关键词: 裂纹, 断裂力学, 压力强度因子, 损伤容限分析, 残余应力

Abstract:

Coldworking of fastener holes has been utilized as an effective technique in aerospace industry to enhance structural components'' fatigue and fracture performance. To quantify the benifical effects of coldworking, stress intensity factors for radial cracks in residual stress fields around the cold-worked hole must be known. Due to the complexity of residual stress distributions, the existing stress intensity factor solution methods are difficult to be used for such problems because they will be loo complicated and time-consuming.in this paper an analytical method for the computation of stress intensity factors for a throuh-the-thickness radial crack at the edge of a circular hole has been presented. The method is based on tite weight function theory in fracture mechanics. The approach is versatile, cost-effective and simple-to-use. and the solution accuracy is very good. Stress intensity factors formulae for such cracks subjucted to various basic load distributions were derived. A technique enabling stress intensity factors to be determined with point-by-point loading specification for a number of points on the crack face was presented. The developed analytical expressions allow stress intensity factors for complex load situations to be determined with minimum efforts.The paper further made a detailed analysis for crack problems involving residual stress fields around a cold-worked hole. Fatigue crack propagation characteristics lor such cracks subjucted o combined action of external loading and residual stress were discussed. The results of this study can be used in quantitative damage-tolerance analysis for aerospace structures containing cold-worked or interference-fitted holes subjected to arbitrary external loading.

Key words: crack, fracture mechanics, stress intensity factor, damage tolerance analysis, residual stress