Download or read book Prediction of Cleavage Fracture in the Brittle to Ductile Transition Region of a Ferritic Steel written by A. Bakker and published by . This book was released on 1995 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: A model is presented to predict the event of cleavage fracture in the brittle to ductile transition region. In this region cleavage fracture could occur after some amount of ductile tearing. The model takes into account the competition between the nucleation of voids at second phase inclusions leading to ductile fracture and the nucleation of unstable micro cracks initiated at second phase inclusions leading to cleavage fracture. The model was tested on four point bend specimens of a ferritic steel tested in the brittle to ductile transition region. It was shown that there could be a significant amount of ductile crack growth before the specimens failed by cleavage. Two different crack growth simulations were performed to investigate the stresses ahead of a ductile growing crack. One simulation takes into account the softening of the material in the process zone, due to damage, around a quasistatically ductile growing crack. The second simulation neglects this damage. It was found that the crack opening stress near the crack tip in the process zone is significantly lower than in the analysis neglecting the effect of damage. Further from the crack tip, outside the damage zone the crack opening stresses are similar in both simulations.
Download or read book Prediction of Cleavage Fracture Probability for Ferritic Steels in the Transition Region written by V. Bicego and published by . This book was released on 1995 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt: A method is described for modelling the stochastic variability of toughness data for ferritic steels in the brittle to ductile transition regime. The present model is based on two ingredients: a weakest link approach using Weibull statistics with a suitable modification to include the effect of ductile tearing, and an accurate expression of the material J-R curve, determined from fractography. The model provides a rationale for the different fracture behaviour of a material over the whole range of temperature, from fully stable J-R behaviour at high temperature down to brittle fracture under LEFM conditions at low temperature.
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 Fracture Toughness of Ferritic Steels in the Ductile to Brittle Transition Region written by Carlos Berejnoi and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Ferritic steels, as other materials, have different failure modes depending on the temperature. At elevated temperatures, they behave as ductile materials, while at low temperatures they are brittle. There is an intermediate temperature region where these alloys have a failure mode resulting from the competition between cleavage and ductile mechanisms. This region is known as the ductile-to-brittle transition zone. The characterization of fracture resistance of ferritic steels in the ductile-to-brittle transition region is problematic due to scatter in results, as well as size and temperature dependences. American Society for Testing and Materials (ASTM) has standardized the determination of a temperature reference (T0) for the fracture toughness characterization of ferritic steels in this region. This chapter presents the evolution of the statistical treatment of fracture toughness data until the present, including some comments on T0 determination, and some aspects that require a deeper analysis.
Download or read book Cleavage Fracture of Steel in the Ductile Brittle Transition Region written by AR. Rosenfield and published by . This book was released on 1985 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fracture-toughness experiments on ASTM A508 (Unified Numbering System [UNS] K13502) steel within the ductile-brittle transition region are a combination of both ductile and brittle behaviors, leading to severe data scatter. Both crack blunting and dimpled rupture are terminated by unstable cleavage. At a lower test temperature, cleavage during blunting predominates, whereas at a higher test temperature, cleavage tends to occur after some stable crack growth. It is suggested that this behavior results from the existence of a distribution of "trigger" sites in the microstructure (for example, inclusions and carbides). Methods for eliminating the dimpled-rupture contribution to the test record are discussed and are shown to be useful for predicting large-specimen behavior.
Download or read book Micromechanical Prediction of Fracture Toughness for Pressure Vessel Steel Using a Coupled Model written by MR. Goldthorpe and published by . This book was released on 1999 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt: A method of analyzing the ductile to brittle transition region of a ferritic steel using a coupled micromechanical model of ductile damage, stable crack growth and cleavage fracture has been developed to improve the definition of upper shelf behavior for actual structures. Ductile damage is modelled using the Gurson model as modified by Tvergaard, along with a specially developed crack growth user element. The probability of cleavage fracture is predicted by post-processing the finite element results using the Beremin model of cleavage fracture. Predictions are made of ductile tearing and cleavage fracture in test specimen and wide plate configurations of A533B steel for a range of temperatures. The coupled model is capable of predicting transition toughness and transition temperature shifts for different levels of structural constraint. An analytically-based definition of the onset of upper shelf temperature (OUST) is the temperature at which the coupled ductile damage/cleavage fracture model predicts a probability of failure by cleavage fracture of 5%. Estimates of the shift in the OUST due to different levels of in-plane crack tip constraint are made using the elastic T-stress as a measure of constraint. There is potential for using the T-stress as a measure of structural constraint in order to determine shifts in transition temperature for materials with degraded toughness.
Download or read book Prediction of the Shape of the KJ Ductile to Brittle Transition Temperature Curve for Ferritic Pressure Vessel Steels Using the Material s Resistance to Crack Extension KJ Versus a Curve written by G. Wardle and published by . This book was released on 2007 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fracture toughness (KJ (cleavage) ) measurements made within the ductile-to-brittle transition region for ferritic pressure vessel steels are not always described by the shape of the Master Curve currently given in ASTM Standard E 1921. The objective of this paper is to show how the shape of the transition toughness curve may be related to the shape of the material's resistance to crack extension curve (KJR) once the crack tip starts to blunt and ductile crack extension precedes cleavage failure. Using an empirical relationship between the mean ductile crack extension (?a) prior to the onset of cleavage failure and temperature (?a=?exp(?T)), then the relationship between KJ and T may simply be given by KJ=KA+?[?exp(?T)]?, where KA, ?, and ? are simply the coefficients to an offset power law to KJ versus ?a data given by KJR=KA+?(?a)?. For specimens of different sizes, a reference temperature TK may be defined for a given reference level of ?a or equivalent KJ. Unique curves may be defined for materials with differing crack extension resistance curves through plots of KJ versus (T-T?a(ref)) or (T-TK(ref)). The generalized form of the transition curve may be given by KJ=KA+??a(ref)exp[?(T-T?a(ref))]?, or KJ=KA+(K(ref)-KA)exp[?(T-TK(ref))]?. Experimentally, ? has been estimated as approximately 0.08 for nuclear pressure vessel materials such as A533B/A508. Using a specific situation wherein the value of KA=30 MPa ?m, K(ref)=100 MPa ?m, and ?=0.25 then, for a B=25-mm specimen, within experimental scatter this provides an almost exact match to the Master Curve given by KJ=30+70exp[0.019(T-TK100)]. The predictions of transition curve shape using the material's resistance to crack extension curve are believed to be complementary to the Master Curve method, and may describe the shape of the transition curve when there is ductile crack extension prior to cleavage failure. Further work is recommended to investigate the relationship between the predicted ductile-to-brittle transition curve and the Master Curve for probabilities of cleavage failure post-initiation.
Download or read book Nonlinear Fracture Mechanics written by John D. Landes and published by ASTM International. This book was released on 1988 with total page 652 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Invariant Probabilities of Markov Feller Operators and Their Supports written by Radu Zaharopol and published by Springer Science & Business Media. This book was released on 2005-01-28 with total page 1008 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book covers invariant probabilities for a large class of discrete-time homogeneous Markov processes known as Feller processes. These Feller processes appear in the study of iterated function systems with probabilities, convolution operators, and certain time series. From the reviews: "A very useful reference for researchers wishing to enter the area of stationary Markov processes both from a probabilistic and a dynamical point of view." --MONATSHEFTE FÜR MATHEMATIK
Download or read book IUTAM Symposium on Nonlinear Analysis of Fracture written by J.R. Willis and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 398 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume constitutes the Proceedings of the IUTAM Symposium on 'Nonlinear Analysis of Fracture', held in Cambridge from 3rd to 7th Septem ber 1995. Its objective was to assess and place on record the current state of understanding of this important class of phenomena, from the standpoints of mathematics, materials science, physics and engineering. All fracture phenomena are nonlinear; the reason for inclusion of this qualification in the title was to reflect the intention that emphasis should be placed on distinctive aspects of nonlinearity, not only with regard to material consti tutive behaviour but also with regard to insights gained, particularly from the mathematics and physics communities, during the recent dramatic ad vances in understanding of nonlinear systems in general. The expertise represented in the Symposium was accordingly very wide, and many of the world's greatest authorities in their respective fields participated. The Symposium remained focussed on issues of practical significance for fracture phenomena, with concentration on aspects that are still im perfectly understood. The most significant unifying issue in this regard is that of scale: this theme was addressed from several perspectives. One important aspect is the problem of passing information on one scale up or down, as an input for analysis at another scale. Although this is not always the case, it may be that the microscopic process of fracture is understood in some particular class of materials.
Download or read book Transferability of Fracture Mechanical Characteristics written by Ivo Dlouhý and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 380 pages. Available in PDF, EPUB and Kindle. Book excerpt: Five laboratories from France, Hungary and the Czech Republic have solved a Project supported fmancially by NATO within the Science for Peace Program (under Nr. 972655) for three years. The project, titled Fracture ResistanceofSteelsfor Containers of Spent Nuclear Fuel, was focused (i) on the generation of data needed for the qualification procedure of a new container introduced by Skoda Nuclear Machinery and (ii) on a number of topics of scientific nature associated with the interesting field of transferability of fracture mechanical data-, It has been found during numerous conference presentations of project results that the knowledge developed within the project would be more attractive when published in a more comprehensive form. This was the reason why the final project workshop was arranged as a meeting of project collaborators and contributing invited experts working in very similar field. The main scope of the final project workshop, titled Transferability of Fracture Mechanical Data and held in Brno from 5 to 6 November 200I, was to bring together project collaborators with a number of invited international experts, both covering the spectrum of topics solved within the project and reviewing the project results in the presence ofthese specialists. A totalof34 colleagues from 7 European countries and the USA participated in the workshop.
Download or read book IUTAM Symposium on Micromechanics of Plasticity and Damage of Multiphase Materials written by André Pineau and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 442 pages. Available in PDF, EPUB and Kindle. Book excerpt: The IUT AM Symposium on "Micromechanics of Plasticity and Damage of Multiphase Materials" was held in Sevres, Paris, France, 29 August - 1 September 1995. The Symposium was attended by 83 persons from 18 countries. In addition 17 young French students attended the meeting. During the 4 day meeting, a total of 55 papers were presented, including 24 papers in the poster sessions. The meeting was divided into 7 oral and 3 poster sessions. The 7 oral sessions were the following: - Plasticity and Viscoplasticity I and II; - Phase transformations; - Damage I and II; - Statistical and geometrical aspects; - Cracks and interfaces. Each poster session was introduced by a Rapporteur, as follows: - Session I (Plasticity and Viscoplasticity): G. Cailletaud; - Session 2 (Damage): D. Franc;:ois; - Session 3 (Phase transformation; statistical and geometrical aspects): D. Jeulin. The main purpose of the Symposium was the discussion of the state of the art in the development of micromechanical models used to predict the macroscopic mechanical behaviour of mUltiphase solid materials. These materials consist of at least two chemically different phases, present either initially or formed during plastic deformation, when a strain-induced phase transformation takes place. One session was devoted to the latter case. Continuously strengthened composite materials, containing long fibers, were out of the scope of the Symposium.
Download or read book A Combined Statistical and Constraint Model for the Ductile Brittle Transition Region written by TL. Anderson and published by . This book was released on 1988 with total page 21 pages. Available in PDF, EPUB and Kindle. Book excerpt: A model is presented which uses weakest link statistics to predict the fracture toughness of ferritic steels in the ductile-brittle transition region. This model is different from previous analyses in that it considers large-scale yielding and specimen geometry effects.
Download or read book Fatigue and Fracture Mechanics written by John H. Underwood and published by ASTM International. This book was released on 1997 with total page 697 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Local Approach to Fracture written by Clotilde Berdin and published by Presses des MINES. This book was released on 2004 with total page 91 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents several aspects of the local approach to fracture: damage mechanisms, experimental techniques, damage evolution law and failure criteria, modelling of damage, and numerical simulation -- Back cover.
Download or read book Fracture Mechanics written by and published by ASTM International. This book was released on 1989 with total page 685 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fatigue and Fracture Mechanics written by Tina Louise Panontin and published by ASTM International. This book was released on 1999 with total page 922 pages. Available in PDF, EPUB and Kindle. Book excerpt:
