Tensile properties of a carbon fiber 2D woven reinforced polymer matrix composite in through-thickness direction

A 2D woven reinforced composite is a typical engineering material used in aerospace applications. For the thickness of these laminated composites is no longer thin, the stress state cannot be considered planar. Therefore, it is necessary to focus on the material's mechanical properties in the through-thickness (abbreviated TT) direction to fully evaluate their mechanical properties. This article considers the tensile properties of a carbon fiber 2D woven reinforced polymer matrix composite in the TT direction under quasi-static and impact loadings. The quasi-static and impact tensile experiments were performed using a material testing machine and split Hopkinson tensile bars, respectively. The micrographs of the fracture surfaces were examined using scanning electron microscope (SEM) analysis. The results show that, before fracture, the material deforms in the linear elastic mode; the TT tensile strength and ultimate strain are very low; the tensile strength increases significantly with increasing loading rates, and the breakage mode changes. An interpretation on the different breakage modes observed is proposed from the point of view of crack propagation. A simple numerical simulation based on ABAQUS is performed to prove that the mesostructure and layer displacements are the two key factors that affect the TT tensile properties. Additionally, an unexpected result, a two-peak stress-strain curve, was found in one of our experiments. By combining the results with the SEM images, a reasonable explanation is proposed.