The PiezoHydraulic Pump (PHP) used in this work currently uses proprietary check valves that allow the PHP to be operated at 1 kHz. At a bias pressure of 500 psi and operating voltage of 1 kV, the PHP produces a mechanical power output of 46 W. The PHP was baseline tested using both the proprietary valves (internal) and external commercial passive check valves. Using the external valves at a bias pressure of 80 psi, the PHP was tested at various frequencies. At an operating frequency of 150 Hz, the maximum flow rate was 0.91 cc/s, while at 125 Hz, the maximum mechanical power output was 0.18 W (0.64 W/kg). This significant decrease in characteristics can be attributed to an increase in system compliance by moving the valves external to the pump housing and possible air entrapment within the chamber.
This paper outlines the testing of a piezoelectric ultrasonic motor (PUSM). The authors propose the use of a pseudoelastic NiTi thin film layer to replace the traditional fiber reinforced polymer contact layer. In accordance with this goal, a literature review of reported accomplishments in the area of the tribology of NiTi, both shape memory and pseudoelastic, is provided. The results of the baseline testing of the commercially acquired PUSMs are presented. The motors were baseline tested using a dead-weight force system, then disassembled and a 10 μm thick layer of NiTi was deposited on the rotor using a dc magnetron sputtering process. The motors were then reassembled and tested again. A comparison of the initial results is presented and discussed.