Interaction of acoustic surface waves induced by inter-digital transducer with wall thinning defect in pipe structure

Abstract

Most structural health monitoring (SHM) systems require transducers permanently attached to or integrated with the monitored structure to form a type of smart structure. It is difficult to permanently attach traditional ultrasonic transducers for non-destructive testing of structures for health monitoring. However, inter-digital transducers (IDTs) can be considered for on-site SHM because of the small size and economic efficiency of the IDT sensor. In this paper, an alternative sensor approach is proposed using IDT rather than conventional transducers to identify the interaction of surface acoustic waves (SAWs) with a wall-thinning defect. The SAWs generated by IDT sensors are modeled using the finite element analysis method. Acoustic wave propagation behavior in plate and pipe structures was reviewed, and the effect of the curvature of curved plate was investigated. From the interaction behavior observed between SAWs and a wallthinning defect in the pipe, which was determined using numerical simulation and tests, a novel concept is proposed for characterizing wall-thinning defects in pipelines.