Scale-dependent analysis of sliding wear between the bushing and the ground plane in micromotors

Abstract

Among the problems in microelectromechanical systems, friction and wear are the most concerned ones. In this paper, a model to predict the sliding wear between the rotor bushing and the substrate plane in a variable capacitance micromotor is presented. The model is based on the Archard's wear law and takes into account the scale effects, including the effects of such surface forces as meniscus force due to humidity and the electrostatic force as a result of the capacitance coupling between the rotor and substrate, as well as the scale effects of material properties, which become scale dependent in microscale. The wear process and durability of the hemispherical bushing are investigated and discussed. Simulation results show that they are largely affected by these effects, and it is indicated that sufficient attention should be taken in the design and fabrication of micromotors on the scaling effects.