bluuebunny/crossref_metadata_2025_split huggingface dataset:
Optimum Lime Content for Fly Ashes and the Role of the Curing Period
Authors: Sivapullaiah PV , Prashanth JP , Sridharan A 
Published: February 2009

Abstract
The determination of the optimum lime content of fly ash is very important to enhance its use. Recently, methods have been established to obtain the optimum lime content of fly ashes. Strength obtained at different ages becomes important for different applications. The effect of the curing period on the optimum lime content of fly ashes is not established, nor are methods available for obtaining the same. Based on detailed strength tests on different fly ashes with various lime contents after curing for different periods, it has been established that the effect of the curing period becomes important for optimum lime content of certain fly ashes depending upon their chemical composition. The optimum lime content corresponds to the production of a maximum amount of calcium silicate hydrate compounds of Type I. In addition to the strength test, the sediment volume test has also been used to study the effect of the curing period on the optimum lime content of the fly ashes. Both methods compared well and hence the simpler free swell sediment volume test may be adopted.
Consolidation Behavior of Bentonite in Electrolyte Solutions
Authors: Sivapullaiah PV , Savitha S 
Published: February 2009

Abstract
Volume change behavior of clays in different pore fluids is very important in their use as compacted clay liners for landfills. The present study brings out the variations in the consolidation behavior of bentonite compacted at Proctor's optimum conditions in different electrolyte solutions. Qualitatively the behavior can be explained using diffuse double layer theory. Existing methods to calculate theoretically e-log p curves based on this theory have been referred to the theoretical curves that agree closely with experimental curves. Clay properties, which are critical in the theoretical prediction of the curves, have been identified. However, the effect of potassium ions, which link bentonite clay particles, cannot be assessed by diffuse double layer theory.
Automatic Field Permeameter for Drainage Properties of Porous Asphalt Mixes
Authors: Tan SA , Fwa TF , Chuai CT 
Published: February 2009

Abstract
A new automatic field permeameter was designed to measure the in situ permeability of porous asphalt roads under field testing conditions. This apparatus works on the falling head principle; the falling head with time is measured through a porous road slab with a precise pressure transducer at the base of the apparatus at very close intervals of 100 (Hz) data points/s. With the falling head data, the specific discharge (υ) can be computed and plotted against the hydraulic gradient (ip1); the 3D flow permeability of the material is obtained at ip1&gt;=1. The falling head data are shown to agree with constant head test data and are independent of the initial head at the start of the test. This demonstrates the repeatability of test measurements and the reliability of the test method, as it agrees very well with the wellaccepted constant head measurements. However, direct 1D permeability measurements of vertical and horizontal cored specimens from tested slabs showed the influence of permeability anisotropy on test results. Therefore, to make the 3D measurements useful for practical applications, a correction factor accounting for the effects of anisotropy, thickness, and size of slab on the test interpretation of the k value is obtained from a comprehensive finite element study, which allows for conversion from the 3D permeability to the effective 1D isotropic permeability. This is validated from the results of 14 porous test slabs (3 asphalt mixes and 1 portland cement concrete mix) where independent measurements of the 3D as well as the 1D horizontal and vertical permeabilities have been made, and excellent agreement is obtained when compared to finite element results.
On the Determination of JIC Using the Stretch Zone Width Method
Authors: Suresh RKV , Ramakrishnan N , Srinivas M , Ramarao P 
Published: February 2009

Abstract
The stretch zone width (SZW=1∕2CTOD, the crack tip opening displacement) method for determining JIC involves fewer specimens and lesser size restrictions compared to the con ventional J-R curve method. However, the accuracy of the SZW-based procedure depends on each term of the J-CTOD relationship, i.e., JIC=m∙σ∙CTODC. This paper presents a numerical investigation of the J-CTOD relationship, which has been carried out using a large-deformation finite element method (FEM). The slope of the blunting line (m) is computed for various combinations of yield strength-to-elastic modulus ratio (σo∕E), power law strain-hardening exponent (n), and different measures of stress (σ in the J-CTOD relationship). This work brings out the importance of the correct choice of the stress measure, and the one suggested here is the integral average of the flow stress [σ*=∫0ε*σdε/∫0ε*dε]. Also, an effective CTOD approach is numerically validated where a sharp fatigue precrack of fracture specimens can be substituted by one with a finite notch root radius without loss of accuracy in JIC.
Interlaboratory “Pilot Run” Study of Small Heat-Flow-Meter Apparatus for ASTM C 518
Authors: Zarr RR , Lagergren ES 
Published: February 2009

Abstract
Thermal conductivity measurements of a high-density glass-fiber thermal insulation material near 24°C are presented for the determination of the precision and bias of ASTM Test Method C 518. The measurements have been conducted by 13 laboratories using small (305 by 305-mm) heat-flow-meter apparatus on three specimens of high-density glass-fiber thermal insulation material that were circulated among the laboratories. Test results are analyzed using ASTM Practice E 691 and subsequently compared to measurements of the same specimens conducted in a guardedhot-plate apparatus using ASTM Test Method C 177. The 95% repeatability and reproducibility indexes for precision have been determined to be no worse than 1.1 and 4.0%, respectively. A method for estimating bias is presented.
Effects of Silica Fume and Steel Fibers on Some Mechanical Properties of High-Strength Fiber-Reinforced Concrete
Authors: Eren Ö , Marar K , Çelik T 
Published: February 2009

Abstract
There are many test methods to measure the impact resistance of fiber-reinforced concrete that are complicated, time consuming, and expensive. A practical test method has been developed to measure the impact resistance of high-strength fiber-reinforced concrete (HSFRC). The equipment developed can also be used for testing aggregate impact values by simply changing the base plate of the machine. A machine was developed to measure the surface abrasion resistance of HSFRC. Testing fiber-reinforced concrete for surface abrasion resistance was found to be extremely difficult if realistic and practical results were desired. In this study the influence of silica fume on the properties of HSFRC was investigated by using silica fume at two different percentages and with three different hooked-end fibers, namely, 30/0.50, 60/0.80, and 50/0.60 length/diameter (mm/mm). Fibers were added to concrete in three different percentages of 0.5, 1.0, and 2.0% by volume of concrete. The results show that including fibers in high-strength concrete improves impact resistance, surface abrasion, and splitting tensile strength.
General Constitutive Relations of Anorthotropic 6061-T6 Aluminum and Its Fatigue Life under Proportional and Non-Proportional Loadings
Authors: Nayeb-Hashemi H , Lin H 
Published: February 2009

Abstract
Anisotropic constitutive relations with respect to the principal axes of an orthotropic solid are formulated using the macroscopic continuum plasticity theory of Shih and Lee. The general anisotropic constitutive relations are derived for predicting the plastic deformation behavior of a new material orientation. Straincontrolled cyclic tests were conducted along the 45° direction in the plane of the plate to verify the general anisotropic constitutive relations. The predictions agree very well with the experimental yield and plastic flow behavior. The axial-torsional coupling terms in the general constitutive relations are also determined and explained.
The constitutive equations were used to predict the low-cycle fatigue life of this material under both proportional and non-proportional loadings. An anisotropic shear cracking model, developed earlier, provided a good prediction of the fatigue life of this material under both proportional and non-proportional loadings.
Reference Verification Fluids for Flash Point Determination
Authors: Montemayor RG , Rogerson JE , Colbert JC , Schiller SB 
Published: February 2009

Abstract
The flash point of a liquid material is used to classify whether the material is flammable or combustible. 1,4-dimethylbenzene (p-xylene) has been used historically to verify the proper operation of different flash point test equipment. Because of the toxicity and low flash point value of 1,4-dimethylbenzene, an interlaboratory study was conducted to determine alternate flash point reference standards. This study reports the flash points of n-decane, n-undecane, n-tetradecane, and n-hexadecane using various flash point test methods. The flash points of these materials were found to be testmethod dependent because of the inherent differences in the various flash point test methods. The reported reference flash point values of these materials are now used to verify the proper operation of flash point test equipment in place of 1,4-dimethylbenzene.
Explaining the Hveem Stabilometer Test: RelatingR-value,S-value, and the Elastic Modulus
Authors: Chua KM , Tenison J 
Published: February 2009

AbstractThe Hveem stabilometer is used by several states to obtain materials characteristics for designing pavements. This paper presents equations that relate the Hveem stabilometer R-value and S-value with the elastic modulus. It is shown that the elastic modulus is dependent on the following: the R- or S-value, the exudation pressure, the overconsolidation ratio, the Poisson's ratio, and the angle of internal friction of the material. It is also shown how the compaction pressure might affect the calculation if the material is time-dependent or viscoelastic. An example problem is provided to show how to calculate the elastic modulus using these pertinent factors. Typical laboratory test data are also presented to demonstrate the relationship between the R-value and the elastic modulus for three different highway soil materials. It is shown that the exudation pressure is indicative of the moisture content of the test samples. The R-value and elastic modulus are shown to be quite sensitive to the moisture content.
The Determination of JIc Using the Time-Frequency Analysis Method
Authors: Ahn S-H , Nam K-W 
Published: February 2009

Abstract
Elastic-plastic fracture toughness, JIc, can be used as an effective design criterion. Among the JIc test methods approved by ASTM, the unloading compliance method has been used in this paper. In order to examine the relationship between the fracture behavior of the JIc test and acoustic emission (AE) signals, the post processing of AE signals was carried out by a joint time-frequency analysis method, i.e., the fast Fourier transform. The objective of this study is to evaluate the application of the characterization of AE signals for the unloading compliance method of the JIc test. Using a time-frequency analysis, AE signals can be extracted from the raw signal and be analyzed at the same time. The AE signal generated in the elastic-plastic fracture of material shows different aspects in the elastic and the plastic range or at the first portion of the crack growth by fracture. For example, energy obtained from the AE count method increases rapidly at the beginning of the plastic fracture. The elastic-plastic fracture of the material can be analyzed using real time AE characteristics.
Fracture Toughness of Thin Polymer Films Using Miniature Specimens
Authors: Bose WW , Landes JD 
Published: February 2009

Abstract
Thin polymer films were tested to determine fracture toughness. This was done to provide a measure of the resistance of the materials to crack-related damage and as a method for material evaluation and selection. The films tested were of a transparent polymeric material and were in the range of 0.03–0.10 mm thick. The testing procedures required to determine the fracture toughness for these materials were new, so several aspects of the testing had to be developed. These included the design and machining of appropriate specimens, the test setup and fixtures needed, and the method of data evaluation. This paper describes the procedures used to do this. The development work was done on a model material, 3M transparency overhead film for copiers. Most of the results presented here are for that material.
Evaluation of the Mean Plastic Strain Ratio rm of Metallic Sheets Prestrained Along Different Biaxial Strain Paths
Authors: Vankudre HV , Date PP 
Published: February 2009

Abstract
ASTM standards are widely used to determine the plastic strain ratio r to characterize the normal anisotropy and the planar anisotropy of sheet metal. The values determined by mechanical testing are quoted at a strain of 15%. These are used for comparing two techniques of measuring the plastic strain ratio or the anisotropy of two materials.
The present work reports the variation in the plastic strain ratio of prestrained material. The r values of biaxially prestrained steel sheet have been investigated using the ASTM as well as the magnetostrictive methods of measurement. An error analysis on the mechanical measurements has been performed to examine the agreement between the different definitions of the plastic strain ratio (rr, rint, rt, and rmx1) and the accuracy (based on coefficient of variation), in view of the need to measure the plastic strain ratio at low strain levels. Various means to ensure accuracy in measurement are described.
Plastic strain ratio of sheet deformed to different biaxial prestrains has also been characterized using the magnetostrictive method (Modul r test). It is found that the difference between the r values determined using the ASTM and the Modul r methods changes with strain and strain path. The nominal difference between the two methods was found to be comparatively consistent over strain paths ranging from plane strain to equibiaxial tension. The Modul r values for prestrains along these strain paths investigated were found to be relatively consistent and hence usable. For prestrain along the strain path β = −0.45 (negative minor strain regime), the nominal difference was considerable.
In view of the above, it is not appropriate to measure rapidly the r value of the material in the negative minor strain regime, in particular using magnetostrictive means, and to correct it using the “systematic error” between the two techniques. This restricts the usability of the Modul r test in measuring the plastic strain ratio of deformed sheet metal, particularly after a prestrain in the negative minor strain region.
Fatigue Crack Closure Evaluation Under Constant Amplitude and Spectrum Loading
Authors: Parida BK , Manjunatha CM , Girish HM 
Published: February 2009

AbstractFatigue crack growth behavior of through-the-thickness cracks emanating from the notch root in an aluminum alloy was investigated with particular emphasis on the evaluation of crack closure and its effects on fatigue crack growth rate. The tests were performed on SE(T) specimens both under constant amplitude (CA) and spectrum (modified FALSTAFF) loads. The near-tip strain measurement method was used for crack closure estimation in the short and long crack ranges. An attempt was also made to determine the crack closure value corresponding to the crack-tip shielding through fractographic analysis.In CA fatigue loading, short cracks grew faster than long cracks under the same nominal applied SIF range, ΔK, and also grew below the threshold SIF range, ΔKth, for long cracks. The crack closure level gradually increased in the short crack range and was observed to stabilize at a crack length of about 0.5 mm. The discrepancy in the observed crack growth rates between long and short cracks was attributed partly to the difference in crack closure levels. The fatigue crack growth rates of short cracks under modified FALSTAFF loading were observed to be rather scattered, and the crack closure level was found to gradually increase and stabilize within a larger scatter band. These observations are explained on the basis of likely effects of several high-peak overloads present in the applied spectrum load. In the long crack range, the crack closure value obtained by the near-tip strain measurement method appears to provide an upper-bound value, whereas that obtained through fractographic analysis provides a slightly lower estimate, which may be considered as a lower-bound fatigue crack closure value.
Effect of Heat Treatment on Mechanical Properties and Surface Roughness of Aluminum Alloy 601
Authors: Frost FF , Karri V 
Published: February 2009

Abstract
Aluminum alloy 601 has an extensive range of industrial applications due to its consistent mechanical properties and structural integrity. The other intrinsic features of this alloy include excellent corrosion resistance and lack of brittleness or susceptibility to stress-corrosion cracking. Continued attempts are being made to decrease the processing time of this alloy without affecting the associated mechanical properties. This paper shows a systematic experimental investigation carried out in a modern aluminum wheel manufacturing plant to study the effects of heat treatment of this alloy. It is shown in this work that a reduction in processing time at the heat treatment stage of manufacturing is achievable without significant effect on the mechanical properties of the alloy wheel produced. A comprehensive set of experimental investigations has shown that the mechanical properties of the alloy, processed using two separate heat treatment methods, are not significantly different. The findings reported in this paper have real implications to aluminum-processing industries in which heat treatment is a fundamental part of the manufacturing process.
A Method to Determine the Transition Point of Fatigue Crack Growth Rate from Near-ΔKth to Paris Regions
Authors: Zheng J , Powell BE 
Published: February 2009

Abstract
The transition point of fatigue crack growth (FCG) between the near-ΔKth and the Paris regions is an important value to study fatigue behavior. This study introduces a curve-fitting technique to identify this point for nickel-based superalloy U720 with stress ratio of R = 0.1 at room temperature. The value of ΔKth under these conditions is also determined.
Comparison of Finite Element Results and Experimental Measurements of CTOD δ5 in CT Specimens
Authors: Nikishkov GP , Heerens J , Hellmann D 
Published: February 2009

Abstract
Elastic-plastic finite element modeling of the CTOD δ5 measuring procedure is performed for CT specimens made from 22NiMoCr37 containing fatigue precracks with curved crack fronts. It is shown that a discrete model with curved crack front and actual position of the clip gage provides reasonable accuracy of results. An approximate model with straight crack front of average crack depth and actual location of the clip gage can also be used. It is proposed to adjust experimental δ5 values for the deviation of actual crack front curvature a from a specific value. The use of the adjustment procedure decreases the scatter of experimental values of CTOD δ5 considerably.
Prediction of Fatigue Performance of Asphalt Concrete Mixes
Authors: Ramsamooj DV 
Published: February 2009

Abstract
The suitability of dense-graded hot-mix asphalt concrete mixtures for fatigue-resistant flexible pavements is investigated. The fatigue lives of several mixes including those with additives of latex, rubber, and sulfur are predicted by a theory derived from fracture mechanics. There is good agreement between the model predictions for the fatigue lives and the experimental results for the laboratory tests. The material properties are then used to predict the fatigue performance of two of these mixes in a simulated full-depth flexible pavement and a three-layer flexible pavement. There is poor agreement between the model predictions for the performance of the simulated pavements and the laboratory tests. Several reasons are postulated for the differences in the fatigue lives for the laboratory beam tests and the simulated pavements.
Instability of Stacked Pallet Loads Due to Misalignment
Authors: Singh SP 
Published: February 2009

Abstract
Double-stacked empty corrugated fiber-board boxes were conditioned in normal and tropical climates and then compression tested in aligned, laterally offset, and diagonally offset configurations to determine the effect on compression strength. The results showed that offsets caused a greater reduction in strength than humidity effects. In a separate experiment, three-high pallet loads of infant formula in two-piece plastic cans were stacked in various staggered positions to evaluate the effect of pallet offset on stack stability. It was found that factors other than the amount of offset, such as pallet strength, uneven floors, and stretch wrapping were most influential.
Displacement and Strain Fields at a Stone/Mortar Interface by Digital Image Processing
Authors: Raffard D , Ienny P , Henry J-P 
Published: February 2009

Abstract
This work is part of a study of historical masonry behavior. It deals with the homogenization of periodic and heterogeneous structures like masonry, which is composed of stones linked by joints of mortar. Combined compressive-shearing tests were performed in order to study the mortar interface behavior. Deformation properties were measured, locally, by an optical extensometer. Like the speckle method, this principle uses digital image correlation processing. Compared to the volume of the joint, the size of aggregates induces heterogeneities. An experimental protocol is proposed to determine homogenous deformation according to joint width and localized deformation according to joint height. This approach accurately characterizes the interface at a microscale level and enhances high compaction strain at the interface.