In-situ study on fatigue failure of plain woven SiC_f/SiC composites based on X-ray computed tomography

SiC_f/SiC ceramic matrix composites (CMCs) have emerged as key materials for thermal protection systems owing to their high strength-to-weight ratio, high-temperature durability, resistance to oxidation, and outstanding reliability. However, due to the complex microstructure of composites, including fibres, matrix, interfaces and manufacturing defects, the damage mechanisms of CMCs are extremely complex. In this study, in-situ X-ray computed tomography (CT) and scanning electron microscopy (SEM) were combined to investigate the damage mechanisms of plain woven SiC_f/SiC composites under fatigue. The X-ray CT system, combined with an in-situ loading stage, allowed for the detailed characterization of internal damage evolution at different stages of fatigue, including changes in geometry morphology and defects. Meanwhile, SEM was used to observe the fracture surfaces of the material. Key results indicated that delamination damage occurs due to crack propagation in the matrix, which reduces the load-bearing area and leads to fibre fracture.