bluuebunny/crossref_metadata_2025 huggingface dataset:
Interlaboratory Comparisons as Used in the Accreditation of Laboratories in New Zealand’s Dairy Industry
Authors: Twomey A
Published: March 2009

With the increase in the diversity of dairy products and their specifications, the laboratories of New Zealand dairy companies are accredited as the government’s agent to test their products to establish their quality for export. In order for governmental bodies like the Dairy Division to accredit these factories and to guarantee their results, all laboratories seeking this status are required to participate in the interlaboratory comparison program.

The interlaboratory comparison program sends up to 9 different dairy products a month to over 60 dairy company laboratories in New Zealand for the entire dairy season. The activity is coordinated at the national coordinating laboratory while the agency-certified laboratories are under the direct control of 4 regional reference laboratories, depending on their geographical position.

The agency-certified laboratories analyze the product, the results of which are sent to the coordinating laboratory via the regional reference laboratories. The regional reference laboratories scan for gross errors and scrutinize the agency-certified laboratories results using preliminary means.

The national coordinating laboratory analyzes these results for statistics (bias, variability, and consistency) and returns the results to the agency-certified laboratories and the regional reference laboratories. Control charts of their performance are also distributed to aid the quality control function of the agency-certified laboratories.
The Standards Council of Canada’s Program for Accreditation of Testing Organizations
Authors: Roué JE
Published: March 2009

The constitution and objectives of the Standards Council of Canada (SCC), which is a statutory corporation established by an act of the Canadian Parliament in 1970, are briefly reviewed. The relationship of the council and accredited organizations in the National Standards System (NSS) is noted. The council-approved document, Criteria and Procedures for Accreditation of Testing Organizations (CANP-4), is reviewed and discussed in some detail. Results obtained from a limited program of accreditation of testing organizations that was established to validate procedures and obtain cost estimates are noted and the current status of an approved national program reviewed. Reference is made to other Canadian as well as foreign national laboratory accreditation programs and the role of the International Laboratory Accreditation Conference (ILAC) is noted. The paper concludes with a brief review and summary of the Standards Council’s national program, noting in particular any changes that may be dictated by experience gained in the initial implementation phase.
Torsion Shear Apparatus for Soil Testing
Authors: Lade PV
Published: March 2009

Laboratory studies of soil behavior during rotation of principal stress directions may be performed using a torsion shear apparatus. The requirements, construction, and operation principles for this apparatus are presented. The same confining pressure is applied to the inside and outside surfaces of a hollow cylindrical specimen. Both clockwise and counterclockwise shear stresses and vertical deviator stresses can be applied to the ends of the hollow cylinder. The entire setup is contained in a pressure cell, and the integrated loading system is located below the table which holds the cell. A variety of initial stress conditions may be used, and the behavior of soils during large stress reversals, as well as reorientation of principal stresses and combinations of these conditions, may be investigated in this apparatus. The loading system and the deformation measurement principles are described, and procedures for preparation of sand specimens are presented. The advantages and limitations of the torsion shear apparatus are discussed.
Tensile Properties of Compacted Soils
Authors: Al-Hussaini M
Published: March 2009

This investigation describes the development of a hollow cylinder testing device and the feasibility of using this equipment for determining the tensile properties of compacted cohesive soils. Hollow cylinder tests were conducted on compacted specimens of Vicksburg buckshot clay (CH), Vicksburg lean clay (CL), and a sandy clay mixture (SC) from DeGray Dam. Unconfined compression tests and indirect tension tests were also conducted to provide comparative compressive properties of the materials.

With this hollow cylinder testing device it is possible to measure the radial deformation along the inner and outer surfaces of the specimen; these measurements enable the determination of the modulus of elasticity (E) and Poisson's ratio (v) of the tested soils. The ratio of tensile modulus to the compression modulus, as determined by hollow-cylinder and unconfined compression tests, ranges from 2.6 to 4.4. On the other hand, approximately equal Poisson's ratio values were measured by hollow-cylinder and unconfined compression tests.

Based upon results of this experimental program, the hollow cylinder test is judged to provide a reasonably accurate method for measuring the tensile properties of compacted soils.
Effect of Organic Material on Soil Shear Strength
Authors: Andersland OB , Khattak AS , Al-Khafaji AWN
Published: March 2009

The term organic soil ordinarily refers to combinations of weathered rock products and partially decayed plant matter. The organic fraction tends to dominate soil physical properties for organic contents in excess of 20 percent by weight. To simulate these materials and to include precise control over organic content, fiber type and size, and mineral type, kaolinite and pulp fibers were used to prepare model organic soils. For comparison, kaolinite and all fiber samples were included. The effect of organic material on soil shear strength is shown in terms of consolidation and stress-strain behavior, undrained shear strength, and the shear strength parameters c' and φ'. Decomposition effects on vane shear strength are reported for selected soil samples and one consolidation pressure.

The experimental work gives a relationship between void ratio and logarithm of pressure that is dependent on both organic content and pressure level. A small initial increase in organic (fiber) content significantly increased the compressive and vane shear strengths of the model organic soil. Higher organic contents changed the material behavior from one with a peak compressive strength at about 7 percent axial strain (kaolinite) to one with an almost straight line stress-strain curve for strains in excess of 20 percent (all fiber). Decomposition in the model organic soils led to a large decrease in vane shear strengths. An increase in organic (fiber) content increased the shear strength parameter φ' for both the CIU¯ and CID triaxial tests. A failure criterion, based on the maximum ratio of shear stress to the effective normal stress (maximum obliquity), gave φ'-values intermediate to the CIU¯ and CID values for high organic contents.
Undrained Shear Behavior of a Marine Clay
Authors: Koutsoftas DC
Published: March 2009

A comprehensive series of undrained shear tests were performed on a lean sensitive marine clay in both the normally consolidated and overconsolidated state. The types of tests performed included triaxial compression and extension and direct simple shear tests on K0-consolidated specimens. It was found that the clay is highly anisotropic with respect to its undrained shear strength and its stress-strain characteristics. Undrained shear strengths from compression tests were 1.7 to 1.8 times greater than from extension tests. Undrained strengths from direct simple shear tests were somewhat higher than the strengths from extension tests. Similar anisotropic behavior was also observed for undrained moduli. Failure strains were found to be influenced by the stress system during consolidation and the mode of shear. K0-consolidated specimens sheared in compression failed at extremely low strains and showed significant strain softening. The importance of these observations as they may relate to problems of undrained stability is discussed.
Shearing Behavior of Compacted Clay after Saturation
Authors: Lovell CW , Johnson JM
Published: March 2009

The purpose of this investigation was to ascertain the relationships among the compaction conditions (dry density moisture content and compaction energy) and the shearing behavior after saturation for a kneading compacted, highly plastic clay. The effective stress strength and pore pressure parameters were evaluated for various compaction conditions through the performance of consolidated undrained triaxial tests with pore water pressure measurement (CU¯) at a constant rate of strain. Long-term environmental effects were approximated prior to shear with backpressure saturation followed by consolidation to an isotropic state of stress representing the vertical load applied by succeeding lifts of an embankment.

The results of the testing program showed that the effective stress friction angle is relatively invariate for the range of compaction conditions investigated. The magnitude and range of variation of the measured values of the effective stress strength intercept were small. However, the volumetric strain upon saturation and the values of Skempton's A-parameter at failure were strongly affected by compaction conditions. Accordingly, the undrained strength of the compacted clay was significantly altered by the details of compaction.

Statistical analyses were performed to construct prediction equations based on the compaction variables for percent volume change due to saturation and consolidation. Skempton's A-parameter at failure, and the effective stress strength intercept. The equations obtained for percent volume change due to saturation and consolidation and Skempton's A-parameter at failure indicate that as-compacted dry density, initial degree of saturation, and consolidation pressure are the critical variables influencing behavior. The equation for the effective stress strength intercept indicates that initial void ratio and compaction moisture content are the significant variables. These equations will aid efforts to predict and modify the long-term shear behavior of compacted cohesive soils.
Plane-Strain Testing of Sand
Authors: Marachi ND , Duncan JM , Chan CK , Seed HB
Published: March 2009

Sand was tested under triaxial conditions, plane strain conditions, and conditions where the intermediate principal strain (ε2) varied between the limits for triaxial and plane strain. Tests were performed using a variety of specimen sizes and shapes, a range of densities from loose to dense, and a range of confining pressures from 70 to 3450 kN/m2 (10 to 500 psi). The results of these tests provide useful guidelines for plane strain testing of cohesionless soils: (1) Plane strain and triaxial test results differ most for dense specimens tested at low pressures, (2) Plane strain equipment need not be elaborate. Specimens with square cross sections and simple lubricated end plates can be used for plane strain tests, and (3) The end plates need not enforce a condition of perfect plane strain. Tests with values of ε2 as large as 40 percent of the axial strain at failure result in essentially the same value of the angle of internal friction (φ) as do perfect plane strain tests.
Field Density, Gradation, and Triaxial Testing of Large-Size Rockfill for Little Blue Run Dam
Authors: Thiers GR , Donovan TD
Published: March 2009

The results of field density and gradation tests involving large-size compacted rockfill (sedimentary rocks) were used to establish gradation and compaction requirements for large-size (38-cm-diameter) and conventional (15-cm-diameter) triaxial tests. The gradation requirements were that the gradation curves for triaxial test materials should be parallel to the corresponding field gradiation curve, except for minor modifications to avoid excessive inclusion of fines. The angle of internal friction decreased as maximum particle size increased, in a manner similar to that reported by others. Extrapolation was used to check the φ-values used in design.
Normalized Stress-Strain for Undrained Shear Tests
Authors: Drnevich VP
Published: March 2009

Normalized stress-strain curves are obtained by use of maximum shearing stress to normalize shear stress and reference strain to normalize shear strain. Reference strain is defined by initial tangent shear modulus and maximum shearing stress. This paper defines initial tangent shear modulus and maximum shearing stress to be functions of effective stress state. Consequently, the normalizing parameters vary with stress points along the stress path. An incremental procedure is established whereby normalized stress-strain curves can be obtained. These curves are relatively independent of effective stress path and are nearly identical to those obtained from drained tests. This method shows promise for correlating results from drained and undrained triaxial tests with results from other types of shear tests.
Nonlinear Anisotropic Stress-Strain-Strength Behavior of Soils
Authors: Prevost JH
Published: March 2009

Soils consist of an assemblage of particles with different sizes and shapes which form a skeleton whose voids are filled with various fluids. The stresses carried by the soil skeleton are conventionally termed “effective stresses” in the soil mechanics literature, and those in the fluid are called the “pore-fluid pressures”. In cases in which some flow of the pore fluid can take place, there is an interaction between the skeleton strains and the pore-fluid flow. The solution of these problems therefore requires that soil behavior be analyzed by incorporating the effects of the flow (transient or steady) of the pore fluid through the voids, and thus requires that a multiphase continuum formulation be available for soils. Such a theory was first developed by Biot (1955) for an elastic porous skeleton. However, it is observed experimentally that the stress-strain behavior of the soil skeleton is strongly nonlinear, anisotropic, elastoplastic, and path-dependent. An extension of Biot's theory into the nonlinear anelastic range is therefore necessary in order to analyze the transient response of soil deposits. Such an extension of Biot's formulation is proposed herein by viewing soil as a multiphase medium consisting of an anelastic porous skeleton and viscous fluids, and by using the modern theories of mixtures developed by Green and Naghdi (1965) and Eringen and Ingram (1965).

In order to relate the changes in effective stresses carried by the soil skeleton to the solid rate of deformation tensor, a general analytical model is used which describes the nonlinear, anisotropic, elastoplastic, stress and strain dependent, stress-strain-strength properties of the soil skeleton when subjected to complicated three-dimensional and, in particular, cyclic loading paths. The theory falls within the general framework of the formalism of classical plasticity theory. It combines properties of isotropic and kinematic plasticity, and allows for the adjustment of the plastic hardening rate to any kind of experimental hardening law by using a collection of nested yield surfaces. It is shown that the model parameters required to characterize the behavior of any given soil can be derived entirely from the results of conventional soil tests. The model's extreme versatility and accuracy is demonstrated by applying it to represent the behavior of both cohesive and cohesionless soils under both drained and undrained, monotonic and cyclic loading conditions.

The use of the proposed formulation for solving boundary value problems of interest in soil mechanics is illustrated.
On the Random Aspect of Shear Strength
Authors: Yong RN , Tabba MM
Published: March 2009

This paper discusses the random nature of shear strength of soils as opposed to the customary deterministic approach, where shear strength is thought of as a property that attains a specific value. In this approach uncertainty resulting from the intrinsic nature of the soil, as well as from the sampling and testing techniques (STT), is identified and supported by actual data.

Implications of the random character of shear strength are discussed insofar as they affect present concepts of soil plasticity. This paper advances the notion that currently used yield criteria are merely theoretical models which fit available data to some extent and could actually be violated.

An analytical model of mapping and prediction of shear strength is introduced, where one, two, or more sets of measurements corresponding to various STT are analyzed and could be combined to enable prediction of the mean, variance, and covariance of shear strength at desired locations.
Preconsolidation Pressure Predicted Using su/¯p Ratio
Authors: Anderson TC , Lukas RG
Published: March 2009

This paper illustrates the use of Skempton's su/¯p relationship along with the undrained shear strength for predicting the preconsolidation pressure for lightly overconsolidated clays. The validity of this prediction procedure is demonstrated by test results on soils from the Chicago area. A good correlation was found between predicted versus measured preconsolidation pressure. The relationship between liquidity index and measured preconsolidation pressure was also evaluated and found to be rather poor for the Chicago area soils studied.
Shear Strength of Cohesionless Soils from Incremental Creep Test Data
Authors: Baladi GY , Lentz RW , Goitom T , Boker TD
Published: March 2009

Results of incremental creep tests performed on cohesionless subgrade materials and stamp sand are presented with the results of conventional triaxial tests performed on the same soil at comparable density and water content. The Mohr-failure envelope and the shear strength data from the incremental creep tests are presented. The shear strength values of the specimens of the incremental creep tests are compared with the shear strength values obtained from conventional triaxial and cyclic triaxial tests. This comparison showed that the incremental creep test data could be and were used to model and predict the behavior of granular materials subjected to cyclic loading.
Residual Shear Strength Determination of Overconsolidated Nespelem Clay
Authors: Miedema D , Byers J , McNearny R
Published: March 2009

Peaking operations at Grand Coulee Powerplant, Washington, could result in future downstream river fluctuations of up to 12 m (38 ft) within a 24-h period and trigger dangerous landslides. Much of the riverbank consists of old landslide deposits in varved, overconsolidated clays and silts. The residual shear strength of the clay was determined from drained, repeated (reversing) direct shear tests on slickensided or precut sliding surfaces under three normal loads. Two displacement rates were initially used. The residual strength, measured after large cumulative displacements, was used in slope stability analyses. This paper describes problems encountered during testing, the test procedure adopted, the fully automated direct shear apparatus and data recording system, results to date, and planned future research. In one of the downstream riverbank areas, a residual shear strength range of 10 to 13 deg was confirmed by a back analysis of a recent slide.
The Need for Pore Pressure Information from Shear Tests
Authors: Shields DH , Skermer NA
Published: March 2009

Geotechnical engineers are familiar with the role that time plays in the stability of the sides of an excavation. The sides of trenches dug through silts and fine sands are often observed to stand vertically for perhaps 10 or 15 min, then start to fail; railroad cuts through London clay started to fail after 60 years. The time to failure is a function of both the permeability and the volume change characteristics of the soil or rock which is involved.

In open pit mining, the time to failure is of utmost importance, yet it is only now that theoretical tools are available which enable the engineer to design slopes for both economy and safety. This recent theoretical work points out the need for the pore pressure response of the soil or rock to be measured during strength testing. The need and the test requirements are the subject of this article.
Discussion of “State of the Art: Laboratory Strength Testing of Soils”
Authors: Lacasse S , Vucetic M
Published: March 2009

Saada and Townsend, in their state-of-the-art paper on laboratory strength testing of soil, present very severe criticisms of the simple shear testing method and the apparatuses presently in use. The discussers do not share this point of view. A fair assessment of a piece of equipment and of the testing procedure calls not only for an enumeration of its shortcomings, but also for a careful evaluation of the significance of these deficiencies on the measured parameters. Saada and Townsend questioned the overall usefulness of the testing method in geotechnical engineering problems.
Discussion of “State of the Art: Laboratory Strength Testing of Soils”
Authors: Christian JT
Published: March 2009

Finite element analyses of the direct simple shear sample do account for the three-dimensional state of displacement, strain, and stress. Three independent analyses indicate substantial uniformity of stress in the central region of a linearly elastic sample, but stress concentrations at the edges may make the device unsuitable for very sensitive soils or for investigation of progressive failure. The results of photoelastic investigations described in the report include unsymmetric distributions of stress that are mathematically anomalous and are probably caused by inadequate restraints at the boundaries.
Discussion on Laboratory Shear Devices
Authors: Ladd CC
Published: March 2009

This discussion starts with a general assessment of the capabilities of several types of laboratory shear devices and their corresponding suitability for use in specialized design practice and for basic research into the constitutive stress-strain-strength relationships of soils. It then focuses in greater depth on two specific topics: use of the Geonor Direct Simple Shear (DSS) device for design practice involving soft clays, and experimental requirements needed to reliably measure stress-strain-strength behavior in cross anisotropic soils.
Some Aspects of Clay Behavior and Their Consequences on Modeling Techniques
Authors: Tavenas F
Published: March 2009

Numerical models, as they are applied presently in geotechnical engineering, present serious weaknesses. Basic features of natural soils behavior are presented, and the differences with the common assumptions in constitutive models are pointed out. Some guidselines for the proper use of models and numerical analyses are given.
Fatigue Crack Growth Rates as a Function of Temperature
Authors: Marci G
Published: March 2009

The equation dadN=C[(KlG−Klmin)+ΔKT][(Klmax−KIG)−ΔKT]2 had been proposed by the author to predict fatigue crack growth rates. By adopting this functional relation and setting KIG = 0.5 KImax (KIG ∼ KIopen under constant-amplitude cyclic loading), there are the two parameters, C and ΔKI, left to be determined from experimental data.

The parameters C and ΔKT for several structural alloys as a function of temperature between room temperature and 811 K had been analyzed. It was found that the “fatigue tolerance range” ΔKT decreased linearly with increasing temperature. Initially, the parameter C increases nearly linearly with increasing temperature and then increases steeply at higher temperatures. In the present work, this temperature dependence is shown to be found between 4 and 911 K by analyzing low-temperature as well as additional high-temperature data for Inconel 718 and Inconel X-750. By assuming the observed qualitative temperature dependence of C and ΔKT as being correct, available fatigue crack growth rates for Type 304 stainless steel obtained at temperatures ranging from 4 to 922 K were analyzed with respect to C and ΔKT.
A Fracture Mechanics Study of Stress-Corrosion Cracking of Some Austenitic and Austeno-Ferritic Stainless Steels
Authors: Balladon P , Freycenon J , Heritier J
Published: March 2009

Crack propagation and plane-strain rupture by stress-corrosion cracking (SCC) have been studied on austenitic stainless steels Grades 304, 316, 316L and a austeno-ferritic steel. Tests were carried out in 45 MgCl2 at 154°C at constant load on fatigue precracked constant tension specimens. These tests show that the presence of macrocrack branching is related to the size of the cyclic plastic zone generated at the fatigue crack tip. A crack propagation threshold KIscc (for a life of 500 h) has been determined. We have noticed the particularly good behavior of the austeno-ferritic steel. The crack propagation rates have been determined for different steel grades and, in the case of the 304 and 316 steels, compared with the rates of anodic dissolution. Fractographic studies have elucidated the crack propagation modes: Up to the end of a region of constant propagation rate, transgranular cracking occurs, and at higher propagation rates, mixed and intergranular cracking is observed. In conclusion, the difficulties of applying fracture mechanics concepts to SCC of austenitic and austeno-ferritic stainless steels (difficulties due to the problem of macrocrack branching) have been overcome by eliminating the plastic zone at the fatigue crack tip (by annealing) such that planar crack propagation is favored.
Anomaly of Toughness Behavior with Notch-Root Radius
Authors: Datta KP , Wood WE
Published: March 2009

The present investigation has studied the effects of notch-root radii on the Charpy apparent toughness of as-quenched and tempered 4340 steel as a function of (1) test temperature (liquid nitrogen and room temperature), (2) strain rate (high and slow strain rates corresponding to Charpy and plane-strain fracture toughness testing rates), and (3) grain size (25 and 250 μm). The toughness was evaluated by instrumented and slow-bend Charpy tests. Fracture surfaces were examined by scanning electron microscopy.

The results showed that initially the toughness increased as the notch-root radius increased, but that after a critical notch-root radius was reached, the toughness dropped. The loss in toughness was coincident with a change to an intergranular fracture mode initiation. Also, the critical root radius at which the drop in toughness occurred was temperature and strain-rate dependent. These results are not in agreement with other published results, which always show increasing toughness with increasing notch root radius beyond a limiting root radius. These results and the limitation of the current theories are presented and discussed in this paper. A physical process for the intergranular fracture mode initiation is also discussed.
Fracture Mechanics Technology Applied to Individual Aircraft Tracking
Authors: Denyer AG
Published: March 2009

The paper presents a crack growth analysis approach to individual aircraft tracking that will meet the intents and objectives of the U.S. Air Force requirements. The structural life definitions are discussed in terms of definitive crack sizes for both the durability and damage tolerance of the structure.

Instituting a tracking program for a specific aircraft fleet requires a background of data relating to baseline spectra, critical structural locations, and expected airplane usage. The sources of such data are outlined. The body of the paper presents a cost-effective crack growth integration technique which makes tracking for durability feasible even if the life is as much as 100 000 h. Closely linked with the crack growth analysis technique is the method of collecting the flight data. The presentation considers two distinct approaches, a pilot form system and a structural loads measuring system. The methodology is being incorporated into the overall tracking system for the USAF T-39 Utility Trainer which will be the first to use the crack growth principle for both durability and damage tolerance tracking. Some T-39 data are presented for explanatory and demonstration purposes.
Dependence of Strength on Particle Size in Graphite
Authors: Kennedy EP , Kennedy CR
Published: March 2009

The strength-to-particle size relationship for specially fabricated graphites has been demonstrated and rationalized using fracture mechanics. In the past, similar studies have yielded empirical data using only commercially available material. Thus, experimental verification of these relationships has been difficult. However, the graphites of this study were fabricated by controlling the particle size ranges for a series of isotropic graphites. All graphites that were evaluated had a constant 1.85-g/cm3 density. Thus, particle size was the only variable. The strength-to-particle size relationship revealed that the fracture strength was logarithmically related to initial defect size by an apparent −1/3 power. Application of Dugdale crack extension model with simple modifications accounting for nonspherical pores and variable defect concentrations explains the −1/3 power relationship. This study also considered the particle size effect on other physical properties: coefficient of thermal expansion, electrical resistivity, fracture strain, and Young's modulus.
Fracture Control in Ballistic-Damaged Graphite/Epoxy Wing Structure
Authors: Avery JG , Bradley SJ , King KM
Published: March 2009

This paper describes the development of a graphite/epoxy wing skin configuration capable of sustaining limit load following damage from a 23-mm high-explosive (HE) projectile impact. The skin configuration incorporates information learned in sawcut and ballistic fracture testing, and consists of a ±45 graphite/epoxy laminate with integral spanwise and chordwise crack-arresting pads formed by adding 0-deg glass/epoxy between the plies of graphite/epoxy. The ±45-ply orientation provides enhanced battle damage tolerance because of its higher residual strain-to-fracture capability relative to quasi-isotropic 0/±45/90 laminates. This permits developing the full load-carrying capability of the spar chords before unstable crack propagation can occur in the damaged skin. The 0-deg glass/epoxy was added to further enhance this capability, and concentrated into pads to avoid undesirable ballistic damage augmentation caused by the glass fibers, and to provide a controlled failure mode under blast pressures. The optimum graphite-to-glass ratio and the required width of the crack-arresting pads were determined using a new analysis method for predicting fracture in laminates containing high-strength 0-deg fibers. The effectiveness of the damage tolerance concept was demonstrated by firing a 23-mm HEI projectile into the tension surface of a full-scale wing-box test component loaded in combined bending and torison. Following damage, limit load was achieved as a result of successful crack arrestment.
An R-Curve for a Surface Crack in Titanium
Authors: Lewis JC , Sines G
Published: March 2009

R-curves for surface cracks in Ti-6A1-4V titanium alloy were generated for the purpose of studying the resistance of the alloy to their subcritical growth under a monotonically increasing load typical of a proof test. Another purpose was to evaluate Ehret's compliance calibration for measuring the instantaneous size of a surface crack using the unloading slope of a load-versus-clip-gage-opening curve. Another purpose was to study “leak-before-burst” during sustained load and during subcritical crack growth under rising load.

Clips were mechanically attached to either side of the surface crack on the face of the specimen. A clip-gage extensometer was used to plot load-versus-clip-gage opening. Slopes were taken periodically by unloading about 10 percent so that subcritical crack growth could be distinguished from crack-tip plastic deformation. The tests were run in accordance with the ASTM Recommended Practice for R-Curve Determination (E 561-78T) as much as possible.
Stress-Intensity Factor for a Corner Crack at the Edge of a Hole in a Plate
Authors: Palusamy SS , Raymund M
Published: March 2009

A corner-cracked hole in a plate, subjected to remote tension loading, is one of the three benchmark problems identified for the validation of three-dimensional techniques at the workshop held in Battelle Columbus Laboratories. Stress-intensity factor results for the case of circular corner crack obtained by the macroelement technique is presented in this paper. Results for the remote tension loading are compared with those obtained by the boundary-integral equation (BIE) method and three-dimensional finite-element technique based on singular elements.

Since this investigation was carried out as a part of an overall program aimed at developing stress-intensity factor values for cracks in reactor vessel nozzles, results for six other crack surface loadings were obtained and compared with the results obtained by BIE method.

For the case of remote tension loading, the results of the macroelement technique in the regions removed from the free surface agree within 2.5 percent of those obtained by BIE and the singularity finite-element method. For the case of crack surface loadings, the results of the macroelement technique are shown to be in good agreement with the BIE method throughout the crack front. Comparisons with the limited results available in the literature which take into account constraint variation at the free surface show that the macroelement results for the free surface will be too conservative for thermal shock applications. However, it is concluded that the macroelement technique will give reasonably accurate results for nozzle corner crack problems except in the regions of free surface.
Estimations on J-Integral and Tearing Modulus T from a Single Specimen Test Record
Authors: Ernst HA , Paris PC , Landes JD
Published: March 2009

This paper presents methods for evaluating the J-integral and the tearing moduli from a single test record. Several different aspects of the problem have been combined in this work. An overview of the conditions for separability of the load into multiplicative functions of displacement and crack length as well as for the existence of η-factors is presented. The consequences of expressing J by a Merkle-Corten type formula are explored in terms of the crack increment, da, the tearing modulus, T, and J itself, including the case of growing cracks. A simple method is suggested to obtain the correct J for crack growth and T from nothing more than the test record itself; the procedure is applied to available experimental data and the results are compared with those obtained by other formulae. Additional physical interpretation is given on the Tmat-versus-Tapp stability criterion and the remaining compliance capacity CCR is defined.
An Experimental Evaluation of Tearing Instability Using the Compact Specimen
Authors: Joyce JA , Vassilaros MG
Published: March 2009

The objective of this investigation was to produce experimental verification of the tearing instability theory proposed by Paris and co-workers [10].3 This theory states that ductile crack extension will occur in an unstable fashion whenever the applied tearing force is greater than the material tearing resistance. In this investigation a series of compact specimens of aluminum, titanium, and steel alloys was tested in a variably compliant test machine to generate a range of applied tearing force. The material tearing resistance was measured from the JI-R curves of the stable specimens and compared with the applied tearing force necessary to generate ductile tearing instability in each material. The Paris theory was found to accurately predict the onset of gross instability behavior. Some limited instability behavior was found, however, at values of tearing force less than the average material tearing resistance obtained from an unloading compliance JI-R curve test. Limited instability behavior was characterized by repeated short steps of rapid but ductile crack extension, separated by regions of slow stable tearing.
Relationship Between Critical Stretch Zone Width, Crack-Tip Opening Displacement, and Fracture-Energy Criterion: Application to SA-516-70 Steel Plates
Authors: Nguyen-Duy P
Published: March 2009

Relationships are developed between the crack-tip opening displacement (CTOD), fracture-energy criterion (JIc), and critical stretch zone width (WSZc) using a simple geometrical model of the crack tip. Stretch zone width is directly measured from micrographs of fracture surfaces.

For three-point-bend specimens of SA-516-70 steel, JIc evaluated from measured values of WSZc is equal to 0.173 MJ-m−2 compared with 0.200 MJ-m−2 determined from the single-specimen method in which the crack onset point is detected by the electrical potential method.
Single-Specimen Tests for JIc Determination—Revisited
Authors: Clarke GA
Published: March 2009

Since the development of the unloading compliance method, numerous improvements to this JIc and J-R curve testing procedure have occurred over the past five years. This paper presents a description of many of these test technique improvements along with the results of the improvements.

Improvements in both mechanical and electrical systems are shown to greatly improve the reproducibility of the unloading compliance data. Computerization of the data reduction has led to a better understanding of the requirements necessary for an accurate J-versus-Δa R-curve.
Small-Specimen Brittle-Fracture Toughness Testing
Authors: Andrews WR , Kumar V , Little MM
Published: March 2009

Accurate estimates of valid plane-strain fracture toughness, KIc, for low-alloy steels in the ductile-to-brittle transition temperature range may be made by using JIc-valid specimens and accounting for a size effect evident for cleavage fracture. The size effect is explained using a “weakest link” theory that predicts variance in test results using constant-size specimens and decreasing average results when the specimen size is increased. Cleavage fracture occurs when the maximum tensile stress near the crack tip equals or exceeds the cleavage stress, σf*, over a microstructurally significant distance, the process-zone diameter. Variation in specimen toughness arises due to variations in the microstructure within the process zone; the weakest feature in the process zone causes catastrophic cleavage fracture of the specimen.

Our work indicates that the size effect on JIc is represented by J1∕J2=(B2∕B1)1∕m where m is the Weibull modulus, Bi is the specimen thickness for specimen i, and Ji is the mean JIc for several specimens. Experimental evidence supporting the theory is shown.
Literature Review of Batch Laboratory Leaching and Extraction Procedures
Authors: Perket CL , Webster WC
Published: March 2009

Major chronological events in the development of standard extraction tests are identified and discussed, concentrating on those events which have led to the current American Society for Testing and Materials (ASTM) and Environmental Protection Agency (EPA) procedures. Major test parameters for the various tests, such as dilution ratio, agitation method, and extraction medium are summarized. Concerns relative to the application of the extraction tests to waste classification and to assessment of environmental risk are outlined.
Analysis and Modeling of the Leaching Process
Authors: Paule RC
Published: March 2009

A statistical analysis has been made on data obtained in the study of the leaching process for the American Society for Testing and Materials special fly ash specimen using distilled water as the extractant. Two laboratories made extractions under a variety of conditions, and after acid stabilization, the leachates were analyzed by a third laboratory using inductively-coupled plasma analysis. Fifteen elements were studied. Three types of experimental variables were examined: (1) the extractor (60 and 180 cpm shaker tables, and the National Bureau of Standards (NBS) mixer); (2) the liquid/solid ratio (4/1, 10/1, and 20/1); and (3) the time (24 and 48 h).

The 60 cpm shaker table at the 4/1 liquid/solid ratio and at 24 h showed the greatest variability of results; the NBS mixer showed the smallest variability. The NBS mixer and the 180 cpm shaker table exhibited very similar extraction efficiencies and were, for a number of elements, noticeably different from that of the 60 cpm shaker table.

The data were examined in terms of three plausible extraction models. Many of the elements studied fit the model that practically all of the elemental material capable of being extracted is extracted under the test conditions, and that for the higher liquid/solid ratios this material is simply diluted. This results in the concentration being inversely proportional to the liquid/solid ratio. Data for the remaining elements appear to be in better accordance with a leaching model based on interrelated chemical equilibria. We observe, for example, that when the aluminum concentration decreases, the silicon concentration increases. This effect appears to be so pronounced that for the cases of the NBS mixer and the 180 cpm extractor, the silicon concentration actually goes up for the higher liquid/solid dilution ratios. A third plausible leaching model which is based on the concept of a constant elemental saturation under all experimental conditions generally was not found to be supported by the data.
Evaluation of the Extraction Procedure Testing of Hazardous Industrial Wastes
Authors: Larson RJ , Malone PG , Myers TE , Shafer RA
Published: March 2009

The U.S. Environmental Protection Agency (EPA) Extraction Procedure (EP) is designed to simulate the leaching action of rain and groundwater in the acidic environment present in mixed landfills or open dumps. The objective of the present project is to compare concentrations of selected constituents obtained in the extraction testing with the concentrations of the same materials in leachate obtained from a large-scale industrial/municipal waste co-disposal test, that simulates conditions in an actual landfill.

The EPA Extraction Procedure was run on specimens of three industrial wastes: a sludge from an electroplating operation, a chlorine production sludge, and a glass etching (calcium fluoride) sludge. These same sludges were also tested by adding approximately one metric ton (dry weight) of industrial wastes to two metric tons (dry weight) of municipal wastes and leaching the combined wastes. Both extractant and leachate were analyzed for arsenic, cadmium, total chromium, copper, mercury, nickel, lead, selenium, and zinc. There was a remarkable lack of correspondence between the concentrations appearing in the extractants and in the leachates. In most cases, the concentrations observed in the leachates were higher than the concentrations observed in the extractant. However, for some metals where redox and the availability of sulfide ion strongly affect oxidation states and solubility, the concentrations in the aerobic extractant were much higher than in the anaerobic leachate.

If the goal of extraction testing is to simulate the effects of a landfill environment on a hazardous waste, additional test development may be required. Present test procedures did not always accurately predict the loss of constituents measured in this study.
Nature and Environmental Behavior of Manufacturing-Derived Solid Wastes of Pulp and Paper Origin
Authors: Marshall DW , Blosser RO
Published: March 2009

A study of 31 solid wastes representing a cross-section of the pulp and paper industry's manufacturing-derived residuals indicates that none would be “hazardous” in terms of the currently established criteria for metals analyzed for, including cadmium, chromium, lead, nickel, copper, and zinc. Any likely occurrence to the contrary is thought to be incidental in nature. This judgment was based on the results of solid waste extractions and characterization of actual landfill leachates and interstitial fluids. Observed solid waste landfill leachate was best simulated with a water extraction.
A Comparative Field and Laboratory Study of Fly Ash Leaching Characteristics
Authors: Dodd DJR , Golomb A , Chan HT , Chartier D
Published: March 2009

The leaching behavior of bituminous coal fly ash has been studied by both field and laboratory tests of ash and water specimens taken from a fly ash disposal site. The site, an abandoned sand quarry which was filled with fly ash, covered, and landscaped in 1974, was instrumented with nine piezometers in January 1978. Six multilevel piezometer nests were installed along the major groundwater table gradient in August 1978. Groundwater specimens have been removed and analyzed periodically since the piezometers were installed. Specimens of ash removed during piezometer installation were tested, first to extract the interstitial water from the ash specimens by a pressure displacement technique, and then to obtain leachates from the ash specimens by shake and column leaching procedures. The results of these tests are used in this paper to compare the composition of leachates derived from the different laboratory leaching methods with the analyses of extracted interstitial waters from corresponding ash specimens and with analyses of groundwater from the field sampling program. The suitability of laboratory leaching tests for predicting the field behavior of coal fly ash is discussed in the light of the results obtained in this comprehensive leaching study.
A Comparison of Groundwater Quality at Selected Landfills to Leaching Test Results
Authors: Rinaldo-Lee MB , Kunes TP , Nichols DG
Published: March 2009

This paper compares the results of groundwater investigations of five industrial waste sites with leaching test data from the wastes produced by these manufacturing facilities. Since leaching test data are used by some regulatory agencies to classify wastes and predict their actual environmental impact, this study was initiated to examine the correlation between leaching test and groundwater quality data. The sites examined represent three different industries, and are located in different parts of the United States. The quality of groundwater directly in contact with the waste, or immediately downgradient, is compared with leaching test results.

Except for barium, the concentrations of metals in groundwater are less than those released by the leaching tests, although apparently anomalously high concentrations of iron and manganese are found in groundwater immediately downgradient of several waste facilities. These high concentrations may be due to release of iron and manganese by the soils. Generally, concentrations of inorganic nonmetallic parameters released by leaching tests from these wastes are less than concentrations in groundwater. Although laboratory leaching tests are important in estimating leaching potential of wastes, these results indicate leaching tests cannot be used alone to predict the actual environmental impact of waste disposal.