The Design Of Piezoelectric Single Crystal Longitudinal Transducer

In recent years, with the development of the Unmanned Undersea Vehicle(UUV),pony-size, high power and medium-high frequency performance is becoming research priority of the underwater transducer gradually. Novel relaxor ferroelectric single crystal PMNT's piezoelectric property is several times higher than the traditional piezoelectric ceramic material PZT. Longitudinal electromechanical coupling factor reached at least 90%, is 20%higher than PZT and y33E is one third of that material. Using single crystal PMNT as the driving material in the transducer, it has the advantage to achieve smaller size, higher power and efficiency. Longitudinal transducer, as the most common midfrequency sound source,is stable , small in size and easy to produce. Then, longitudinal transducer with PMNT as its driving material can provide us high power, midfrequency, high efficiency acoustic signal.In this paper, by the comparison between single resonant transducers with different piezoelectric materials PMNT and PZT, it can be proved that PMNT has many advantages. In the end, a broadband transducer achieved through the method of double excitation will be designed and produced with PMNT .Firstly,admittance grid and transmitting voltage response(TVR) about the single resonant and double excitation transducers had been calculated by software Matlab with equivalent circuit method. Then,using the software ANSYS designed this two kind transducers. By the comparison of the single resonant transducers with diffierent materals, we found that PMNT really had many advantages, include lower frequency, smaller size and higher response. Optimizing the structure and dimension of the double excitation transducer,emulating the impedance characteristic and TVR in water, then, the performance of the broadband transducer could be determined. Its working band was 29.3-61.3kHz and the maximum response was 152.1dB. Finally, this two kind longitudinal transducers with PMNT as its driving materials had been produced and tested.The test results showed that resonance frequency, TVR of the single resonant transducer is similar with the imitated results. And,the practical working band of the double excitation transducer is 27-65kHz, in which the maximum response is 150.69dB and the ripple of TVR did not exceed ± 6dB.