배관 감육부의 탄성파에 대한 Wavelet 분석

We studied on the nondestructive evaluation of the elastic wave signals of straight pipe with local wall thinning, Wavelet transform was applied for the time-frequency analysis of wave forms obtained by fracture wave detector due to the dropping steel ball. The time-frequency analysis provides time variation of each frequency component involved in a waveform, which makes it possible to evaluate the shape of local wall thinning at each frequency. In this study, comparison by wavelet transform of the AE signals and monotonic bending tests without internal pressure are conducted on 1.91 inch diameter full-scale carbon steel pipe specimens. As the results of tests, fracture behaviors could be shown the characteristic of mechanical strength of locally wall thinned pipes and the wave forms could be evaluated for the integrity insurance of the piping system according to the length and depth range between the defected shape pipes in the real field.