Abstract:
Under fatigue loading of fiber-reinforced ceramic matrix composites(CMCs), the fatigue hysteresis phenomenon appears as the fiber slipping repeatedly relative to matrix in the interface debonded region. The area of the hysteresis loops, i.e., the hysteresis dissipated energy, can be used to monitor the damage evolution in fiber-reinforced CMCs under fatigue loading. An approach to predict the fatigue life of fiber-reinforced CMCs has been developed based on the hysteresis dissipated energy. The hysteresis loops models considering fiber failure has been developed. The relationships between the hysteresis dissipated energy, hysteresis dissipated energy-based damage parameter, stress-strain hysteresis loops and fatigue damage mechanisms, i.e., matrix multicracking, fiber/matrix interface debonding, interface wear and fiber failure, have been established. The effects of fatigue peak stress, fatigue stress ratio and fiber volume content on the fatigue life S-N curve, hysteresis dissipated energy and hysteresis dissipated energy-based damage parameter as functions of cycle number have been investigated for fiber-reinforced CMCs. The fatigue life decreases with increasing fatigue peak stress, and increases with increasing fiber volume content; the hysteresis dissipated energy increases with increasing fatigue peak stress, and decreases with increasing stress ratio and fiber volume content; and hysteresis dissipated energy-based damage parameter decreases with increasing fiber volume content.