Piezoelectric ultrasonic transducer for longitudinal-flexural vibrational mode-conversion

- We study a longitudinal-flexural vibrational mode-conversion ultrasonic transducer.
- Firstly, the equivalent lumped parameters for a circular plate are derived.
- Electro-mechanical equivalent circuit and resonance frequency equation are derived.
- Vibrational mode and frequency characteristics of the transducer are studied.

A new type of piezoelectric ultrasonic transducer for longitudinal-flexural vibrational mode-conversion is proposed. The mode-conversion transducer has a back metal mass, longitudinally polarized piezoelectric ceramic pieces, and a circular metal plate. The longitudinal vibration of the piezoelectric vibrator drives the circular metal plate to produce flexural vibration. The analytical method for designing this type of mode-conversion transducer is mainly given in this paper, and the numerical simulation and the experimental measurement are used to verify this method. The performance analysis of the mode-conversion transducer is focused on comparing frequencies and mode shapes. Based on equivalent lumped mass and elastic parameters, the equivalent circuit and resonance frequency of the mode-conversion transducer are given. The vibrational modes and the harmonic response of the transducer are simulated via the numerical method. The results show satisfying concurrence among the analytical theory, numerical simulation, and experimental measurement. The suitability of this type of mode-conversion transducer for ultrasonic liquid processing, which requires high power and a large radiation area, will be investigated in the future.