飞机结构多部位损伤发生的可能性分析

基于疲劳统计学与断裂力学的基础,利用已有的飞机单细节结构试验结果,提出一种定量计算飞机结构发生多部位损伤(MSD,Multiple Site Damage)可能性的方法.该方法简化了飞机结构发生MSD可能性的计算,为飞机结构的安全性评估提供基础.该方法认为单细节的裂纹萌生寿命服从正态分布或对数正态分布.对于多细节的飞机结构,到某一时刻,当2个或2个以上细节萌生裂纹时,则认为该结构发生了MSD.给出了具体的方法介绍和理论推导,并给出了一个具体的计算示例,得到MSD产生概率与应力水平的关系曲线.计算结果表明,该方法计算合理,较符合实际情况,利于工程应用.

Reliability analysis on structure with multiple site damage

A quantitative analysis method on the occurrence probability of MSD(multiple site damage)was presented based on the theory of statistics in fatigue and fracture mechanics and the existing experimental results. It predigested the calculation for the occurrence probability of MSD and provided reference for the evaluation of fatigue life of aircraft structures. It assumed that the initiating life of single crack follows logarithmic normal distribution or normal distribution according to existing research and experimental results. The assumption was rational and it didn′t affect the foundation of calculation and theory. For the structures with multiple details, MSD in the structure happened when two or more than two details emanated cracks at certain time. According to these, method and formula were proposed. A numerical example and corresponding stress-MSD probability curve were given for the proposed approach. The result indicates that the method is reasonable and can be used in engineering.