转动惯量法在多轴疲劳本构关系预测中的应用

一些金属材料在承担多轴非比例加载过程时，会产生额外非比例附加强化或软化现象，这一现象往往会导致在评估疲劳寿命时因为材料本构关系的不确定而引起预测结果出现较大误差．因此基于单轴疲劳理论得出的寿命预测模型并不能准确地预测多轴非比例疲劳加载下的材料寿命．针对此问题，本文阐述了非比例附加强化效应产生的原因及结果，结合转动惯量法的理论和塑性增量法，建立了预测多轴低周疲劳加载下循环应力-应变曲线的数值计算模型．利用316L 不锈钢试样在5 种加载路径下的实验数据对预测结果进行了验证，结果表明该模型具有良好的预测有效性及精度．

Application of the Moment of Interia Method in Predicting the Constitutive Relationship of Multiaxial Fatigue

Under multiaxial non-proportional loading, additional non-proportional hardening or softening can be induced in some metallic materials, which often leads to incorrect fatigue life prediction due to the uncertainty of the material constitutive relationship. Therefore, fatigue models based on uniaxial fatigue theory cannot accurately predict the multiaxial non-proportional fatigue life. This paper discusses the reasons and results of non-proportional additional hardening effect. Combining the Moment Of Inertia (MOI) and the plastic increment methods, the numerical simulations for estimating the cyclic stress- strain curve under multiaxial low-cycle fatigue loading are carried out. The effectiveness and accuracy of the proposed model are verified by the experimental results of 316L stainless steel specimens under 5 strain-controlled loading paths.