主副梁式机翼结构破坏危险性分析

PROBABILITY ANALYSIS OF STRUCTURE FAILURE FOR THE WINGS WITH MAIN AND SUBORDINATE COMPONENTS

本文在综合考虑裂纹检出概率、检查间隔、初始裂纹尺寸分布,裂纹扩展、剩余强度分布等因素的条件下,提出了基于概率断裂力学原理的主副梁式机翼结构的破坏危险性分析方法。并以某型飞机机翼为例,进行了数值计算。结果表明:副梁疲劳寿命对主梁的破坏危险性有显著影响。

A reliability analysis methodology based on the probability fracture mechanics is developed for the wing with main and subordinate components under conisdering several factors, such as crack detection probability, inspection interval, initial flaw distribution, crack growth,residual strength,etc.. The initial fatigue quality(IFQ)of a structural components is represented by an equivalent initial flaw size (EIFS). It is assumed that the equivalent initial crack growth curve conincides with the actual crack growth curve in the crack length region larger than 0.5mm. In this paper, the following crack size-time realtionship is used: a(t) =a(0)exp(at) in which the EIFS a(0) is a lognormal random variable. The correlation between the main and subordinate components in fatigue properties is considered. Several equations to compute the failure rate and the failure probability of structures in any service interval are derived. A calculation example for the wings of some fighter is given in this paper. The results show that the fatigue life of the subordinate component has much effect on the probability of failure of the main component.