Bending Behavior and Failure Mode of 3D Needle-Punched C/C-SiC Composites: Multi-scale Analysis and Experimental Investigation

The failure mode of three-dimensional (3D) needle-punched C/C-SiC composites (NP-C/C-SiCs) is complex because they are heterogeneous and demonstrate multi-scale characteristics. It is generally difficult for macroscopic experiments to fully capture the fracture mechanism of the material at a small scale. This paper presents a multi-scale methodology to examine the flexural behavior of NP ceramic-matrix composites (CMCs) considering their real microstructure. The mechanical parameters of the NP-CMCs across different scales are evaluated based on the finite element method (FEM) combined with the progressive damage analysis. Bending properties of the composite material are acquired at the macro-scale, and the damage evolution law at the meso-scale is revealed through transferring the stress history back into the low-scale model. Finally, the flexural test is performed to verify the presented method. The result indicates that the stress-deflection curve and the fracture mode obtained through the FEM simulation agree well with the experimental outcome. The dominant failure mode of 3D NP-C/C-SiCs undergoing the bending load contains matrix cracking, interface debonding, fiber/fiber bundle pull-out, and fiber fracture. The fracture of 0 degrees fiber bundles is the main reason that causes the material to lose its load-carrying capacity.