Simulating damage and permanent strain in composites under in-plane fatigue loading

Fibre-reinforced composites are used in many fatigue-critical applications (wind turbine blades, aircraft components, leaf springs, …). Due to their heterogeneous and anisotropic nature, their fatigue behaviour is rather complex and several damage mechanisms can develop during fatigue life. This paper presents a damage mechanics-based fatigue model for fibre-reinforced plastics, where both stiffness degradation and (possible) accumulation of permanent strain are simulated from the first loading cycle up till final failure. The model has been validated for cantilever bending fatigue tests of plain woven glass/epoxy composite. Although the damage growth rate varies along the specimen length, the finite element simulations with the damage model are able to account for decreasing (bending) stiffness and permanent strain.