Analysis of an Ultrasonic Piezoelectric Motor Using Numerical Modeling

Ultrasonic motors use a frictional force, produced by high frequency vibrations created by the piezoelectric effect of the stator, to drive the rotor. These devices have been widely stud ied, especially in Japan. A stator of a piezoelectric ultrasonic rotating motor, which uses Lamb waves vibrations, has been modeled using the finite element code ATILA. It takes into account three-dimensional piezoelectric effects and electrical excitations. ATILA permits the computation of the resonance frequency and the effective coupling coefficient of each vibrational mode, the electrical impedance and the elliptical displacement field. The governing electromechanical coupling has been determined. Con sequently, the selection of active material and stator geometry may be optimized to provide an improved transduction efficiency.