Residual Strength Evaluation of Multi-site Damage Structures with Irregular Cracks

Multi-site damage is an important damage mode to be considered in the aircraft design stage, which significantly reduces the residual strength of the aircraft structure and threatens its reliability. The objective of this paper is to propose an efficient engineering approach of residual strength for multi-site damage structures with three types of cracks: non-collinear cracks, inclined cracks and inclined hole-edge cracks. Additionally, the numerical analysis based on elastic-plastic finite element method were conducted to obtain the load-carrying capabilities of multi-site damage structures. The results obtained by elasto-plastic FE model were consistent with experimental results, and the maximum error was only 5.53%, which were more precise compared with the ones of the engineering approach. Yet we recommended to apply the engineering approach to analyze the residual strength of these typical multi-site damage structures in view of its convenience and simplicity of aeronautical application.