In situ investigation of failure in 3D braided SiCf/SiC composites under flexural loading

The mechanical failure of three-dimensional (3D) 4-step braided SiCf/SiC composites, processed by precursor infiltration pyrolysis, has been studied under flexural loading to investigate the condition at failure. investigation integrated advantages continuous data acquisition optical imaging and 3D reconstruction internal structure in X-CT imaging, for situ microstructure-related mechanisms. Optical with digital image correlation acquired surface displacements. X-ray computed tomographs, obtained situ, were analysed volume measure displacement fields. Image subtraction, informed displacements, was used detect visualize crack development. Curvature measurement, via fields, monitored change effective modulus. observed modes included matrix cracking, inter- intra-bundle debonding fibre breakage. Tensile cracks arrested heterogeneous microstructure, ultimate due multiple cracking compression.