Abstract: The radial vibration characteristic of a new kind of radial composite piezoelectric ultrasonic transducer is studied. Based on the electromechanical analogy principle, the equivalent circuit is set up and the frequency equation of the transducer is derived. Numerical computation indicates that the product of radial resonance frequency and diameter of piezoelectric ceramic slice of the transducer is constant if the radius ratio and the material of transducer are specified. Furthermore, the radial composite transducer cannot meet the conventional half-wave length cascade law, so an overall design is necessary. In addition, the relationships between the resonance frequency constant and the radius ratios of the transducer, which consists of steel-PZT4, titanium-PZT4 and aluminum-PZT4, are obtained. By testing the radial resonance frequency of two composite piezoelectric ultrasonic transducers and comparing to that of theoretical results, it is shown that the error is less then 3%, which can satisfy the requirement of engineering application.

Key words: Disc-type ultrasonic transducer, Equivalent circuit, Frequency constant, Frequency equation, Radial vibration system