Fatigue cohesive zone modelling of a benchmark test for composites under complex loading sequences resulting in non-self-similar damage evolution

In this work, the fatigue CZM developed in C. G. Dávila (2020, April. NASA/TP–2020-220584) and the simulation strategy proposed in I. Lecinana (Engineering Fracture Mechanics, 2023, vol.286, art. num.109273) are adopted to simulate a novel fracture benchmark test that is considered as equivalent of in-service loading since it considers the transient effects of alternating different loading modes, monotonic, and fatigue loading. The case study was performed on a AS4D/PEKK-FC thermoplastic composite. Different combinations of loading modes, monotonic, and fatigue loading were applied. The non-self-similar damage evolution of different failure mechanisms such as brittle fracture, plastic deformation, and large-scale fibre bridging were correlated qualitatively to the different superposed cohesive laws, giving an insight on the phenomenological nature of superposing cohesive laws