CHARACTERIZATION OF FAILURE BEHAVIOR OF SILICON CARBIDE COMPOSITES BY ACOUSTIC EMISSION

摘要

A silicon carbide fiber reinforced silicon carbide matrix (SiC/SiC) composite is a promising candidate material for various nuclear applications such as a fusion blanket. Due to the inherent brittle-like failure, identifying failure scenario with consideration of reliability and reproducibility of composite's characteristics is undoubtedly important to develop design codes specialized for composites. This study aims to identify failure behavior of SiC/SiC composites by varied test modes. For this purpose, acoustic emission (AE) was applied to detect composites' failure. The tensile, compressive and in-plane shear tests were conducted for plain-weave (P/W) chemical-vapor-infiltration (CVI) SiC/SiC composites. Various loading angles were applied to discuss an anisotropic issue. AE results distinguished damage accumulation processes in axial and off-axial loading cases. Specifically, test results indicated a clear difference of damage density between tensile and compressive tests. This study also classified the characteristic failure modes by separately discussing localized variations of power within a lime series by wavelet analysis.