Concept and electromechanical-coupling modeling of a torsional vibration excitation method

Abstract

The sandwiched type torsional piezoelectric actuators have widely been employed in the fields of ultrasonic cutting, ultrasonic drilling, ultrasonic welding, ultrasonic wire drawing, ultrasonic spraying, and microdroplet generation, due to their unique vibration form. However, the circular piezoelectric ceramic plate polarized in the circumferential direction holds a complicated manufacturing process, a long processing period, and a high price. It can only be used for the excitation of the torsional vibration of circular rods, and cannot be used for square cross-section beams, severely restricting its applications. In order to solve the above problems, a novel excitation method is proposed for generating torsional vibration in the square cross-section beam in this study, which uses the d15 vibration mode of rectangular piezoelectric ceramic plates to produce the torsional vibration, and a novel transfer matrix model of square torsional piezoelectric element is created. Then a case study is conducted in this paper to confirm the proposed excitation method and the developed model, in which two novel sandwiched type torsional piezoelectric actuators are designed. Moreover, electromechanical coupling models of these two torsional piezoelectric actuators are developed using the transfer matrix method, in order to reveal their dynamics behaviors. Finally, the finite element method and the experimental investigations are adopted to analyze and test the frequency response characteristics and vibration shapes of the proposed piezoelectric actuators. Both simulation analysis and experimental tests verify the effectiveness of the proposed excitation method and the correctness of the developed electromechanical coupling dynamic models. The proposed excitation method provides a new idea for the design of sandwiched type torsional piezoelectric actuators, and the developed theoretical model lays a theoretical foundation for the further research of torsional piezoelectric actuators.