率相关非比例循环塑性内时本构模型

AN ENDOCHRONIC CONSTITUTIVE MODEL FOR RATE DEPENDENT, NONPROPORTIONAL CYCLIC PLASTICITY

将材料响应的总应力表示为平衡态应力和非平衡态过应力的和，分别定义描述率无关和率相关变形过程的内时．在平衡态响应的描写中，假定反映非比例加载效应的附加等向强化和异向强化函数与沿应力迹法向的塑性应变分量的累积量相关，并在其中考虑加载路径几何性质变化的影响，建立一组率相关非比例循环塑性内时本构方程．对ＸＣｒＮｉ１８．９不锈钢在不同加载率下的单轴比例和多轴非比例响应进行预测，与Ｈａｕｐｔ和Ｌｉｏｎ的实验结果取得良好的一致。

The total stress response of material is decomposed into a sum of an equilibrium stress response and a non-equilibrium overstress response. Correspondingly, a rate independent intrinsic time and a rate dependent intrinsic time are defined respectively. Additional hardening functions to describe the isotropic and anisotropic nonproportional effects are assumed to relate to the accumulation of plastic strain component along the normal of eqilibrium stress trajectory, in which the effects of geometry of the loading path are included. An endochronic constitutive model for rate dependent, nonproportional cyclic plasticity is formulated and is applied to simulate the stress responses of stainless steel XCrNi18 9 for some typical loading programs at different loading rates. The predictions are compared with the experimental results by Haupt and Lion, showing good agreement and demonstrating the capability of the model.