Ultrasonic motors with poly phenylene sulfide/alumina/PZT triple-layered vibrators.

Highlights • An ultrasonic motor with a PPS/alumina/PZT triple-layered vibrator has been proposed. • The force factor of the triple-layered vibrator reaches its maximal value when the neutral axis locates on the boundary between the alumina and PZT disks. • The output torques and power have been markedly enhanced after the triple-layered vibrators were used. Abstract Our previously reported ultrasonic motors with poly phenylene sulfide (PPS)/lead zirconate titanate (PZT) double-layered vibrators were capable of providing high rotation speeds and light weight, but their output torques and power were limited owing to the low stiffness of PPS vibrating bodies. In this study, we constructed a triple-layered vibrator by sandwiching a thin alumina disk between the PPS vibrating body and PZT disk to compensate the stiffness. First, their fundamental vibration characteristics were investigated as some of key dimensions were varied. The force factor of the PPS/alumina/PZT triple-layered vibrator reached the maximal value when the neutral axis located at the boundary between the PZT and alumina disks. In contrast, the neutral axes existed in the PZT disks for the PPS/PZT double-layered vibrators; this caused the relatively low force factors compared to the triple-layered vibrators. Subsequently, the load characteristics of the PPS/alumina/PZT triple-layered motors were experimentally assessed. The maximum output torque and power of the triple-layered motors were 5 and 13 times the values of the double-layered motors, respectively, owing to the enhanced force factor and electromechanical coupling factor. Besides, the optimal thickness was lower for the triple- than for the double-layered motor. These advantages indicate the potential of our newly designed triple-layered motors for practical applications. [ABSTRACT FROM AUTHOR]