204 パルス圧縮援用TOFD法に適した入力信号変調方式の検討(OS6-1 非破壊評価と構造モニタリング,OS6 非破壊評価と構造モニタリング)

抄録

Ultrasonic flaw sizing is important issue for insuring structural reliabilities. Time-of-Flight Diffraction (TOFD) method is recognized as one of the most accurate flaw sizing method. However, the method is not applicable to high attenuation thick materials due to the low SN ratio of lateral wave and flaw tip diffraction wave. In order to overcome this problem, the pulse compression technique is often used for enhancing SN ratio of flaw tip diffraction wave and lateral wave. Although this method is effective to improve SN ratio, sometimes the time resolution of received signal becomes slightly lower than ordinary method. In this study, the new pulse compression technique utilizing wavelet transform was developed for enhancing time resolution of received signal. The pulse width and crack sizing accuracy were compared to the ordinary methods experimentally. As a result, the time resolution could be enhanced by wavelet modulation pulse compression technique compared ordinary pulse compression technique. Moreover, the sizing accuracy was enough for practical using.