Experiments for Mode Identification of Ultrasonic Guided Waves and Fault Detection in a Curved Pipe

Ultrasonic guided waves can perform long-range inspection from sensor without moving its position. However they have not only numerous modes but also dispersive characteristics that the velocity of modes depends on the frequency and thickness. Thus to understand reflected signals correctly, modes of the signals should be identified exactly. This report describes (1) general theory of ultrasonic guided waves, (2) preliminary experiments for the defect detection of a curved pipe and analysis results of reflected signals according to the distance from defects, and (3) LPIS (Long-range Piping Inspection System) which is unitary system for the defect detection in a pipe, and wedges used in experiments