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Ductile Fracture At Intermediate Stress Triaxialities
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Book Synopsis Ductile Fracture at Intermediate Stress Triaxialities by : Matthieu Dunand
Download or read book Ductile Fracture at Intermediate Stress Triaxialities written by Matthieu Dunand and published by . This book was released on 2013 with total page 256 pages. Available in PDF, EPUB and Kindle. Book excerpt: Accurate predictions of the onset of ductile fracture play an increasingly important role in the design of lightweight sheet metal structures. With the development of virtual prototyping practices, most transportation vehicles are now computer-engineered in great detail before launching their mass production, thereby requiring reliable models for plasticity and fracture. This thesis reports on a comprehensive investigation into the effect of stress state on the onset of ductile fracture of an Advanced High Strength Steel (AHSS), covering development of new experimental procedures, material characterization and phenomenological as well as micro-mechanical modeling of the onset of fracture. Based on an extensive multi-axial experimental program, the anisotropic plasticity of the present material is described by a non-associated quadratic anisotropic model. Comparison of model predictions to experimental results reveals that the proposed model provides better predictions than associated isotropic or anisotropic quadratic models. Moreover, a structural validation is presented that demonstrates the higher prediction accuracy of the non-associated plasticity model. A hybrid experimental-numerical approach is proposed to investigate the dependence of the onset of fracture to stress state. The experimental program covers the complete range of positive stress triaxialities, from pure shear to equibiaxial tension. It includes different full thickness specimens as well as multi-axial fracture experiments where combinations of tension and shear loadings are applied to a newly developed butterfly-shaped specimen. Loading paths to fracture are determined for each experiment in terms of stress triaxiality, Lode angle parameter and equivalent plastic strain and show a non-monotonic and strong dependence of ductility to stress state. The extensive fracture characterization is used to evaluate the predictive capabilities of two phenomenological and physics-inspired fracture models (the Modified Mohr-Coulomb and a shear-modified Gurson model) that take the effect of the first and third stress tensor invariants into account in predicting the onset of fracture. Finally, a micro-mechanical model relating the onset of fracture to plastic localization into a narrow band at the micro-scale is developed. The effect of stress state on localization is investigated numerically by means of a 3D void-containing unit cell submitted to well-controlled and proportional loadings in the macroscopic stress state. Based on simulation results, an analytical localization criterion is proposed which defines an open convex envelope in terms of the shear and normal stresses acting on the plane of localization and correlates well with experimental results.
Book Synopsis Engineering Damage Mechanics by : Jean Lemaitre
Download or read book Engineering Damage Mechanics written by Jean Lemaitre and published by Springer Science & Business Media. This book was released on 2006-01-16 with total page 396 pages. Available in PDF, EPUB and Kindle. Book excerpt: Reflecting his major contributions to the field, Jean Lemaitre’s "Engineering Damage Mechanics" presents simplified and advanced methods organized within a unified framework for designers of any mechanical component. Explains how to apply continuous damage mechanics to failures of mechanical and civil engineering components in ductile, creep, fatigue and brittle conditions. Incorporates many basic examples, while emphasizing key practical considerations such as material parameter identification, and provides perspective on the advantage and disadvantages of various approaches.
Book Synopsis The Effect of Stress Triaxiality on the Occurrence of Ductile Fracture in Low Strength Steels by : Akio Otsuka
Download or read book The Effect of Stress Triaxiality on the Occurrence of Ductile Fracture in Low Strength Steels written by Akio Otsuka and published by . This book was released on 1982 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Studies on Strain Localization, Ductile Fracture and Damage in Structural Metals by : Yazhi Zhu
Download or read book Studies on Strain Localization, Ductile Fracture and Damage in Structural Metals written by Yazhi Zhu and published by . This book was released on 2017 with total page 666 pages. Available in PDF, EPUB and Kindle. Book excerpt: One of the most important limit states in structural metals is ductile fracture, and the prediction of ductile fracture is of great importance in many engineering applications. The overall objective of the research reported in this dissertation is to advance the understanding and modeling of ductile fracture in metals. This research addresses three main issues: micromechanical modeling of ductile fracture, the development of a micromechanics-based ductile fracture model and its numerical implementation, and a numerical investigation of geometry and damage induced strain localization based on a nonlocal formulation. It has long been recognized that stress triaxiality is a key parameter affecting initiation of ductile fracture. More recently, shear stress has been identified as another important parameter, in addition to stress triaxiality, that influences the process of ductile fracture. In this research, a micromechanics-based model is proposed for predicting initiation of ductile fracture that couples both stress triaxiality and shear stress. The new model is based on a combination of the existing Rice-Tracey and modified maximum shear stress models. The new model is applied to construct the fracture locus of different types of metal alloys and is used to predict fracture initiation by numerical tools. The predicted results are in good agreement with experimental data reported in literature that covers a wide range of triaxialities and shear stress. Another portion of this research, within the framework of micromechanics, investigated the effect of combined normal and shear stress components on micro-void evolution and material behavior. This work involved finite element modeling of a cubic unit cell associated with a spherical void. The results show that the void growth process and macroscopic stress-strain response is highly dependent on the shear stress component. At different ranges of triaxialities, and with different void growth and coalescence mechanisms, shear stress has an important effect on the ductile fracture process. Numerical modeling of strain localization in ductile metals based on standard continuum mechanics exhibits non-convergent mesh sensitivity. This issue is addressed in the final portion of this research. A one-dimensional model based on the nonlocal theory is proposed to analyze geometry-induced strain localization, i.e., necking in structural metals. A nonlocal continuum damage model using the same enhanced continuum law is developed to deal with the damage induced strain localization in metals. Both models provide encouraging performance in eliminating the non-convergent mesh sensitivity problem. Such improved strain localization modeling techniques show potential to be useful for further exploration of ductile fracture phenomena.
Book Synopsis Metal Forming by : William F. Hosford
Download or read book Metal Forming written by William F. Hosford and published by Cambridge University Press. This book was released on 2011-02-07 with total page 345 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book helps the engineer understand the principles of metal forming and analyze forming problems - both the mechanics of forming processes and how the properties of metals interact with the processes. In this fourth edition, an entire chapter has been devoted to forming limit diagrams and various aspects of stamping and another on other sheet forming operations. Sheet testing is covered in a separate chapter. Coverage of sheet metal properties has been expanded. Interesting end-of-chapter notes have been added throughout, as well as references. More than 200 end-of-chapter problems are also included.
Book Synopsis Studies in Large Plastic Flow and Fracture by : Percy Williams Bridgman
Download or read book Studies in Large Plastic Flow and Fracture written by Percy Williams Bridgman and published by Cambridge : Harvard University Press. This book was released on 1964 with total page 384 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Ductile Fracture and Ductility by : Bradley Dodd
Download or read book Ductile Fracture and Ductility written by Bradley Dodd and published by Academic Press. This book was released on 1987 with total page 328 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Ductile Fracture in Metal Forming by : Kazutake Komori
Download or read book Ductile Fracture in Metal Forming written by Kazutake Komori and published by Academic Press. This book was released on 2019-10-11 with total page 294 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ductile Fracture in Metal Forming: Modeling and Simulation examines the current understanding of the mechanics and physics of ductile fracture in metal forming processes while also providing an approach to micromechanical ductile fracture prediction that can be applied to all metal forming processes. Starting with an overview of different ductile fracture scenarios, the book then goes on to explain modeling techniques that predict a range of mechanical phenomena that can lead to ductile fracture. The challenges in creating micromechanical models are addressed alongside methods of applying these models to several common metal forming processes. This book is suitable for researchers working in mechanics of materials, metal forming, mechanical metallurgy, and plasticity. Engineers in R&D industries involved in metal forming such as manufacturing, aerospace, and automation will also find the book very useful. Explains innovative micromechanical modeling techniques for a variety of material behaviors Examines how these models can be applied to metal forming processes in practice, including blanking, arrowed cracks in drawing, and surface cracks in upset forging Provides a thorough examination of both macroscopic and microscopic ductile fracture theory
Book Synopsis A Course on Damage Mechanics by : Jean Lemaitre
Download or read book A Course on Damage Mechanics written by Jean Lemaitre and published by Springer Science & Business Media. This book was released on 2013-12-14 with total page 225 pages. Available in PDF, EPUB and Kindle. Book excerpt: A new branch of science usually develops thus. Somebody publishes the basic ideas. Hesitatingly at first, then little by little, other original contributions appear, until a certain threshold is reached. Then, overview articles are printed, conferences are held, and a first mention is made in textbooks, until specialized monographs are written. Continuum darnage mechanics has reached that status now. To analyze or, if possible, to predict the failure of machine parts or other structures is one of the main goals of engineering science. Consequently fracture mechanics became one of its leading branches. It was based on the analysis of existing cracks. However, especially under conditions of cyclic loading, this might be too late to prevent a disaster. Therefore, the question regarding the precursory state, that is, the evolution of intemal darnage before macrocracks become visible, was then posed. One of the successful approaches to the problern was Weibull's theory which examined, in a statistical manner, the "weakest link" in the material volume under consideration. Unfortunately it proved too difficult mathematically to be applied to complicated parts or structures. Therefore it was highly appreciated by the scientific of material community when L. M. Kachanov published in 1958 a simple model darnage which subsequently could be extended to brittle elastic, plastic or viscous materials under all conditions of uniaxial or multiaxial, simple or cyclic loadings, so that it may be considered nearly universal.
Book Synopsis State of the Art and Future Trends in Material Modeling by : Holm Altenbach
Download or read book State of the Art and Future Trends in Material Modeling written by Holm Altenbach and published by Springer Nature. This book was released on 2019-10-23 with total page 505 pages. Available in PDF, EPUB and Kindle. Book excerpt: This special anniversary book celebrates the success of this Springer book series highlighting materials modeling as the key to developing new engineering products and applications. In this 100th volume of “Advanced Structured Materials”, international experts showcase the current state of the art and future trends in materials modeling, which is essential in order to fulfill the demanding requirements of next-generation engineering tasks.
Book Synopsis Fractography and Failure Analysis by : Jorge Luis González-Velázquez
Download or read book Fractography and Failure Analysis written by Jorge Luis González-Velázquez and published by Springer. This book was released on 2018-03-19 with total page 172 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents fractography and failure analysis at a level that is accessible for non-expert readers, without losing scientific rigor. It offers a comprehensive description of fracture surfaces in engineering materials, with an emphasis on metals, and of the methodology for the observation of fracture surfaces. It also discusses in detail the main fracture mechanisms and their corresponding fracture surfaces, including brittle, ductile, fatigue, and environmental fractures. The last chapter is dedicated to the use of fractography in determining of the causes component failure. In modern engineering, the analysis of fractured components is a common practice in many fields, such as integrity management systems, materials science research, and failure investigations. As such this book is useful for engineers, scientists, engineering students, loss adjuster surveyors and any professional dealing with fractured components.
Book Synopsis Micromechanics Modelling of Ductile Fracture by : Zengtao Chen
Download or read book Micromechanics Modelling of Ductile Fracture written by Zengtao Chen and published by Springer Science & Business Media. This book was released on 2013-04-02 with total page 335 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book summarizes research advances in micromechanics modeling of ductile fractures made in the past two decades. The ultimate goal of this book is to reach manufacturing frontline designers and materials engineers by providing a user-oriented, theoretical background of micromechanics modeling. Accordingly, the book is organized in a unique way, first presenting a vigorous damage percolation model developed by the authors over the last ten years. This model overcomes almost all difficulties of the existing models and can be used to completely accommodate ductile damage developments within a single-measure microstructure frame. Related void damage criteria including nucleation, growth and coalescence are then discussed in detail: how they are improved, when and where they are used in the model, and how the model performs in comparison with the existing models. Sample forming simulations are provided to illustrate the model’s performance.
Book Synopsis Blast Mitigation Strategies in Marine Composite and Sandwich Structures by : Srinivasan Gopalakrishnan
Download or read book Blast Mitigation Strategies in Marine Composite and Sandwich Structures written by Srinivasan Gopalakrishnan and published by Springer. This book was released on 2017-12-14 with total page 477 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book primarily focuses on methodologies to enable marine structures to resist high velocity impact loadings. It is based on invited talks presented at the recent India–USA workshop on “Recent Advances in Blast Mitigation Strategies in Civil and Marine Composite Structures” The book comprises content from top researchers from India and the USA and covers various aspects of the topic, including modeling and simulation, design aspects, experimentation and various challenges. These failure modes significantly reduce the structural integrity of the marine structures unless they are designed to resist such harsh loadings. Understanding the mechanics of these structures under harsh loadings is still an open area of research, and the behavior of these structures is not fully understood. The book highlights efforts to reduce the effects of blast loadings on marine composite structures. Intended for researchers/scientists and practicing engineers, the book focuses not only the design and analysis challenges of marine composite structures under such harsh loading conditions, but also provides new design guidelines.
Book Synopsis Numerical Modelling and Simulation of Metal Processing by : Christof Sommitsch
Download or read book Numerical Modelling and Simulation of Metal Processing written by Christof Sommitsch and published by MDPI. This book was released on 2021-08-16 with total page 374 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book deals with metal processing and its numerical modelling and simulation. In total, 21 papers from different distinguished authors have been compiled in this area. Various processes are addressed, including solidification, TIG welding, additive manufacturing, hot and cold rolling, deep drawing, pipe deformation, and galvanizing. Material models are developed at different length scales from atomistic simulation to finite element analysis in order to describe the evolution and behavior of materials during thermal and thermomechanical treatment. Materials under consideration are carbon, Q&T, DP, and stainless steels; ductile iron; and aluminum, nickel-based, and titanium alloys. The developed models and simulations shall help to predict structure evolution, damage, and service behavior of advanced materials.
Book Synopsis Ductile Fracture After Complex Loading Histories by : Stephane Jean Marie Marcadet
Download or read book Ductile Fracture After Complex Loading Histories written by Stephane Jean Marie Marcadet and published by . This book was released on 2015 with total page 173 pages. Available in PDF, EPUB and Kindle. Book excerpt: In engineering practice, sheet metal often fails after complex strain paths that deviate substantially from the widely studied proportional loading paths. Different from previous works on the ductile fracture of sheet metal, this thesis research addresses the experimental and modeling issues related to the crack initiation in advanced high strength steels after loading direction reversal. The main outcome of the present work is a fracture initiation model for proportional and non-proportional loading. The starting point of this thesis is a first chapter on the development of a micromechanically-motivated ductile fracture initiation model for metals for proportional loading. Its formulation is based on the assumption that the onset of fracture is imminent with the formation of a primary or secondary band of localization. Motivated by the results from a thorough unit cell analysis, it is assumed that fracture initiates after proportional loading if the linear combination of the Hosford equivalent stress and the normal stress acting on the plane of maximum shear reaches a critical value. A comprehensive fracture initiation model is then obtained after transforming the localization criterion from the stress space to the space of equivalent plastic strain, stress triaxiality and Lode angle parameter using the material's isotropic hardening law. Experimental results are presented for three different advanced high strength steels. For each material, the onset of fracture is characterized for five distinct stress states, including butterfly shear, notched tension, tension with a central hole, and punch experiments. The comparison of model predictions with the experimental results demonstrates that the proposed Hosford-Coulomb model can predict with satisfactory accuracy the instant of ductile fracture initiation in advanced high strength steels. In a subsequent chapter, experimental methods are developed to perform compression tension experiments. In addition, a finite strain constitutive model is proposed combining a Swift-Voce isotropic hardening law with two Frederick-Armstrong kinematic hardening rules and a Yoshida-Uemori type of hardening stagnation approach. The plasticity model parameters are identified from uniaxial tension-compression stress-strain curve measurements and finite element simulations of compression-tension experiments on notched specimens. The model predictions are validated through comparison with experimentally-measured load-displacement curves up to the onset of fracture, local surface strain measurements and longitudinal thickness profiles. The extracted loading paths to fracture show a significant increase in ductility as a function of the compressive pre-strain. The Hosford-Coulomb model is therefore integrated into a non-linear damage indicator modeling framework to provide a phenomenological description of the experimental results for monotonic and reverse loading. Another extension of the modeling framework is presented in a third chapter inspired by the results from loss of ellipticity analysis. It is demonstrated that the Hosford-Coulomb model can also be expressed in terms of a stress-state dependent critical hardening rate. Moreover, it is shown that the critical hardening rate approach provides accurate predictions of the instant of fracture initiation for both proportional and non-proportional loading conditions. Enhancements of the finite strain constitutive model are also proposed to enable a fast identification of all model parameters. The plasticity model parameters are identified from stress-strain curve measurements from shear loading reversal on specimens with a uniform thickness reduced gage section. The model is used to estimate the local strain and stress fields in fracture experiments after shear reversal. The extracted loading paths to fracture show a significant increase in ductility as a function of the strain at shear reversal, a feature that is readily predicted by the prosed critical hardening rate model.
Book Synopsis Fundamentals of Fracture Mechanics by : John Frederick Knott
Download or read book Fundamentals of Fracture Mechanics written by John Frederick Knott and published by Gruppo Italiano Frattura. This book was released on 1973 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Ductile Fracture Strain in Uniaxial Tensile Test of Plane Specimen's by : Mohamed Zulqarnain Mohamed Akram
Download or read book Ductile Fracture Strain in Uniaxial Tensile Test of Plane Specimen's written by Mohamed Zulqarnain Mohamed Akram and published by . This book was released on 2012 with total page 94 pages. Available in PDF, EPUB and Kindle. Book excerpt: This project was performed to determine the ductile fracture strain in uniaxial tensile test of plane specimen. In this project, uniaxial tensile test was performed for three difference material that is aluminum, brass and mild steel. The objective of the test is to identify the value of uniaxial fracture strain for these three difference materials. The specimens have been divided into three difference area: L, P-lateral and S-middle zones. The zones are measured using optical microscope before and after the tensile test to determine the value of ductile fracture strain at those zones. However, the result from tensile test gives an average value of ductile fracture strain. The second step was to determine the suitable point or area to get the accurate uniaxial ductile fracture strain. The element of the material with stress triaxiality,k = 0.33 is the location where the uniaxial fracture strain was occurred. Finite element analysis using MSC Patran/Marc 2008r1 software was used to determine the element with stress triaxiality,k = 0.33. In MSC Patran software, the specimen was divided into several nodes to represent the study location for lateral and middle zones. In this project, the model was divided into eleven points. Each point has differences values of stress triaxiality after ultimate tensile strength occurred. The finite element analysis data of engineering stress-strain curve was compared with experiment engineering stress-strain curve in order to determine the fracture point of the model. The state of stress for each material was determined in order to get the uniaxial ductile fracture strain nodes. The result shows that uniaxial ductile fracture strain occurred at nodes 2577 for aluminium and brass, while uniaxial ductile fracture strain for mild steel occurred at node 2598. It is also shown that the fracture strain at L and P-lateral zones was the nearest to the uniaxial ductile fracture strain.
