Prediction of fatigue limit stress in C/SiC composites: Effect of stochastic load spectrum

Abstract Under cyclic‐fatigue loading, stochastic loading may occur and affect the fatigue limit stress (FLS) in C/SiC composites. In this paper, the FLSs in different C/SiC composites were predicted considering stochastic loading spectrums. Damage mechanisms of interface wear and fibers failure were considered in the global load sharing criterion to determine the fracture life and fiber's failure probability in three different stochastic loading spectrums, that is, constant, increasing and decreasing stochastic stress spectrum. Experimental FLS and fatigue life degradation rate were predicted using the developed micromechanical approach, and the effect of cyclic duration under stochastic spectrums on the FLS was analyzed. Relationships among the FLS, life degradation rate, stochastic spectrum, and cyclic duration were established.