ASSESSMENT OF NUMERICAL APPROACHES FOR QUASI-STATIC, FATIGUE, AND DYNAMIC PROPAGATION OF DELAMINATION IN CURVED LAMINATES

The accurate prediction of fatigue delamination growth and critical damage size remains an open challenge in enabling the Slow-Growth design and damage-tolerance substantiation in composite aircraft structures. Delamination is especially important due to difficult detectability and the high sensitivity of laminated composites to this failure mode. This work presents a preliminary experimental characterization of the fatigue-driven delamination in a thick, pre-damaged L-shaped composite specimen. To support and interpret these results, a cohesive zone-based finite element (FE) fatigue modelling framework was first verified on standard Mode I (DCB), Mode II (ENF), and Mixed-Mode (MMB) specimens, using experimental data from the literature. The framework was then applied to simulate the fatigue behaviour of the L-shaped specimen. Finally, the variation of energy release rate with crack-growth was investigated to explain the observed failure modes, highlighting the strong sensitivity of delamination growth to initial loading conditions.