A competitive peridynamic model on oxygen diffusion–reaction process in mechano-oxygenic coupling failures of C/SiC composites

Matrix cracks, serving as oxygen diffusion channels, are inevitable in Carbon/Silicon Carbide (C/SiC) ceramic matrix composites (CMCs). These cracks accelerate the oxidation of carbon reinforcements, significantly degrading the material's mechanical performance under mechano-oxygenic coupling conditions. Applicable for addressing discontinuous mechanical problems induced by crack and oxidation, a peridynamic model on mechano-oxygenic coupling failures of CMCs is proposed. Notably, the competition between oxygen diffusion and reaction is incorporated, providing a unified description of the oxidation process governed by varying kinetics. Furthermore, a peridynamic simulation framework is established enabling simultaneous mechanical and oxidation analysis numerically. Model validation is performed via the proposed framework, including oxidation kinetics and mechano-oxygenic coupling responses. The model captures the linear recession process controlled by reaction and the parabolic recession process governed by diffusion under varying conditions. Additionally, the model successfully predicts the stress-oxidation behaviors of CMCs, with predictions corroborated by experimental data in terms of oxidation morphologies and mechanical degradation trends. Compared to existing simulation approaches, the proposed method, enabling both 2D and 3D analysis, offers more intuitive insights into the mechano-oxygenic coupling failure process. That will enhance the understanding of CMCs’ failure mechanisms and provide a promising tool for evaluating their mechanical performance in extreme environments.