Determination and prediction of axial/off-axial mechanical properties of SiC/SiC composites

A SiC/SiC composite is a candidate material for a demonstration fusion power reactor (DEMO). Identifying the inherent anisotropy of composites is required to predict axial/off-axial mechanical properties for various failure modes. This study evaluated crack propagation behavior by the various modes to provide strength anisotropy maps and we discussed a method to analytically predict this trend. The strength anisotropy maps identified for various fabric orientations clearly indicate that the composites failed in the mixed modes. Specifically, due to the axial anisotropy, five individual mode strengths such as tensile/compressive strengths in the axial/transverse directions, respectively, as well as the in-plane shear strength, are identified to become essential input parameters. With the analytical criterion based on the Tsai–Wu model, the strength anisotropy could satisfactorily be described.