Fatigue Damage Evolution Model of Ceramic Matrix Composites Structures Based on Hysteresis loss Energy and life Prediction at Elevated Temperatures

Abstract

Due to the multiple damage modes and the variable amplitude cyclic loading, fatigue life prediction for ceramic matrix composites structures is still a challenge. In the present study, to measure the fatigue damage degree, the accumulated hysteresis loss energy was used. A linear function is used to describe the growth law of accumulated hysteresis loss energy with the number of cycles. The growth rate of the accumulated hysteresis loss energy is positively associated with the temperature. A unified equation was then developed to describe the degradation of the residual modulus. To describe the fatigue damage evolution under variable amplitude cyclic loading, the concept of the equivalent number of cycles was proposed. Based on the developed fatigue damage evolution model, the fatigue life of a SiC/SiC dovetail was predicted. Experimental validation revealed that the damage evolution model developed in the present work, which is based on hysteresis loss energy, can effectively predict the fatigue life of ceramic matrix composite structures, and the maximum deviation is less than 20% from the experimental results.