bluuebunny/crossref_metadata_2025_split huggingface dataset:
Uptake, Depuration, and Toxicity of Hexamethylphosphoramide in Aquatic Organisms
Authors: Schneider PW , Gibson JR , Cramm GC , Shrivastava SP 
Published: March 2009

Aquatic toxicity tests were undertaken to evaluate the environmental significance of hexamethylphosphoramide (HMPA), an industrial solvent which has been shown to be an animal carcinogen.
Hexamethylphosphoramide's 48-h LC50 to Daphnia magna and 96-h LC50 to bluegill sunfish (Lepomis macrochirus) were 4220 mg/litre and 7420 mg/litre, respectively. In concentrations up to and including 5140 mg/litre, HMPA did not interfere with the normal development of Eastern oyster (Crassostrea virginica) embryos to the veliger stage. Both sheepshead minnows (Cyprinodon variegatus) and Eastern oysters developed concentrations of HMPA in their tissues rapidly from 0.5, 8.4, and 40.4 mg/litre treatments, with the plateau concentrations rarely exceeding the exposure concentrations. Whole-body residues peaked in about three to seven days after the initiation of exposure. Sheepshead minnows demonstrated a greater ability to metabolize HMPA than oysters, while oysters depurated HMPA and its metabolites more rapidly than fish. Both species largely eliminated HMPA and its metabolites within one day of depuration. The bioconcentration factors for fish and oysters were less than four, which suggests that HMPA does not pose a substantial environmental hazard from the standpoint of its accumulation in aquatic organisms. The oyster mortality in the 8.4 and 40.4 mg/litre treatments was appreciably greater than that in the controls, while the fish mortality was similar among all the treatments and the control.
An Approach to the Toxicological Evaluation of a Complex Industrial Wastewater
Authors: Pearson JG , Glennon JP , Barkley JJ , Highfill JW 
Published: March 2009

The U.S. Army is currently conducting research to develop the data base required to establish water quality criteria for wastewater discharged from 2, 4, 6-trinitrotoluene (TNT) production facilities. Because over 30 munitions-related compounds are involved, a traditional compound-by-compound approach to the toxicological evaluation of this complex wastewater was considered both technically unacceptable and economically prohibitive. An alternate approach was developed that placed research emphasis on the toxicological evaluation of a representative wastewater mixture. The initial task, therefore, was to conduct a detailed wastewater chemical characterization study over a period of several months. Wastewater constituents were identified and quantified, and, through the use of statistical procedures, a mixture representative of the actual wastewater was defined. Only 22 of the compounds identified in the actual wastewater were detected consistently above the parts-per-billion detection limit. These were included in the mixture designated for detailed toxicological testing. To identify possible trace constituents with extraordinary toxicological properties, all the identified compounds received screening-type toxicological testing. In addition, in attempting to relate the toxic properties of the mixture to its components, detailed toxicological studies are continuing to be conducted on selected components of the mixture, that is, on major components and on extremely toxic minor components.
We believe that this combined approach of single compound and mixture testing provides both an economical and scientifically acceptable approach to the development of water quality criteria for complex industrial wastewaters that remain relatively constant over time. In this approach the “no-effect” level determined from chronic toxicity studies with the mixture will be the principal basis for the water quality criteria. This will be supplemented with the identification of components with extraordinary toxicological properties and the definition of the dose-response relationship for the major toxic compounds in the mixture.
Development of Basic Material(s) Data for Evaluating Crack Growth Life
Authors: Bucci RJ 
Published: March 2009

Fracture toughness, fatigue crack growth rate, and sustained load crack growth data comprise a basic package of materials property information used in predicting growth of cracks by fracture mechanics methods. Accurate analysis requires carefully developed laboratory results using various simple specimen configurations to describe these properties. A contributing factor to variability in life prediction is the lack of consistent procedures for obtaining and reporting this information for use in design. Though a standard does exist for direct fracture toughness determinations (ASTM Method E 399), standards for subcritical crack growth measurement are in various stages of development. Accuracy of life prediction is further confounded by judgment required of the analyst in selecting the most appropriate test and interpreting material property data for use in the computational methodology.
This paper reviews the status on standardization of test practices for characterizing basic material properties used in crack growth analysis. Emphasis is given to aspects of fatigue crack growth because of the relative importance of its characterization to life prediction by damage integration techniques. Other criteria are outlined to provide helpful guidelines to the design engineer seeking to recognize problems and minimize variability in life prediction.
Acoustic Emission—Some Examples of Increasing Industrial Maturity
Authors: Spanner JC 
Published: March 2009

During the past 15 years, acoustic emission (AE) has been applied throughout the world to a variety of engineering structures in the aerospace, chemical, petroleum, nuclear, transportation, manufacturing, and utility industries. In addition, many reports and articles have described the merits of AE as a method for characterizing the metallurgical processes that occur during tests to measure the mechanical and physical properties of solid materials.
Documented applications of AE have been numerous and imaginative, and may generally be categorized as: (1) monitoring of components and systems during proof testing for the purposes of qualification or requalification; (2) on-line surveillance of systems and components; (3) detection and location of leaks; (4) in-process weld monitoring; (5) characterization or measurement of mechanical properties; and (6) monitoring of geologic structures. On-line surveillance may take several forms including continuous monitoring, intermittent monitoring, limited-zone monitoring, and acoustic signature analysis (loose parts, vibration, fluid flow, etc.).
This paper reviews a cross section of industrial applications to develop the theme that AE is an emerging nondestructive testing (NDT) method. The technology is exhibiting definite signs of increasing industrial maturity, and several related factors will be discussed to illustrate this point. Surveys of defects that have been found in the pressure boundaries of components manufactured in the United States, United Kingdom and West Germany will be reviewed since they add perspective to the current level of industrial interest in AE. Selected examples of typical AE applications are also described to provide an assessment of acoustic emission as a complementary NDT method, rather than as a recently discovered panacea.
Some Examples of Evaluating Structural Integrity by Acoustic Emission Monitoring during Pressure Testing
Authors: Keledy FC , Hartman WF 
Published: March 2009

Several examples of acoustic emission (AE) testing of piping and vessels are presented. For each case, the procedure, results, and comparison of the results with independent test methods are discussed. Also, consideration is given to the economics of using AE monitoring, especially in relation to alternative methods of inspection.
A convection coil assembly, consisting of 432 m of Incoloy tubing, was monitored during hydrotesting. The AE results indicated four critically active sources and then the coil was selectively disassembled for additional examinations of the suspected thermally induced cracks. In a second field application, thirteen autoclaves were individually monitored during hydrotesting. The AE records indicated a number of sources in five autoclaves. Four of these were scheduled for reexamination in two years. On the basis of the AE results, one autoclave was taken out of service and a major crack in the vessel's jacket was confirmed.
A chemical processing vessel, having a surface area of 170 m2, was AE tested during filling with water. Eight regions, having significantly active AE sources, were identified and evaluated. The unit was subsequently removed from service and replaced. A metals processing vessel, having a surface area of 158 m2, was monitored during pressurization. Eight regions of regular AE activity were documented. None of these were considered to indicate critical flaw size. Several of the defects were confirmed by other types of inspection.
Acoustic Emission Inspection of Buried Pipelines
Authors: McElroy JW 
Published: March 2009

This paper describes the results of a five year testing program utilizing acoustic emission (AE) techniques to locate defects in buried gas distribution pipelines. Several weld failures on these lines emphasized the need to develop inspection techniques in order to locate weld flaws in high stress regions to permit prompt repair and assure system integrity. Acoustic emission testing was found to be a feasible technique to locate the flaws. To date over 40 000 m of oxyacetylene welded buried steel pipelines have been tested on the Philadelphia Electric gas system.
This paper discusses some of the procedural and calibration problems encountered in applying the AE technique. The manner in which the emitters were ranked is developed. The contributions of mechanical and electrical error involved in locating the flaw is discussed in the paper. Correlation of AE results with visual examination and other methods of nondestructive evaluation (NDE) is accomplished through comparing the AE emitter ranking with the flaw criticality.
Inspection of Nuclear Reactors by Means of Acoustic Emission during Hydrostatic Test
Authors: Votava E , Jax P 
Published: March 2009

The paper presents the state of the art for the surveillance of nuclear reactor components by acoustic emission (AE) during hydrostatic tests, as obtained during several inspections made by the Kraftwerk Union (KWU) and Battelle.
The necessary preconditions, wave propagation, calibration method, location accuracy, attenuation of AE signals due to geometrical configurations (nozzles), and the correlation between AE sources and defects as detected by other nondestructive testing methods (NDT) are presented and discussed.
The present results indicate the following:
∎ AE has a high sensitivity for detecting small leakages.
∎ AE signals from inside and outside of a thick reactor component can be located with approximately the same degree of sensitivity and accuracy.
∎ AE is a very sensitive NDT method, able to detect even very small flaws.
∎ AE indications lie preferentially in areas of seam welds, nozzles, welded-on attachments (auxiliary welds), closure studs, or other prominent areas.
The Theory of Instability of the Tearing Mode of Elastic-Plastic Crack Growth
Authors: Paris PC , Tada H , Zahoor A , Ernst H 
Published: March 2009

This paper presents a new approach to the subject of crack instability based on the J-integral R-curve approach to characterizing a material's resistance to fracture. The results are presented in the chronological order of their development (including Appendices I and II).
First, a new nondimensional material parameter, T, the “tearing modulus,” is defined. For fully plastic (nonhardening) conditions, instability relationships are developed for various configurations, including some common test piece configurations, the surface flaw, and microflaws. Appendix I generalizes these results for the fully plastic case and Appendix II treats confined yielding cases.
The results are presented for plane-strain crack-tip and slip field conditions, but may be modified for plane-stress slip fields in most cases by merely adjusting constants. Moreover, an accounted-for compliance of loading system is included in the analysis.
Finally, Appendix III is a compilation of tearing modulus, T, properties of materials from the literature for convenience in comparing the other results with experience.
Elastic-Plastic Fracture Mechanics for Two-Dimensional Stable Crack Growth and Instability Problems
Authors: Kanninen MF , Rybicki EF , Stonesifer RB , Broek D , Rosenfield AR , Marschall CW , Hahn GT 
Published: March 2009

An elastic-plastic fracture mechanics methodology for treating two-dimensional stable crack growth and instability problems is described. The paper draws on “generation-phase” analyses in which the experimentally observed applied-load (or displacement) stable crack growth behavior is reproduced in a finite-element model. In these calculations a number of candidate stable crack growth parameters are calculated for the material tested. The quality of the predictions that can be made with these parameters is tested with “application-phase” analyses. Here, the finite-element model is used to predict stable crack growth and instability for a different geometry, with a previously evaluated parameter serving as the criterion for stable growth. These analyses are applied to and compared with measurements of crack growth and instability in center-cracked panels and compact tension specimens of the 2219-T87 aluminum alloy and the A533-B grade of steel.
The work shows that the crack growth parameters (COA)c, Jc, dJc/da, and the linear elastic fracture mechanics (LEFM)-R, which sample large portions of the elastic-plastic strain field, vary monotonically with stable crack extension. However, the parameters (CTOA)c, R, Go, and Fc, which reflect the state of the crack tip process zone, are essentially independent of the amount of stable growth when the mode of fracture does not change. Useful, stable growth criteria can therefore be evaluated from the crack tip state at the onset of crack extension and do not have to be continuously measured during stable crack growth. The possibility of making accurate predictions for the extent of stable crack growth and the load level at instability is demonstrated using only the value of J c at the onset of crack extension.
Numerical Study of Initiation, Stable Crack Growth, and Maximum Load, with a Ductile Fracture Criterion Based on the Growth of Holes
Authors: d'Escatha Y , Devaux JC 
Published: March 2009

Considering a material at the ductile plateau, fracture tests on small specimens in generalized yielding conditions are common. We need to extract from them adequate information to characterize the fracture resistance properties of the material. We also need to predict initiation, crack growth, and maximum load for a crack found in a ductile structure. But the real problems are three-dimensional; for instance, semi-elliptical surface cracks or through-cracks in “small” thicknesses (tunneling and mixed-mode fracture). Moreover, they are not only in the symmetrical Mode I case (angled crack extension).
The common denominator of all these phenomena is the ductile fracture processes in the material at the crack border; these micromechanisms extend over some characteristic length which needs to be introduced at a crack tip because of the very intense strain gradient. We thus need a ductile fracture damage function belonging to the continuum mechanics frame and related to the history of stresses and strains averaged over such a characteristic volume. In this numerical feasibility study, using elastic-plastic finite-element computations and guided by a ductile fracture model in three stages—void nucleation, void growth, and coalescence—we tried such a differential damage history, in a most simplified form. We integrated this during the whole stress and strain history in each finite element along the crack path, and we studied the influence of the mechanical and numerical parameters playing a role in this methodology. We describe herein the evolution, which results from this criterion, of some parameters used in the literature as initiation and crack growth criteria.
Dislocation Structures Around the Crack Tips in the Early Stage in Fatigue of Iron
Authors: Katagiri K , Awatani J , Omura A , Koyanagi K , Shiraishi T 
Published: March 2009

Dislocation structures around the early stage fatigue cracks up to 170 µm in length formed in polycrystalline iron specimens were directly observed through an ultrahigh-voltage electron microscope operating at 2 MV. For this purpose, thin foils perpendicular to the surface were prepared from bulk specimens cycled up to 60 percent of the fatigue life of 2.5 × 105 cycles, by means of electroplating and jet electropolishing technique.There were found some small straight cracks penetrating the cells (size: 2 to 5 µm), formed beneath the specimen surface as well as in the interior. Some straight screw dislocation lines parallel to the direction of the crack growth, one of the projections of the 〈111〉 directions, were observed in the cells just ahead of the crack. No marked entanglement of dislocations was observed within these cells.On the other hand, some tangled dislocations were observed in the cells formed just around the cracks growing along grain boundaries.The results just described are compared with those of the early stage fatigue crack formed in two kinds of face-centered-cubic (fcc) metals with different stacking fault energy (copper and α-brass) obtained previously, and the mechanisms of fatigue crack initiation and growth in the early stages are discussed.
Titanium Release from Implants: A Proposed Mechanism
Authors: Solar RJ , Pollack SR , Korostoff E 
Published: March 2009

The excellent corrosion resistance of titanium surgical implant alloys is well documented. However, titanium compounds have been occasionally found in tissues adjacent to titanium implants, and these findings were reported to be unrelated to wear processes. The purpose of this study was to determine a mechanism by which titanium is released from an implant.
The corrosion behavior of commercially pure titanium and Ti-6Al-4V was studied by electrochemical means, namely, anodic polarization and differential capacitance techniques. Tests were performed in Ringer's solution at 37°C. Solution pO2, pH, and surface finish of the specimen were varied to include all probable in vivo conditions.
The corrosion resistance of commercially pure titanium and Ti-6Al-4V was not significantly altered by variations in pH, pO2, or surface finish. The electrochemical reaction which occurred was growth of the metal's protective passive film. The data indicated that the effective area of a specimen was less than its apparent surface area and was dependent on pH and surface finish. These findings suggest a model of the implant surface in which the natural air oxide that initially forms is comprised of microscopic oxide needles at surface irregularities plus a smooth planar oxide. It is proposed that the oxide needles can be broken off or dissolved in vivo, providing the source of the titanium sometimes found in tissue adjacent to an implant. Use of certain pretreatments may remove the needles prior to surgery, resulting in the more common case in which titanium is not found in the tissue.
Corrosion Studies on Nickel-Based Casting Alloys
Authors: Meyer JM , Wirthner JM , Barraud R , Susz CP , Nally JN 
Published: March 2009

Three different methods—electrochemical measurements (polarization curves, polarization resistance curves, and open-circuit potentials), immersion tests, and in-vivo evaluation—have been used to investigate the corrosion resistance of commercial nickel-chromium dental casting alloys and of the newly developed nickel-vanadium and nickel-vanadium-chromium alloys.Nickel-chromium alloys can be assigned to five different classes, according to their composition. All of the three methods of investigation used in this study have demonstrated that the electrochemical behavior of these alloys differs markedly among classes, and even within a given class. The molybdenum and manganese contents do play a significant role in corrosion resistance: alloys with high molybdenum and manganese content exhibit a much wider passivation range and a better resistance to pitting in chloride-containing solutions than those without. Alloys without any molybdenum are constantly active and corroding. The addition of cobalt or gallium as a ternary constituent also enhances corrosion resistance.The nickel-vanadium-chromium system offers good promise for the development of a new type of alloy for possible use in dentistry. The alloy 57Ni-25V-18Cr, for example, compares favorably with existing nickel-chromium alloys and even outclasses them for yield strength and polarization resistance.A thorough evaluation of the biocompatibility of all nickel-based alloys, according to the newest recommended practices, is still needed.
Determining Fracture Directions and Fracture Origins on Failed Graphite/Epoxy Surfaces
Authors: Morris GE 
Published: March 2009

During this investigation, methods were developed for determining the fracture directions of failed graphite fiber/epoxy resin composite test specimens and structures. Notched test specimens with 90-deg unidirectional fiber orientations were failed in tension by delamination. The resulting fracture surface features consisted of the graphite fiber and epoxy components. Epoxy fracture surface topographic features were identified with a scanning electron microscope (SEM). These features, designated as “hackles,” were correlated with the fracture direction. The direction of hackle overlap or tilt reversed when the fracture direction changed. This characteristic can be used to isolate fracture origins on failed test specimens or structures.
Test specimens having cracks with known fracture directions were sectioned, mounted, and polished using standard laboratory techniques and were examined with an optical microscope. A crack tip was detected which provided evidence to support a proposed theory for delamination crack initiation and propagation in graphite/epoxy structures.
Finally, graphite/epoxy test specimens and structural test articles that had been tested to failure in tension and fatigue were examined, and the hackle features were correlated with the fracture directions and origin locations within the specimens.
A Stress Corrosion Cracking Model for Pellet-Cladding Interaction Failures in Light-Water Reactor Fuel Rods
Authors: Roberts JTA , Jones RL , Cubicciotti D , Miller AK , Wachob HF , Smith E , Yaggee FL 
Published: March 2009

A model for pellet-cladding interaction (PCI) fracture of light-water reactor (LWR) fuel rods is presented, the basis of which is that Zircaloy cladding fails by iodine stress corrosion cracking (SCC). Laboratory data on iodine SCC of irradiated Zircaloy provide the primary input to the model, but unirradiated Zircaloy SCC data and theoretical analyses are utilized to broaden the regime of validity to encompass the various power reactor observations.
The PCI model postulates a threshold stress below which cladding cracks are unable to form. The cladding hoop stress must exceed this threshold for a finite time at any particular fission product iodine availability for the crack(s) to form. Crack formation is the controlling event in cladding failure due to SCC, and therefore, “remedies” must address the situation at the cladding inner surface.