We studied the nondestructive evaluation of the elastic wave signal of SiC ceramics and SiC/SiC composite ceramics under monotonic tensile loading. The elastic wave signal of cross and unidirectional SiC/SiC composite ceramics were obtained by the pencil lead method and a bending test. This was applied for the time-frequency method which used the discrete wavelet analysis algorithm. The time-frequency analysis provides the time variation of each frequency component involved in a waveform, which makes it possible to evaluate the contribution of the SiC fiber frequency. The results were compared with the characteristic of the frequency group from SiC slurry and fibers. Based on the results, if it is possible to shift up and design a higher frequency group, we can then make a superior material better than those of exiting SiC/SiC composites.

Keywords: SiC/SiC composites ceramics, Wave propagation, Elastic wave, Wavelet analysis, Dominant frequency