Fatigue analysis of composite sandwich panel by continuum damage mechanics method with interlayer element

According to the structure of sandwich panels, different failure modes occur during periodic loading in these structures. When the effect of these modes on each other is considered the predictions will be more accurate. In this research, a new tool presented with the help of the combination of USDFLD and UMAT subroutine in the Abaqus software to see the mutual fatigue effect of the face and the delamination between the face and the core using the existing models. This tool is used to fatigue analysis of a sandwich beam with a PVC core with different stiffness and AS4/3501-6 composite faces with [0]4, [90]4 layup. The delamination between the face and the core is analyzed by cohesive zone model and the face fatigue by an energy-based model simultaneously. The results showed that with the increase of the core stiffness, the delamination between the face and the core, caused by fatigue, begins later and moves towards the free edges of the plate. It was also observed that the failure mode that controls the life of this structure is the delamination between the face and the core. The results show the decrease in the growth rate of the damage parameter in the cohesive zone for specified element, increase of the crack growth rate and growth rate of the damage parameter in the face during loading.