P3-21 配管中を長手方向に伝播するSH波について(ポスター発表)

抄録

Guided wave has been widely used in nondestructive evaluation for elongated structures such as plates, pipes and rails. Guided wave inspection for pipes has been carried out using low frequency ultrasonic range, 30-100kHz, for long-range propagation. But in many cases, some hazardous defects cannot be found due to the low sensitivity of low frequency ultrasonic and obstacles such as pipe elbows and defect lines. Authors and other Japanese inspection companies, therefore, are now trying to inspect, more accurately, 5.5m range of pipes that is generally maximum length of pipes between weld lines. Thus, SH wave from 100kHz to 1MHz is used for such pipe inspection instead of low frequency torsional mode of guided wave. But SH wave in a pipe shows complex wave motion because widely spread SH waves circumferentially propagate around and superimpose on straight SH waves.