A Hybrid Constitutive Model for Cyclic Viscoplasticity

近十年来，关于循环塑性或循环粘塑性本构关系的研究得到了广泛的发展，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循环预加载后SUS 304不锈钢的棘轮行为起着重要作用。因此，针对循环塑性和蠕变的统一本构模型的制定，有效应力的概念，它被定义为从屈服面的当前中心测量的应力。然后对循环预应变后的间歇蠕变期、循环蠕变和机械棘轮效应的实验结果进行了分析，得到了一些规律性的结论，为建立高温下的统一本构模型提供了依据。

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.