Download or read book Constraint Effects in Fracture written by E. M. Hackett and published by ASTM International. This book was released on 1993 with total page 514 pages. Available in PDF, EPUB and Kindle. Book excerpt: Papers presented at the symposium on [title] held in Indianapolis, Indiana, May 1991, provide a framework for quantifying constraint effects in terms of both continuum mechanics and micro-mechanical modeling approaches. Such a framework is useful in establishing accurate predictions of the fracture

Download or read book Constraint Effects on Fracture Toughness written by and published by . This book was released on 2001 with total page 47 pages. Available in PDF, EPUB and Kindle. Book excerpt: The crack growth resistance (toughness) of a structural material depends on the geometry of the crack and the type of loading. These produce differences in the crack tip stress state referred to as the constraint. The stress state controls the deformation required to initiate fracture, and the mechanisms of fracture in steels are profoundly affected by the local constraint. This report describes the crack tip behaviour of 350WT ship steel, based on tests that characterized the fracture toughness of a ship steel plate over a range of constraint conditions. The tests were performed at room temperature on three-point bend bars that were pre-cracked to different crack depths. The mode of fracture was ductile tearing and resistance curves were calculated. Results for initiation toughness and growth resistance are characterized in both the linear elastic and elastic plastic formats. In addition, finite element modelling was used to determine numerically the crack tip stress fields, with special attention to the crack tip blunting behaviour.

Download or read book Constraint Effects in Fracture Theory and Applications written by Mark Kirk and published by ASTM International. This book was released on 1995 with total page 546 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Ductile Fracture of Metals written by P. F. Thomason and published by Pergamon. This book was released on 1990 with total page 240 pages. Available in PDF, EPUB and Kindle. Book excerpt: An account of the recent developments in research into ductile fracture in metals and alloys. Aspects covered include localized fracture at the root of notches and sharp cracks, and fracture in bulk plastic-deformation processes of the metal and metal forming type. Also discusses various theoretical

Download or read book Modeling the Constraint Effects on Fracture Toughness of Materials written by Sunil Kumar Prakash and published by . This book was released on 2009 with total page 87 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Cleavage fracture has been a very important subject for engineers for a long time because of the catastrophic result it may cause. The experimental results of cleavage fracture exhibit a large amount of scatter and show significant constraint effect, which motivated the development of statistical and micromechanics based methods in order to deal with such problem. The Weibull stress model, which is based on the weakest link statistics, uses two parameters, m and [sigma]u?, to describe the inherent distribution of the micro-scale cracks once the plastic deformation has occurred and to define the relationship between the macro and micro-scale driving forces for cleavage fracture. In this paper we examine constraint effects on cleavage fracture toughness numerically using a constraint function g(M) derived from the Weibull stress model. The non-dimensional function g(M) describes the evolution of constraint loss effects on fracture toughness relative to reference plane-strain small scale yielding (SSY) condition (T-stress=0). We performed detailed finite element analyses of single-edge notched bending speciments and compute g(M) functions for them. The g-function varies with parameters of the Weibull stress model, material flow properties and speciment geometry but not with absolute specimen size. Knowing the g-function one can construct fracture driving force curves for each absolute size of interest."--Abstract.

Download or read book 3 D Constraint Effects on Models for Transferability of Cleavage Fracture Toughness written by RH. Dodds and published by . This book was released on 1997 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since the late 1980s there has been renewed interest and progress in understanding the effects of constraint on transgranular cleavage in ferritic steels. Research efforts to characterize the complex interaction of crack tip separation processes with geometry, loading mode and material flow properties proceed along essentially two major lines of investigation: (1) multi-parameter descriptions of stationary crack-tip fields under large-scale yielding conditions, and (2) rational micromechanics models for the description of cleavage fracture which also reflect the observed scatter in the ductile-to-brittle transition (DBT) region. This article reviews the essential features of a specific example representing each approach: the J-Q extension to correlative fracture mechanics and a local approach based on the Weibull stress. Discussions focus on the growing body of 3-D numerical solutions for common fracture specimens which, in certain cases, prove significantly different from long-established plane-strain results.

Download or read book Evidence Concerning Crack tip Constraint and Strain rate Effects in Fracture toughness Testing written by and published by . This book was released on 1986 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The procedures for measuring the plane strain fracture toughness, K/sub Ic/, of metals were originally developed for relatively high yield strength materials, the toughnesses of which were not affected by stain rate. The application of these procedures to lower yield strength and higher toughness structural and pressure vessel steels have since revealed a perplexing combination of problems involving the effects of geometry, stable crack growth and strain rate on the measured values of toughness. Only the geometric problems were encountered in the development of the procedures for measuring K/sub Ic/. For fracture in the linear elastic range of the load-displacement curve, these problems were overcome by specifying specimen dimensions sufficiently large with respect of the plastic zone size at fracture. However, in the case of structural and pressure vessel steels, it is not always possible to test specimens large enough for fracture to occur prior to general yielding. Therefore, in these cases, the effects of large-scale yielding prior to fracture cannot be avoided, but since they presently have no analytical explanation they are being treated empirically.

Download or read book Fracture Mechanics written by Walter G. Reuter and published by ASTM International. This book was released on 1995 with total page 842 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Fracture Mechanics written by Fazil Erdogan and published by ASTM International. This book was released on 1995 with total page 716 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Constraint Effects on Fracture Toughness for Circumferentially Oriented Cracks in Reactor Pressure Vessels written by B. R. Bass and published by . This book was released on 1992 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Contact and Fracture Mechanics written by Pranav H. Darji and published by BoD – Books on Demand. This book was released on 2018-05-30 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book contains two sections: Chapters 1-7 deal with contact mechanics, and Chapters 8-13 deal with fracture mechanics. The different contributions of this book will cover the various advanced topics of research. It provides some needed background with respect to contact mechanics, fracture mechanics and the use of finite element methods in both. All the covered chapters of this book are of a theoretical and applied nature, suitable for the researchers of engineering, physics, applied mathematics and mechanics with an interest in computer simulation of contact and fracture problems.

Download or read book Advanced Fracture Mechanics and Structural Integrity written by Ashok Saxena and published by CRC Press. This book was released on 2019-02-06 with total page 348 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advanced Fracture Mechanics and Structural Integrity is organized to cover quantitative descriptions of crack growth and fracture phenomena. The mechanics of fracture are explained, emphasizing elastic-plastic and time-dependent fracture mechanics. Applications are presented, using examples from power generation, aerospace, marine, and chemical industries, with focus on predicting the remaining life of structural components and advanced testing metods for structural materials. Numerous examples and end-of-chapter problems are provided, along with references to encourage further study.The book is written for use in an advanced graduate course on fracture mechanics or structural integrity.

Download or read book Fracture Toughness Testing and Its Applications written by ASTM Committee E-24 Staff and published by ASTM International. This book was released on 1981-10 with total page 430 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Effects of Constraint on Upper Shelf Fracture Toughness written by JA. Joyce and published by . This book was released on 1995 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: The upper shelf fracture toughness and tearing resistance of two structural steels, HY-100 and ASTM A533, Gr. B, were determined over a wide range of applied constraint. The constraint conditions were varied by changes in specimen geometry and loading mode. Bend specimens with shallow and deep cracks, compact specimens, and single and double edge notched tension specimens were used in this study. A rotation correction was developed for the single edge notch tension specimen which greatly improved the behavior of the J-R curves determined using this specimen. The experimental results were used to investigate the applicability of the Q and T stress parameters to the correlation of upper shelf initiation toughness, JIc, and tearing resistance, Tmat. The J-Q and J-T stress loci, and corresponding plots of material tearing resistance plotted against Q and T, were developed and compared with the expectations of the O'Dowd and Shih and the Betégon and Hancock analyses. The principle conclusions of this work are that JIc does not appear to be dependent on T stress or Q while the material tearing resistance, Tmat, is dependent on T stress and Q, with the tearing modulus increasing as constraint decreases.

Download or read book Biaxial Loading and Shallow flaw Effects on Crack tip Constraint and Fracture Toughness written by B. R. Bass and published by . This book was released on 1994 with total page 61 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Effects of Tensile Loading on Upper Shelf Fracture Toughness written by and published by . This book was released on 1994 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Constraint has been an important consideration in fracture mechanics from the earliest work that was done to develop the 1974 version of the ASTM Standard E399. OD̀owd and Shih (1991) have proposed that the difference in crack tip stress fields can be quantified in terms of a field quantity that they have call Q. The Q quantity is a function of J, the crack shape and size, the structural geometry, mode of loading and on the level of deformation and can only be calculated from a high resolution elastic-plastic computational analysis. A similar, simpler, but more controversial approach has been suggested by Betegon and Hancock (1991), who use the non-singular term of the elastic, crack singularity solution, called the T-Stress, as a measure of elastic-plastic crack tip constraint. The objective of this work is to develop some upper shelf, elastic-plastic experimental results to attempt to investigate the applicability of the Q and T stress parameters to the correlation of upper shelf initiation toughness and J resistance curves. The first objective was to obtain upper shelf J resistance curves, J{sub Ic}, and tearing resistance results for a range of applied constraint. The J-Q and J-T stress loci were developed and compared with the expectations of the OD̀owd and Shih and the Betegon and Hancock analyses. Constraint was varied by changing the crack length and also by changing the mode of loading from bending to predominantly tensile. The principle conclusions of this work are that J{sub Ic} does not appear to be dependent on T stress or Q while the material tearing resistance is dependent on T stress and Q, with the tearing modulus increasing as constraint decreases.

Download or read book Influence of Material and Constraint Variation on the Fracture Toughness Behaviour of Steels written by Robert Kulka and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The analysis of fracture toughness test data from standard specimens is often based upon the assumptions of planar crack fronts and homogenous material properties. However, these assumptions do not hold true for all test geometries or real components. The overall objective of this EngD was therefore to develop the methodologies used in fracture assessment of steel components, by incorporating a reduction in the conservatisms inherent in the assessment procedures. These conservatisms are associated with applying a 'lower bound' treatment to steel components, which in reality contain significant variability in effective fracture toughness, due to either material considerations (macroscopic or microstructural), or geometrical considerations including the effect of crack tip constraint. The first method developed allows a comparison of a variation of fracture toughness values throughout a component, to a variation of the localised effective crack driving force. The main feature of this method takes advantage of the nature of the ductile-to-brittle transition regime of fracture toughness, where there is significant scatter. This leads to a probabilistic prediction of the location of fracture initiation, and a less conservative estimate of failure load, used to derive enhanced fracture toughness for the component. The second method calculates less conservative fracture toughness values for steels where there is significant heterogeneity in the dataset. The effects of measurement uncertainty on derived fracture toughness values can be monitored to improve probabilistic estimates of the heterogeneous fracture toughness values. These methods have been developed into predictive software tools, validated against data from the literature. Finite element analysis of various configurations of compact tension and bend specimen, under different constraint conditions, was used to identify fracture mechanics parameters and constraint factors that will be of use in deriving accurate fracture toughness relationships from future testing programmes. The viability of low constraint specimens for accurately characterising increases in fracture toughness has been assessed. These recommendations enhance the relationships and advice suggested in the testing standards and literature. Loss of constraint in thin components can be quantified by a triaxiality parameter, which can be used to predict an increase in fracture toughness through use of a damage model, in this case developed based on a ductility exhaustion approach. This model can be used to predict initiation of ductile fracture in configurations with low constraint, leading to less conservative fracture toughness values, enhancing the guidance in the various defect tolerance assessment procedures.