# Predictive Constitutive Modelling of Oxidation-Induced Degradation in 2.5D Woven C/SiC Composites

## TL;DR

This paper develops a model to predict how oxidation affects the strength and durability of ceramic composites used in high-temperature environments.

## Contribution

A novel meso-scale constitutive model incorporating oxidation damage and fiber defect distribution in 2.5D woven C/SiC composites is proposed.

## Key findings

- The model effectively characterizes strength degradation and stiffness reduction caused by oxidation.
- High-temperature tests validated the model's accuracy at 700 °C, 900 °C, and 1100 °C.
- The model provides a physics-based foundation for reliable design and life assessment of C/SiC components.

## Abstract

Oxidation can lead to intrinsic degradation and loss in the load-bearing capacity of ceramic matrix composites (CMCs) in high-temperature service, thereby compromising structural integrity and operational safety. To elucidate the mechanism of its oxidation effects, this study predicted the oxygen diffusion coefficient within 2.5D woven C/SiC fibre bundles based on gas diffusion and oxidation kinetics theory, and subsequently constructed a meso-scale constitutive model incorporating oxidation damage and fibre defect distribution. Furthermore, a micro-scale framework for yarns was established by integrating interfacial slip behaviour, and an RVE model for 2.5D woven C/SiC was constructed based on X-ray computed tomography reconstruction of the actual microstructure. Building upon this foundation, an oxidation constitutive model applicable to loading–unloading cycles was proposed and validated through high-temperature oxidation tests at 700 °C, 900 °C, and 1100 °C. Results demonstrate that this model effectively characterizes the strength degradation and stiffness reduction caused by oxidation, enabling prediction of CMCs’ mechanical properties under oxidizing conditions and providing a physics-based foundation for the reliable design and life assessment of C/SiC components operating in oxidizing environments.