【摘要】 对调质42CrMo钢的棘轮-疲劳交互作用的实验结果进行了分析,揭示了材料在非对称应力循环下的全寿命棘轮变形特征和低周疲劳损伤演化特性.在统一粘塑性循环本构模型框架下,基于连续损伤力学理论,提出一个耦合损伤的粘塑性本构模型.该模型中将损伤分为宏观弹性损伤和塑性损伤两部分,并采用不同的损伤演化方程来描述这两类损伤.针对材料不同的失效模式,分别采用损伤变量门槛值和最大应变作为失效判据.将模型应用于调质42CrMo钢单轴应力循环下全寿命棘轮行为的描述和低周疲劳寿命预测中,模拟结果和实验结果吻合较好.更多还原

【Abstract】 Based on the experimental results of ratcheting-fatigue interaction for tempered 42CrMo steel,the whole-life ratcheting deformation features and the low-cycle fatigue(LCF) damage evolution characteristics of the material were first discussed.Then,in the frame work of unified visoco-plasticity and continuum damage mechanics,a damage-coupled visoco-plastic cyclic constitutive model was proposed to describe the ratcheting-fatigue interaction of the material.In the proposed model,the damage was divided into two parts,i.e.,macroscopic elastic damage and plastic damage,which were described by different evolution equations.The threshold value of damage and maximum strain were adopted as failure criterion to reflect fatigue failure and ductile failure respectively.It was shown that the model simulated the whole-life ratcheting behavior and fatigue life of tempered 42CrMo steel reasonably.更多还原