A Fundamental Study on Dynamic Contact Behavior of an Ultrasonic Motor (Coexistence of Stick and Slip Contact Zone)

We discuss the dynamic complex contact behavior between the stator and the liner that sticks to the rotor of an ultrasonic motor. An ultrasonic motor is powered by the vibration of the stator and operated by a frictional force between them. Therefore, it is important to examine the dynamic mechanism of the contact behavior to improve the energy efficiency and durability of the ultrasonic motor. We already proposed a numerical technique using the finite element method (FEM) on the basis of incremental theory to analyze the behavior of the complex contact zone which contains non-contact zone, slip contact zone and stick contact zone in a non-rotating rotor as a static contact problem. In this paper, we expand this numerical technique from a non-rotating rotor to a rotating rotor and propose a numerical technique to analyze the dynamic behavior of this complex contact zone. Moreover, we clear the dynamic contact mechanism and the driving characteristics of the ultrasonic motor such as the dependency of driving torque on the maximum frictional co-efficient.