Effect of interface and matrix strength on transverse tensile strength of unidirectional CFRP composite

To illustrate the effect of interface and matrix on the transverse mechanical properties of unidirectional carbon fiber reinforced polymer (UD-CFRP) composites, a calculation method for the transverse tensile strength of UD-CFRP considering the interface cracking process was proposed. The effect of interface crack on the composite stress field was considered based on the representative volume element model with a crack interface, and the crack propagation behavior of interface was simulated by the Benzeggagh-Kenane criterion. The transverse tensile strength of unidirectional T300/BSL914C composites was studied using the theoretical method and finite element (FE) model with random fiber distribution. The theoretical results agreed well with the FE results and the relationships between composite strength, interface strength and matrix strength were provided by the theoretical method. The results show that the interface could be divided into three types according to the strength ratio of interface and matrix, including weakest interface, weak interface, and strong interface. When the interface belongs to the weakest or strong interface, the transverse tensile strength is unaffected by the interface strength and it increases linearly with the increase of matrix strength. When the interface belongs to the weak interface, the transverse tensile strength increases linearly with the increase of interface strength and it is unaffected by matrix strength.