bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fatigue and Stress Analysis of a Novel Test Coupon Geometry Developed for Hydraulic Pressure Impulse Testing
Authors: Savas TP , Earthman JC 
Published: February 2009

Abstract
Pressure impulse fatigue testing of a novel test coupon geometry was conducted to simulate hydraulic flight con trol manifolds under multiaxial stress conditions. The configuration of the coupon was particularly useful for evaluating complex multiaxial stress states and for comparing the impulse fatigue performance of different types of alloys under conditions of high stress concentration. In this article, three-dimensional linear elastic finite element analyses are presented to quantify the von Mises equivalent and maximum principal stress distributions at the stress-critical regions. Fatigue life results using the present coupon geometry are provided for two high-strength aluminum alloy variants, including Types 7075 and 6013. Post-test macroscopic and scanning electron microscopy examinations are presented to characterize the fatigue fractures and to show that fatigue crack initiation takes place at the maximum stress locations as predicted by finite element analysis.
Leaching Behavior of Indian Fly Ashes by an Oedometer Method
Authors: Pandian NS , Balasubramonian S 
Published: February 2009

Abstract
Thermal power stations use pulverized coal as fuel, producing enormous quantities of ash as a by-product of combustion. Currently, with very low utilization of the ash produced, the ash deposits at the thermal power stations are increasing rapidly. The disposal problem is expected to become alarming due to the limited space available for ash disposal near most thermal power stations. Among the various applications available for the use of fly ash, geotechnical application offers opportunity for its bulk utilization. However, the possibility of ground and surface water contamination due to the leaching of toxic elements present in the fly ash needs to be addressed. This paper describes a study carried out on two Indian fly ashes. It is found that pH is the controlling factor in the leaching behavior of fly ashes.
Evaluation of the Gavarti Associates-Comprehensive Abrasion Tester
Authors: Burgess G , Singh P , Knudsen E 
Published: February 2009

Abstract
The GA-CAT (Gavarti Associates-Comprehensive Abrasion Tester) was put through sensitivity and repeatability studies to determine the variability associated with the machine. This was done to evaluate its ability to detect differences in quality within a batch of production run labels. The results showed that repeatability was poor so that quality variations in labels could not be assessed. The focus of the study therefore shifted to evaluating the causes of machine variability.
Angle of Internal Friction for Pond Ashes
Authors: Pandian NS , Sridharan A , Srinivas S 
Published: February 2009

Abstract
Thermal power stations use pulverized coal as fuel, producing enormous quantities of ash as a waste product of combustion. Nearly 800 million metric tons of ash is produced each year all over the world. In India, presently 97 million metric tons of ash is produced annually by power stations. The problem of ash disposal is a difficult one due to the limited availability of vacant space around the power plants. In view of the large quantities of ash, its bulk utilization is essential, which is possible only through geotechnical applications such as embankments, back-fill material, subbase material, and the like. For the above applications, one of the important engineering properties is the angle of internal friction, which is determined either by box shear or triaxial shear tests. This paper examines the angle of repose of pond ashes and its relation with the angle of internal friction, using direct shear tests. Determination of the angle of repose is an easy and quick procedure for cohesionless materials. The angles of repose of sand and of quarry dust also are examined for comparison purposes. A relationship between angle of internal friction for materials in the loose, dry condition and the angle of repose is established. Further, a simpler method of measurement of the angle of repose is proposed.
Liquid Limit Determination of Class F Coal Ash
Authors: Sridharan A , Pandian NS , Prasad PS 
Published: February 2009

Abstract
Large production of coal ash, a waste material, demands its bulk utilization. Bulk utilization of these ashes is possible only through geotechnical applications such as embankment construction, as a back-fill material, a subbase material, and the like. Hence their physical and engineering properties need to be determined for effective utilization. Liquid limit is one of the important physical properties. The existing popular methods of liquid limit de termination of soils, namely Casagrande's percussion method and the falling cone method, have limitations for their use in nonplastic materials like coal ash. In this paper, a new method has been proposed to determine the liquid limit of coal ash. The proposed method is based on the premise that at its liquid limit water content, soil/coal ash does not imbibe or give out any water under a particular vertical stress under the Ko condition. This vertical stress is found to be 0.9 kPa. Experimental results are presented to substantiate the proposed method.
Fault Diagnosis Theory: Method and Application Based on Multisensor Data Fusion
Authors: Wang HF , Wang JP 
Published: February 2009

Abstract
This article discusses the elementary theory and method of condition monitoring and fault diagnosis in complex mechanical systems, using multisensor data fusion and integration technology. The basic concept of decision-layer multi-sensor data fusion, i.e., Dempster-Shafer evidence theory, is concisely described. The algorithms and implementation of decision-layer data fusion for condition monitoring and fault diagnosis, based on Dempster-Shafer evidence theory, are studied. We present an approach to diagnose multiple faults of a working diesel engine, based on the above algorithms. The analysis results show that this approach effectively improves the accuracy and reliability of fault diagnosis of the diesel engine.
Development of a Multiple Linear Regression Model to Estimate the Ductile-Brittle Transition Temperature of Ferritic Low-Alloy Steels Based on the Relationship Between Small Punch and Charpy V-Notch Tests
Authors: Saucedo-Muñoz ML , Matsushita T , Hashida T , Shoji T , Takahashi H 
Published: February 2009

AbstractThe transition temperatures of Cr-0.5Mo, Cr-Mo, and Cr-Mo-V steels were determined using the Charpy V-notch (CVN) and the small punch (SP) tests. It was confirmed that there was a linear correlation between the transition temperature of ductile-brittle behavior determined by the Charpy V-notch test and that obtained from the small punch test. However, the estimation of CVN transition temperature by means of this linear equation is not completely reliable because of the large experimental scatter of data. In order to improve the reliability of the transition temperature estimation, a multiple linear regression (MLR) analysis was conducted to evaluate the effect of different variables of the manufacturing process and service conditions. This analysis permitted the determination of the following regression equation: CVNDBTT=1.35SPDBTT−0.84×103d−1∕2+326. This equation enables one to assess more accurately the transition temperature corresponding to the Charpy V-notch test using that of the small punch test and the austenitic grain size, expressed by d−1∕2.
The Effect of Kinematic Viscosity on the Flash Point of Liquids Determined by ASTM D 93 Procedure A, ASTM D 93 Procedure B, and ASTM D 56
Authors: Montemayor RG 
Published: February 2009

Abstract
The flash point of a liquid material is used to classify whether the material is flammable or combustible. ASTM D 93 is used to determine the flash point of various liquids either by Procedure A or Procedure B. There have been reports of flash point depression when viscous materials were tested using ASTM D 93 Procedure A relative to ASTM D 93 Procedure B. A multi-sample interlaboratory study was conducted to determine the effect of the kinematic viscosity of a liquid material on the observed flash point when tested according to ASTM D 93 Procedure A relative to the results when tested according to ASTM D 93 Procedure B. The results of the study indicate that liquid materials with kinematic viscosities greater than 13 mm2/s at 40°C gave lower observed flash points when the flash point was tested using ASTM D 93 Procedure A compared to the flash point tested by ASTM D 93 Procedure B. A possible explanation is a lag in the temperature detected by the temperature-measuring device as the kinematic viscosity of the liquid increases, especially when equilibration of the temperature of the vapor and the bulk of the specimen is not established before the flash point is detected. This temperature lag effect is more pronounced when using D 93 Procedure A than when using D 93 Procedure B. A similar study was conducted with ASTM D 56, another flash point test method. The effect of kinematic viscosity on the observed flash point by D 56 is less apparent than that observed when using D 93 Procedure A.
A Methodology for Determining Rate-Dependent Flow Surfaces for Inconel 718
Authors: Lissenden CJ , Gil CM , Lerch BA 
Published: February 2009

Abstract
A detailed set of experiments has been conducted in an attempt to characterize the inelastic flow behavior of materials used in aeronautics applications. These experiments have shown that aged (precipitate-hardened) Inconel 718 exhibits an initial nonlinear elastic behavior as well as a strength differential in tension and compression at room temperature. This nonlinear elastic behavior correlates reasonably well with a second order stress-strain law that was developed to account for interactions between dislocations and interstitial solute atoms. Flow loci in the axial-shear stress plane at 25 and 650°C have been determined from yield locus data using both inelastic power and equivalent inelastic strain definitions of flow. Flow loci are more theoretically meaningful than yield loci for describing the time-dependent material response. These flow loci are especially important if they are proportional to the dissipation potential since the normality rule is associated with dissipation and not necessarily with a particular yield or flow definition employed in an experiment. A threshold function that depends only on the second deviatoric stress invariant, J2, is inadequate for predicting the threshold surface (initial yield locus) for Inconel 718 due to the difference in flow behavior in tension and compression. Threshold functions including all three stress invariants (I1, J2, and J3) with each term having units of stress raised to the first or third power were equally successful in fitting the initial flow locus. Additionally, both F=aI1+bJ21/2−1 and F=b3J23/2+c3J3−1 are shown to represent the data very well. The outward normals for these two representations of the threshold surface are consistent with experimentally determined directions of the inelastic strain rate vectors.
Early Detection of Fatigue Damage Through Ultrasonic Non-Destructive Evaluation—Part II: Experimental
Authors: Bayer P , Singher L , Notea A 
Published: February 2009

Abstract
Ultrasonic wave velocities (longitudinal and transverse waves) and the attenuation coefficient were used to investigate damage of aluminum 7075-T651 before and after progressive stages of fatigue. Repeated observations under controlled conditions allied to digital signal acquisition, autocorrelation, and regression were used to estimate small velocity and attenuation changes. Although comparatively small uncertainties were observed, the feasibility of utilizing the velocity of ultrasonic waves as a fatigue monitor was not substantiated under actual research conditions. However, careful measurements of the ultrasonic attenuation parameter demonstrated its potential to provide an early assessment of damage during fatigue.
Part I of this work discussed the theoretical approach and described the fatigue testing procedures adopted in this investigation. This is a presentation and discussion of the experimental results.
A New Facility to Simulate Simultaneous Wind and Thermal Effects on Roofing Systems
Authors: Baskaran A , Liu K , Lei W , Delgado A 
Published: February 2009

Abstract
Roofing systems are exposed to wind pressures and thermal stresses. Through a North American roofing consortium (Special Interest Group for Dynamic Evaluation of Roofing Systems—SIGDERS) the National Research Council Canada fabricated a facility to evaluate roof assemblies under simultaneous wind and thermal effects. The overall objective of this paper is to present the commissioning process of the facility based on experimental investigations that were carried out on a single-ply roofing system with a PVC membrane. For this study, roofing system responses were measured under simulated simultaneous wind and heat/cold conditions. A systematic attempt also was made to quantify the system response and to characterize the membrane properties. This was performed on a cold-conditioned system as well as by subjecting the membrane samples to the same cold-conditioning program in a laboratory freezer. Membrane samples were characterized by mechanical and chemical methods. Comparison of laboratory-conditioned membranes and wind-tested systems revealed the effects of cold conditioning and wind loading. Neither the wind uplift nor the mechanical properties (tensile breaking strength, elongation at break, tear strength, and seam strength) nor the chemical properties (glass transition temperature and weight loss) were affected by the selected cold conditioning. Based on these findings, directives for further studies are presented for this ongoing project.
Evaluating the Quality of a Mechanical Testing System Using Displacement Field Contours
Authors: Zhao B , Asundi A 
Published: February 2009

Abstract
A technique using displacement field data to qualify mechanical tests for in-plane deformation is proposed. Contour lines of the displacement fields that result from applied forces in mechanical tests are used for quantitative analysis and graphical representation of quality of the mechanical testing system in the tests. This method can visually, directly, and sensitively detect loading problems, such as misalignment, existing in the tests. A theoretical analysis using a displacement contour map to describe quantitatively the effect of the misalignment in a uniaxial tension test is described in detail. A technique to obtain the displacement contour map from the displacement field data and on-line inspection of some test system misalignment is presented. Several examples, including an eccentric tension test, a tension test with inhomogeneous fixing of a specimen in the grips, and an Iosipescu composite shear test with various degrees and sources of misalignment are analyzed with this contour method.
A Low-Temperature Modification to the Charpy Impact Test, with an Example Study of the Fracture Toughness of Mg-12%Li between 4.2 to 77 K
Authors: Russell AM , Ostenson JE 
Published: February 2009

Abstract
A modification to the Charpy test for measuring impact fracture toughness has been developed that permits the specimen to be bathed in flowing liquid helium while mounted on the testing machine's anvil immediately prior to impact. This method permits samples to be tested at any temperature between 4.2 and 77 K, which extends the Charpy test to temperatures lower than those achievable by the conventional liquid bath immersion technique. A body-centered cubic Mg-12%Li single-phase alloy was tested by this new method and found to have anomalously high impact fracture toughness in the temperature range 4.2 to 77 K.
Effect of Crack Front Curvature and Side Grooving on CTOD δ5 and J-Integral in CT and 3PB Specimens
Authors: Nikishkov GP , Heerens J , Hellmann D 
Published: February 2009

Abstract
Fracture testing on compact tension (CT) and threepoint bend (3PB) specimens is preceded by fatigue precracking. Fatigue cracks have curved crack fronts. Nevertheless, crack front curvature is not taken into account in numerical modeling of fracture toughness testing procedures. In this paper we analyze actual fatigue cracks in CT specimens and show that the difference between crack depth at the center plane and at the surface of specimens is typically 0.01 to 0.03 of the specimen width. Three-dimensional elastic-plastic finite element analyses were performed for CT and 3PB specimens with crack fronts of different curvatures, and the CTOD δ5 and the J-integral were determined. It is found that the ratio δ5C∕δ5 is sensitive to the crack front curvature and strongly affected by side grooves. It is also shown that crack front curvature variations that are within the limits given by the test standards affect to a certain extent the η factor employed for the determination of the experimental value of the J-integral using the area under the force versus load-point displacement record. These facts should be kept in mind when toughness is measured.
Prediction of Permanent Deformation of Asphalt Concrete in Cyclic and Monotonic Loading
Authors: Ramsamooj DV , Ramadan J 
Published: February 2009

Abstract
New theoretical developments are presented to predict the permanent deformation in asphalt concrete caused by constant-load creep and by cyclic loads. The constitutive model utilizes multi-yield surfaces and isotropic hardening. A new hardening law for the changes in the values of the plastic moduli during monotonic or cyclic loading is derived from Rowe's stress-dilatancy theory. A complete description of the permanent deformation of asphalt concrete under constant load creep and cyclic loading is given, including the elastic, viscoelastic, plastic, and microcracking components, to predict the permanent deformation under cyclic loading. The model parameters have clearly defined physical meanings and can be determined from simple conventional laboratory tests. A computer program called RUT determines the permanent deformation. There is good agreement between the model predictions and the experimental data.
Yield of Inconel 718 by Axial-Torsional Loading at Temperatures up to 649°C
Authors: Gil CM , Lissenden CJ , Lerch BA 
Published: February 2009

AbstractAn experimental program has been implemented to determine small offset yield loci for the nickel-base superalloy In conel 718 (IN718) under axial-torsional loading at elevated temperatures. Initial and subsequent yield loci were determined for solutioned IN718 at 23 and 454°C and for aged (precipitation-hardened) IN718 at 23 and 649°C. The shape of the initial yield loci for solutioned and aged IN718 agrees well with the von Mises prediction. However, in general, the centers of initial yield loci are eccentric to the origin due to a strength-differential (S-D) effect that increases with temperature. Subsequent yield loci exhibit kinematic and distortional hardening, and solutioned IN718 shows a weak cross effect. This work demonstrates that it is possible to determine yield surfaces for metallic materials at temperatures up to at least 649°C using multiple probes of a single specimen. The experimental data are first of their kind for a superalloy at these temperatures and will enable a better understanding of multiaxial material response.
Low and High Cycle Fatigue Interaction in 316L Stainless Steel
Authors: Wong YK , Hu XZ , Norton MP 
Published: February 2009

Abstract
The interaction between initial low cycle fatigue (LCF) and high cycle fatigue (HCF) in 316L stainless steel is reported. Specimens were introduced to varying degrees of LCF and subsequently subjected to HCF until failure. LCF involves bulk plasticity where stress levels are usually above the yield strength of the material. On the other hand, HCF is predominantly elastic, and stress levels are below the yield strength of the material. Fatigue was carried out under strain control where two strain amplitudes in the LCF range with a common HCF strain amplitude were investigated. Results show that fatigue life decreased when specimens were introduced to increasing numbers of initial LCF. A linear life trend is observed for high numbers of LCF introduction, which deviates from linearity when lower numbers of LCF were introduced. It is therefore concluded that initial LCF causes substantial irreversible damage, subsequently reducing fatigue life in the HCF regime.
A Critical Appraisal of Fracture Toughness Measurements on AA6061 and an Al2O3-Particle Reinforced AA6061 Alloy for Various Heat Treatments
Authors: van Gorp AC , Mussert KM , Janssen M , Bakker A , van der Zwaag S 
Published: February 2009

Abstract
A disadvantage of metal matrix composites (MMCs) is their assumed brittleness, which results in a low KIc. A possible way to make aluminum MMCs tougher is to heat treat them. In this investigation the influence of three different heat treatments on the KIc of AA6061 and AA6061 with 20 vol% Al2O3 is investigated. Special attention is paid to the set of requirements needed to obtain a valid KIc, as in some studies these are given little attention. In MMC material, the specimen geometry is governed by the delivered shape, which increases the risk of obtaining KQ instead of KIc values. It proves to be possible to obtain valid KIc data for the MMC using the standard disk-shaped compact tension geometry.
The KIc of the MMC is around 21 MPa √m and the influence of the heat treatments on the KIc seems to be very small. The reduction in KIc by the addition of 20 vol% Al2O3 particles to AA6061 is moderate, in view of the KIc of the matrix material, which on average is 27 MPa √m.
A Finite Element Investigation into the Effect of a Skew Insert in a Double-Cantilever Beam Specimen on Calculating Mode I Delamination Fracture Energy of Unidirectional Composites
Authors: Javidrad F , Mashadi MM 
Published: February 2009

Abstract
In the present paper, the effect of a skew insert in a double-cantilever beam specimen in evaluating Mode I delamination fracture energy (GIc) of unidirectional laminated composites is investigated numerically. A delamination growth analysis incorporating the finite element method is utilized to calculate variation of load-displacement-delamination length for a prescribed GIc as delamination propagates along the specimen. In order to evaluate the values of GIc as a function of delamination length, the calculated data were treated as experimental data and processed using two ASTM standard test data reduction methods. These are the modified beam theory and the compliance calibration methods.
It is found that the skew front moves progressively to form a thumb-nail curved front during a few millimeters of growth. Part of this growth occurs within the specimen, not visible from the specimen edges where the delamination lengths were recorded during a test. It also is found that the difference between delamination lengths measured at each side of the specimen can have a significant effect on the calculated GIc. To eliminate this error in an actual test, it is suggested that the larger delamination length be used for data processing.