SYNERGISTIC EFFECTS OF FREQUENCY AND TEMPERATURE ON FATIGUE HYSTERESIS OF A CROSS-PLY SiC/MAS COMPOSITE UNDER TENSION-TENSION LOADING

In this paper, the synergistic effects of the loading frequency and testing temperature on the fatigue hysteresis behaviour of a cross-ply SiC/MAS ceramic-matrix composite are investigated. The fatigue stress-strain hysteresis loop models, considering different matrix cracking modes, are developed to establish the relationships among the fatigue hysteresis loops, fatigue hysteresis dissipated energy and fibre/matrix interface shear stress. Comparing the experimental fatigue hysteresis dissipated energy with the theoretical values, the fibre/matrix interface shear stress of the cross-ply SiC/MAS composite under the loading frequency of 1 and 10 Hz at 566 C and 1093 C in air conditions are obtained for different applied cycle numbers and fatigue peak stresses. At a low loading frequency of 1 Hz, the fibre/matrix interface shear stress and interface shear stress degradation rate of the cross-ply SiC/MAS are higher than that at the loading frequency of 10 Hz. At 1093 C in air conditions, the fibre/matrix interface shear stress and interface shear stress degradation rate of the cross-ply SiC/MAS are higher than that at 566 C in air conditions.