Mode conversion behavior of SH guided wave in a tapered plate

The present study explores mode conversion of shear horizontal (SH) guided wave when it impinges on smooth defects in plates. The fundamental (SH0) and the first higher (SH1) modes were selectively generated by an electromagnetic acoustic transducer in aluminum plates and the propagating modes at various points were detected by a pinducer. The defects had a flat bottom region and tapered edges. Remaining thickness at the bottom defected region was smaller than the so-called cut-off thickness of SH1 mode. Both modes exhibited unique mode conversion behaviors in tapered edge, which were interpreted with the dispersion relation. Total reflection of SH1 mode was also observed at a specific condition. Numerical simulation revealed that the continuous wavenumber change in the tapered region and the consequent zero value at cut-off thickness cause this total reflection.