Low-frequency broadband magnetostrictive-piezoelectric hybrid excitation Janus-Helmholtz transducer

A triple-resonant Janus-Helmholtz transducer achieves broadband performance via longitudinal, liquid cavity, and flexural modal coupling. However, uniform in-phase excitation of its four driving modules causes anti-phase superposition of flexural vibration, severely suppressing flexural resonance output and restricting acoustic radiation efficiency. To address this inherent modal cancellation issue, this work proposes a magnetostrictive-piezoelectric hybrid excitation strategy that leverages the intrinsic 90° material vibration phase difference to enable constructive flexural modal superposition while preserving stable longitudinal and liquid cavity resonance responses. Finite element simulations based on the piezoelectric-piezomagnetic analogy verify the enhanced bandwidth and radiation performance of the hybrid configuration over pure piezoelectric and pure magnetostrictive counterparts. A prototype device is fabricated and experimentally characterized, with results showing strong agreement with simulation predictions. The prototype exhibits resonant frequencies at 350, 800, and 1250 Hz, achieving an operational bandwidth exceeding two octaves. Further tests reveal that separate excitation of piezoelectric and magnetostrictive drive modules reduces impedance variation and doubles driving efficiency in comparison to parallel combined excitation, providing reliable guidance for the high-efficiency design of hybrid broadband underwater acoustic transducers.