Effect of porosity on high-temperature tensile properties of 2D woven C/SiC with hole-edge densification structure

This study proposes a modeling approach that characterizes the hole-edge densification structure of open-hole 2D braided C/SiC composites during chemical vapor infiltration (CVI). An embedded multi-scale progressive damage modeling method is proposed to characterize the densified structure of hole edges·, considering the random distribution of pores. Subsequently, a macro-meso model was established, integrating 2D woven C/SiC composites with hole-edge densification. A high-temperature progressive damage model for 2D braided C/SiC composites was established. The stiffness matrix was modified according to the various damage modes and loading conditions of the fiber and matrix to simulate the nonlinear mechanical behavior of the composites. Compared to the experimental data and the homogenized model, the errors in the macro and micro models can be reduced by 69.1 %. The analysis indicates that the average thermal stress in the matrix and warp increases with rising temperature, while the thermal stress in the weft yarn exhibits minimal variation with temperature changes. When the porosity is below 10 %, the average stress in the dense area near the hole edge remains low. Conversely, when the porosity exceeds 10 %, the average thermal stress in the dense area surpasses that in the non-dense area. The uniaxial tensile strength of 2D braided C/SiC composites with varying porosity initially increases and then decreases with rising temperature. Additionally, at different temperatures, the locations of fracture damage in 2D braided C/SiC composites with different porosities vary.