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裂纹闭合行为将很大程度改变疲劳裂纹扩展行为。针对316L不锈钢,结合常幅加载和单个拉伸过载试验和动态数值模拟方法,对疲劳裂纹扩展行为中的裂纹闭合现象开展了一系列研究工作。详细对比了不同扩展阶段的裂纹闭合行为随裂纹长度、应力比和过载影响因素的变化,以及对裂纹扩展速率的影响。同时,研究了单个拉伸过载和裂纹闭合行为之间的内在联系和机理。结合裂纹闭合理论和有限元计算结果,等效应力强度因子被用来描述316L不锈钢的裂纹扩展过程,并提出316L不锈钢的裂纹扩展速率的预测模型。
Crack closure behavior will greatly change the fatigue crack growth behavior. Aiming at 316L stainless steel, a series of research works on crack closure in fatigue crack propagation are carried out in combination with normal loading, single tension overload test and dynamic numerical simulation. The changes of crack closure behavior with crack length, stress ratio and overload influencing factors at different stages of expansion are compared in detail and the effects on crack propagation rate are also compared. At the same time, the intrinsic relationship and mechanism between single tension overload and crack closure behavior were studied. Combined with the crack closure theory and the finite element calculation results, the equivalent stress intensity factor is used to describe the crack propagation process of 316L stainless steel and the prediction model of the crack growth rate of 316L stainless steel is proposed.