Abstract:

The regular polygon composite piezoelectric ultrasonic transducer is studied. The transducer consists of a metal inner core, a regular polygon of rectangular piezoelectric ceramic piles and a prestress metal tube. Using the piezoelectric ceramic piles, the effective electro-mechanical coupling coefficient and the power capacity of the transducer are greatly improved. Based on the electro-mechanical analogy theory, the equivalent circuit and the resonance frequency equation of the transducer in radial vibration are derived. The relationships between the first and second order resonance and anti-resonance frequency, the effective electro-mechanical coupling coefficient and the geometrical dimensions of the transducer are analyzed by theoretical and finite element numerical simulation analysis and experimental testing. It is shown that the first radial resonance frequency is decreased monotonically with the inner diameter of the inner core and the outer diameter of the outer prestress tube of the transducer increased. The second radial resonance frequency of the transducer gets extremum value with the increase of the inner diameter of the inner core, while decreased monotonically with the increase of the outer diameter of the outer prestress tube. In addition, the effective electro-mechanical coupling coefficient of the second order radial vibration mode is higher than that of the first order. It is also shown that the results of the theoretical analysis and the finite element analysis are in a good agreement with that of the measurements.

Key words: piezoelectric ultrasonic transducer, power ultrasonic, regular polygon structure, radial vibration