Fatigue crack paths in light aircraft wing spars

Different cracks paths in three different wing spar designs are analysed (differential, integral and optimized integral) to explore how those cracks paths affect fatigue life estimation. First, numerical analysis was carried out and verified, using the experimental data for differential wing spar, followed by numerical analysis of both optimized integral wing spars. The optimized integral spar was obtained by analysing three different cross sections regarding fatigue life. Crack propagation simulation and fatigue life estimation were carried out by the extended finite element method, using Morfeo/Crack for Abaqus. Results provided better understanding and prediction of multiple cracks propagation in 3D structures.