A Multi-Point Contact Model Considering Rough Surface for Linear Ultrasonic Motors: Validation and Simulation

The performance and wear life of linear ultrasonic motors are directly determined by the stator–mover frictional contact behaviors. A complete contact model is important to clearly understand the stator–mover contact mechanism and accurately estimate the motor performance. In this paper, a multi-point frictional contact model considering the roughness of contact interfaces is presented based on a finite model of the stator and an analytical model of the mover. The static/dynamic contact behaviors and output performance of the motor can be simulated efficiently. A quantitative measuring methodology for the dynamic contact forces between the stator and mover is developed. The effectiveness of the contact model for simulating the stator–mover contact forces is first evaluated by experiment. Based on the developed model, several dynamic characteristics of a linear ultrasonic motor are discussed: (a) the static force transferred between contact interfaces under pre-pressure; (b) the transient forces and energy exchange between contact interfaces; (c) the steady-state output performance of motor under different electric excitation parameters; (d) the effects of micro-topography parameters on the output performance of the motor and the force transmission of the contact interface.