Modelling of thermal and mechanical fatigue delamination growth in composites using XFEM

Carbon fibre reinforced polymers (CFRP) are one of the prospective materials being investigated for use in the fuel tanks of future reusable space launch vehicles (RSLV). The extreme thermomechanical loading that these structures experience can lead to damage build-up in the CFRP in the form of microcracking and delamination of laminates, which can be difficult to detect and predict using conventional methods. This work presents a method of modelling delamination growth in a CFRP composite laminates due to thermal and mechanical fatigue loading using the extended finite element method (XFEM). The aim is to increase the accuracy and efficiency of delamination length prediction over current techniques. XFEM models of standard static fracture tests for CFRP materials are developed and compared with experimental data to validate the approach for static failure. The effectiveness of XFEM for modelling mechanical and thermal fatigue growth is subsequently investigated. The predictions are compared to relevant test data from the literature.