and strain at failure. All test results were analyzed statistically. The majority of the test results (compression and tension) showed no significant effect of test specimen orientation on the test parameters at the 5% level of significance and for the test conditions used in the study. These results indicated that anisotropic effects might be ignored for the asphalt mixture used in this study using the special preparation method in the Superpave gyratory compactor.
Liquid-Metal Embrittlement of 7075 Aluminum and 4340 Steel Compact Tension Specimens by Gallium
Authors: Kolman DG , Chavarria R
Published: February 2009

Liquid-metal embrittlement of aluminum alloy 7075-T6 and AISI 4340 steel by gallium has been observed previously. Unfortunately, quantitative data regarding the level of embrittlement are limited due to the difficulty of testing fracture mechanics specimens. This study uses L-T compact tension specimens to determine the threshold stress intensity for crack initiation during exposure to gallium. Sample surfaces were wet with gallium prior to exposure at 35°C by removing the crack tip and side groove oxide film with a scalpel in the presence of gallium. Both 4340 steel and 7075 Al were embrittled by Ga as measured by threshold stress intensity. Kthi, the stress intensity at crack initiation as detected by direct current potential drop (DCPD), for 4340 and 7075 was 33% and 5% of KIci (the fracture toughness as detected by DCPD), respectively. In contrast to air-exposed samples, extremely rapid crack propagation to failure of Ga-exposed samples was observed. Fractography revealed intergranular fracture of Al 7075 and 4340 steel following Ga exposure.
A Procedure for Extended Extrapolation of Creep Rupture Data
Authors: Sandström R
Published: February 2009

To be able to perform extended extrapolation of creep rupture data, i.e., extrapolation by more than a factor of three in time, a new procedure is proposed. A free temperature model for the time-temperature parameter is used that provides a high degree of flexibility. Postassessment tests are formulated to verify that the chosen time-temperature parameter has sufficient stability. In the analysis, criteria are introduced for the position of the predicted creep rupture curve in relation to the scatter band of data as well as criteria on derivatives of the predicted creep rupture curves. The procedure has been applied successfully to five common creep-resistant pressure vessel steels: one low-alloy steel (2Cr 1Mo) and four austenitic stainless steels: 304H, 316, 253MA, and 800H. The small deviations between the full datasets and strongly culled sets demonstrate the validity of the proposed procedure.
A Comparison of Results on Helmet Impact Testing
Authors: Ingmar Johnson G
Published: February 2009

Drop impact testing of head protection helmets has been based on different methods in the European Committee for Standardization (CEN) and International Organization for Standardization (ISO) standards. Since it would be desirable to unite these two into one international standard, work was initiated to find out whether the corresponding test methods could be considered equivalent and interchangeable for helmet certification.
The Reliability and Self-Diagnosis of Sensors in a Multisensor Data Fusion Diagnostic System
Authors: Wang J , Wang H
Published: February 2009

Any error in a data fusion system that is used to diagnose and detect machine faults, especially an error in sensor measurement information, will result in an incorrect diagnostic conclusion. The accuracy and reliability of sensor measurement is a prerequisite for reducing the uncertainty of the fusion system and accurately diagnosing system faults. The measurement error of the multisensor and the degree of reliability of the detecting system can be determined by a multisensor consistency check. In this paper, we use the “probability distance measure” to determine the compatibility of multisensor information and to ensure that the measurements represent the same target (or state). We show our experimental results, which demonstrate a good result.
Fault Diagnosis of Loaded Water Hydraulic Actuators by Online Testing with LabVIEW®
Authors: He Y , Chua PSK , Lim GH , Tan ACH
Published: February 2009

In recent years, with the development of technology in materials and machining, it is becoming possible to produce modern water hydraulic components that are made of lubricant-free and anticorrosive materials and to achieve very close tolerances to reduce internal leakage due to the low viscosity of water. As water is nontoxic, environmentally friendly, and readily available, many industries are already turning to modern water hydraulic systems to replace their oil hydraulic counterparts. As with all systems, the increasing use of water hydraulic systems by more industries will result in a greater need to monitor and maintain the systems. This paper is concerned with online testing and fault diagnosis of loaded modern water hydraulic cylinders and axial piston motors. LabVIEW® (Laboratory Virtual Instrument Engineering Workbench) data acquisition hardware and development software were used for data acquisition and processing. Likely real-life faults were simulated on the hydraulic actuators' internal components. The actuators also were operated to capture their unique vibration signals in their faulty states and the results compared with reference signatures of the same actuators when they were in their new or healthy states. The vibration signatures and amplitude spectra, average extension/retraction duration, and flow trending amplitude of the water hydraulic actuators versus piston seal wear, rod seal wear, piston shoe wear, and capstan surface wear under different operating conditions of simulated loads and speeds are presented and discussed. The results show that there is a distinctive variation in vibration signals, flow rate, and average stroking duration with increase in loads for both actuators.
A Study on the Beginning of Secondary Compression of Soils
Authors: Robinson RG
Published: February 2009

The time-compression curve obtained from a laboratory one-dimensional consolidation test generally consists of three parts, namely initial compression, primary consolidation, and secondary compression. While the initial compression occurs immediately after the application of a load increment, the primary consolidation and the secondary compression are time-dependent. It is not known whether both primary consolidation and secondary compression occur concurrently or if the secondary compression begins after the end of primary consolidation, as assumed in general practice. This paper examines this aspect based on the pore water pressure measured at the base of the sample during consolidation. It was observed that the beginning of secondary compression strongly depends on the load increment ratio (LIR). For the inorganic soils tested, the secondary compression begins practically after the end of primary consolidation. When a small LIR of 0.2 is adopted, the secondary compression starts as early as about 55 % of the primary consolidation is over. For the organic soil tested, the secondary compression begins much earlier, compared to the inorganic soils even at a higher load increment ratio. The secondary compression-time relationship can be well represented by a hyperbolic model. The method adopted in this article is capable of separating the primary consolidation and secondary compression from time-compression data once the pore water pressure at the base of the sample is known.
Review and Evaluation of Medical Image Segmentation Using Methods of Optimal Filtering
Authors: Trichili H , Bouhlel MS , Kammoun F
Published: February 2009

Image segmentation is an important process of image analysis. It consists of subdividing an image into its constituent parts and extracting these interesting parts. A large variety of segmentation algorithms have been developed. The evaluation and comparison of these algorithms turns out to be important and even indispensable for correctly using them. This paper presents an objective study of segmentation algorithms using the methods of optimal filtering. This study is distinguished from other studies by its consideration of both evaluation and comparison, treating both image cases (noisy and non-noisy ones). The results of implementation, an evaluation of the advantages and the drawbacks of each one of them, and a study of their immunity towards three types of noise are also presented. All these characteristics make this study a general and effective one for revealing the performance of segmentation algorithms using the methods of optimal filtering.
Influence of the Geometry of the Extrusion Die on the Melt Strength of Polymers
Authors: Baldi F , Rösch D
Published: February 2009

In the past some studies have been carried out to investigate the melt strength of polymers with the purpose of comparing the results obtained with different materials and at different temperatures. In those experimental activities, once that the testing instrument had been chosen, the polymers were considered the object of the investigation and the attention was rarely focused on the testing geometry. The present work, instead, intends to analyze the influence that the geometry of the extrusion die has on the melt strength of polymers. In particular, attention is focused on the analysis of the differences produced on the melt strength of a material, when the extruded filament is subjected, via the use of two different dies specifically designed, to two distinct temperature profiles along the stretching axis. This investigation highlights that the testing geometry chosen for an experimental activity based on melt tension tests, via haul-off measurements, plays a fundamental role in the correct interpretation of the results. In fact it is demonstrated that the correct choice of the extrusion die allows one to obtain results much more similar to the real processing type that, using melt tension tests, has to be analyzed.
Testing of Bridge Weigh-In-Motion System in a Sub-Arctic Climate
Authors: McNulty P , O'Brien EJ
Published: February 2009

Systems for weighing vehicles while they are in motion are in widespread use in many countries. The accuracy of these weigh-in-motion (WIM) systems is strongly influenced by the road profile and vehicle dynamics. Systems based on sensors that are embedded in the pavement or placed on top of the road surface can measure the axle load only for the fraction of a second for which the wheels are present on the sensor. An alternative to pavement WIM systems that increases the length of the load-sensitive element is to use an existing bridge as a weighing scale (Bridge WIM). A major test of a Bridge WIM system at a test site near the Arctic Circle is described in this paper. The test was conducted along-side a larger test of pavement WIM systems. A large number of trucks from random traffic were weighed statically and the results compared to those from the Bridge WIM system. The accuracy of the system is assessed in accordance with the COST 323 WIM specification, which provides a standardized method of accuracy classification. The Bridge WIM system is proven to perform satisfactorily and consistently for a wide range of temperatures in near-Arctic climatic conditions.
Investigation of Effects of Testing Methods on Characterization of Asphalt Concrete
Authors: Wen H
Published: February 2009

A variety of testing methods are employed by researchers to characterize the fatigue performance of asphalt concrete. These testing methods need to be evaluated based on their performance to characterize the fundamental properties and field performance of mixtures. In this study, the indirect tensile tests and the uniaxial tests were investigated. The indirect tensile creep tests and the uniaxial tensile creep tests were performed on a North Carolina mix to study the characterization of the fundamental properties and on WesTrack mixes to study the characterization of field performance. It was found that that the values of creep compliance from the indirect tensile creep and the unaxial tensile creep tests on North Carolina mix cannot be compared favorably. Fracture energies from the indirect tensile strength tests on WesTrack mixes highly correlate with the field performances, while those from uniaxial direct tension tests did not match field performances. It is believed that anisotropicity could be the cause of differences in performance of the two test methods. It is disconcerting when researchers attempt to establish a constitutive relationship between the property parameters of mixtures and laboratory fatigue life using different testing methods, without knowing if the laboratory fatigue life from these testing methods really reflects field performance. Further research is needed to obtain a better understanding of different testing methods.
Overcoming Multicollinearity in Near Infrared Analysis for Lycopene Content Estimation in Tomatoes by Using Ridge Regression
Authors: Pasternak H , Schmilovitch Z , Fallik E , Edan Y
Published: February 2009

High intercorrelation between absorbance at different wavelengths is common in near infrared analysis and was observed in an experiment to determine lycopene in tomatoes. Simulation analysis and experiments were conducted to estimate the effects of this problem on the estimators and on the predictive ability of linear regression and ridge regression. Applying linear regression to the experimental data resulted in very large parameter values, implying poor predictive ability. When linear regression gives very large parameter values, the estimated parameters are practically random numbers and are not correlated to the true ones. Ridge regression yielded estimators with normal values, but which are still poorly correlated with the true parameters. However, the predictive ability of the derived equation is good and may be used in practice to determine lycopene content in tomatoes since it is relatively easy to update.
On Experimental J Estimation Equations Based on CMOD for SE(B) Specimens
Authors: Kim YJ , Schwalbe KH
Published: February 2009

This note addresses the accuracy of the J-estimation equation for shallow-cracked single edge cracked bars, SE(B), as originally proposed by Kirk and Dodds (1993), based on 2D finite element analysis. Our study placed particular emphasis on the sensitivity of the Kirk-Dodds equation to the nature of the material, including continuously-hardening materials and those exhibiting Lüders strain. It was found that the Kirk-Dodds equation provides acceptable results except for specimen bars with very deep cracks such as those with a/W = 0.7 or greater. Accordingly, based on slip line field analysis, a modification of the original equation is suggested, which when used provides consistent results for all crack lengths.
A New Method for Testing the Abrasive Properties of Paper and Other Sheet Materials
Authors: Srinivasan R , Puttaswamygowda G
Published: February 2009

Manufacturing operations such as die cutting and slitting of sheet materials result in wear of the tooling. A new method for measuring the abrasive properties of paper and other sheet materials is proposed. The method continuously monitors the force required for penetrating a sheet sample as multiple punches are made with a needle. Abrasive wear caused by the sheet sample changes the geometry of the needle, and consequently changes the penetration force. The trend of the force is used as a measure of the abrasivity of the sheet sample. Several sheet paper samples were tested using this method with two different needle geometries. In all cases, the magnitude of the force decreased with an increasing number of punches. The rate of change of force depends on the type of paper and the initial geometry of the needle.
Application of a Geotechnical Centrifuge for Estimation of Unsaturated Soil Hydraulic Conductivity
Authors: Singh DN , Kuriyan SJ , Madhuri V
Published: February 2009

Contamination of the groundwater regime and subsurface soils is one of the major problems that has arisen due to rapid industrialization. Spread of contaminants in the unsaturated soil strata, mainly close to the ground surface and lying above the water table, depends on the hydraulic conductivity of the soil. As such, estimation of unsaturated soil hydraulic conductivity becomes very important. However, it is quite difficult to estimate the same in a reasonable amount of time, due to the very low hydraulic conductivity of unsaturated soil. The potential of a geotechnical centrifuge for modeling various geoenvironmental engineering problems being very well established, an effort has been made to obtain the unsaturated state of a silty soil, starting from its saturated state, by centrifugation. The soil water characteristic curves obtained have been used for determining the unsaturated soil hydranlic conductivity.
Packaging Specifications for Corrugated Boxes with Heavy Flowable Products in Single Parcel Shipments
Authors: Singh SP , Burgess G , Pratheepthinthong S , Singh J
Published: February 2009

This study investigated the corrugated board specifications that are recommended in the Fibre Board Association Handbook as part of Item 222 of the National Motor Freight Classification for shipping flowable items such as nuts and bolts using the single parcel shipping environment (UPS, FedEx, USPS). The study found that the existing specifications are greatly insufficient to contain these types of products in this environment. The study recommends to double the requirements for bursting strength when such items need to be shipped in the single parcel environment and to limit the maximum package weight to 40 lb.
Microindentation Test for Charaterization of Plastic Properties of Laser Alloyed Layers
Authors: Kucharski S , Radziejewska J
Published: February 2009

In this paper a method of characterization of plastic material properties of the surface layers constituted by laser alloying is proposed. The applied characterization method is based on the analysis of load-penetration depth curves obtained in repeated loading-unloading-reloading microindentation tests. Spherical indenters were used. A Stellite™ alloyed layer and a tungsten carbide alloyed layer were considered. The results of metallographic analysis of the layers and their microstructure are presented. The method was also used for the characterization of plastic parameters for carbon steel. Its stress-strain curve generated by the characterization process is compared with that obtained in a tension test.
Methods for Fatigue Testing Off-Road Bicycle Handlebars Based on Assembly Effects Using Two Different Stem Designs
Authors: McKenna SP , Hill MR , Hull ML
Published: February 2009

Assembly of off-road bicycle handlebars with a stem that clamps the handlebar around its circumference would be expected to affect fatigue performance by introducing both assembly stresses and stress concentration. Because the effect of clamping on fatigue performance is unknown and because of the need to insure structural reliability in the stem-handlebar assembly to prevent serious injury, the objectives of the work reported by the present article were fourfold. One was to determine the stresses due to assembly and the stress concentration induced in a handlebar for two different clamp designs (i.e. 1-bolt and 2-bolt), a second was to determine experimentally the high cycle constant amplitude load fatigue lives of the two stem-handlebar assemblies, a third was to determine experimentally the variable amplitude load fatigue lives, and the fourth was to predict the variable amplitude load fatigue life with constant amplitude load fatigue test results. The handlebar was instrumented with strain gages and the assembly strains were measured when the stem clamps were tightened. The handlebar was also loaded as a cantilever beam while the applied strains were measured for each assembly. Stresses were computed and the maximum stresses induced by clamping exceeded 200 MPa for both assemblies. A method unique to this study was devised to determine the stress concentration at an arbitrary angular location around the circumference of the handlebar and for an arbitrary loading direction in the plane of the bicycle. For a load directed along an angle of -38° (clockwise rotation from horizontal viewed from the right), both stems created similar stress concentration; the location of maximum applied stress was shifted by 30° from the point that would be expected in the absence of assembly and the stress was increased by 40% at this location. The measured fatigue lifetimes for constant amplitude loading were similar for the two stem designs but the variable amplitude load fatigue lifetime for the 1-bolt stem assembly was shorter than that for the 2-bolt stem assembly by 19%. The fatigue lifetimes for variable amplitude loading based on constant amplitude load fatigue test results were predicted to within 3% and 33% for the 1-bolt and 2-bolt stems, respectively. Thus, constant amplitude load fatigue test results can be used to approximate the variable amplitude load fatigue life. However, the ranking of different assemblies may not be accurately indicated by constant amplitude load fatigue data.
Evaluation of a Boron-Nitrogen, Phosphate-Free Fire-Retardant Treatment. Part II. Testing of Small Clear Specimens per ASTM Standard D 5664-95, Methods A and B
Authors: Winandy JE , Herdman D
Published: February 2009

The objective of this work was to evaluate the effects of a new boron-nitrogen, phosphate-free fire-retardant (FR) formulation on several mechanical properties of FR-treated wood and to assess the potential of this treatment for in-service thermal-induced strength loss resulting from exposure to high temperature. Fire-retardant-treated and untreated small clear specimens were cut from three wood species, Douglas-fir, southern pine, and white spruce, according to ASTM D 5664-95 and evaluated in bending and tension, compression, and shear parallel to grain. Evaluations were conducted before and after matched specimens were exposed at elevated temperature (150°F(66°C)) for 36, 72, or 108 days. The results indicate that treatment with FR and redrying followed by long-term exposure at high temperature could significantly affect some mechanical properties when compared to the same properties of untreated and unexposed controls. However, FR treatment and redrying in themselves did not have an across-the-board effect on all properties of specimens or on the rate of strength loss compared to the properties of matched untreated lumber exposed at 150°F (66°C) for up to 108 days. Our analysis indicated that for some species, some engineering properties will require modification, whereas other species-property combinations will not. Our results indicate that the likelihood of FR-treated lumber to experience in-service reduction in mechanical properties when exposed to elevated temperatures is no different than that of matched untreated material.
Evaluation of a Boron-Nitrogen, Phosphate-Free Fire-Retardant Treatment. Part III. Evaluation of Full-Size 2 by 4 Lumber per ASTM Standard D 5664-95 Method C
Authors: Winandy JE , McNamara W
Published: February 2009

The purpose of this work was to evaluate the effects of a new boron-nitrogen, phosphate-free fire-retardant (FR) formulation on the initial strength of No. 1 southern pine 2 by 4 lumber and its potential for in-service thermal degradation. The lumber was evaluated according to Method C of the D 5664 standard test method. The results indicated that for lumber exposed at 150°F (66°C) for 108 days, FR treatment and redrying significantly (α ≤ 0.10) decreased initial bending strength by about 13% compared to that of untreated controls. No significant difference occurred in the rate of strength loss over time of exposure. This infers that, after accounting for the initial reduction in strength, the field performance of FR-treated lumber should be comparable to that of untreated lumber. From a practical standpoint, the effect of FR treatment on maximum load capacity was similar to that on bending strength. Treatment significantly reduced work to a maximum load by 29%, but it had no differential effect on the rate of change in this property when the lumber was exposed to elevated temperatures. Although modulus of elasticity was not significantly changed by treatment, this property was significantly increased by extended exposure at high temperature. In summary, the reduction in mechanical properties for FR-treated 2 by 4 lumber occurred at a rate no different than that for matched untreated lumber when exposed to elevated temperature.
Fatigue-Creep Dynamic Strain Rate Map of a Fe-Ni-Cr Alloy with Coarse Branch Crystals
Authors: Fu HQ , Liang CG , Hua ZS
Published: February 2009

The effect of branch crystals on fatigue-creep deformation behavior of a Fe-Ni-Cr casting alloy has been studied. The different orientations between the branch crystal boundaries and the loading axis played an important role in inducing the deformation process. The fatigue-creep dynamic strain rate curves could be classified into three interaction regions according to the differing stress dependence of the fatigue creep strain rate. A new characteristic strain rate map with three fatigue-creep interaction regions of a Fe-Ni-Cr casting alloy with different branch crystal orientations has been established to provide full information on deformation under a wide range of combinations of fatigue and creep stresses.