A novel experimental method to evaluate the shear behavior and failure mechanism of CCC

The superior mechanical properties of carbon/carbon composites (CCC) make them widely applicable in aerospace thermal structures. In CCC structures, shear fracture serves as the primary failure mode during operational loading. Therefore, understanding the shear behavior and failure mechanisms of CCC is critically important. To this end, a hat-shaped shear specimen is specifically designed. Fracture morphology is examined to reveal the failure mechanism of CCC. The results show that the shear failure processes of the CCC exhibit two damage stages. Compared with the interlaminar properties, the in-plane direction exhibits significantly greater shear performance, with strength and modulus increased by 88.45% and 91.39%, respectively. Under in-plane shear loading, the CCC predominantly fails due to deflection and tension of the x-direction fiber bundles within the carbon fabric layers. In contrast, interlaminar shear failure mainly results from matrix shear failure and the bending and tensile fracture of z-direction fiber bundles.