基于变载荷间隔的MSD结构疲劳可靠性研究  

Investigation into Fatigue Reliability of MSD Structure by Modifiable Division of Cyclic Loading Method

作　　者：薛小锋[1] 郑香伟[2] 冯蕴雯[1] 冯元生[1] 

机构地区：[1]西北工业大学航空学院,中国西安710072 [2]中国航空工业集团公司第一飞机设计研究院,陕西西安710089

出　　处：《华南理工大学学报（自然科学版）》2015年第11期145-150,共6页Journal of South China University of Technology(Natural Science Edition)

基　　金：国家自然科学基金资助项目(10577015)~~

摘　　要：多部位损伤(MSD)会使结构的强度大幅降低,为了防止由此造成的灾难性破坏,必须对MSD结构在整个寿命周期内的裂纹扩展情况及可靠性水平进行准确评估.文中在假设MSD结构断裂韧性和应力强度因子服从对数正态分布的基础上,结合应力强度干涉模型和二阶窄边界理论,建立了MSD结构的裂纹扩展可靠性模型;考虑MSD结构多裂纹扩展过程中的两类影响因素,推导了疲劳载荷作用下的裂纹扩展增量递推公式;结合变载荷间隔分段处理方法,提出了MSD结构随载荷循环次数变化的失效概率计算方法.通过对一受远场均匀载荷作用的含共线孔边裂纹的MSD壁板结构的分析计算,得到了MSD壁板结构失效概率随疲劳载荷作用次数的变化趋势,并将其与试验值进行比较,较为准确地反映了MSD壁板的失效趋势.MSD( Multiple Site Damage) can cause the structure strength to degrade,which may lead to a catastrophic failure. In order to avoid the failure,the crack growth and reliability of the MSD structure in its whole life cycle should be exactly evaluated. In this paper,assuming that the fracture toughness and stress intensity factor of the MSD structure follow the lognormal distribution,a multiple-crack propagation reliability model of the MSD structure is constructed by combining the stress-strength interference model and the second boundary theory. In view of two influencing factors related to the crack growth of the MSD structure,a recursion relation of crack growth length under fatigue load is deduced. Then,by drawing on the modifiable division of the cyclic loading method,a calculation method of the failure probability of the MSD structure with changing load cycles is proposed. Finally,by analyzing and calculating a MSD panel with collinear hole-edge cracks under far-field uniform load,the variation trends of the failure probability of the MSD panel with fatigue load cycles are obtained,and the calculation results are compared with the experimental ones. It is found that the proposed method can reflect the failure trends of the MSD panel more accurately.

关 键 词：多部位损伤 裂纹扩展 可靠性 应力强度因子 概率 

分 类 号：O346.2[理学—固体力学]