Fatigue damage identification of SiC coated needled C/SiC composite by acoustic emission

The fatigue damage process of SiC coated needled C/SiC composite specimen was monitored by acoustic emission (AE) under tension-tension cyclic loading. By analyzing the collected AE parameters of the composite, it is found that Kaiser effect enhances with the increase of stable cycles in the fatigue process. Moreover, multivariate K-means cluster analysis of AE parameters was carried out after the standardization of energy, amplitude, peak frequency and duration of AE signal. By comparing the objective function values of different number of clusters, and referring to the intra group variance and the variance between groups, the damage modes of the needled C/SiC composite are finally divided into four clusters, and the characteristics of AE parameters with different damage modes can be obtained. Furthermore, by referring to the microstructure characteristics of needled C/SiC composite, various damage modes at different fatigue stages were analyzed. In addition, the fracture morphology of the specimen was also observed by scanning electron microscope after fatigue fracture.