Abstract
Ultrasonic testing is important issue for insuring structural reliability of industrial plants. In recent years, the flaw visualization technique by ultrasonic testing becomes widely used. Basically, ultrasonic echoes come from only the flaw tip or flaw root. However, sometimes unexpected echoes come from bottom surface due to the surface roughness. In this study, the relationship between the surface roughness and the intensity of scattered ultrasonic echo was investigated by both numerical simulation and experiment. Ultrasonic waves were generated from various incident angles for the specimens with various roughness of bottom surface. The intensity distributions of the scattered longitudinal waves and mode converted share waves were investigated. As a result, on the flat surface, the angle of reflected longitudinal wave corresponded to incident angle. The mode converted share wave was also observed. On the other hand, on the rough surface, the ultrasonic beam scattered widely and the amplitude of mode converted share wave was lower compared to flat surface. Besides, the results of numerical simulation and experiment were corresponds well each other.
