bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fracture Mechanics Tests on Welded Joints
Authors: Dawes MG , Pisarski HG , Squirrell SJ 
Published: February 2009

This paper gives recommendations and reasons for modifying existing plain material test methods for application to welded joints. The test methods are based upon those described in the ASTM and British Standards (including drafts) for plane-strain fracture toughness, KIc, crack-tip opening displacement (CTOD), and J contour integral tests, but with appropriate modifications to suit the testing of weldments.
A distinction is made between tests for general assessments of welded joint fracture toughness and those for specific assessments of the toughness associated with known or postulated cracks in welded structures, that is, tests that can be used as part of a specific fracture mechanics based fitness-for-purpose design or assessment. These applications are considered in relation to the choice of specimen geometry and notch location within the weld heat-affected zones and weld metals of single and multipass welds.
The special techniques that need to be employed in preparing welded specimens for testing are described. Details are given of how the results from the tests may be interpreted, together with a recommendation for metallurgical examination of the specimens after testing.
This paper is intended to provide a framework for standard fracture mechanics tests on welded joints.
Elastic-Plastic Fracture Mechanics Evaluations of Stainless Steel Tungsten/Inert-Gas Welds
Authors: M Nakagaki , CW Marschall , FW Brust 
Published: February 2009

A combined experimental and analytical study of ductile crack growth in a high-toughness austenitic stainless steel weld was performed. The substantially greater yield strength of the weld metal relative to the base metal favored plastic deformation in the base metal adjacent to the weld. Accordingly, the analytical studies focused on the stress/strain interaction between the crack tip and the weld/base-metal interface.
Experimental work included development of J-resistance curves from both compact (tension) specimen tests and pipe bend tests. To provide several ratios of weld size to specimen size, the compact specimens were of three planform sizes (0.5T, 1.5T, and 3T) machined from a tungsten/inert-gas (TIG) weldment, also known as a gas/tungsten-arc (GTA) weldment, in Type 304 stainless steel plate. A TIG-welded pipe test conducted by the David Taylor Naval Ship Research and Development Center was also analyzed.
A clear dependence of the crack initiation toughness on the weld size relative to the specimen size was found.
Elastic-plastic finite-element methods were used to model the tests. Because of stress/strain nonproportionality associated with local unloading due to crack growth, attention was focused on crack-tip integral parameters, such as Tp* and , that remain path independent under these conditions. However, an engineering J-estimation scheme also was employed in attempting to predict the load-carrying capacity of the welded pipe with a circumferential through-wall crack under bending.
A Viewpoint on the Failure Assessment Diagram
Authors: DE McCabe 
Published: February 2009

This paper presents the results of a study to evaluate certain features of interest in the failure assessment diagram (FAD). The concept of one universal calibration curve of interpolation between the two extremes of linear elastic and plastic collapse behavior is examined. One universal curve is implicit in the Dugdale strip yield elastic-plastic model, and this is examined in the light of trends that other elastic-plastic models suggest. Material work hardening, variable constraint, and geometry were identified as variables to consider by the other models. However, in some cases the universal calibration curve concept is not appreciably affected by these additional variables.
A major problem area is the consistency of load normalization by limit-load equations. These generally are imprecise estimates of the collapse load which impart a detrimental influence on the calibration curve shape and introduce the weakest link into a universal curve based FAD methodology. Three examples are given on the use of key curves to develop FAD calibration curve Kr values (elastic KI/elastic-plastic KR). A good fundamental relationship was shown to exist which, in effect, showed that FAD calibration curves represent another form of dimensional analysis. The key curve could also be used to study ways to reduce the deleterious effects associated with plastic collapse load determination problems.
A procedure was shown on a way to apply FAD calibration curves to develop K-applied curves for conventional R-curve analysis.
A Methodology for Ductile Fracture Analysis Based on Damage Mechanics: An Illustration of a Local Approach of Fracture
Authors: Rousselier G , Devaux J-C , Mottet G , Devesa G 
Published: February 2009

Major solutions needed in fracture analysis are (a) simple and accurate material characterization and (b) easy transferring of material data to cracked structures. In the proposed methodology, constitutive relationships, including cavity growth and coalescence, are used. Material characterization is based on the simple notched tension test. Several structural steels have been characterized, especially A508 steel, and the direct transferring of material data has been demonstrated with tests on circumferentially cracked tension specimens.
In addition, the extrapolation of material data to different inclusion contents and temperatures was attempted, with favorable results for the first factor through a specific parameter of the model. The temperature dependence of A508 steel ductility is related to an inverse strain rate effect on the flow curve; the modeling of this effect gives encouraging results, but it must be refined to produce an effective prediction.
Critical Depth of an Internal or External Flaw in an Internally Pressurized Tube
Authors: Leitch BW 
Published: February 2009

Using a combination of theoretical and experimental techniques, the critical depth of a long, internal or external surface flaw in an internally pressurized cylinder can be found. The theoretical study is performed using nonlinear finite-element methods. Assuming an infinitely long, axially oriented, surface crack in the wall of a pressure tube, a quarter of the tube cross section was modeled in plane strain. Three different crack penetrations were examined by specifying crack depth to wall thickness ratios (a/t) equal to 0.25, 0.5, and 0.75. The crack-tip stress-strain field was simulated using collapsed isoparametric elements containing a 1/r singularity.
The J-integral, and thus the stress-intensity factor, was found using the virtual crack extension method. Initially, elastic values were calculated, but, as the tube is manufactured from a zirconium alloy having a work-hardening material behavior, the analyses were extended into the elastic-plastic regime. Choosing the J-integral as the crack-driving force parameter, elastic and elastic-plastic theoretical crack-driving force curves were produced for internal and external surface flaws.
Experimental J-resistance curves have previously been determined using small-specimen test pieces. In the experimental tests, various property states of the zirconium alloy, such as unirradiated versus irradiated conditions and different levels of hydrogen concentrations, have been examined. Using the theoretically derived crack-driving force curve for an internal or external surface flaw, and the appropriate experimental J-resistance curve, an estimate of the critical depth can be obtained. The depth values obtained using this method compare very favorably with the result of a recent experimental burst test of a pressure tube containing a long external surface flaw.
Use of a Ductile Tearing Instability Procedure in Establishing Pressure-Temperature Limit Curves
Authors: Yoon KK , Bloom JM , Van Der Sluys WA 
Published: February 2009

Fracture mechanics analysis procedures have been used in the nuclear power industry for almost 15 years to establish allowable pressure-temperature limit curves. In this procedure, a reference flaw is assumed to exist, and the pressure-temperature limits that will allow safe operation of the plant are determined. As a plant ages, the analysis must be updated periodically to take into account any possible degradation of the pressure vessel material due to irradiation.
Until recently, this procedure was based on linear elastic fracture mechanics and was applicable only over a limited portion of the operating temperature range. This paper describes a proposed new approach to this analysis procedure which makes use of both elastic fracture mechanics techniques and a new ductile tearing instability analysis to establish allowable pressure-temperature limit curves over the entire operating temperature range.
The ductile tearing instability analysis is based on the deformation plasticity failure assessment diagram. The paper describes in detail how this procedure will be applied. Safety factors and acceptance criteria are proposed.
A discussion of the materials properties needed to perform the analysis is presented. The properties used in the analysis include the KIR curve from the American Society of Mechanical Engineers Boiler and Pressure Vessel Code, J-R curves, and stress-strain properties of the vessel material. An example problem showing the application of the overall approach is included in the paper.
A Study of the Initiation and Growth of Complex Cracks in Nuclear Piping Under Pure Bending
Authors: Kramer GS , Papaspyropoulos V 
Published: February 2009

In this study the validity of various analyses in the prediction of crack initiation, maximum load, and the corresponding displacements for 168-mm (6.625-in.)-diameter circumferentially complex-cracked pipe under pure bending was assessed. The results of six pipe fracture experiments on three materials (SA-376 TP304 stainless steel, Inconel 600, and A106 Grade B carbon steel) were used to verify the accuracy of these analytical predictions. All experiments were conducted at 288C (550F).
Two different sets of analyses were conducted using J-R curves and J-estimation schemes. J-resistance (J-R) curves were calculated from each pipe experiment using the -factor method. These results revealed that the J-R curves from the complex-cracked pipe experiments were significantly lower than J-R curves from 0.5T compact tension specimens. Furthermore, the pipe J-R curves decreased systematically with increasing ratios of surface crack depth to pipe wall thickness.
Predictions of loads and displacements in each experiment were made using four different J-estimation schemes. Good agreement was obtained between the predictions and the experimental data up to maximum load. Once past maximum load, however, the J-estimation schemes overpredicted loads and displacements.
Separation of Energies in Elastic-Plastic Fracture
Authors: Mecklenburg MF , Joyce JA , Albrecht P 
Published: February 2009

The area under load versus the load-line displacement record represents the sum of the stored potential energy, the released elastic energy, and the dissipated plastic energy necessary to grow a crack through a test specimen. When partitioned as presented in this paper, these energy components can be evaluated in terms of current elastic-plastic fracture parameters. The authors show that the elastic energy release rate, G, as calculated by measuring the appropriate component from the test record, is identical to G calculated from Kq. The plastic energy dissipated, as measured directly from the load-displacement record, represents a much higher value than would be indicated by current J-type calculations.
In all cases examined, it is further shown that energy released or dissipated is strongly dependent on the size of the test specimen and the size of the initial crack length. Further, while the rolling orientation and prestraining of the steels investigated affect the plastic energy dissipation rate, there seems to be little effect on the elastic energy release rate.
Microcomputer-Based Data Acquisition Systems for Triaxial Testing of Soft Yielding Rocks
Authors: Reeves M 
Published: February 2009

The structure and design of a generic, device-independent, set of software data acquisition and control routines for long-term rock mechanics monitoring are described. The routines are designed for an Intel 8086/8088-microprocessor-based microcomputer running under the MS-DOSR (Microsoft Disk Operating System). It is assumed that the rock will undergo long-term, slow deformation rather than rapid elastic rupture, and the routines are designed primarily for low strain rate and creep/consolidation testing.
The main features of the package include instrumental drift compensation, inputs from multiple interfaces, on-line configuration changes, complex control functions based on multiple sensor values, automatic elimination of erratic sensors, background acquisition and control, and on-line real-time graphics.
Triaxial Relaxation Tests on a Soft Clay
Authors: Silvestri V , Soulié M , Touchan Z , Fay B 
Published: February 2009

Results of consolidated undrained triaxial relaxation tests on a soft sensitive clay of eastern Canada are presented and discussed. The initial consolidation phases of the traxial tests are carried out under both isotropic and anisotropic stress conditions.
The results show that pore water pressures remain approximately constant during the relaxation phases of the tests. The phenomenological model developed by Prevost (Journal of the Geotechnical Engineering Division, ASCE, Vol. 102, No. GT12, 1976, pp. 1245–1259) describes the observed response quite well. In addition, because the clay possesses a well-defined volumetric yield curve, the position of this curve should be taken into account when analyzing the resuls. Finally, triaxial test procedure and equipment modifications used in the laboratory investigation are fully described.
Interpretation of Triaxial Test Results of Cohesionless Soils: A New Model
Authors: Baladi GY , Wu TTH 
Published: February 2009

The demand for more reliable methods of predicting the stress-strain relationship of large particle soils, and for more realistic assessment of the influence of grain characteristics on the shear behavior of cohesionless materials, makes it very important that the geotechnical profession develop a reliable modeling technique to accurately evaluate the effects of test and specimen variables. Large size particles in a soil matrix make it difficult to determine the strength parameters using conventional laboratory equipment. The relevant properties of the prototype materials (which contain large size particles) could be evaluated by using laboratory-reconstructed specimens with smaller particle sizes.
Traditionally, shear strengths of different types of cohesionless soils were compared using a constant relative density or void ratio. It was found that because of the differences in the range of limiting densities, soils with a constant relative density or void ratio but with different grain sizes would undergo different behavior during shear. At a constant void ratio or a constant relative density, some soils may experience volume increase; others may undergo a volume decrease; still others may experience no volume change during shear. Thus, comparing the shear strengths of different types of soils (that is, different grain size materials) based on the soils' relative densities or void ratios may led to inaccurate conclusions. The model should be based instead on the soils' response under the applied loads rather than their states of compaction.
This paper presents a new model (percent dilatation) whereby the shear strength of cohesionless soils, comprised of different particle sizes, can be compared and studied based on their behaviors during shear. The percent dilatation (PD) model was developed using data from 178 drained static triaxial tests, designed and conducted to study the effects of soil density, confining pressure, moisture content, and grain characteristics (size, gradation, shape, and particle angularity) on the shear strength of cohesionless soils.
Pore Pressure Response of an Undisturbed and Reconstituted Anglian Till in Undrained Triaxial Compression
Authors: Little JA 
Published: February 2009

Laboratory tests designed to expose fundamental mechanical behavior of very stiff, heavily overconsolidated soils can be difficult to interpret. Parallel testing of soil reconstituted from the matrix of the undisturbed soil therefore enables the observed behavior during testing to be assessed in a comparative way, and such effects as previous stress history, sampling, and soil fabric to be examined.
Undrained 38-mm-diameter triaxial compression testing of an Anglian till sampled undisturbed was carried out in conjunction with a soil reconstituted from its matrix. Analysis of pore pressure data showed that the critical state parameter Ac.s gave good predictions of pore pressures generated in the normally and lightly overconsolidated specimens, but tended to overestimate pore pressure in the most heavily overconsolidated specimens. It is shown that this may be accounted for by the overconsolidated specimens not reaching ultimate failure at the critical state. Parry's (1958) method of presenting pore pressure data at failure is used to construct pore pressure paths for the tills during undrained compression.
The Role of Electron Microscopy in Gas Turbine Materials Development
Authors: Sprague RA , Smashey RW 
Published: February 2009

Future gas turbine engines will require improved materials that cost less and overcome current design limitations without compromising product performance and reliability.
Advanced materials R&D emphasis has changed to address the challenges of new materials, including nonmetals, such as carbon/carbon, composites, and ceramics. Process redirection now focuses upon defect minimization and quicker reduction to practice (i.e. cost reduction and enhanced design property minimums. These objectives will also apply to 21st century power plants.
These changes require increased understanding of microstructural and property relationships which are being defined with the assistance of modern electron microscopy techniques. Examples of the application of some of these techniques to the development of new aircraft engine materials and processes are presented.
“The Wordtree”: An Add-On, Binomial Brancher of Process Words
Authors: Burger HG 
Published: February 2009

Niels Bohr's complementarity principle requires that we measure radiation either as particle (= matter) or wave (= process), but not both as simultaneously. We must now broaden Bohr's discovery to the words that describe phenomena.
Most terminological words are structural. We report a missing link, “The Wordtree®.” It is a new kind of concept-pinpointer (ISBN 0-936312-00-9) that groups all words by their effect on the environment—by procedure (= transitive verb). It behavioristically, not mentalistically, divides each binarily into its subprocesses, such as TO JOCKEY = TO RIDE AND TO MANEUVER. The Hierarchy half of the book arranges the 24,600 transitives from simple to complex. The Index half alphabetizes them. Thus the user can trace any process back, phase by phase, toward its components (its causes) or forward toward its potential effects. There are a quarter million words, including all parts of speech. Thereby the reader can pinpoint any idea and then skip-branch (instead of plodding) to its causes or effects. It includes 90,000 words of instruction and theory.
Terms as Database Records
Authors: Strehlow RA 
Published: February 2009

The standardized definitions of the American Society for Testing and Materials reflect a significant effort by many specialists working in numerous technical committees. The compiled set of ASTM terms and their definitions include attribution and source information as well as other important data associated with the definitions.
Enhanced awareness of terminology in recent years has led to an increase in the number of terms presented in the Compilation of ASTM Standard Definitions. This increase is associated with a larger number of multiply defined terms. Because of this and the several functions served by the Compilation, a need has become evident to attempt an enhancement of terminology management capability. With the recognition that definitions are amenable to being cast as database records, explorations have been conducted on structuring definitions of terms in this form.
The objective being developed by a working group of ASTM's Committee on Terminology is to convert the Compilation to a database structure. The desired goals include the need for simplicity and user transparency, economy of implementation, and, most importantly, usefulness to the technical committees and ASTM as a whole in the Society's terminology management effort.
A description is presented of a draft database record structure that is intended to address some of the important issues of this ongoing effort. Examples of applications are also discussed.
Management of Technical Terminology in Standards Organizations
Authors: Ellis WP 
Published: February 2009

The pioneering work of Wuster carried on by Felber in Austria, together with the activities of the Vienna School of Terminology and its progeny INFOTERM, have established principles of terminology practice and management that are well accepted in worldwide terminology circles. It appears, however, that in the United States this work is little known or ignored in consensus standards organizations.
In 1982 the ASTM symposium Terminology: The Cornerstone of Global Communications Through Standards (later made into an STP entitled Standardization of Technical Terminology: Principles and Practices), sponsored by the ASTM Standing Committee on Terminology, brought to the attention of that standards organization the realization that terminology has become a recognized technology, if not a science. Therefore, ASTM ought to use the principles and practices of technical terminology to manage the development and maintenance of the special vocabularies specific to ASTM technical committees. This usage will result in coherent and efficient employment of term concepts and meanings to give authority, credibility, and improved user comprehension to the pertinent standards.
The purpose of this paper is: (1) to relate experiences of ASTM technical committees in the process of revising their separate terminology standards; and (2) to show how a uniform system of terminology management, tailored to the special requirements of those committees, can produce terminology standards that are useful and probably essential to the experts within the committees and to the larger group of users, who do not have specialized knowledge of the field.
These committee experiences within one standards organization indicate procedures that would lead to a uniform policy of terminology management by the ASTM Committee on Terminology, and more widely, to improved and uniform terminology development in U.S. standards bodies.