16MnR钢过载峰作用下的疲劳裂纹扩展行为研究

Study on Crack Growth Behavior of 16MnR Subjected to Single Tensile Overload

基于有限元法和Jiang-Sehitoglu循环塑性本构模型,动态模拟单个过载峰作用下裂纹扩展中的裂纹闭合行为。提取不同加载工况下的裂纹闭合和张开载荷,并考察不同工况和不同裂纹长度对裂纹闭合和张开载荷的影响。根据详细的裂纹闭合分析结果,研究单个拉伸过载下疲劳裂纹在不同阶段的扩展行为与裂纹闭合的对应关系,认为过载后裂纹闭合行为的改变是引起裂纹扩展行为改变的主要机理。根据有限元分析结果,提出一种改进的等效应力强度因子范围的计算方法,将其作为疲劳裂纹在整个扩展过程中的驱动力。拟合出单个过载峰作用下16MnR材料的裂纹扩展速率的预测公式,并将预测结果与试验结果进行对比,结果吻合。

The crack closure in the process of dynamic crack propagation is modeling by the finite element method and Jiang-Sehitoglu cyclic plastic constitutive model.The crack closure loading and opening loading are obtained by the FE results with different loading conditions.The influence of different maximum loadings and crack lengths will be analyzed.The relationship between crack propagation behavior and crack closure will be studied based on the FE results.The crack closure is considered as the main mechanism on crack propagation behavior.An improved model to calculate the effective stress intensity factor range will be proposed and the effective stress intensity factor range is considered as the driving force of crack propagation.The prediction formulation of crack growth rate is fitted about the 16MnR steel.The predicted results will be compared with the results of the crack growth experiments and the predicted results are very close to the obtained results in experiments.