bluuebunny/crossref_metadata_2025 huggingface dataset:
Analytical Techniques for Fluorescent Chemicals Used as Systemic or External Wildlife Markers
Authors: Johns BE , Pan HP
Published: March 2009

New approaches to wildlife marking with fluorescent chemicals were examined using the analytical techniques of fluorometry, chromatography, and tissue examination under ultraviolet light. A miniaturized, portable, and economical chromatography system was utilized. Quinacrine dihydrochloride was used as a marker and was found to be detectable at 50 ppb in 1 ml of blood. Rhodamine B was demonstrated to be a long-lasting marker of coyote (Canis latrans) claws and hair when the chemical was ingested orally and systemically distributed. The use of the analytical methods presented, in combination with fluorescent chemicals, will provide researchers and managers with additional ways to mark wildlife. The possibility of the systemic marking of hair with a variety of chemicals offers an expanded future for wildlife marking.
Considerations in the Design of Test Methods for Measuring Bait Shyness
Authors: Robbins RJ
Published: March 2009

Data are presented to show that the ingestion of sublethal quantities of toxic bait can modify rodents' subsequent acceptance of that and other baits by way of two separate mechanisms: a learned aversion to that specific toxicant-bait combination and a nonlearned aversion to novel foods in general. A test procedure is offered which provides separate measures of the degree of bait shyness produced by these two mechanisms and which also avoids confounding the results with the direct effect of toxicant flavor upon bait palatability.
Trends of Predator Losses of Sheep and Lambs Calculated from U.S. Department of Agriculture Mortality Statistics
Authors: Terrill CE
Published: March 2009

Sheep and lamb losses to predators have been determined since 1958. Predators kill many more lambs than sheep and therefore the upward trend of lamb losses in relation to sheep losses indicates that relative predator losses are increasing. Losses were estimated separately for each of the 33 states that showed definite losses and were then added together for areas and for the United States. The fact that independent estimates of predator losses in National Forest regions showed a high correlation with losses estimated from U.S. Department of Agriculture mortality data helps verify the accuracy of each set of estimates. During the 21-year period from 1958 through 1978, the area of predator damage was enlarged as losses tended to increase both eastward and southward. In general, adult sheep losses were about one third as great as lamb losses in the range states and two thirds as great in the farm states. Total numerical losses of sheep and lambs to predators were 1.5 million head in 1958 and 1.3 million in 1979. The percentage of loss steadily increased from 4.0 in 1958 to 6.8 in 1977, the year of the greatest percentage of loss. Sheep numbers declined during this period, in part because of predator losses. In fact, predator losses appear to have been a major cause of the decline of the sheep industry since 1960. The value of the loss increased fairly steadily from a low of $25 million in 1961 to a high of $103 million in 1979, the most recent year statistics were available. All of the eastern states showed relatively minor losses when compared with losses in the western states. Predator losses have had a significant effect on income from sheep. On the average, net income per ewe in 1974 would have increased from $3.88 to $8.12 if predator losses could have been eliminated.
Chapter 2—Diagnosis Is Measurement: Measurement Is the Basis for Standards
Authors: Caceres CA , Hanlin DC
Published: March 2009

Often the physician today faces a questioning public. No one is truly geared to any failure on the part of modern medicine. On the other hand, the practice of medicine is not able to ensure the certainty the public desires. Every diagnosis that the physician provides often contains some element that is not yet thoroughly understood.
Chapter 7—Biomaterials: Orthopedic Implants
Authors: Laing, PG , Galante JO , Lautenschlager E
Published: March 2009

The human body is a dehcately balanced chemical entity. It is composed of a variety of materials, a variety of living organisms. The introduction of “foreign” bodies, such as man-made implants, presents a rather precarious task to the surgeon. Not all people will tolerate the same bodily invasions with the same degree of success. Rehabilitation may be relatively quick for some, and time-consuming and painful for others. The orthopedic surgeon is the pivot on which successful implantation may depend.
Chapter 8—Clinical Measurement Instruments: Blood Pressure Measurements and Devices
Authors: Bruner JMR
Published: March 2009

The human condition tolerates uncertainty poorly. Relief from uncertainty is sought in codification, such as a system of codification stemming from commercial imperatives and based upon self-evident relationships or readily reproducible experiments: standards. Measurement of blood pressure is considered important, but there are uncertainties in the process. Are standards appropriate solutions to every observed uncertainty? Assessment of standards as solutions depends on an understanding of measurement systems in general and the measurement system to be applied.
Chapter 10—Broad Goals for a Standards-Development Organization
Authors: Brown PG
Published: March 2009

Many have commented that the medical environment is unique when compared to other business environments, and, so, the medical device standards, which direct manufacturers and health care providers and users, must also be unique.
Chapter 16—Assessment of Standards Needs: Implantable Devices and Treatment
Authors: Horowitz E
Published: March 2009

Implantable devices are, perhaps, some of the most complex devices in the world of medical technology. They can sustain life, ease pain, and increase personal freedom by functioning as permanent or semipermanent fixtures in the human body, much as the heart or a limb. It is this aspect—as implants— that makes such devices very complex. Some of the problems related to surgical implants include biocompatibility, prolonged and reliable performance, development and introduction of new materials and devices, the lack of adequate data on device failure, and the need for timely and adequate standards.
Chapter 17—Devices and Compatibility: The Innovation Process and Standards
Authors: Kahn AR
Published: March 2009

Standards have no true meaning, no life of their own, unless they are implemented, adopted, and used. Implementation can be voluntary, or a result of regulation or marketplace pressures. The development of standards for interface compatibility exemplifies one area of standards-setting which directly involves industry and the unique sides of the environment of the medical technology industry, the concerns of innovation and the innovative process, and raises questions regarding the introduction of new products to the marketplace.
Chapter 20—Therapeutic Assist Devices: Hydrocephalic Shunt
Authors: Watt CC
Published: March 2009

A timeworn but nevertheless accepted cliche is “medicine is more an art than a science.” This applies not only to the practice of medicine but also to the evaluation of medical practice, and the research that forms the basis of that practice. This is certainly true in the development and use of the shunt for hydrocephalus. The following outlines the development of the shunt, explores the pathophysiologic basis for the use of the shunt, attempts to correlate the principles learned in these two processes, and highlights primary concerns with standardization efforts.
Chapter 21—Complex Electronics in Clinical Therapy: Clinical Use of Cardiac Pacemakers
Authors: Parsonnet V , Bernstein AD , Raythen W
Published: March 2009

Pacing of the heart has become quite complex, especially in comparison to its relative simplicity two decades ago when there was but one indication (complete heart block with Stokes-Adams seizures), one simple pacemaker (fixed rate), and only one way to implant it (through a left thoracotomy). Despite this growing complexity, pacemakers are implanted in 2500 “centers” in the United States, and approximately 100 000 units are implanted each year. In order to be a pacemaker “expert” one must be familiar with such disparate subjects as electrophysiology, clinical cardiology, surgery and its complications, and basic electronics. As will be seen, the extent of clinical need and the intricacy of device technology pose unusual problems for establishing standards for pacemaker function and clinical effectiveness.
Chapter 22—Standardized Labeling and Packaging as a Device for Prevention of Medication Errors
Authors: Wang BC , Turndorf H
Published: March 2009

Accurate identification of products has been a matter of great concern to both manufacturers and consumers, and has received much attention in the past few years. Clearly, there is an urgent need for the development of standards by which manufacturers can best communicate important information concerning products to consumers, so that users can effectively comprehend all essential information and instructions provided by the manufacturers. Failing this, confusion and mishaps, some of which could be catastrophic but preventable, will result. Therefore, the importance of proper labeling and packaging cannot be overemphasized.
Chapter 24—Clinical Environment and the Law: Product Liability
Authors: Piehler HR
Published: March 2009

Historically, voluntary consensus standards were first developed to facilitate commercial transactions and ensure uniform product quality and performance, as well. Concerns for health and safety were not often explicitly involved in developing these early consensus standards, and the principal legal concerns involved issues of restraint of trade. While the courts have mitigated the concerns of standards writers stemming from potential allegations of restraint of trade, the current concerns with medical malpractice and product liability litigation have not only endured but increased. Within this context, what then are the opportunities, responsibilities, and legitimate limitations of standards development organizations and their participants?
Silicon Crystal Growth and Processing Technology: A Review
Authors: Bonora AC
Published: March 2009

Crystal growing and shaping technologies are being influenced by a combination of new discoveries in materials properties and new requirements from the marketplace. Key elements of change in crystal growth include control of carbon and oxygen, coupled with a transition to computerized large-charge growers, and investigation of magnetic field influence.

Materials shaping is being driven by stringent quality requirements coupled with newly available processing technologies including laser marking, gettering, and edge profiling. New instruments for inspection of particles, material composition, and wafer flatness are contributing to an overall trend towards automation of critical processes. Planarity of the polished slice continues to be a significant concern, since some complex lithography processes show performance gains with ultraflat wafers.
Influence of Laser Marking on Silicon Wafer Properties
Authors: Christ MH , Maurantonio BS
Published: March 2009

The effects of laser marking on silicon wafers were studied by oxidation and preferential etching for structure characteristics. Scanning electron microscopy (SEM) and optical microscopy were used to study cleanliness and epitaxial growth characteristics. Laser marking not followed by etching is seen to cause dislocations and slip patterns in the vicinity of the mark after an oxidation. If the wafer is etched after marking in either caustic (KOH) or acid (HF/nitric/acetic) no dislocations or slip patterns develop after an oxidation cycle. Marking done in dot matrix mode exhibits slag around the dots which is above the plane of the polished surface. It is shown that epitaxial growth on this slag is slower than on the polished surface. No epitaxial spikes are observed on marks engraved before polishing. No contamination is observed on finished polished slices. However, at high magnification (×4000 and ×20 000) particulate matter is seen after a photoresist has been applied, baked, exposed, developed, and stripped.
Epitaxy: An Introspective Review
Authors: Williams JH
Published: March 2009

The evolution of reactor design and gas control techniques for the deposition of silicon epitaxial layers is described. An approach to controlling a large epi factory with digital electronics is discussed. From the viewpoint of ever-growing technology and quality requirements, the present approach is to furnish the options for an automatic operation in an individual reactor.
Modeling and Applications of Silicon Epitaxy
Authors: Srinivasan GR
Published: March 2009

Demands for low-temperature, defect-free, thin silicon epitaxial films have produced significant progress in process modeling and process design. This review paper discusses recent developments with new additional data, with an emphasis on autodoping, defect control, and process-device interactions, as they relate to bipolar applications. A brief discussion of a low-temperature epitaxial process is provided, and calculations are presented to illustrate the advantages of low epitaxial temperatures in terms of profile tolerance and device performance.
Effects of Processing Parameters on Shallow Surface Depressions During Silicon Epitaxial Deposition
Authors: Boydston MR , Gruber GA , Gupta DC
Published: March 2009

Buried layer patterns of high dopant concentration are required in semiconductor processing. These patterns are produced by diffusion through patterned oxide and are marked by shallow flat-bottomed depressions bounded by steps of a few hundreds to a few thousands angstroms in height.

The shape and position of the surface depressions relative to the original buried layer patterns are affected by various parameters and processing steps during epitaxial deposition.

Data from a barrel reactor are presented on the lateral displacements of surface depressions, showing the dependence of deposition parameters on symmetrical and asymmetrical distortions. Horizontal and barrel reactor configurations are compared.
Improvement in MOS VLSI Device Characteristics Built on Epitaxial Silicon
Authors: White LS , Mohan Rao GR , Linder P , Zivitz M
Published: March 2009

Two advantages (freedom from ground loops and enhanced performance of diffused guard rings) of P+/P− epitaxial versus homogeneous crystal substrates in 64K DRAM are presented. Reduced refresh time and pattern sensitivities of the early TMS 4164, built on homogeneous substrate, are chronicled. To better understand the significant improvements with epitaxy, models are investigated for substrate capacitive/drift current coupling and for guard rings. Substrate-coupling modeling primarily used an instantaneous view of potential distributions via solution of Laplace's equation, followed by time-domain analysis. A comparison is made with a discrete resistor mesh. Guard ring study was empirical. Sets of biased diffused annular rings, surrounding an n+ dot used for minority carrier injection, were fabricated on both types of substrate. Results of the theoretical and experimental studies are compared with device performance.
Hydrogen/Chlorine Distributions in Silicon Dioxide: Detection and Model
Authors: Monkowski JR , Monkowski MD , Tsong IST , Stach J
Published: March 2009

Secondary ion mass spectrometry (SIMS) and electron microscopy have been used to investigate the distribution of hydrogen and chlorine in SiO2 films thermally grown on silicon. These films have been grown in various ambients, including pure O2, steam, HCl/O2, and Cl2/O2, as well as HCl/O2 mixtures diluted with N2. The data suggest that there exists a strong interaction between the chlorine and the hydrogen, with the chlorine being a very effective gettering agent for hydrogen. The results of this investigation, as well as a model explaining the incorporation and distribution of the hydrogen and chlorine, are presented.
Dependence of Thin-Gate Oxide Properties on Processing
Authors: Lai SK
Published: March 2009

Thin-gate oxides (23 nm or less) will be very important for future very-large-scale-integration (VLSI) circuits. Oxides in this thickness range can be grown in different environments and temperatures. Breakdown, interface properties, and electron and hole trapping are affected by the growth conditions. The effect of growth and anneal temperature on insulator and interface properties will be examined. Such information is useful in optimizing process conditions for the long-term reliability of thin-gate oxides.
Polyimide-Substrate Effects During Wet Chemical Processing of Polyimide Films in VLSI
Authors: Belton DJ , van Pelt P , Morgan AE
Published: March 2009

The application of polyimides as insulators in multilevel interconnect systems is receiving considerable attention for very-large-scale integration (VLSI) production. For a tight control of wet chemical pattern formation, as well as for the ultimate adhesion in the finished device, a fundamental understanding of polymidesubstrate interactions is important.

We have examined the effects of molecular weight, chemical composition, and interphase structure on the dissolution behavior of polyimides on silicon substrates. The dissolution rate of partly cured polyimides was found to depend strongly on the above parameters, and showed distinct regions of behavior. The overall-etching characteristics of the materials examined were dominated by surface adhesive interactions.

A method was developed to quantify the chemical adhesion during etching of polyimides. A phenomenological model of the dissolution behavior will be presented and its implications for VLSI processing will be discussed.
Modeling Anomalous Junction Formation in Silicon by the Codiffusion of Implanted Arsenic with Phosphorus
Authors: Fair RB , Meyer WG
Published: March 2009

Cross-contamination of phosphorus in arsenic-implanted layers has been found to occur in mechanically scanned ion implantation systems. Phosphorus introduced at low levels exhibits a diffusivity that depends upon n2, where n is the free electron concentration of the highly doped arsenic background layer. If the arsenic layer is shallow and the phosphorus diffuses through the arsenic junction, an enhanced phosphorus tail region is formed. Tail diffusion coefficients at 900°C were ∼20 times greater than the intrinsic phosphorus diffusion coefficient. Also, when a phosphorus tail is formed, the mechanism that enhances the tail diffusion also enhances the high concentration arsenic diffusion. These results are remarkable, since arsenic by itself will not produce an enhanced tail during diffusion in silicon, nor will it cause any emitter push effect.

These results have been modeled and provide strong support for a Fermi-level-controlled point-defect model of phosphorus diffusion with impurity-point-defect pair dissociation creating the tail region. We have essentially duplicated high-concentration phosphorus diffusion results by replacing the highly doped portion of the profile with arsenic. The fact that arsenic diffusion is also predictably enhanced when a phosphorus tail is formed strongly implies that the point-defects involved are vacancies.
Material Defect Factors Affecting MOS Device Performance
Authors: Matlock JH
Published: March 2009

Substrate-related defects that affect MOS yield center around either bulk impurities and precipitates or surface contamination. Uncontrolled bulk defects can cause significant refresh or leakage problems, but it has been shown that with proper processing the defects can form the basis for internal gettering that improves production performance. Surface-related yield problems reflect a joint responsibility of the wafer producer and the user, since residues, particularly organics, may also cause device performance problems. Control of these problems requires a careful analysis of all chemicals used in processing and cleaning the wafer prior to oxidations.
Oxygen Precipitation Studies at Various Impurity Levels Using Thermal Donor Activation
Authors: Allison JC , Maxwell OF , Schindler R , Domenici M
Published: March 2009

Thermal donor activation and related intrinsic pn-junctions are used to characterize outdiffusion and precipitation of oxygen in silicon wafers. It is found that the depth of the p-layers and the depth of the denuded zones do not coincide. Both are found to depend on the wafer position within the crystal and are not solely related to the oxygen content.
Effects of Oxygen Precipitation on Minority Carrier Lifetime in Silicon Crystals
Authors: Varker CJ , Whitfield JD , Fejes PL
Published: March 2009

Infrared (IR) absorption measurements of the interstitial oxygen concentration [O] for two-step annealed wafers, with reverse recovery time Trr and capacitance relaxation time Ts measurements on processed devices, have been used to investigate the influence of oxygen on the minority carrier lifetime (τ) in a Czochralski-grown silicon crystal. Measurements of Trr and Ts show a strong dependence on the axial distribution of the initial interstitial oxygen concentration and on the concentration of precipitated oxygen. For a two-step anneal at 800°C and 1050°C for 16 h, the maximum average lifetimes of 4 µs and 180 µs are obtained from Trr and Ts respectively in wafers with an initial oxygen concentration [O]i ⋍ 1.3 × 1018 cm−3, where oxygen precipitation is minimal. Minimum lifetime values of 0.31 μs and 10 μs for the same respective measurements are obtained for wafers with [O]i ≥ 1.8 × 1018 cm−3, where oxygen precipitation dominates. The experimental results indicate that oxygen precipitation is the dominant mechanism contributing to the degradation of minority carrier lifetime. The detection of an SiO2 phase in the infrared spectrum and the detection of precipitate platelets in these wafers subsequent to the two-step anneal provide additional supporting evidence of a direct relation between oxygen precipitation and minority carrier lifetime degradation.
Computer-Aided Process Modeling for Design and Process Control
Authors: Dutton RW , Fahey P , Doganis K , Mei L , Lee HG
Published: March 2009

The use of computer aids for process modeling has grown rapidly over the past five years. Currently, industrial organizations are simulating thousands of process steps each month, both to cut development costs and to create more reproducible results. This paper will review recent progress in the field of process modeling and show typical applications. Both the design and process control aspects of modeling will be discussed.
Characterizing Process Nonuniformities on Large-Diameter Wafers: An Overview
Authors: Perloff DS
Published: March 2009

An overview is presented of the techniques available for characterizing process nonuniformities on large-diameter wafers. Examples are given of the use of two-dimensional and three-dimensional mapping techniques for displaying within-wafer variability, and of relative and cumulative frequency plots for representing process tolerances. Two new display methods are recommended for dealing with small data sets: minicontour maps and folded-axis cumulative frequency plots.
Analysis of Infrared Spectra for Oxygen Measurements in Silicon
Authors: Graupner RK
Published: March 2009

The effect of multiple reflections when analyzing the infrared spectra for oxygen measurements in silicon wafers is important. It may cause errors up to 20% when ignored. The procedure and calculations to derive oxygen concentration from the spectra by taking into account this effect is described in detail. The effect of back-surface finish on the measurements is also discussed.
Determination of Oxygen Concentration in Silicon by Infrared Absorption
Authors: Abe T , Gotoh S , Ozawa N , Masui T
Published: March 2009

Infrared absorption measurement and activation analyses were carried out for various CZ crystals with different oxygen concentrations. Data for infrared (IR) absorption were found to vary depending upon various factors such as wafer thickness and surface finishing. Under well-defined experimental conditions, however, an accurate linear correlation between the IR absorption and oxygen concentration measured by activation analysis was obtained: 6.0 × absorption coefficient = oxygen concentration in parts per million atomic (ppma).
Thickness Measurement of Thin (1.0-µm) Epitaxial Silicon Layers by Infrared Reflectance
Authors: Weeks SP
Published: March 2009

Current infrared reflectance techniques for measurement of the thickness of silicon epitaxial layers are generally unreliable for thicknesses below 2.5 μm. In order to extend these methods to thinner layers, an increased understanding of the physics of infrared reflectance from thin silicon layers is required. A model has been developed to calculate the complex refractive index as a function of impurity concentration and wavelength. It has been coupled with a multiple-layer treatment of reflectivity, allowing the simulation of the optical properties of an epitaxial layer above a substrate with arbitrary impurity distribution. The model is used to evaluate the shortcomings of both dispersive and interferometric measurement techniques.
Application of Two Approximate Methods for Ductile Failure Assessment
Authors: Hodulak L , Blauet JG
Published: March 2009

Test results of large-scale specimens are analyzed on the basis of the tearing instability concept. The “Engineering Approach” of Shih et al and the extended “Failure Assessment Diagram” of Milne are used together with crack resistance J-R curves obtained from small-scale compact specimens to evaluate the loads at crack initiation and instability and the amount of stable crack growth. A detailed parameter study is conducted to show the sensitivity of the numerical results to the variation of input data such as stress-strain law, limit load, and the material resistance curve.
Development of a Plastic Fracture Methodology for Nuclear Systems
Authors: Marston TU , Jones RL , Kanninen MF , Mowbray DF
Published: March 2009

This paper describes research conducted to develop a fundamental basis for flaw tolerance assessment procedures suitable for components exhibiting ductile behavior. The research was composed of an integrated combination of stable crack growth experiments and elastic-plastic analyses. A number of candidate fracture criteria were assembled and investigated to determine the proper basis for plastic fracture mechanics assessments. The results demonstrate that many different fracture criteria can be used as the basis of a resistance curve approach to predicting stable crack growth and fracture instability. While all have some disadvantages, none is completely unacceptable. On balance, the best criteria were found to be the J-integral for initiation and limited amounts of stable crack growth and the local crack-tip opening angle for extended amounts of stable growth. A combination of the two, which may preserve the advantages of each while reducing their disadvantages, also was suggested by these results. The influence of biaxial and mixed flat/shear fracture behavior was investigated and found to not alter the basic results. Further work in the development of simplified ductile fracture analyses for routine engineering assessments of nuclear pressure vessels and piping evolving from this research is also described.
Studies on the Failure Assessment Diagram Using the Estimation Method and J-Controlled Crack Growth Approach
Authors: Shih CF , Kumar V , German MD
Published: March 2009

The failure assessment diagram procedure for assessing the integrity of flawed structures evolved from the “two criteria” approach due to Dowling and Townley. The present form of the diagram, also referred to as the R-6 diagram, is due to Harrison, Loosemore, and Milne. Chell and Milne generalized the approach to account for thermal and residual stress and for crack growth problems, respectively. The failure assessment curve is obtained by using the Dugdale solution to interpolate between brittle fracture governed by Klc and plastic collapse governed by the limit load Po. This leads to a single failure curve in the R-6 approach. However, it should be noted that the Dugdale solution is intended for a finite crack in a thin infinite sheet subjected to remote tension and also assumes that the material is elastic-perfectly plastic.

Failure assessment diagrams can be determined directly using the estimation method and the J-controlled crack growth approach. The essential elements for constructing the diagrams are the elastic crack solutions (available in several elastic crack handbooks) and the fully plastic crack solutions for the specific crack configurations. It will be shown that the failure assessment equation can be obtained by rearranging the crack growth equilibrium equation associated with the JR-curve approach. The more precise derivations show that the shape and position of the failure assessment curve depend on crack configuration, the relative size of the crack, type of loading, and material deformation properties. Explicit equations for failure curves are derived for elastic-strain hardening material and for elastic-strain hardening material with saturation stress.

Failure curves are constructed for several fracture test specimens and for axially and circumferentially flawed cylinders. The curves are generated for a practical range of deformation properties and crack length-to-width ratios. The usage of these curves is illustrated with several problems. Load-deformation and crack growth behavior of flawed structures can be determined (albeit indirectly!) from the failure curves for the specific structures being evaluated.
Lower-Bound Solutions and their Application to the Collapse Load of a Cracked Member Under Axial Force and Bending Moment
Authors: Okamura H , Kageyama K , Takahata Y
Published: March 2009

The lower bound of collapse load of an edge-cracked member subjected to axial force and bending moment is remarkably improved by introducing the statically admissible stress field in plane-strain and plane-stress conditions. A procedure for the calculation of collapse load of a member with a surface flaw is also proposed. In addition, a method of evaluation of the J-integral for compact specimen is derived by using the aforementioned lower-bound solution. Finally, the applicability of the failure assessment diagram through the collapse load and fracture toughness is confirmed experimentally and numerically under the combined loading of bending and tension, as long as the JIc criterion is valid.
Engineering Methods for the Assessment of Ductile Fracture Margin in Nuclear Power Plant Piping
Authors: Ranganath S , Mehta HS
Published: March 2009

When a crack is discovered during inspection of a piping component in a nuclear power plant, the decision on replacement is dependent on the available design margin of the pipe in the presence of the crack. This paper describes the development of engineering methods to assess the design margin in cracked pipes. Procedures are outlined to evaluate cracks in piping, using methods consistent with the American Society of Mechanical Engineers (ASME) Code design basis, and to develop failure diagrams for piping. A criterion based on net section collapse is shown to predict adequately the load capability of piping with cracks. The predictions of the net section collapse approach are shown to be consistent with results from elastic-plastic fracture analysis based on J-integral and R-curve methods. Finally, the methodology is used to recommend acceptance criteria for flaws in power plant piping. The proposed criteria assure that the minimum safety margins inherent in the ASME Code are preserved during operation. Since allowable flaw sizes can be determined using information already available in piping stress reports, the proposed criteria offer a simple conservative method for assessing flaws in piping.
On the Unloading Compliance Method of Deriving Single-Specimen R-Curves in Three-Point Bending
Authors: Willoughby AA , Garwood SJ
Published: March 2009

The application of unloading compliance for deriving single-specimen R-curves in three-point bending has been examined. Various methods, including the use of a double-clip-gage arrangement, are investigated. Finite-element calculations show that the best estimate of crack length is likely to be obtained from the conventional clip gage/load compliance, using a/W ≥ 0.5. The results are compared with those from blunt-notched calibration test specimens and with fatigue-cracked specimens, both with and without side grooves, of two pressure vessel steels. It is found that the initial crack length may be estimated accurately, but that the estimate becomes less precise as tearing occurs. Consequently, predictions of crack extension are rather inaccurate. However, there is considerable scope for improvement in the measurement technique employed, and for the use of correction factors.

The use of two clip gages allows good estimates of load-point displacement, crack-tip opening displacement (CTOD) and J to be made, particularly when plastic displacements become significant. It is suggested that the technique could prove valuable in routine measurements of CTOD and J on bend specimens.
Evaluation of Several JIc Testing Procedures Recommended in Japan
Authors: Ohji K , Otsuka A , Kobayashi H
Published: March 2009

The JIc testing procedures proposed by the American Society for Testing and Materials (ASTM) and the Japan Society of Mechanical Engineers (JSME) were evaluated using medium-strength heat-treated steels. Among the three multiple-specimen methods investigated, the ASTM R-curve method generally gave the largest JIc-values, while the JSME R-curve method provided the smallest values. The JSME stretched zone width (SZW) method, which was developed with emphasis on accurate identification of the initiation of ductile tearing, yielded relatively high toughness values that were rather close to those by the ASTM method. The ASTM method provided a relatively stable procedure for toughness determination and yielded values higher than that at the onset of ductile tearing for these materials. The JSME R-curve method seemed to give the values closest to the onset of ductile tearing among the three methods investigated. The JSME SZW method showed sensitivity to interpretation and definition of the critical values of SZW. Development of a stable procedure for determining the critical SZW values may be of primary importance for improving reliability of the JSME SZW method.
Evaluation of Blunting Line and Elastic-Plastic Fracture Toughness
Authors: Kobayashi H , Nakamura H , Nakazawa H
Published: March 2009

The Japan Society of Mechanical Engineers (JSME) has made an effort towards standardization of the JIc test method. The recommended procedure includes two multiple-specimen methods [obtained at the intersections of the experimentally determined J-stretched zone width (SZW) blunting line and the R-curve, and of the J-SZW blunting line and the critical stretched zone width (SZWc)] and three single-specimen methods (ultrasonic, electrical potential, and acoustic emission). Concerning the blunting line and the R-curve, many experimental data have been accumulated by the present authors in recent years.

In this paper, the evaluation method of the blunting line and of the R-curve and their application to the JIc test are discussed with special attention to a comparison between two methods recommended by JSME and the American Society for Testing and Materials.
Instability Testing of Compact and Pipe Specimens Utilizing a Test System Made Compliant by Computer Control
Authors: Joyce JA
Published: March 2009

The aim of this paper is to demonstrate that a computer-controlled test machine can replace a test machine made compliant by a mechanical spring for tearing instability testing of simple compact and cracked pipe geometries. For both geometries tested herein, close agreement was demonstrated between the “computer compliant” and “spring compliant” test systems. The results show that though the computerized system utilized here is slower than the spring machine, this is not a serious drawback for structural materials with low to moderate rate dependence. The “inertia free” response of the computerized system is in fact a positive feature for studying tearing instability arrest and promises to be very useful to further studies in that area.

Experimental results obtained in this study on the circumferentially cracked pipe geometry show that J-R curves from the pipe geometry lie well above J-R curves obtained from subscale compact specimens removed from the pipe wall. Tearing instability occurs in the pipes at crack extension values well in excess of what was obtained from compact specimens of the scale utilized, and a prediction of pipe instability based on the compact J-R curve alone would give very conservative results.
Combined Elastic-Plastic and Acoustic Emission Methods for the Evaluation of Tearing and Cleavage Crack Extension
Authors: Khan MA , Shoji T , Takahashi H , Nütsuma H
Published: March 2009

A synergism between the acoustic emission and fracture mechanics techniques to predict failure in laboratory specimens of different structural materials is discussed. Emphasis is placed on situations in which fracture occurs by a cleavage crack propagation or controlled by the slow growth to fracture of a single crack. Results obtained during the tests indicate that acoustic emission is capable of detecting the onset of flaw growth and provide a precursor of the immediacy of fracture in a variety of steel and aluminum alloys. A new J/Ji key resistance curve procedure is developed for the evaluation of ductile fracture toughness (JIc) and tearing modulus with a single small specimen. Moreover, a new acoustic emission rating parameter for predicting tearing instability of elastic-plastic crack growth is proposed and related to the tearing modulus parameter.
An Analysis of Elastic-Plastic Fracture Toughness Behavior for JIc Measurement in the Transition Region
Authors: Iwadate T , Tanaka Y , Ono S , Watanabe J
Published: March 2009

Fracture toughness tests were performed in the transition region for ASTM A508 Class 3 and A470 nickel-chromium-molybdenum-vanadium steels using about 300 specimens of 0.5T, 1T, 2T, and 4T compact tension (CT) specimens. The KJ-values which are converted from Jc of the smaller specimens indicated a wide scatter ranging from below the KIc-value to much higher toughness. The fracture behavior was investigated with a scanning electron microscope in detail and the sources of scatter of the toughness in small specimens were studied. The fast brittle fracture behavior in the transition regime can be divided into two regions: (1) the region where fracture occurs on a blunting line (Region I) and (2) the region where fracture occurs on an R-curve (Region II). The scatter of the KJ-values in each region is caused by the amount of crack extension contained in the specimens.

Methods to obtain the fracture toughness equivalent to the KIc from the KJ-values are presented. In Region I the lowest bound of KJmin-values obtained using specimens that meet the requirement NB ⩾ 3000 Jcmin/σY is recommended, and this method may also be used in Region II. In Region II a modified R-curve method is proposed.
A Method of Application of Elastic-Plastic Fracture Mechanics to Nuclear Vessel Analysis
Authors: Paris PC , Johnson RE
Published: March 2009

The primary purpose of this work was to develop analytical relationships which could be used to assess the safety of irradiated nuclear reactor pressure vessels against unstable fracture. The need for such a calculation occurs when the Charpy uppershelf energy of the vessel steel is predicted to fall below the required 50 ft ∙ lb (67.8 J) level from accumulated neutron radiation damage. The method used was based on “tearing instability” concepts under “J-controlled growth” conditions for the crack stability criterion. The aforementioned purpose was served by developing fracture mechanics methods of wider applicability than previously available and applying them in analyses at uppershelf conditions (above the transition temperature). Elastic-plastic fracture mechanics concepts were used to extend recognized linear elastic fracture mechanics flaw analysis equations for through-the-thickness flaws and surface flaws into the plastic range. The approach also made use of J-R curve characterization of the material fracture resistance.

A crack stability diagram in the form of J as a function of Tplot was shown to be useful in demonstrating safe levels of loading (applied J) by comparison with the material J-R curve, reduced onto the same diagram. Consequently, a safe level of applied load, J50 [for J/T = 50 in. ∙ lb/in.2 (8.756 kJ/m2)], was suggested and the possibility of its correlation with upper-shelf Charpy energy values discussed.
Experimental Validation of Resistance Curve Analysis
Authors: Milne I
Published: March 2009

The experimental evidence which supports the existence of stable ductile crack extension in metallic specimens and structures is reviewed and compared with modern failure assessment procedures. The evidence includes data from the following: 1. Materials—aluminium alloys, mild steel, two nickel-chromium-molybdenum-vanadium forging steels, A533B and A508 pressure vessel steels, a quenched-and-tempered steel, austenitic steels, and HY-130. 2. Geometries—3-point bend specimens of various sizes, compact tension specimens plane and side-grooved, single-edge-notched tension specimens, double-edge-notched tension specimens, center-cracked tension panels, wide plate specimens, pressurized pipe geometries, and pressurized nozzle geometries with the crack located in the crotch corner, 3. Section sizes—thicknesses ranged from 2 to 700 mm in specimen geometries with crack sizes between 0.1 and 0.9 of the section.

It is concluded that for materials with a low to moderate capacity for strain hardening, an adequate engineering assessment can be obtained using a simple form of assessment such as the Central Electricity Generating Board's procedures, R6. However, for materials with a high capacity for strain hardening, total elastic plastic behavior can be predicted only by a procedure which allows for this strain hardening capacity explicitly. Nevertheless, the load capacity of such materials appears to be satisfactorily predicted using a flow stress criterion.
Elastic-Plastic Crack Propagation Under High Cyclic Stresses
Authors: Tanaka K , Hoshide T , Nakata M
Published: March 2009

The effects of the loading condition and the specimen geometry on the elastic-plastic crack growth in structural low-carbon steel under high cyclic stresses are investigated experimentally. The acceleration of crack growth rate, deviating from the stable relation between the rate and the J-integral range, was found to take place coincidently with the onset of the ratcheting extension of the specimen. Based on the fractographic observation, the crack growth acceleration is attributed to the incomplete reversal of plastic deformation in ratcheting extension and to the inclusion of dimple-mode fracture in crack growth. The maximum amount of crack growth acceleration through the former mechanism is predictable by considering the increase in crack-tip opening displacement. A method to evaluate the transitional behavior from stable fatigue growth to unstable fracture is proposed by introducing the concept of fatigue crack growth resistance curve.
Infrared Wavelength Modulation Spectroscopy of Laser Window Materials
Authors: Braunstein R , Kim RK , Braunstein M
Published: March 2009

We have previously shown that the infrared wavelength modulation system that we have developed is capable of measuring the complete spectral distribution of the extrinsic absorption in highly transparent solids at levels of 10−5 cm−1 in the spectral range from 2.5 to 12 microns [1]. The previous measurement techniques that were employed for KBr and KCℓ have been extended to other crystalline systems which are of interest in light guiding applications, namely: CaF2, LiF, NaCℓ, NaF, LaF3, BaF2, MgF2, SrF2, and MgO. Rich and varied absorption structures were observed in all of these crystals enabling an identification of volume and surface absorption. Similar dominant bands are observed in many of these substances indicating the presence of common impurities regardless of the crystal and the origin of its growth. However, varied fine structures are observed in different crystals which are indicative of the individual characteristics of the chemistry of the crystal preparation. These measurements were performed in laboratory and dry N2 ambients and readily show the physisorption and desorption of surface contaminants. In appropriate materials, measurements were extended into the intrinsic multiphonon region.
Pulsed CO2 Damage Threshold Measurements of Rb:KCl and NaCl
Authors: Detrio JA , Dempsey DA
Published: March 2009

The l-on-N damage threshold of specimens of forged NaCl, Rb:KCl and antireflection coated KCl were measured at 10.6 μm with a pulse duration of 10 μ sec. An acid etch significantly improved the survivability of the NaCl specimens which normally received surface damage while the response of KCl was not influenced by the etch treatment. The coated KCl survived about as well as the uncoated specimens. The measured damage thresholds were: etched NaCl, 24.2 J/cm2; NaCl, 12.0 J/cm2; etched KCl, unetched KCl, and coated KCl, 10 J/cm2.

The damage morphology included entrance and exit surface damage on all types of specimens and bulk damage in the KCl specimens. The surface damage observed in some cases was an artifact produced by a plasma which formed at the specimen entrance face.
Infrared Absorption in Highly Transparent Glasses Based on Hafnium Fluoride
Authors: Grexhage MG , Bendow B , Lipson HG , Moynihan CT
Published: March 2009

There has been considerable research activity recently in the preparation and characterization of multicomponent glasses based on heavy metal fluorides. These glasses offer excellent prospects for multispectral transmission (from 5–7μm to 0.2–0.3μm), are amenable to the incorporation of a wide variety of atomic species, possess a moderately low refractive index (∼1.5), and are readily forged into optical components. In previous work we reported investigations of the infrared edge of fluorozirconate glass. In this paper, we report investigations of the infrared absorption in the transparent regime of several new hafnium fluoride glasses developed recently at our laboratories. We find, as expected, that the infrared edge is shifted to longer wavelengths compared to Zr-based glass, but with most other spectral features remaining similar for both families of glasses. One interesting feature, for example, is a shoulder in the vicinity of 1300–1400 cm−1 in the infrared edge spectrum of these glasses. We discuss the influence of processing conditions on the mid-IR absorption; it appears that at this time that RAP processing utilizing CCl4 yields the best glasses, with somewhat steeper IR edges and reduced absorption in the 3μm regime. An analysis of the infrared edge data in terms of multiphonon theory is utilized to estimate the intrinsic limiting absorption in the 3–5μm regime. Finally, the infrared edge measurements are correlated with the fundamental vibrational spectra of the glasses deduced from Raman and reflectivity studies.