A micromechanical model for longitudinal compressive failure in unidirectional fiber reinforced composite

A micromechanics-based 2D numerical model is proposed to comprehensively trace the longitudinal compressive failure of unidirectional carbon fiber reinforced polymers (UD-CFRP), in which microscopic damage mechanisms (namely the fiber fracture, matrix plastic yield and fiber-matrix interface crack) are considered. With this model, the predicted compressive modulus, strength and failure pattern are in good agreements with the experimental results, which validate the effectiveness of the proposed model. It concludes that the longitudinal compressive failure is governed by the matrix damage rather than the fiber fracture and the interface crack triggers the matrix damage. In addition, the influence of some microscopic parameters, including the fiber volume fraction, initial fiber misalignment, initial fiber-matrix interface stiffness, interface strength and fracture energies, on the longitudinal compressive failure is disclosed. The compressive modulus increases with the fiber volume fraction while it is almost unaffected by the rest four parameters. The compressive strength increases with the increment of the initial interface stiffness or the decrement of the initial fiber misalignment while it is immune to the interface fracture energies. Moreover, a limited increment of the fiber volume fraction or the interface strength is beneficial for enhancing the compressive strength.