Download or read book Micromechanical Modelling of Damage and Fracture of Ductile Materials written by Dirk Steglich and published by . This book was released on 1998 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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.

Download or read book Micromechanics of Fracture and Damage written by Luc Dormieux and published by John Wiley & Sons. This book was released on 2016-03-31 with total page 249 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book deals with the mechanics and physics of fractures at various scales. Based on advanced continuum mechanics of heterogeneous media, it develops a rigorous mathematical framework for single macrocrack problems as well as for the effective properties of microcracked materials. In both cases, two geometrical models of cracks are examined and discussed: the idealized representation of the crack as two parallel faces (the Griffith crack model), and the representation of a crack as a flat elliptic or ellipsoidal cavity (the Eshelby inhomogeneity problem). The book is composed of two parts: The first part deals with solutions to 2D and 3D problems involving a single crack in linear elasticity. Elementary solutions of cracks problems in the different modes are fully worked. Various mathematical techniques are presented, including Neuber-Papkovitch displacement potentials, complex analysis with conformal mapping and Eshelby-based solutions. The second part is devoted to continuum micromechanics approaches of microcracked materials in relation to methods and results presented in the first part. Various estimates and bounds of the effective elastic properties are presented. They are considered for the formulation and application of continuum micromechanics-based damage models.

Download or read book Damage Mechanics and Micromechanics of Localized Fracture Phenomena in Inelastic Solids written by George Z Voyiadjis and published by Springer Science & Business Media. This book was released on 2012-01-29 with total page 426 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book resulted from a series of lecture notes presented in CISM, Udine in July 7 -11, 2008. The papers inform about recent advances in continuum damage mechanics for both metals and metal matrix composites as well as the micromechanics of localization in inelastic solids. Also many of the different constitutive damage models that have recently appeared in the literature and the different approaches to this topic are presented, making them easily accessible to researchers and graduate students in civil engineering, mechanical engineering, engineering mechanics, aerospace engineering, and material science.

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.

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.

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 296 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

Download or read book A Homogenization Based Continuum Plasticity damage Model for Ductile Fracture of Materials Containing Heterogeneities written by Jie Bai and published by . This book was released on 2008 with total page 138 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: This paper develops an adaptive concurrent multi-level computational model for multi-scale analysis of composite structures undergoing damage initiation and growth due to microstructural damage induced by debonding at the fiber-matrix interface. The model combines macroscopic computations using a continuum damage model with explicit micromechanical computations of stresses and strain, including explicit debonding at the fiber-matrix interface. The macroscopic computations are done by conventional FEM models while the Voronoi cell FEM is used for micromechanical analysis. Three hierarchical levels of different resolution adaptively evolve in this to improve the accuracy of solutions by reducing modeling and discretization errors. There levels include: (a) level-0 of pure macroscopic analysis using a continuum damage mechanics (CDM) model; (b) level-1 of asymptotic homogenization based macroscopic-microscopic RVE modeling to monitor the breakdown of continuum laws and signal the need for microscopic analyses; and (c) level-2 regions of pure micromechanical modeling with explicit depiction of the local microstructure. Numerical examples are solved to demonstrate the effectiveness and accuracy of the multi-scale model. To use the framework of this multi-scale computational model for ductile fracture analysis, This paper develops an accurate and computationally efficient homogenization based continuum plasticity-damage or HCPD model for macroscopic analysis of ductile failure in multi-phase porous ductile materials, such as cast aluminum alloys. The overall framework of the HCPD model follows the structure of an anisotropic Gurson-Tvergaard-Needleman (GTN) type elasto-plasticity model for porous ductile materials. To account for orientation dependence, the anisotropic HCPD model is expressed in the evolving material principal coordinate system and is assumed to remain orthotropic in it throughout the deformation history. Parameters in this model are calibrated from results of homogenization of microstructural variables obtained by LE-VCFEM analysis of the microstructural RVE containing inclusions, matrix and voids. Anisotropy parameters are found to evolve with plastic deformation in the microstructure. The model also incorporates a novel void nucleation criterion obtained by homogenizing micromechanical damage evolution by inclusion and matrix cracking. The overall model also incorporates realistic estimates of RVE length scales in the microstructure, as well as non-local characteristic length scales in the macrostructure. Comparison of the anisotropic HCPD model results with homogenized micromechanics results shows excellent agreement. On the other hand, the HCPD model has a huge efficiency advantage over the micromechanics models and is hence a very effective tool in making macroscopic damage predictions in structures with explicit reference to the microstructural composition.

Download or read book Fracture micromechanics of polymer materials written by V.S. Kuksenko and published by Springer Science & Business Media. This book was released on 2013-04-17 with total page 319 pages. Available in PDF, EPUB and Kindle. Book excerpt: Within the last two decades fracture theory has been one of the most rapidly advancing fields of continuous media mechanics. Noteworthy suc cess has been achieved in linear fracture mechanics where the propagation of the macrocrack in elastic materials is under study. However, fracture of materials is by no means a simple process since it involves fracture of structural elements ranging from atomic sizes to macrocracks. To obtain all information about how and why materials fail, all stages of the process must be studied. For a long time both mechanical engineers and physicists have been concerned with the problem of the fracture of solids. Unfortunately, most of their work has been independent of the others. To solve the problem not only requires the minds and work of mechanical engineers and physicists but chemists and other specialists must be consulted as well. In this book we will consider some conclusions of the "physical" and "mechanical" schools acquired by the A. F. Joffe Physics-Technical Institute of the USSR Academy of Sciences in Leningrad and the Institute of Polymer Mechanics of Latvian SSR Academy of Sciences in Riga. The methods for studying the phenomena of fracture applied at both Institutes are different yet complimentary to one another; the materials tested are also sometimes different.

Download or read book Begynnelsebokst vernas placering m m written by Wald Zachrisson and published by . This book was released on 1920 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Micro mechanical Simulation of Ductile Fracture Processes in Structural Steel written by Ryan James Cooke and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The micro-mechanics based approach to the study of ductile fracture has successfully overcome many of the limitations (such as large scale material yielding, cyclic loading, and size/scale dependence of J) of traditional fracture mechanics approaches (i.e. K, J and CTOD's). A number of the currently available micro-mechanics models (i.e. SMCS, Hancock and McKenzie, 1975; VGM, Kanvinde and Deierlein, 2006) predict fracture accurately under high triaxiality and axisymmetric conditions; however, the mentioned conditions do not encompass the full range of stress states (including low-triaxiality or non-axisymmetric conditions) which are relevant to the structural, mechanical and aerospace industries. As such, the primary objective of the work presented in this dissertation is to inform the development of a more general damage model which is applicable to a broader range of stress states and seismic (i.e. cyclic) loading which can result in ultra-low cycle fatigue (ULCF) failures. New model development is realized through a collaborative multi-scale approach which combines the results of an extensive test series (Smith, 2014) and a series of computational void simulations. To probe the full range of practical stress/loading conditions, a more general finite element (FE) framework for simulating the response of micro-voids is developed. The new void cell framework and the results of the 146 void simulations comprise the primary body of work presented in this dissertation. The void simulations can be divided into two groups: (1) those which effectively simulate an array of voids while modeling a representative void cell, and (2) those which explicitly model an array of voids. Void growth rates measured from the single void model (SVM) are used to inform the selection of a new functional form for the damage model presented in this dissertation while the multi-void model (MVM) provides qualitative and quantitative insights regarding localized deformation between neighboring voids. Findings from the MVM simulations are (1) in agreement with observations obtained from sectioned images (Smith, 2014) of fracture coupons that expose undergrown voids in the near vicinity of the failure surface and (2) are used to develop a strain-based indicator for localization initiation that shows strong agreement with failure strains observed from coupon scale tests (Myers, 2009). Moreover, the trends observed from both model types indicate that there is minimal void growth and that localization does not occur at low triaxialities. Both finding suggest that an alternate fracture mechanism than the traditionally excepted 'growth to coalescence' mechanism is active under these conditions. Despite the power of micro-mechanics based models, the ability to arrive at accurate fracture predictions is contingent on the calibration of the parameters which define the material constitutive response. The capability for complementary FE simulations to reproduce the force-displacement response obtained from physical tests (which is typically relied upon for model calibration) provides a false sense of security and neglects issues (i.e. non-uniqueness of the model parameter set) associated with model over-fitting. To investigate the susceptibility of typical calibration approaches to result in non-unique fits, a simple example is employed. Results of the example demonstrate that (1) multiple (and therefore non-unique) parameter sets may adequately reproduce the force-displacement response of typical calibration specimen and (2) that local plastic strains (often used to evaluate local fracture criteria) can result in error more than 65% despite agreement with the calibration metric. Thus, selection of parameter sets based solely on qualitative agreement between test data and complementary simulations can lead to erroneous results when evaluating material resistance to fracture.

Download or read book Application of Micromechanical Models to the Prediction of Ductile Fracture written by R. Kienzler and published by . This book was released on 1992 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: The ductile fracture behavior of different specimens is analyzed by continuum damage-mechanics techniques. A model introduced by Gurson and modified by Needleman and Tvergaard has been implemented in the finite element program package, ADINA. The damage parameters of the model are measured and calculated from smooth tension tests, and the characteristic material distance is estimated from compact tension experiments.

Download or read book Structural Impact written by Norman Jones and published by Cambridge University Press. This book was released on 2011-12-26 with total page 605 pages. Available in PDF, EPUB and Kindle. Book excerpt: Structural Impact is concerned with the behaviour of structures and components subjected to large dynamic, impact and explosive loads which produce inelastic deformations. It is of interest for safety calculations, hazard assessments and energy absorbing systems throughout industry. The first five chapters introduce the rigid plastic methods of analysis for the static behaviour and the dynamic response of beams, plates and shells. The influence of transverse shear, rotatory inertia, finite displacements and dynamic material properties are introduced and studied in some detail. Dynamic progressive buckling, which develops in several energy absorbing systems, and the phenomenon of dynamic plastic buckling are introduced. Scaling laws are discussed which are important for relating the response of small-scale experimental tests to the dynamic behaviour of full-scale prototypes. This text is invaluable to undergraduates, graduates and professionals learning about the behaviour of structures subjected to large impact, dynamic and blast loadings producing an inelastic response.

Download or read book Recent Trends in Fracture and Damage Mechanics written by Geralf Hütter and published by Springer. This book was released on 2015-09-01 with total page 438 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book covers a wide range of topics in fracture and damage mechanics. It presents historical perspectives as well as recent innovative developments, presented by peer reviewed contributions from internationally acknowledged authors. The volume deals with the modeling of fracture and damage in smart materials, current industrial applications of fracture mechanics, and it explores advances in fracture testing methods. In addition, readers will discover trends in the field of local approach to fracture and approaches using analytical mechanics. Scholars in the fields of materials science, engineering and computational science will value this volume which is dedicated to Meinhard Kuna on the occasion of his 65th birthday in 2015. This book incorporates the proceedings of an international symposium that was organized to honor Meinhard Kuna’s contributions to the field of theoretical and applied fracture and damage mechanics.

Download or read book Micromechanical Modelling of the Constitutive and Fracture Properties of Ductile Single Crystals written by Alberto Manuel Cuitino and published by . This book was released on 1994 with total page 312 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Micromechanics and Nanosimulation of Metals and Composites written by Siegfried Schmauder and published by Springer Science & Business Media. This book was released on 2008-10-20 with total page 432 pages. Available in PDF, EPUB and Kindle. Book excerpt: The strength of metallic materials determines the usability and reliability of all the machines, tools and equipment around us. Yet, the question about which mechanisms control the strength and damage resistance of materials and how they can be optimised remains largely unanswered. How do real, heterogeneous ma- rials deform and fail? Why can a small modification of the microstructure increase the strength and damage resistance of materials manifold? How can the strength of heterogeneous materials be predicted? The purpose of this book is to present different experimental and computational analysis methods of micromechanics of damage and strength of materials and to demonstrate their applications to various micromechanical problems. This book summarizes at a glance some of the publications of the Computational Mechanics Group at the IMWF/MPA Stuttgart, dealing with atomistic, micro- and meso- chanical modelling and experimental analysis of strength and damage of metallic materials. In chapter 1, the micromechanisms of damage and fracture in different groups of materials are investigated experimentally, using direct observations and inverse analysis. The interaction of microstructural elements with the evolving damage is studied in these experiments. Chapter 2 presents different approaches to the - cromechanical simulation of composite materials: embedded unit cells, multiphase finite elements and multiparticle unit cells. Examples of the application of these models to the analysis of deformation and damage in different materials are given. Chapter 3 deals with the methods of numerical modelling of damage evolution and crack growth in heterogeneous materials.

Download or read book A Micromechanics Based Ductile Damage Model for Anisotropic Titanium Alloys written by Shyam Mohan Keralavarma and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The hot-workability of Titanium (Ti) alloys is of current interest to the aerospace industry due to its widespread application in the design of strong and light-weight aircraft structural components and engine parts. Motivated by the need for accurate simulation of large scale plastic deformation in metals that exhibit macroscopic plastic anisotropy, such as Ti, a constitutive model is developed for anisotropic materials undergoing plastic deformation coupled with ductile damage in the form of internal cavitation. The model is developed from a rigorous micromechanical basis, following well-known previous works in the field. The model incorporates the porosity and void aspect ratio as internal damage variables, and seeks to provide a more accurate prediction of damage growth compared to previous existing models. A closed form expression for the macroscopic yield locus is derived using a Hill-Mandel homogenization and limit analysis of a porous representative volume element. Analytical expressions are also developed for the evolution of the internal variables, porosity and void shape. The developed yield criterion is validated by comparison to numerically determined yield loci for specific anisotropic materials, using a numerical limit analysis technique developed herein. The evolution laws for the internal variables are validated by comparison with direct finite element simulations of porous unit cells. Comparison with previously published results in the literature indicates that the new model yields better agreement with the numerically determined yield loci for a wide range of loading paths. Use of the new model in continuum finite element simulations of ductile fracture may be expected to lead to improved predictions for damage evolution and fracture modes in plastically anisotropic materials.