Abstract: A new kind of radial-torsional composite mode ultrasonic transducer with multiple slanting slots is presented and studied. Two mechanical conversion coefficients are introduced by resolving the stress at chutes. Based on the electromechanical analogy, the coupled equivalent circuit model of the vibration system is set up and the frequency equation is derived. The effect of the oblique angle of the slots on the resonance frequency of the transducer is analyzed. It is concluded that the resonance frequency decreases with the increase of oblique angle. Furthermore, the resonance frequencies of three transducers with different oblique angle of slots are measured and simulated by using finite element method. Experimental results show that the measured frequencies of the transducers are in good agreement with the theory and simulation results.

Key words: Coupled equivalent circuit, Frequency equation, Piezoelectric transducer, Radial-torsional vibration mode