Mesh size objective fatigue damage propagation in laminated composites using the multiscale discrete damage theory

Abstract

A mesh size objective multiscale modeling is developed for fatigue failure prediction of long fiber-reinforced composites based on the multiscale discrete damage theory (MDDT). MDDT tracks the failure processes along discrete failure surfaces at the microscale and concurrently bridges it to continuum-based description of damage at the macroscale. The proposed approach achieves mesh-size objectivity by introducing a length scale operator which effectively adjusts the microstructure size as a function of macroscale element size; and when a non-additive fatigue damage evolution law is used to describe progressive cracking at the microscale. Temporal multiscaling is used to track long-term fatigue damage evolution with high computational efficiency. The performance of the proposed model is demonstrated by the analysis of unnotched and open-hole laminate configurations. The results indicate mesh-size objectivity even in the presence of multiple failure mechanisms including splitting, delamination and transverse matrix cracks. The interaction between splitting and transverse cracks is investigated by a parametric study, which reveals the effects of mode I and mode II dominated degradation on the failure behavior under fatigue loading.