基于J积分的复合型疲劳裂纹扩展分析

Analysis of Mix-mode Fatigue Crack Growth Based on J-Integral

为研究Ⅰ型(张开型)、Ⅱ型(剪开型)复合裂纹的扩展行为,通过数值方法结合试验数据分析Ⅰ-Ⅱ复合型(30°、45°、60°)加载下AA7075材料高周疲劳裂纹扩展,分别利用等效应力强度因子幅值(ΔK^(*))和循环J积分(ΔJ)描述疲劳裂纹扩展速率,给出相应的Paris公式表达式;推导ΔK^(*)与ΔJ在线弹性断裂力学理论下两者之间的关系式。结果表明:所推导的ΔK^(*)与ΔJ理论关系式可以提供与数值方法相同的结果;由于等效应力强度因子均需经验公式复合获得,利用ΔJ能有效代替ΔK^(*)作为参数描述高周复合型疲劳裂纹扩展速率。

In order to study the growth behavior of typeⅠ(opening)and typeⅡ(shearing type)compound cracks,numerical methods and experimental data are used to analyze the height of AA7075 material underⅠ-Ⅱcompound type(30°,45°,60°)loading.Cycle fatigue crack growth,the equivalent stress intensity factor amplitude(ΔK^(*))and cyclic J integral(ΔJ)are used to describe the fatigue crack growth rate,and the corresponding Paris formula expression is given.ΔK^(*)is derived the relationship between the two andΔJ under the theory of linear elastic fracture mechanics.The results show that the derived theoretical relationship betweenΔK^(*)andΔJ can provide the same results as the numerical method;since the equivalent stress intensity factors need to be obtained by empirical formulas,usingΔJ can effectively replaceΔK^(*)as a parameter that describes the growth rate of high-cycle composite fatigue cracks.