Cross-scale static/dynamic shear damage evolution mechanism of 2D C/SiC ceramic matrix composite with transient hysteresis effect

Abstract

The intricate woven structure of two-dimensional woven carbon fiber-reinforced silicon carbide (2D C/SiC) poses challenges to the investigation of damage failure mechanisms and the prediction of material performance, thereby limiting its further application in aerospace engineering. In this work, static/dynamic short beam shear tests with different densities of 2D C/SiC were carried out. It was observed that high-density specimens with fewer microporous defects exhibited better strength characteristics than those with lower density. Specifically, the shear strength of 2D C/SiC with a density of 2.07 g/cm³ increased by 18.6% compared to that of the specimen with a density of 1.94 g/cm³. The transient hysteresis strengthening effect of materials at high strain rates was discovered through cross scale research methods. It was found that deformation coordination ability of 2D C/SiC under dynamic loading was weaker than that under quasi-static conditions. Moreover, the deformation hysteresis in temporal and spatial distributions induced significant fiber plucking, further accelerating dislocation movement within the internal lattice and thereby enhancing strength of the material. The failure path of materials often follows the direction of pore defects, and stress concentration leads to cracking behavior of fiber bundles. Furthermore, microcracks within the matrix, caused by residual stress, resulted in localized regions of reduced strength. This induced the matrix cracking failure with further crack expansion within the material structure under external loads. To provide technical references for practical engineering applications and design, a realistic and effective finite element prediction model was developed for 2D C/SiC composites based on their structural characteristics.