Study on the sandwich piezoelectric ceramic ultrasonic transducer in thickness vibration

Abstract

A sandwich piezoelectric ceramic ultrasonic transducer in thickness vibration isstudied. The transducer consists of front and back metal masses, and coaxiallysegmented, thickness polarized piezoelectric ceramic thin rings. For this kindof sandwich piezoelectric transducers in thickness vibration, it is required thatthe lateral dimension of the transducer is sufficiently large compared with itslongitudinal dimension so that no lateral displacements in the transducer can occur(laterally clamped). In this paper, the thickness vibration of the piezoelectricceramic stack consisting of a number of identical piezoelectric ceramic thin rings isanalysed and its electro-mechanical equivalent circuit is obtained. The resonancefrequency equation for the sandwich piezoelectric ceramic ultrasonic transducer inthickness vibration is derived. Based on the frequency equation, two sandwichpiezoelectric ceramic ultrasonic transducers are designed and manufactured, and theirresonance frequencies are measured. It is shown that the measured resonancefrequencies are in good agreement with the theoretical results. This kind of sandwichpiezoelectric ultrasonic transducer is expected to be used in megasonic ultrasoniccleaning and sonochemistry where high power and high frequency ultrasound isneeded.