Transition of in-plane compressive strength and failure mechanism of 2D-C/SiC: Influence of off-axis loading angle and loading rate

In this study, the in-plane compressive behavior of two-dimensional plain-woven carbon fiber-reinforced silicon carbide composite (2D-C/SiC) was investigated using on- and off-axis compression experiments under both quasi-static and dynamic loading conditions. The failure mechanisms were elucidated through in-situ observations and microanalysis-based methods. As the loading angle increased from 0 to 45°, stress–strain curves exhibited stronger nonlinearity, and the in-plane compressive strength decreased by 50.2% and 41.1% under quasi-static and dynamic loading conditions, respectively. The failure mechanism shifted from fiber-dominant to interface- and matrix-dominant as the loading angle increased, which was responsible for the strength degradation and intensified nonlinearity in curves. A positive strain rate effect on the in-plane compressive strength attributed to the interface enhancement and multiple crack propagation was identified. Additionally, owing to the competition between the dynamic strengthening and damage aggravation effects, the strain-rate sensitivity factors increased with the loading angle up to 30° and then decreased at 45°.