Fragile Points Method with Interface Fatigue Debonding Model to Simulate Laminate Damage

Aircraft composite laminates exhibit complex fatigue damage behaviors coupling multiple damage modes, including delamination and matrix/fiber cracking, for which reliable numerical simulations remain challenging. In this work, a fragile points method (FPM) with an interface fatigue debonding model is proposed to simulate laminate fatigue damage. The FPM is a novel discontinuous meshless method that can predict complex quasi-static damage and fracture. To simulate fatigue damage, an interface fatigue debonding model is developed, with the interface damage criterion and evolution law based on fatigue life and crack growth models, respectively. With this model, damage and cracking can be introduced across any interior interfaces in an FPM laminate model, enabling the simulation of coupled inter- and intraply fatigue damage with explicit cracks, which is challenging for many existing methods. The proposed method has been validated by mode I and mixed-mode fatigue delamination, as well as fatigue delamination migration involving coupled intra- and interply damage. This work shows that the proposed FPM with an interface fatigue debonding model can explicitly predict laminate fatigue damage with complex crack patterns and has the potential for use in the damage-tolerance design of aircraft composite structures.