Abstract: Research is done on vibration behavior of trave- ling-wave ultrasonic motor (TWUSM) by means of composite beam vibration theory. The stator is simplified to a series of simply supported beams according to the feature of confi- guration. A forced vibration beam’s equation is then formulated which considers the external moment produced by the applied voltage with the aid of piezoelectric ceramics by means of inverse piezoelectric effectiveness. Also the viscous damping moment and external damping force are added to this equation. The equation is solved based on model expansion method. To validate the effectiveness of this model a prototyped motor is manufactured and tested. Experimental results show good agreement with those of calculation.

Key words: Mathematical model, Piezoelectric, Travelling-wave, Ultrasonic motor, Vibration