Damage evolution and real-time non-destructive evaluation of 2D carbon-fiber/SiC-matrix composites under fatigue loading

Electrical resistance acquisition, acoustic emission (AE) monitoring and infrared thermography were employed to evaluate damage evolution of 2D carbon-fiber/SiC-matrix composite under fatigue loading. Damage evolution was discussed on the basis of the calculation results of the modulus and mechanical hysteresis variation. At lower stress levels, the majority of damage was produced in the first few cycles and then the rate of damage accumulation gradually approached a steady value as the cycles proceeded. When the applied stress exceeded the endurance fatigue limit, extensive damage took place and led to failure of the composite. Changes of composite electrical resistance, AE activity and surface temperature had fairly well agreement with the modulus and hysteresis responses. It can be concluded that it is possible to employ these real-time non-destructive evaluation methods as in-situ damage evolution indicators for this kind of composites under fatigue loading.