Change in mode configurations and propagation velocity of guided wavesthrough an elbow section of a pipe

Guided waves, propagating over long distances with low damping along thelongitudinal direction of pipes, are expected as an efficient method fornon-destructive testing of such long structures. In industrial applications,structures to be inspected often have both straight sections and curvedsections. Therefore, it is important to consider appropriate conditions fortransmitting guided waves propagating with less damping through multiple areaswith different shapes. This research theoretically analyzes and experimentallyverifies propagation of guided waves from a straight section to an elbow sectionof a pipe, and discusses change of the mode configurations and the propagationvelocity under the influence of the elbow curvature of the pipe. The resultsshow a good possibility of predicting the receiver signals detecting guidedwaves through an elbow section of a pipe, by clarifying change of the modeconfigurations and the propagation velocity under the influence of the elbowcurvature in a semi-analytical way. The approach shown in this study will beuseful for propagating guided waves efficiently in pipes with elbow sections.