Stress-type hybrid ultrasonic motors of using longitudinal and torsional vibration modes based on the d31 effect of piezoelectric ceramics

A new type of hybrid ultrasonic motors of stress-type using longitudinal and torsional vibration modes based on the d31 effect of PZT8 ceramics is developed. The torsional vibration was only excited in the stator and the longitudinal vibration was excited in the whole motor. The torsion was put out through the friction effect on the interface of the rotor and stator and exported by the axis of rotation. Finite element analysis has been accomplished to optimize the structure of the motor. A prototype was manufactured and tests on the prototype validated the feasibility of the new excitation theory.