Finite element analysis and experiment on traveling-wave ultrasonic motor with two-sided cone-shaped teeth and self-supported shafting

The conventional one-sided travelling-wave ultrasonic motor (TWUSM) needs bearing to support and oil to lubricate, does provide sufficiently high torque and power due to limited contact area between the stator and the rotor, consequently its application is limited. So, a TWUST with the two-sided cone-shaped teeth and self-supported shafting was developed. Its structure was designed and its excitation mechanism was analyzed. The model, harmonic, and transient analyses of the motor stator were performed using the FEA software ANSYS. The excitation frequency was predicted precisely, the shapes of the vibration modes, the vibration amplitude and impedance versus frequency behaviors and displacement versus time curve of the tooth tip on the stator and its elliptical locus were obtained theoretically. The developed motor prototype was tested and its load characteristics were measured. The maximum stall torque of 0.48 N·m is reached which is 1.7 times as high as the conventional one-sided TWUSM, and its idle speed is 86 r/min.