中文摘要：

基于疲劳裂纹尖端循环应力-应变场,引入损伤力学概念,提出了非对称载荷下考虑累计塑性影响的疲劳裂纹扩展预测模型.基于有限元法和Chaboche循环塑性本构模型,动态模拟单个过载峰作用下的裂纹扩展行为.采用Q345标准紧凑拉伸试样为研究对象,分析不同时刻单峰过载前后裂纹尖端参数变化规律.着重研究了应力比相同且为正值的情况下,不同过载比对疲劳裂纹扩展速率的影响.结果表明,过载比的增加,会得到更大的裂纹扩展迟滞区域以及更小的裂纹扩展速率.并将理论模型预测结果与有限元结果进行对比,结果吻合.

英文摘要：

An analytical model for predicting the low cycle fatigue crack propagation rate of plates has been proposed taking into account the accumulative plastic damage by the concept of damage mechanics and cycling stress and strain field at crack tip.The dynamic crack propagation behavior is modeled by the finite element method and Chaboche cyclic plastic constitutive model.The change rule of the crack tip parameter in the different time near the peak of single overloading uses the Q345 steel as experimental subject.The comparison between the theoretical predicted results and the FE results shows good agreement.In this study,the focus is to obtain the effect of overload ratios on fatigue crack propagation rate when the stress ratio stays the same and is positive.The FE results show that the increase of overload ratio induces more significant retardation after single tensile overload.