一种广义Bodner-Partom黏塑性本构模型

A generalized Bodner-Partom viscoplastic constitutive model

针对Bodner-Partom黏塑性本构模型描述合金材料的率相关塑性和循环硬化行为时精度不足的问题,在无屈服面统一黏塑性本构理论框架内对其进行了改进:利用塑性势函数重塑了流动法则,摆脱了Mises材料的限制;在内变量演化方程中引入塑性应变率修正项并由非线性因子控制,拓展了不同的硬化/恢复演变方向。利用FGH96合金在550℃下的单轴拉伸及低周疲劳试验数据将广义B-P模型与原始B-P模型进行了对比验证,结果表明本文模型的模拟效果与材料非弹性特征吻合良好,具有克服应力应变滞回曲线“过方”问题和表达平均应力循环松弛的能力。模型对不同硬化机制的考虑对于高温合金材料更具优越性。

To improve the modeling of rate-dependent plasticity and cyclic hardening behaviors of alloys with the Bodner-Partom unified viscoplastic constitutive model,the flow rule is established based on a plastic potential function and no longer limited to Mises criteria.In addition,a plastic strain rate term is introduced to diversify the dynamic recovery of kinematic hardening evolution.By comparing the fit of both generalized and original models with the experimental results,the characterized uniaxial tensile and low-cycle fatigue properties of FGH96 at 550℃show that the modifications provide sound agreement with the inelastic properties,and the adaptability to overcoming the"oversquare"in hysteresis loop and the capability to express mean stress cyclic relaxation accurately are confirmed.The consideration of different hardening mechanisms brings more flexibility for alloys subjected to high temperature.