13th International Conference on Fracture June 16–21, 2013, Beijing, China -1- Modeling of Strain Localization and Failure in Vanadium under Quasistatic Loading Anastasia Kostina*, Yuriy Bayandin, Oleg Plekhov, Oleg Naimark Institute of continuous media mechanics UB RAS, Perm, 614013, Russia * Corresponding author: kostina@icmm.ru Abstract The process of plastic deformation and failure of metals is accompanied by set of phenomena which cannot be easily modeled in the framework of classical models. The effects of strain localization and energy dissipation under deformation and failure require an adequate description of structure evolution at different stages of deformation process. This description can be developed based on the results of statistical model of typical mesodefect ensemble proposed in the Institute of continuous media mechanics UB RAS. The model takes into account bulk and shear parts of defect density tensor. Defect evolution is described by kinetic equations for two structural parameters: second order defect density tensor and scalar parameter, depending on the ratio of two characteristic scales (the mean size of defects and mean distance between them). The numerical simulation of strain localization and crack propagation were carried out in the finite-element package Simulia Abaqus Student Edition using procedure UMAT and XFEM. Keywords defect evolution, energy dissipation, numerical simulation 1. Introduction Nowadays investigation of metal fracture and knowledge of its laws have great importance in the developments of various designs and constructions. To create new technologies and improve existing ones one has to reach a more deep understanding of physical nature of failure. This understanding is needed in order to describe such phenomena, accompanying failure, as energy dissipation and strain localization. Most existing models assume that the material failure takes place at the final stage of plastic deformation. However, the data obtained from systematic studies of defects evolution, carried out at Physical-technical institute named after A.F. Ioffe RAS [1] shows that the defects play the important role in deformation process at every stage of plastic deformation. These defects emergence at the early stage of deformation and effect on the microplasticity and failure processes. The models described the interaction between damage accumulation and plasticity processes were developed in [2-3] In this paper, the metal deformation behavior under quasi-static loading is described by one of such models, developed at the Institute of continuous media mechanics UB RAS. The description of damage accumulation includes a consideration of the mesodefect ensemble evolution, their coherent development and interaction, the effect on the relaxation properties of materials and merging into the main crack. The practical application of developed model requires both the verification of materials functions and generalization of the model for three dimension case. The most effective way for modeling of complex deformation phenomena is incorporation of this model for the standard finite - element packages. This work is devoted to the generalization of developed earlier statistical based phenomenological elasto-visco-plastic model of defect evolution under deformation and failure in metals. The model takes into account defect density tensor separation bulk and shear parts. Defect evolution is described based on the kinetics of two parameters: the first parameter is second order defect density tensor, the second one - scalar parameter, depending on the ratio of two characteristic scales (the mean size of defects and mean distance between them). The numerical simulation of strain localization on (plastic wave propagation) and crack propagation
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