| Nowadays, with the rapid development of the aerospace industry, the defense industry and theprecision positioning system, urgent requirements for ultrasonic motors that can work in varioussituations have been provided. Ultrasonic motors have received unprecedented attentions as a result.Utilizing the converse piezoelectric effect of piezoelectric materials, ultrasonic motors obtain dynamicin virtue of use friction to transfer elastic ultrasonic vibration. Friction materials are one of the mostimportant parts of ultrasonic motors. The efficiency of energy transform and serving life of ultrasonicmotors depend on a great extent on the properties of friction materials.In this paper, a systematic experimental study of formula design, process parameters and theoutput performance of ultrasonic motors was conducted for the following cases:(1) Based on theepoxy resin composites reinforced with glass fiber cloth, ultrasonic motors have high output torqueand low wear under normal temperature.(2) Based on the polyurethane composites reinforced withglass fiber cloth, ultrasonic motors can run stably at low temperature. High-performance glass fibercloth reinforced friction polymer composites were prepared with the hand lay-up molding process inthis thesis work.The main research work and results of this paper are as follows:(1) Based on glass fiber cloth, Nano-Al2O3and carbon fiber reinforced friction epoxy compositesfor ultrasonic motors were prepared. The research showed that both the mechanical properties and thewear resistance properties were improved with the addition of Nano-Al2O3and carbon fiber. Thecomposites performance tests show that the mechanism of the friction materials reinforced withNano-Al2O3is different from that with carbon fiber. The epoxy resin composites reinforced with glassfiber cloth were the best friction materials for ultrasonic motors with filling10wt.%Nano-Al2O3or10wt.%carbon fiber.(2) Based on glass fiber cloth, the friction epoxy resin composites of ultrasonic motors reinforcedwith potassium titanate whiskers were prepared. The effect of the potassium titanate whiskers contenton the properties of the epoxy resin composites reinforced with glass fiber cloth was studied. Theresults reveal that the epoxy resin composites reinforced with glass fiber cloth have the lowest frictioncoefficient and wear rate with addition of5wt.%potassium titanate whiskers. Ultrasonic motors havethe biggest no-load speed and stall torque.(3) Five friction polyurethane composites of ultrasonic motors reinforced with glass fiber cloth were prepared. The research showed that the different filler (Nano-Al2O3and potassium titanatewhiskers) can not only increase the hardness and elastic modulus of the polyurethane compositesreinforced with glass fiber cloth, but also collaboratively modify the properties of the polyurethanecomposites reinforced with glass fiber cloth at the low temperature. The results show that ultrasonicmotors can run stably at low temperature. |
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