Finite element analysis of a ring type ultrasonic motor

In this paper, a finite element method to simulate the overall behavior of ultrasonic motor (USM) is proposed. Firstly, an iterative algorithm using ABAQUS (R) version 6.4 to solve the contact problem with piezoelectric actuation is presented. In each iteration, the dynamic responses of stator actuated by piezoelectric force and updated contact force are solved, from which static (or steady state) contact between deformed stator and rotor are estimated. For the dynamics of stator, three dimensional solid elements are adopted and direct integration method is used because modal-based procedures do not adequately transform the electric loads into modal loads. Rayleigh damping is adopted with the ratio set to 0.5 %. For the contact between deformed stator and rotor, Lagrange multiplier method is used to impose the normal and tangential contact constraints between the stator and rotor respectively. Based on the proposed procedure, given the applied torque, axial force, and piezoelectric drive voltages as inputs, the general measures of motor performance are obtained and compared with published numerical and experimental results. The approach presented here provides a more accurate framework with moderate computational cost for modeling USM and serves as a design tool for optimizing prototypes.