DYNAMIC MODELLING OF A TRAVELING-WAVE TYPE ULTRASONIC MOTOR WITH BEAM TEETH VIA FINITE ELEMENTS

Abstract

The study is dedicated to establish the dynamic model of a traveling-wave type ultrasonic motor (USM) with beam teeth via finite elements. The modeling is accomplished mainly by finite elements, the task of which consists of three parts for stator, rotor and contact. It is first assumed that the complex dynamics of the stator emulates a single one-dimensional Euler-beam vibrating harmonically in the transverse direction. On the top surfaces of the stator are vertical beam teeth that is in contact with rotor, which is simply a thin disk fixed to spindle. The friction between the teeth tips and stator rotates the spindle moves the stator and finally rotates the disk to the desired speed. A contact model between beam tips and rotor disk with proper friction assumed is next built in conjunction with the established finite element model of the rotor disk. With a complete model in hands, the dynamics of the USM is predicted along with associated exerted torques. Experiments are finally conducted for collecting sets of data of rotation speeds versus torques that validate the effectiveness of the built models for the motor, stator and contact force.