A Hybrid Constitutive Model for Cyclic Viscoplasticity

近十年来，对循环塑性或循环粘塑性本构方程的研究得到了广泛的发展，文献中提出了许多模型。研究表明，循环塑性中的拉应力和背应力对描述SUS-304不锈钢在循环预加载后的棘轮行为起着重要作用。因此，为了建立循环塑性和蠕变的统一本构模型，采用了有效应力的概念，有效应力的定义是从屈服面当前中心测得的应力。循环预应变、循环蠕变和机械棘轮后的间歇期蠕变实验结果显示出惊人的规律性，可以方便地建立高温下的统一本构模型。

In the last decade, the research on the constitutive formulation for cyclic plasticity or cyclic viscoplasticity has developed extensively that many models have been proposed in literatures. This work shows that the drag stress and back stress in cyclic plasticity play a important role to describe the ratcheting behavior of SUS 304 type stainless steel following cyclic preloading. Consequently, aiming at a formulation of the unified constitutive model of cyclic plasticity and creep, the concept of the effective stress, which is defined as the stress measured from the current center of theyield surface, is employed. Then the experimental results of the intermittent creep period after cyclic prestraining, cyclic creep and mechanical ratcheting show a marvelous regularity which might make us easily to construct the unified constitutive model in high temperature.