Design and Experiments of a Novel Rotary Piezoelectric Actuator Using Longitudinal–Torsional Convertors

A bolt-clamped type piezoelectric actuator, which could output rotary motions by using longitudinal-torsional hybrid vibration, was proposed and tested in this paper. The proposed actuator is mainly composed of a piezoelectric stack, a leftward bending longitudinal-torsional convertor (LBLTC), and a rightward bending longitudinal-torsional convertor (RBLTC). The piezoelectric stack, which is clamped between the LBLTC and RBLTC, is utilized to generate longitudinal vibration under exciting of a sinusoidal signal with a certain frequency. The two convertors transform part of the longitudinal vibration generated by the piezoelectric stack into the torsional vibration and generate elliptical motions at the ends of the driving tips, which can push the rotors to rotate step by step. The structure of the proposed actuator was designed, and the working principle for the rotary driving was analyzed. Then, modal, harmonic, and transient analyses were carried out by the finite element method to determine the structural dimensions of the convertors and verify the movement trajectories of the driving tips. Finally, a prototype was fabricated, and its vibration and output characteristics were tested. The experimental results indicated that the maximum no-load speed and maximum torque of the actuator were 342 r/min and 0.072 N·m under the preload of 11 N and the voltage of 300 V
_P-P
. The simulation and experimental results verified the feasibility of the proposed actuator.