Damage Mechanism Research For C/SiC Composite Material Based On Acoustic Emission Signal Analysis

Ceramic Matrix Composites(CMCs)with low density,high strength,high temperature resistance are widely used in aero engines.However,due to the complicated structure of CMCs and the existence of pores and micro-cracks in the interior and the surface,it put a great test on material research.Acoustic emission(AE)technology is a nondestructive testing technology.There will be a lot of AE signals during the loading process of CMCs.These signals contain many information of damage sources.So analyzing these signals can help us understand the mechanism of CMCs damage failure.To achieve the above goal,the first to do is to classify the acquired AE signals and establish the relationship between the AE signals and the damage mechanism.A complete set of AE signal clustering analysis method was developed based on the theory of pattern recognition,combined with SPSS data analysis software and clustering algorithm based on Matlab software.Single fiber tensile test,fiber bundle tensile test,C/SiC composite loading-unloading test and C/SiC composite in situ tensile were carried out.The characteristics of AE signal of matrix cracking,fiber fracture,fiber/matrix interfacial debonding and interface friction in the basic failure mode of CMCs were obtained.On this basis,the static tensile experiments of plain weave and two-dimensional needled C/SiC composites were carried out.By means of cluster analysis,the AE signals were divided into 6 categories and 8 categories separately.The relationship between AE signals and its damage source was established by studying the characteristics of each kind of AE signals,and combining the analysis of AE waveform and spectrum,the evolution of each kind of AE signals and the analysis of SEM fracture.