Fatigue performance of carbon fiber reinforced epoxy resin: A molecular simulation

Abstract

In this work, mechanical behavior of multilayer graphene reinforced epoxy resin during fatigue was studied by molecular dynamic method. Transversely isotropic atom based model was established to simulate the carbon fiber reinforced plastics. The reinforced phase was multilayer graphene, and the matrix phase was epoxy resin. Performance degradation in the fiber direction (axial fatigue) and the vertical fiber direction (transversal fatigue) was studied, respectively. Mean stress was considered as the performance per cycle and the power function was employed to describe the tendency of performance degradation. Evolution of energy and structure in atomic scale was used to characterize the cause of performance degradation. The results showed that performance degraded slower in the fiber direction than that in the vertical fiber direction and faster in atomic scale than that in macroscopic experiment. Transformation of molecular structure, which could be represented by the radius of gyration (Rg) of molecular fragments, was one of the reasons that caused performance degradation. Besides, it could cause a change in microscopic energy. Both bond stretch energy and non‐bond interactional energy decrease obviously in the fiber direction while only non‐bond interactional energy decrease in the vertical fiber direction. This phenomenon indicates that existence of carbon fiber effectively slows down the rate of performance degradation in the fiber direction.