多裂纹结构可靠性研究方法

多处损伤和广泛分布疲劳损伤是影响军用老化飞机结构完整性的主要因素之一.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.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

Multi-site damage and wide spread fatigue damage are the main factors which affect structure integrity of military aging aircraft.The structural reliability is the probability that the multivariate random variability cont rolling 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.