Micromechanical Modeling of Unidirectional CFRP Composites with Proportional Stressing

In this paper, we present a computational micromechanical analysis of unidirectional (UD) carbon fiber-reinforced plastics (CFRPs) using representative volume elements (RVEs). The RVEs consist of randomly distributed fibers, matrix, and interfaces between the fibers and matrix. Periodic boundary conditions (PBCs) and proportional stressing are implemented to facilitate micromechanical analysis of the composites under controlled stress states. In particular, the failure mechanisms of the RVEs under combined transverse and in-plane shear stressing are investigated. The ratio of in-plane shear stress over transverse stress is kept constant during each simulation. By varying this ratio, the mechanical responses of composites under different stress states are systematically studied and the failure envelopes for different fiber volume fractions are extracted. We find the failure envelope converges as the fiber volume fraction increases. The framework developed in this study can be extended to different stress states allowing us to conveniently examine the failure criteria for UD CFRP composites comprehensively.