Ultrasonic motors with polymer vibrator

With the nature of low density and elastic modulus, polymers are promising materials for making light weight and large output ultrasonic motor (USM). However, it has been believed for a long time that polymer is too lossy to be applied in high amplitude vibrator. In order to explore the possibility of polymers for USM, we made a bimorph vibrator and a standing wave USM, respectively, and investigated their vibration and friction characteristics experimentally. It was found that polymer-based bimorphs had larger vibration velocity than the aluminum-based one. The polymer-based USMs using orthogonal bending vibrations exhibited higher angular velocity than the aluminum-based one under light preload, and the maximum torque of the polymer-based USMs were smaller than the aluminum-based one. Polyphenylenesulfide (PPS) was prospective material for USM under light preload because of the large high amplitude and lightweight.