On the relation between crack densities, stiffness degradation, and surface temperature distribution of tensile fatigue loaded glass-fibre non-crimp-fabric reinforced epoxy

In mechanically loaded laminated composites different damage types occur and interact with each other. This work contributes to the understanding of the damage and degradation process in fatigue loaded E-glass fibre non-crimp fabric reinforced epoxy (GF-NCF-EP). In particular, it is focused on the relation between crack density, stiffness degradation, surface temperature distribution and failure of fatigue loaded GF-NCF-EP. The stiffness degradation of quasi-statically loaded GF-NCF-EP can be related to and modelled by the change of crack density. The location of the final failure in fatigue loaded GF-NCF-EP can be detected via thermography already in an early stage of fatigue life. The location of final failure cannot be related to the local crack density. Thus, the stiffness degradation and failure of GF-NCF-EP under fatigue loading seems to be governed by different, decoupled, mechanisms.