两平行热疲劳裂纹的应力强度因子计算方法

针对直接计算热疲劳裂纹网中裂纹的应力强度因子有困难的问题,提出用有限元方法计算了若干组(每组两条)平行裂纹发生屏蔽效应时的应力强度因子,研究裂纹间屏蔽效应的规律.定义了热疲劳裂纹的比间距n、屏蔽剩余百分数s和裂纹长度比值f,发现此三者有确定关系且与边界条件及裂纹长度无关.给出了n-s-f的关系曲线,据此可根据单条裂纹的应力强度因子推算两条裂纹发生屏蔽效应时主裂纹的应力强度因子.算例表明,该方法是正确的、有效的.

Stress Intensity Factor of Double Parallel Thermal Fatigue Cracks

FEM is proposed to solve the stress intensity factors of thermal fatigue crack networks are hard to solve,where those factors include several groups with two parallel cracks each and are due to the occurrence of shielding effect.The aim is to investigate the relationship between the shielding effect and the gap between cracks.The specific gap n,unshielded percentage s and crack length radio f of the thermal fatigue cracks are all defined,and it was found that the three factors are in a certain relationship with each other and irrelevant with the boundary condition and length of crack.The n-s-f relationship curves are given so that the stress intensity factor of the main crack can be deduced according to that of a single crack when the shielding effect occurs.Numerical example showed that the method proposed is correct and valid.