Experimental research on the evolution characteristics of a bending hybrid ultrasonic motor during long-time...

The characteristics evolution rules of an ultrasonic motor (USM) based on the hybrid of bending modes during long-time operation are tested and analyzed in this work. The alumina and nitride silicon ceramics are used as the driving feet and rotor respectively. The variations of mechanical performances including the speed, torque, and efficiency with time are tested and evaluated in the whole life period of the USM. Meanwhile, the vibration characteristics of the stator such as the resonance frequencies, amplitudes, and quality factors are also tested and analyzed every-four hours. Moreover, the real-time test for performances is conducted to assess the effect of temperature on mechanical performances. Furthermore, the effect of wear and friction behavior of the friction pair on the mechanical performances is analyzed. The torque and efficiency have apparent decreasing trends and fluctuated widely before about 40 h, and then gradually stabilize for 32 h, and finally fall rapidly. By contrast, the resonance frequencies and amplitudes of the stator only decrease by less than 90 Hz and 2.29 μm at first, and then keep fluctuant. During the continuous operation of the USM, the amplitudes will decrease as the increase of surface temperature, and followed by long-time wear and friction of the contact surface, the decrease of contact force is incapable to support the operation of the USM at last. This work is helpful to understand the evolution characteristics of the USM and provides the guidelines for the design, optimization, and practical application of the USM.