Frequency Characteristic Analysis of Omnidirectional Shear Horizontal Wave Transducer Using an Array of Segmented Lead-free Piezoelectric Elements

In this study, the frequency characteristics of an omnidirectional shear horizontal (SH) wave transducer were analyzed theoretically and experimentally. The transducer, developed recently using segmented trapezoidal lead-free piezoelectric elements, generates and measures SH waves omnidirectionally. However, its frequency characteristics have not been investigated yet. Hence, based on analytical and experimental approaches, we attempted to systematically investigate the frequency response of the transducer. To this end, the transducer output was calculated using theories explaining annular array transducer responses. Subsequently, the output was compared to the experimental results. For the experiment, the transducer was used as a transmitter while a unidirectional SH wave magnetostrictive patch transducer (MPT) was used as a receiver at various positions. Additionally, the effect of using the MPT was considered through experiments with a pair of MPTs, which is necessary to obtain an MPT transfer function for accurate comparison. Accordingly, the theoretically analyzed frequency characteristics were confirmed to agree well with those of the experimental results. Further, these results can be used to maximize transducer output at a specific target frequency.