含多裂纹结构的可靠性分析方法

为了对含多裂纹结构的可靠性进行评估,在疲劳多裂纹扩展随机模型的基础上,建立了含多裂纹结构的可靠性分析模型.结构的可靠度是控制裂纹扩展的多维随机变量落在等寿命曲面(线)与坐标面(轴)围起的范围内的概率,即多维随机变量的概率密度函数在等寿命曲面(线)与坐标面(轴)围起的范围内的积分.针对较为简单的情况,建立了完全积分可靠性模型;针对复杂结构但各条裂纹扩展特性相差不大的情况,建立了简化串联可靠性模型;针对复杂结构各条裂纹扩展特性相差较大的情况,建立了修正简化串联可靠性模型.考虑结构可靠性的粗略分析,给出了可靠度的上限值.结合多裂纹扩展随机模型给出了算例. 

Reliability Analysis Models for Multi-Crack Structure

Reliability analysis models for multi crack structure are established in this paper. These models are based on the FMPRM(Fatigue Multi crack Propagation Random Model) and can be used to evaluate the multi crack structural reliability. The structural reliability is the probability that the multivariate random variability controlling the crack propagation falls into a range from the equal life curved surface(curve) to the coordinate surface(axis). It's equal to the integrity of the probability density function of the multivariate random variability in the same range. Three models are established corresponding to different conditions: CIRM(Complete Integral Reliability Model) for simple case, SSRM(Simplistic Series Reliability Model) for complex structure with small difference to each crack propagation behavior and MSSRM(Modified Simplistic Series Reliability Model) for complex structure with large difference to each crack propagation behavior. Finally, two illustrative examples are presented along with the FMPRM to illustrate the reliability.