一种混合的非线性强化模型M-NH研究

Study in the Mixed Nonlinear Hardening(M-NH) Model for Multiaxial

基于Lemaitre and Chaboche非线性随动强化和等向强化理论,提出了一种有效的背应力修正方法,采用Mises屈服准则,建立了复杂加载模式下非线性混合强化材料模型(M-NH)的弹塑性应力应变本构关系,采用高效的Backward Euler切向预测径向返回算法给出应力应变增量的计算,引入最小二乘法根据单轴拉伸实验数据点获得材料的硬化模型参数。为了计算背应力及弹塑性刚度矩阵开发了Fortran程序,编制了M-NH模型的实现代码。针对采用本模型获得的单轴拉伸应力应变曲线,分析了材料相关硬化参数对曲线变化趋势的影响。本模型及Chaboche1991、Basu&Voyiadjis强化模型分别与Chaboche的实验数据对比表明,基于M-NH获得的计算数据与实验结果更为接近。

Based on the nonlinear kinematic hardening model and isotropic hardening model proposed by Lemaitre and Chaboche, a new term is added in the plastic strain dependent terms. The constitutive equations of the mixed nonlinear hardening （M-NH） model are derived at the complicated loading using Mises＇ yield function. The effi- cient implicit backward Euler scheme with radial return is used to obtain strain and stress increments. The least- square error approach is adopted to get material parameters using a finite set of points in the uniaxial stress-strain curve. M-NH model is fulfilled with Fortran codes in order to get backstress and elasto-plastic stiffness matrix. The behavior of the present model constants is analyzed against different conditions. Those individual importance and contribution to stress-strain curve is highlighted. The comparisons between the present results and that of experi- ment by Chaboche show that it is in better agreement with those results of Chaboche 1991 and Basu ＆ Voyiadiis.