Fatigue life prediction method for central hole of needled ceramic matrix composite

Based on the consideration of matrix porosity and representative volume element of needled structure, the macroscopic elastic constants of needled C/SiC ceramic matrix composite and the stress concentration factor of the hole-edge were calculated by the finite element method first. Then, based on the fatigue test data of the smooth and central hole specimens, the fatigue notch factors corresponding to different stress levels were ob-tained. In view of the different characteristics of the fatigue notch factor obtained under different limit lives, the relationship between the fatigue notch and stress concentration factors was established, and the influence of nominal stress on the fatigue notch factor was also considered. Based on this, a fatigue life prediction method for central hole of needled C/SiC composite was proposed. The proposed method can predict the fatigue life of central hole by using the S-N curve of smooth specimen and the stress concentration factor of central hole specimen. The comparison between predicted and experimental lives showed that the proposed method can better predict the fatigue life of central hole specimen for needled C/SiC composite.