Bending-bending Fatigue Behaviors Of 2D Carbon Cloth Laminates Carbon/Carbon Composites

Carbon-Carbon (C/C) composites can act as both functional and structural materials due to their outstanding physical and high-temperature properties, including high specific strength and modulus, excellent ablation and friction resistance, good heat-shock tolerance, low creep rate, high strength preservation under elevated temperature, and so on. As the ideal candidates for high temperature structural materials, carbon/carbon composites are no doubt involved in fatigue loads. Therefore, the study on fatigue behavior is meaningful. In this study, guided by mass test results, the mechanical behaviors and damage evolution of C/C composites are investigated systematically. The article contains three sections, including the fabrication of samples, mechanical behaviors of C/C composites under static flexural loading, and the room-temperature fatigue behaviors.The two-dimensional (2D) carbon cloth laminates C/C composites is fabricated by an isothermal chemical vapor deposition (CVD) process. The room-temperature mechanical behavior is investigated using a static three-point bend test. And an unconventional fatigue test is designed based on the results of static test, in order to explore the change of residual flexural strength and flexural modulus of C/C composites after bending fatigue loading with different applied stress. The final test results indicate that after cyclic bending-bending loaded, the residual flexural strength and flexural modulus of tested C/C samples increase, instead of decrease, which is different with general materials. It shows the beneficial influence of fatigue load on material performance, viz. the strengthening effect.By analyzing the fracture mode of C/C composites during fatigue loading process, the fracture mode is discovered change from brittle manner to plastic-like manner. It also confirmed that the C/C composites has reinforcing behavior of fatigue.The fracture pattern of C/C composites is observed by scanning electron microscopy (SEM). Start with the interior structure, the unique fatigue property and the extra phenomenon of reinforcing behavior of fatigue have been reasonably explained. Some viewpoints for further investigations are also made in this paper.