新的空洞型损伤演化律及损伤弹塑性大变形有限元描述

THE NEW EVOLUTION LAW OF VOID MODE DAMAGE AND ITS LARGE DEFORMATION ELASTOPLASTIC FEM DESCRIPTION

本文通过对细观空洞模型的分析，推导出各向同性／运动混合强化材料更为真实和简单的损伤演化和弱化函数的表达式，式中考虑了空洞形状变化对损伤演化的影响。将所得到的空洞演化率和弱化函数嵌入新的增量型内时本构框架，并考虑损伤引起的塑性体积膨胀，得到了损伤弹塑性大变形内对本构方程．发展相应的轴对称有限元分析程序，用其分析圆柱拉伸试件的颈缩和开有切糟的圆柱试件在切槽前缘的应力和损伤分布，得到与实验较为吻合的结果．

On analysis of a mesoscopic void model,a truer and simpler expression of damage evolu-tion and weakening function is derived for tnixd isotropic/kinetic hardening. In this expres-sion,the influence of the void shape change on the damage evolution is taken into considera-tion. With the void evoIution rate and the weakening function obtained put into the new in-cremental mode endochronic constitutional frame, and the plastic volumetric expansioncaused by damage considered,the endochronic constitutional equation of large deformation e-lastoplastic damage is worked out. Then,a corresponding axial-symmetric finite element anal-ysis program is deveI6ped and used to analyze the necking of a cylindrical tensile specimenand the stress and damage distribution at the front of another cylindrical specimen's notch.Results pretty identical to those from experiments are attained.