金属材料非比例循环塑性的本构描述

多晶金属在非比例循环过程中的强化与其内部组织结构的变化密切相关。根据循环过程中金属位错子结构的变化,将强化函数分解为乘积形式,各因子分别决定于非强化区尺度与非比例度,由此将各种不同的强化机制嵌入热力学相容的本构方程。对304与316不锈钢室温下二维非比例循环的本构响应进行了分析,并与Benallal等、Tanaka等、和Ohashi等的实验结果进行比较,符合得很好。

NONPROPORTIONAL CYCLIC PLASTICITY FOR METALLIC MATERIALS

In order to describe nonproportional cyclic plasticity of polycrystalline metallic materials, the hardening function is separated into three factors, in which,f1 is related to the hardening parameter determined by plastic strain range, and f2 and f3 are related to the change of plastic deformation path characterized by a measure of nonproportionality. The main features of this work are: (a)cyclic hardening is described by f1, and additional hardening is separated into instantaneous and hereditary one which is described by f2 and f3 respectively; (b)a general form of the evolution of f1(i= 1,2, 3) is proposed; (c)parameters a1 and a3 are introduced to keep the memory to the largest cyclic hardening and additional hardening respectively; (d)various hardening mechanisms are embedded into a thermomechanically consistent constitutive equation. The capability of the developed model is verified with the analysis of biaxially nonproportional experiments by Benallal et al, Tanaka et al and Ohashi et al.