Stress Field and Damage Evolution in C/SiC Woven Composites: Image-Based Finite Element Analysis and in situ X-Ray Computed Tomography Tests

In this study, the construction and examination of meso-structural finite element models of a Chemical-Vapor-Infiltrated (CVI) C/SiC composite is carried out based on X-ray microtomography digital images (i.e. image-based finite element method: IB-FEM). The accurate meso-structural features of the C/SiC composites, which are consisted of carbon fiber tows and CVI-SiC matrix, in particularly the cavity defects, are reconstructed in the meso-structural models. With the IB-FEM, the damage evolution and fracture behaviors of the C/SiC composite are investigated using the Abaqus standard program. Influences of the meso-structures on deformation, damage evolution, and fracture features of the C/SiC textile composite are studied, and they are compared with the results from a perfect RVE model. At the same time, an in situ tensile test is applied to the C/SiC composite under a CT real-time quantitative imaging system, aiming to investigate the damage and failure features of the material as well as to verify the IB-FEM. The IB-FEM results indicate that material damages initially occur at the defects, followed by propagating toward the fiber-tow/SiC-matrix interfaces with increasing load. Ultimately, the damages would be combined into marco-cracks, which is in good agreement with the in situ CT experiment results.