一种考虑平均应力松弛的多级硬化本构模型

在无屈服条件的粘塑性本构理论框架内,提出了关于内变量和内应力以及材料具有不同硬化趋势的假设,并在Bodner-Partom模型的基础上,发展了新的内变量演化模型,即双级硬化模型(Two Stages Hardening,TSH模型)和多级硬化模型(Multi-Stages Hardening,MSH模型),提高了Bodner-Partom模型对同时模拟应变率相关单调拉伸和循环特性的精度,特别是增强了对Ratcheting的模拟能力,使得无屈服条件的本构方程以较高精度模拟Ratcheting成为可能.并将TSH模型和MSH模型用于Udimet720Li材料高温非弹性变形特征的描述,TSH模型改善了B-P模型在模拟单调拉伸和循环硬化方面的精度,但MSH模型在描述非对称循环载荷下平均应力松弛和Ratcheting应变方面具有更强的能力.

A multi-stage hardening constitutive model considering mean stress relaxation

In the framework of visco-plastic constitutive theory without yield condition,some assumptions dealing with internal variables,internal stress and different potential hardening of material were used to develop new evolutionary equation of internal variables.Based on the Bodner-Partom model,a two-stage hardening (TSH) model and a multi-stage hardening(MSH) model were established to improve the accuracy of modeling strain rate-dependent tension and cyclic visco-plasticity,especially for ratcheting.The TSH model improves the precision of modeling monotonic tension and cyclic hardening,while the MSH model has more capability of modeling cyclic mean stress relaxation and ratcheting under asymmetric loading condition.