A Theoretical Model of the Intermittent Contact of Piezoelectric Actuator Based on Greenwood-Williamson Theory

Abstract A theoretical model of the intermittent contact mechanism of linear piezoelectric actuator was proposed, in which the microscopic characteristics of the contact surfaces were taken into account. Greenwood-Williamson (GM) theory was involved for the first time to describe the microscopic characteristics of the contact surfaces in which the contact surfaces were considered as random rough surfaces that were composed of large amounts of asperities and the heights of the asperities conformed to a Gauss distribution. The developed theoretical model gives an insight into the influence of the microscopic properties, as well as the macroscopic and material properties on the output performance of the actuator, which may provide guidance for the design of such type of piezoelectric actuator. During the modeling, normal kinetic contact force, kinetic friction coefficient, friction force and steady-state output force of were obtained in sequence. And some simulations were carried out to analyze how factors such as the type of material, the roughness of the contact surface, the initial distance between the stator and the rotor, and the preload, et.al, affect the contact performance. A set of experiments were carried out to reveal the influence of surface roughness, material type and preload on the steady-state output thrust. The simulated results were found in good agreement with the experiment ones at most of the tested points. Finally, surface roughness of the stator and rotor were tested before and after the operation, which indicated that the rotor and stator had similar roughness after operation.