The Radial-torsional Vibration Of Disc-type Piezoelectric Ultrasonic Transducer With Variable Thickness

With the development of ultrasound technology, the kind of ultrasonic transducer and its application extended rapidly in recent years. The composite vibration mode transducer have some unique vibration characteristics, showing specifically broad application prospects in the field of medical ultrasound, ultrasonic motors, ultrasonic cutting, ultrasonic tube and wire drawing and so on. In recent years, researchers have focused on the composite vibration mode of transducer about Longitudinal-torsional, longitudinal-bending and radial-torsion mode, etc.There are two common methods in the design of the composite vibration piezoelectric ultrasonic transducer. One is that using two different polarization of the piezoelectric ceramic group as a drive source. The piezoelectric ceramic produce two different vibration. Then, two vibration coupling in the metal plate to achieve the composite vibration of ultrasonic transducer. The other method is using a type piezoelectric ceramic as the drive source, then, a single vibration mode is broken down or converted into a composite vibration mode by a special structure of the metal block, such as Multiple Slanting Slots and Bending Bar type.In this paper, a radial-torsional vibration of disc-type piezoelectric ultrasonic transducer with variable thickness is established. The radial-torsional composite vibration of the transducer are realized by multiple slanting slots. Based on the Finite Element Method (FEM) and the equivalent circuit theory, the frequency and the displacement characteristics of the transducer in resonance mode are obtained. And the details are as follows:(1) The electro-mechanical equivalent circuit of the transducer in radial-torsional vibration mode are acquired The relationship between the resonance frequency and the geometric dimensions of multiple slanting slots are analyzed.(2) The frequency and the effective electromechanical coupling coefficient of the first and second-order resonance mode in radial-torsional vibration are obtained according to the Model analysis of ANSYS Software. And the displacement ratio between torsion and radial are calculated in the light of vibration displacement contours. They both have a relationship with the geometric dimensions of the multiple slanting slots. The trajectories of vibration particle of the radiation surface of the transducer are acquired by using transient analysis of ANSYS Software. The trajectories are also have a relationship with the geometric dimensions of slanting slots.(3) The trial transducer are produced, and the frequency and vibration characteristics of the trial transducer are tested. The electrical impedance and phase angle versus frequency are measured by using an impedance analyzer. And the displacement of radial and torsional vibrations are detected respectively by using the Laser Vibrometer. The experimental tests are consistent with the results of theoretical calculation and simulation analysis.