Tensile, Compressive and InPlane/InterLaminar Shea r Failure Behavior of CVIandITESiC/SiC Composites

Abstract . A SiC/SiC composite is an attractive candidate material but it is a challenge to apply it to the practical components because of the inherent brittle-like failure and structural anisotropy. This study aims to evaluate the failure behavior of SiC/SiC composites by various test modes. Comparison between tensile and compressive strengths revealed the clear axial anisotropy of failure strength. The in-plane shear strength by the off-axial tensile method is invalid unless considering the mixed failure modes. Alternatively, it was demonstrated that the in-plane shear strength can successfully be obtained by the Iosipescu method. The true inter-laminar shear strength can be identified by the diametral compression method. 1. Introduction A silicon carbide composite (SiC/SiC composite) is one of attractive candidates for fission (e.g., control rods for Very High Temperature Reactor) and nuclear fusion (e.g., flow channel inserts) due to the proven irradiation tolerance coupled with the excellent baseline properties as refractory ceramics [1]. For the practical applications, identifying the failure scenario and lifetime under service environments is important for the design code establishment. For instance, considering the fusion, the high heat flux induced by the fusion plasma gives a steep thermal gradient inside the material [2]. This thermal gradient subsequently gives differential swelling under irradiation, as well as differential thermal expansion, resulting in the complicated stress state. Considering the inherent brittle-like failure behavior and anisotropy of composites due to the variety of fabric architecture, it is, therefore, required to identify the crack propagation behavior of SiC/SiC composites by various failure modes. This study aims to evaluate failure behavior of SiC/SiC composites by various mode tests such as tensile, compressive, inplane shear and inter-laminar shear modes.