Study on the bending vibration of bimorph rectangular transducer based on type 2-2 piezoelectric composites

In order to improve the acoustic radiation capability of piezoelectric ultrasonic transducer in gas, a bimorph rectangular transducer based on type 2-2 piezoelectric composites is proposed in this paper, which is composed of two piezoelectric composite rectangular slices with thickness polarization. First, the bending vibration of the rectangular transducer is divided into two bending vibrations of the thin rods in the x and y directions using the equivalent elastic method. When the mechanical coupling coefficient is introduced and combined with the anisotropic piezoelectric equations, the resonance frequency equations of the thickness-polarized transducer are derived with simply supported boundary conditions. Then the bending vibration of the transducer is numerically simulated. The results show that the resonance frequency obtained by the analytical method is in good agreement with the numerical simulation results. Finally, the influence of geometrical size and two-phase volume ratio on the bending vibration performance of the transducer is analyzed. Compared with the piezoelectric bimorph transducer, the piezoelectric composite bimorph transducer has a larger bending vibration displacement amplitude, a larger transmitting voltage response, a lower resonant frequency and better acoustic radiation capability.