Fatigue hysteresis behavior in fiber-reinforced ceramic-matrix composites at room and elevated temperatures

The fatigue hysteresis behavior of different fiber-reinforced ceramic-matrix composites (CMCs), i.e., C/SiC, SiC/SiC, SiC/Si-N-C, SiC/Si B4C and Nextel 610 (TM)(TM)/Aluminosilicate, at room and elevated temperatures has been investigated. Based on the developed hysteresis loops models, the relationships between fatigue hysteresis dissipated energy, interface frictional slip and interface shear stress have been established. The evolution of fatigue hysteresis dissipated energy and interface shear stress versus cycle number curves have been analyzed. For C/SiC, the fatigue hysteresis dissipated energy decreases with increasing cycle number at room temperature, and increases with increasing cycle number at 550 degrees C in air; for SiC/SiC and SiC/Si B4C, the fatigue hysteresis dissipated energy increases with increasing cycle number at room temperature, 800 degrees C and 1200 degrees C in air; and for SiC/Si-N-C and Nextel 610 (TM)/Aluminosilicate, the fatigue hysteresis dissipated energy decreases with increasing cycle number at 1000 degrees C in air. The evolution of fatigue hysteresis dissipated energy versus cycle number can be used to monitor the interface debonding and slipping condition inside of composite.