一种基于微观组织演化的率形式本构模型

 为建立塑性变形中微观组织演化与宏观响应的关系,依据定义的率扩散势导出了考虑温度影响的率形式流动应力方程,修正了Chaboche非线性各向同性硬化准则以考虑位错密度演化对硬化的贡献,以位错密度为内变量建立了位错密度演化模型,提出了一种基于微观组织演化机理的率形式本构模型。以927℃钛合金Ti-6Al-4V热单拉实验数据为基础,通过遗传算法确定了模型材料常数。将计算结果与实验数据进行比较,最大应力误差在12%以内,最大晶粒尺寸误差在4%以内,证明了模型的有效性。

A Rate Dependent Constitutive Model Based on the Microstructure Evolution

For establishing the relation of microstructure evolution and macro-performance in the plastic deformation,a rate dependent flow stress equation is derived based on the rate diffusion potential density which takes into consideration the influence of temperature.The Chaboche’s nonlinear isotropic hardening criterion is modified to consider the influence of dislocation density on hardening.The evolution of dislocation density is modeled by using dislocation density as the internal state variable.A rate dependent constitutive model is proposed based on the mechanism of microstructure evolution.The material constants in the model are determined based on the single tension experimental data of Ti-6Al-4V by using the genetic algorithms.The comparison of calculation results and experimental data shows that the maximum errors of stress and grain size do not exceed 12% and 4% respectively.Thus,the validity of the model is verified.