Stress Intensity Factors Evaluation at Tips of Multi-Site Cracks in Unstiffened 2024-T3 Aluminium Panel Using XFEM

Abstract

The aim of this paper was to establish and demonstrate significant capacity and performances of extended finite element method (XFEM) to calculate stress intensity factors (SIFs) histories versus crack length for problems involving multiple, interacting cracks resulting from multiple site damage (MSD). A typical aero structural configuration was analysed: unstiffened flat panel made of aluminium Al 2024-T3, containing 11 holes, each of which is a site for crack growth. Analysed model makes a unique 3D configuration with 22 cracks, propagating at the same time. Short theoretical background information is provided on the XFEM, as well as representation of cracks and SIFs computation. The computations were carried out in Morfeo/Crack for Abaqus software which relies on the implementation of XFEM. The accuracy of these computations was verified through FRANC2D/L software and superposition based approximate method. The conducted analysis showed that XFEM is efficient tool for the simulation of crack propagation even in the case of 3D configurations with MSD, and that the obtained solutions can be used for the prediction of SIFs in analysed MSD configuration with acceptable accuracy.