Modeling the effect of oxidation on hysteresis loops of carbon fiber-reinforced ceramic-matrix composites under static fatigue at elevated temperature

An analytical method has been developed to investigate the effect of oxidation on the hysteresis loops of fiber-reinforced ceramic-matrix composites (CMCs) under static fatigue at elevated temperature. The oxidation region propagating model has been adopted to analyze the oxidation effect on the hysteresis loops, which is controlled by interface frictional slip and diffusion of oxygen gas through matrix multicrackings. Based on the damage mechanism of fiber slipping relative to matrix, the hysteresis loops models corresponding to different interface slip cases considering interface oxidation have been established. The relationships between hysteresis loops, hysteresis dissipated energy, interface slip and oxidation time have been established. The effects of stress level, matrix crack spacing, fiber volume content and oxidation temperature on the hysteresis dissipated energy, interface debonding, oxidation and slip lengths versus oxidation time have been analyzed. The experimental hysteresis loops of C/[Si-B-C] composite under static fatigue in air at 1200 °C have been predicted.