Numerical simulation on stress rupture life of C/SiC under wet oxygen condition

Stress oxidation, accompanied by a complex coupling process between thermal, stress, and chemical reactions, is one of the primary failure types of C/SiC thermal structures. To predict the rupture life of C/SiC, a finite element analysis (FEA) model was established on a representative volume element (RVE) extracted from the periodic structure of plain weave C/SiC. Considering the diffusion mechanism of the oxidizing atmosphere and the oxidation kinetics of carbon fibers, an oxidation damage variable was defined. The FEA model accounts for both stress failure and oxidation damage of the carbon fiber bundles. Stress rupture lifetimes under the conditions of different stress levels and temperatures were predicted. The comparison between simulation results and experimental results proves the reliability of the proposed model. The competition mechanism between diffusion and oxidation was also discussed.