Investigation of Deep-Sea Longitudinal Vibration Cavity Resonant Coupling Transducers Made of Relaxor Ferroelectric Single-Crystal Material

Deep-sea transducers are of great significance for improving the performance of sonar, and we cannot greatly improve the performance of the piezoelectric ceramic transducers through structural optimization without increasing their size. To solve this problem, we use the relaxor ferroelectric single crystal to design the longitudinal vibration cavity resonant coupling transducer, which couples the longitudinal vibration and cavity vibration to improve the performance. First, the transducer structure is designed to withstand high hydrostatic pressure. Then, the finite element method is used to analyze the influence of the metal cylindrical plate on the transducer performance, and the metal cylindrical plate size is optimized. Finally, we manufacture piezoelectric ceramic and single-crystal transducers of the same size. The experimental result in an anechoic water tank shows that for the single-crystal transducer, the maximum transmitting voltage response (TVR) is 139.9 dB at 2.7 kHz, and the TVR is more than 9 dB higher than that of the piezoelectric ceramic transducer in the 1.6–2.7 kHz region, indicating that the single-crystal transducer has better low-frequency performance. The 50 MPa pressure test result shows that the admittance and TVR are consistent before and after high hydrostatic pressure, and the measured maximum source level (SL) is 192.9 dB after high hydrostatic pressure. The experimental result shows that the transducer can withstand deep-sea pressure and has good pressure stability.