Research Progresses in Friction Material for Ultrasonic Motor

Ultrasonic motor is a new type of motor which is driven by friction force generated at the interface between the rotor and the stator. Development and applications of ultrasonic motor largely rely on the performance of friction material. The research progress and basic demand of friction material for ultrasonic motor in home and abroad in recent years are discussed. Based on drive mechanism and characteristics of ultrasonic motor, the special demand of friction material should be achieved primarily from in three aspects, i.e. tribology, contact mechanics and material. The three aspects are specified as good tribological properties, proper contact deformation and proper structrual properties. Finally, according to the current problems of friction material for ultrasonic motor, four important topics are proposed. The topics are establishment of better contact model of ultrasonic motor, development of several kinds of friction materials for various environments, development of customized testing method and experimental equipment for friction material and setup method of life prediction.