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Three Dimensional Molecular Dynamics Simulations Of Void Coalescence During Dynamic Fracture Of Ductile Metals
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Book Synopsis Three-Dimensional Molecular Dynamics Simulations of Void Coalescence During Dynamic Fracture of Ductile Metals by :
Download or read book Three-Dimensional Molecular Dynamics Simulations of Void Coalescence During Dynamic Fracture of Ductile Metals written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Void coalescence and interaction in dynamic fracture of ductile metals have been investigated using three-dimensional strain-controlled multi-million atom molecular dynamics simulations of copper. The correlated growth of two voids during the coalescence process leading to fracture is investigated, both in terms of its onset and the ensuing dynamical interactions. Void interactions are quantified through the rate of reduction of the distance between the voids, through the correlated directional growth of the voids, and through correlated shape evolution of the voids. The critical inter-void ligament distance marking the onset of coalescence is shown to be approximately one void radius based on the quantification measurements used, independent of the initial separation distance between the voids and the strain-rate of the expansion of the system. The interaction of the voids is not reflected in the volumetric asymptotic growth rate of the voids, as demonstrated here. Finally, the practice of using a single void and periodic boundary conditions to study coalescence is examined critically and shown to produce results markedly different than the coalescence of a pair of isolated voids.
Book Synopsis Void Coalescence Processes Quantified Through Atomistic and Multiscale Simulation by :
Download or read book Void Coalescence Processes Quantified Through Atomistic and Multiscale Simulation written by and published by . This book was released on 2007 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: Simulation of ductile fracture at the atomic scale reveals many aspects of the fracture process including specific mechanisms associated with void nucleation and growth as a precursor to fracture and the plastic deformation of the material surrounding the voids and cracks. Recently we have studied void coalescence in ductile metals using large-scale atomistic and continuum simulations. Here we review that work and present some related investigations. The atomistic simulations involve three-dimensional strain-controlled multi-million atom molecular dynamics simulations of copper. The correlated growth of two voids during the coalescence process leading to fracture is investigated, both in terms of its onset and the ensuing dynamical interactions. Void interactions are quantified through the rate of reduction of the distance between the voids, through the correlated directional growth of the voids, and through correlated shape evolution of the voids. The critical inter-void ligament distance marking the onset of coalescence is shown to be approximately one void radius based on the quantification measurements used, independent of the initial separation distance between the voids and the strain-rate of the expansion of the system. No pronounced shear flow is found in the coalescence process. We also discuss a technique for optimizing the calculation of fine-scale information on the fly for use in a coarse-scale simulation, and discuss the specific case of a fine-scale model that calculates void growth explicitly feeding into a coarse-scale mechanics model to study damage localization.
Book Synopsis Void Coalescence Processes Quantified Through Atomistic and Multiscale Simulation by : R. E. Rudd
Download or read book Void Coalescence Processes Quantified Through Atomistic and Multiscale Simulation written by R. E. Rudd and published by . This book was released on 2005 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: Simulation of ductile fracture at the atomic scale reveals many aspects of the fracture process including specific mechanisms associated with void nucleation and growth as a precursor to fracture and the plastic deformation of the material surrounding the voids and cracks. Recently we have studied void coalescence in ductile metals using large-scale atomistic and continuum simulations. Here we review that work and present some related investigations. The atomistic simulations involve three-dimensional strain-controlled multi-million atom molecular dynamics simulations of copper. The correlated growth of two voids during the coalescence process leading to fracture is investigated, both in terms of its onset and the ensuing dynamical interactions. Void interactions are quantified through the rate of reduction of the distance between the voids, through the correlated directional growth of the voids, and through correlated shape evolution of the voids. The critical inter-void ligament distance marking the onset of coalescence is shown to be approximately one void radius based on the quantification measurements used, independent of the initial separation distance between the voids and the strain-rate of the expansion of the system. No pronounced shear flow is found in the coalescence process.
Book Synopsis Void Growth and Coalescence in Dynamic Fracture from the Atomistic Level by :
Download or read book Void Growth and Coalescence in Dynamic Fracture from the Atomistic Level written by and published by . This book was released on 2010 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: An important example of multiscale material response is the fracture of ductile solids. In the process of ductile fracture, voids nucleate, grow and coalesce, and it is this linking process that creates the fracture. Ductile fracture has typically been modeled at the continuum level, in a variety of models that may or may not model voids explicitly. Previously we have studied the plasticity associated with void growth in fcc metals, focusing on copper. In the work discussed here we examine void growth in single crystal and polycrystalline body-centered cubic (bcc) metals (V, Nb, Ta, Mo and W) subjected to tension at a high rate and high triaxiality. Large-scale atomistic models provide detailed information on void nucleation and growth and the plasticity generated as voids coalesce, based solely on the constitutive properties inherent in the interatomic forces. The details of the plasticity may be used to inform dislocation dynamics and continuum plasticity models in order to develop models that scale beyond the nanoscale. We also discuss concurrent multiscale modeling of void growth using Coarse-Grained Molecular Dynamics.
Book Synopsis Molecular Dynamics Simulation by : Kun Zhou
Download or read book Molecular Dynamics Simulation written by Kun Zhou and published by Academic Press. This book was released on 2022-02-10 with total page 375 pages. Available in PDF, EPUB and Kindle. Book excerpt: Molecular Dynamic Simulation: Fundamentals and Applications explains the basic principles of MD simulation and explores its recent developments and roles in advanced modeling approaches. The implementation of MD simulation and its application to various aspects of materials science and engineering including mechanical, thermal, mass transportation, and physical/chemical reaction problems are illustrated. Innovative modeling techniques that apply MD to explore the mechanics of typical nanomaterials and nanostructures and to characterize crystalline, amorphous, and liquid systems are also presented. The rich research experience of the authors in MD simulation will ensure that the readers are provided with both an in-depth understanding of MD simulation and clear technical guidance. Provides a comprehensive overview of the underlying theories of molecular dynamics (MD) simulation Presents application-based examples pertaining to a broad range of mechanical, thermal, and mass transport problems Explores innovative modeling techniques for simulating typical nanomaterials and nanostructures and for characterizing crystalline, amorphous, and liquid systems
Book Synopsis Effect of Stress-triaxiality on Void Growth in Dynamic Fracture of Metals by :
Download or read book Effect of Stress-triaxiality on Void Growth in Dynamic Fracture of Metals written by and published by . This book was released on 2003 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt: The effect of stress-triaxiality on growth of a void in a three dimensional single-crystal face-centered-cubic (FCC) lattice has been studied. Molecular dynamics (MD) simulations using an embedded-atom (EAM) potential for copper have been performed at room temperature and using strain controlling with high strain rates ranging from 107/sec to 101°/sec. Strain-rates of these magnitudes can be studied experimentally, e.g. using shock waves induced by laser ablation. Void growth has been simulated in three different conditions, namely uniaxial, biaxial, and triaxial expansion. The response of the system in the three cases have been compared in terms of the void growth rate, the detailed void shape evolution, and the stress-strain behavior including the development of plastic strain. Also macroscopic observables as plastic work and porosity have been computed from the atomistic level. The stress thresholds for void growth are found to be comparable with spall strength values determined by dynamic fracture experiments. The conventional macroscopic assumption that the mean plastic strain results from the growth of the void is validated. The evolution of the system in the uniaxial case is found to exhibit four different regimes: elastic expansion; plastic yielding, when the mean stress is nearly constant, but the stress-triaxiality increases rapidly together with exponential growth of the void; saturation of the stress-triaxiality; and finally the failure.
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 Incipient Spallation Fracture in Light Metals From 3D X-Ray Tomography, 2D Microscopy, and Molecular Dynamics Simulations by : J. H. Kinney
Download or read book Incipient Spallation Fracture in Light Metals From 3D X-Ray Tomography, 2D Microscopy, and Molecular Dynamics Simulations written by J. H. Kinney and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The dynamic fracture of ductile metals is known to occur through the nucleation and growth of microscopic voids. As the voids grow, the surrounding metal is plastically deformed to accommodate the change in void volume. In order to gain better insight into void growth, gas gun recovery experiments were used to study incipient spallation fracture in light metals (Al, Cu, V). In addition to in-situ free surface velocity wave-profiles, the recovered samples were first analyzed using 3D X-ray tomography and then sectioned for 2D microscopy. The void size and spatial distribution were determined directly from the X-ray tomography. The single crystal samples show a bimodal distribution of small voids with large (50-100 micron) well separated voids. The plastically damaged region surrounding the large voids is quantified using optical and electron backscattering microscopy. Microhardness measurements indicate this region to be harder than the surrounding metal. Concurrently, a molecular dynamics model of void nucleation and growth at high strain-rate was developed. The model is consistent with experimental observations, e.g. voids nucleate at the weakest points in the metal such as inclusions and grain boundary junctions. The nature of void growth in a single crystal is sensitive to the crystal structure with initially spherical voids in FCC metals growing into octahedral shapes as observed in experiment. Details of the dislocation mechanisms of void growth will be presented.
Book Synopsis Multiscale Analysis of Void Coalescence in Ductile Metals by : Matthew Kenneth Jones
Download or read book Multiscale Analysis of Void Coalescence in Ductile Metals written by Matthew Kenneth Jones and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A mulitscale approach is used to model the coalescence of voids. At the microscale, cylindrical and spherical voids in nickel and the magnesium alloy AM60 are simulated through finite element analyses. The nickel cylindrical void simulations are compared to a set of experiments to validate this micromechanical finite element approach used to study void coalescence. At the macroscale, the coalescence portion of a microstructure-property material model is modified to reflect the behavior of three-dimensional spherical voids using results from the micromechanical simulations. An analysis of an automotive component illustrates the influence of void coalescence at the structural scale.
Book Synopsis Multiscale Analysis of Void Coalescence in Ductile Metals by :
Download or read book Multiscale Analysis of Void Coalescence in Ductile Metals written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A mulitscale approach is used to model the coalescence of voids. At the microscale, cylindrical and spherical voids in nickel and the magnesium alloy AM60 are simulated through finite element analyses. The nickel cylindrical void simulations are compared to a set of experiments to validate this micromechanical finite element approach used to study void coalescence. At the macroscale, the coalescence portion of a microstructure-property material model is modified to reflect the behavior of three-dimensional spherical voids using results from the micromechanical simulations. An analysis of an automotive component illustrates the influence of void coalescence at the structural scale.
Book Synopsis Sheet Metal Meso- and Microforming and Their Industrial Applications by : Xin Min Lai
Download or read book Sheet Metal Meso- and Microforming and Their Industrial Applications written by Xin Min Lai and published by CRC Press. This book was released on 2018-08-06 with total page 477 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book presents a compilation of research on meso/microforming processes, and offers systematic and holistic knowledge for the physical realization of developed processes. It discusses practical applications in fabrication of meso/microscale metallic sheet-metal parts via sheet-metal meso/microforming. In addition, the book provides extensive and informative illustrations, tables, case studies, photos and figures to convey knowledge of sheet-metal meso/microforming for fabrication of meso/microscale sheet-metal products in an illustrated manner. Key Features • Presents complete analysis and discussion of micro sheet metal forming processes • Guides reader across the mechanics, failures, prediction of failures and tooling and prospective applications • Discusses definitions of multi-scaled metal forming, sheet-metal meso/microforming and the challenges in such domains • Includes meso/micro-scaled sheet-metal parts design from a micro-manufacturability perspective, process determination, tooling design, product quality analysis, insurance and control • Covers industrial application and examples
Book Synopsis Microstructural Origins of Dynamic Fracture in Ductile Metals by : Alfred Schwartz
Download or read book Microstructural Origins of Dynamic Fracture in Ductile Metals written by Alfred Schwartz and published by . This book was released on 2004 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dynamic fracture is a material failure process at high strain-rates. Here, we limit our discussion to spallation fracture during shock wave loading. When a compressive shock wave reflects from a free surface, internal states of tension are created. If this tension exceeds the rupture strength of the material, it fails by nucleating and growing microscopic voids in ductile metals and cracks in brittle solids. This effect, known as spallation, was reported by Hopkinson in 1872 [1]. Rinehart and Pierson [2] give an historical introduction to spallation and other aspects of high strain-rate deformation. This phenomenology of the nucleation and growth of microscopic voids is common to all fracture in ductile metals, including dynamic fracture. The importance of pulse duration was not fully appreciated until the 1960's through the work of Butcher and colleagues [3, 4], leading to the concept of cumulative damage. This concept of damage accumulation was put on a strong experimental foundation by Barbee et al. [5], who performed gas gun recovery experiments and tediously measured the size and distribution of microscopic flaws using 2D microscopy. The resulting continuum material model of dynamic fracture is known as the SRI-NAG model [6, 7], for Nucleation And Growth. In a critical assessment of dynamic fracture, Meyers and Aimone [8] reviewed the abundant continuum spallation models and found the model of nucleation, growth, and coelescense of voids to qualitatively reproduce the observed extent of damage from spall recovery experiments. As in the work of Barbee et al. [5], Meyers and Aimone do not find any voids smaller than about 1 {micro}m, suggesting that the voids either nucleated at that scale or when they are nucleated they rapidly grow to the micron size scale. The continuum models are phenomenological in nature with parameters fit to experiment. The advent of the Advanced Strategic Computing program has enabled direct numerical simulation of the nucleation and growth of microscopic voids. However, there exists no experimental data to both guide the modeling to the essential physical phenomena and to validate meso-scale modeling of dynamic fracture in ductile metals. The goal of this project is to obtain this new experimental data for dynamic fracture in ductile metals by characterizing and analyzing the microscopic processes using modern experimental facilities not previously available. In particular, we measured with increased precision the damage produced during spallation fracture in ductile metals. Dynamic gas-gun recovery experiments were used to generate incipient spallation damage while concurrently measuring the free surface velocity wave profile. This wave profile has been used extensively to characterize spallation fracture. The concurrent measurement enables us to correlate the observed incipient damage with features in the wave profile, such as the velocity pull back. The incipient spallation damage was characterized using both advanced Synchrotron-based 3D X-Ray tomography and traditional 2D microscopy. A direct correlation was made between the traditional 2D microscopy and the 3D distribution of voids on the same sample. 2D microscopy, including optical, EBS/OIM, and TEM, was used to quantify, for the first time, the plastically deformed zone in the metal surrounding an incipiently grown void. Nanoindentation hardness experiments were used to quantify the increased strength in the plastically deformed zone from the greatly increased dislocation density.
Book Synopsis Molecular Dynamics Study of Void Growth and Dislocations in Dynamic Fracture of FCC and BCC Metals by :
Download or read book Molecular Dynamics Study of Void Growth and Dislocations in Dynamic Fracture of FCC and BCC Metals written by and published by . This book was released on 2003 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: Void growth with concomitant dislocation formation has been studied in single crystal face-centered-cubic and body-centered-cubic metals using molecular dynamics method with Embedded-Atom and Finnis-Sinclair potentials for copper and tantalum, respectively. We have concentrated on the quantitative analysis of the void shape evolution, on the structure of dislocations, which emerge from the void, and on the continuum measures such as plastic strain. The effects of strain-rate, differences between lattice structures, and loading conditions as uniaxial, biaxial, and triaxial expansion on the shape of the void and on the dislocations have been investigated.
Book Synopsis Magnesium Technology 2011 by : Wim Sillekens
Download or read book Magnesium Technology 2011 written by Wim Sillekens and published by Springer. This book was released on 2016-12-10 with total page 599 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Magnesium Technology Symposium, which takes place every year at the TMS Annual Meeting & Exhibition, is one of the largest yearly gatherings of magnesium specialists in the world. Papers are presented in all aspects of the field, ranging from primary production to applications to recycling. Moreover, papers explore everything from basic research findings to industrialization. Magnesium Technology 2011 covers a broad spectrum of current topics, including alloys and their properties; cast products and processing; wrought products and processing; forming, joining, and machining; corrosion and surface finishing; ecology; and structural applications. In addition, you'll find coverage of new and emerging applications in such areas as biomedicine and hydrogen storage.
Book Synopsis Fracture Nanomechanics by : Takayuki Kitamura
Download or read book Fracture Nanomechanics written by Takayuki Kitamura and published by CRC Press. This book was released on 2011-09-06 with total page 306 pages. Available in PDF, EPUB and Kindle. Book excerpt: Small structures of the micro/nanometer scale, such as electronic/optic devices and MEMS/NEMS have been developed, and the size of their elements now approaches the nano/atomic scale. This book discuses the fracture behavior of nano/atomic elements (nanofilms, nanowires, and so on) and focuses on the initiation and propagation of interface crack and mechanical instability criterion of atomic structures. This covers the fundamentals and the applicability of the top-down (conventional fracture mechanics to nanoscale) and bottom-up (atomic mechanics including ab initio simulation) concepts. New areas, such as multiphysics characteristics of nanoelements, are introduced as well.
Book Synopsis Material and Environmental Science, Building Engineering, Biomedical and Bioinformatics Technologies by : H.W. Liu
Download or read book Material and Environmental Science, Building Engineering, Biomedical and Bioinformatics Technologies written by H.W. Liu and published by Trans Tech Publications Ltd. This book was released on 2013-09-04 with total page 750 pages. Available in PDF, EPUB and Kindle. Book excerpt: Collection of selected, peer reviewed papers from the 2013 International Conference on Advanced Engineering Materials and Architecture Science (ICAEMAS 2013), July 27-28, 2013, Xian, Shaanxi, China. The 163 papers are grouped as follows: Chapter 1: Material Science and Engineering; Chapter 2: Civil Engineering, Building and Construction Materials and Technologies, Architecture and Geo-engineering Applications; Chapter 3: Transportation and Traffic Engineering, Environmental Engineering, Urban and Landscape Planning; Chapter 4: Biomedical, Bioinformatics, Biology Systems and Medical Informatics; Chapter 5: Automation Methods in Industry and Manufacture, Modelling and Analysis; Chapter 6: Computing and Information Science; Chapter 7: Management Engineering.
Book Synopsis Ductile Fracture Due to Plastic Flow, Void Growth and Localization for 3D Randomly Voided Materials by : Yaning Li
Download or read book Ductile Fracture Due to Plastic Flow, Void Growth and Localization for 3D Randomly Voided Materials written by Yaning Li and published by . This book was released on 2006 with total page 486 pages. Available in PDF, EPUB and Kindle. Book excerpt:
