A Flexible Film Magnetostrictive Patch Transducer for Nondispersive Shear Horizontal Wave Testing

The fundamental shear horizontal (SH0) wave shows great potential in structural health monitoring (SHM) of plate-like structures because it is a completely nondispersive guided wave mode. However, the existing transducers used to excite SH0-mode guided waves are usually rigid or brittle structures, which means that the transducers have a significant challenge in detecting irregular or curved structures due to the difficulty in contacting the structure surface. Moreover, due to its large volume and weight, the additional mass of the monitoring system can lead to an increase in monitoring costs, especially in high-precision fields such as aerospace. This study presents a flexible film magnetostrictive patch transducer (FFMPT) for exciting pure SH0 guided waves. It is manufactured by flexible printed circuits (FBCs), and the overall structure consists of two layers of FPC and one layer of alloy thin patch. The finite-element analysis results indicate that pure SH0 waves can be generated and received in the excitation direction. Then, the defect detection ability of the transducer on curved structures was verified through experiments, and the frequency response of the dynamic magnetic field of the transducer was tested. Finally, the performance of the proposed SH0-mode transducer was validated on thicker specimens closer to actual working conditions, further validating the advantages of SH0-mode guided waves. Considering the flexible structural characteristics, cost-effectiveness, and detection capability of the proposed transducer, it has great potential in SHM of curved structures.