Operational verification of a new disc-type ultrasonic motor by finite element simulations

In this paper, a 3-D mechanical element with an extra electrical degree of freedom is employed to simulate the dynamic vibration modes of the linear piezoelectric, mechanical and piezoelectro-mechanic behaviours of a metal disc structure embedded with a piezoelectric actuator. In piezoelectric finite element formulation, a discretized equation of motion is developed and solved by using the integration scheme to explain why an adaptive boundary condition, a simple support condition with three non-equal-triangular (120/spl deg/-90/spl deg/-150/spl deg/) fixed points near the edge for the mechanical design of a new disc-type piezoelectric ultrasonic stator, is defined so that a lateral elliptical motion of the contact point between stator and rotor can be realized for driving the rotor. It starts from eight-node hexahedral elements with displacement and electric potential as the nodal d.o.f.s model and uses Guyan reduction and Householder-Bisection inverse iteration to find the modal frequencies and associated mode shapes. Some other important factors affecting the behaviour of this motor are also studied, including structure design, amplitude of input voltage, exciting frequency, and contact phenomena.