Contact modeling of viscoelastic friction layer of traveling wave ultrasonic motors

A simple viscoelastic contact model for describing the contact mechanics between the stator and rotor of a traveling wave ultrasonic motor is presented. The asymmetric contact region and contact pressure distribution are computed. The deformation of the contact layer in the tangential direction and the relative velocity between the rotor and the layer surface are taken into account in the modeling. The velocity and the tangential force distribution of the contact interface are obtained. Some contact features such as the contact size and the maximum contact pressure as a function of the loss ratio of the material are presented. In addition, a comparison of the torque-speed characteristics between the elastic model and the present model is presented.