Contact Dynamics of the Rotor and Bearing Hub in Electrostatic Micromotor

A mathematical model of the contact between the rotor and bearing hub of electrostatic micromotor, which actuated MEMS, is constructed to investigate the contact dynamics. It is illustrated that in what way the contact problem of the contact stress and strain equations can be presented under the scaling effects of micro-scale. The parameters, the geometries of the micromotor, the electrostatic force, the material characteristics, and the applied gap voltages, which are related to the contact, are discussed in detail. The discriminations between unchanged gap and maximum changed gap under different applied voltages and various materials are studied. Some results of the contact width, the contact stress, the contact strain, are compared with finite element model (FEM) solutions of an equivalent problem. The 1st principal stress and strain and whole contact stress for expressing the distributions are shown. The small differences between the both methods, showing characteristic features of FEM and the theoretical assumptions, are explained.