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Research Introduction Lab of Smart Structures

Research Introduction Lab of Smart Structures. 精密机械与精密仪器系 P recision M achinery and P recision I nstrumentation. Contents. 1. Smart piezoelectric actuators. 2. Piezoelectric transformers. 3. Precision control of piezoelectric actuators. 4. Energy harvesting. 5.Other researches.

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Research Introduction Lab of Smart Structures

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  1. Research IntroductionLab of Smart Structures 精密机械与精密仪器系Precision Machinery and Precision Instrumentation

  2. Contents 1. Smart piezoelectric actuators 2. Piezoelectric transformers 3. Precision control of piezoelectric actuators 4. Energy harvesting 5.Other researches 精密机械与精密仪器系Precision Machinery and Precision Instrumentation

  3. Small Piezoelectric Actuators • a. Fiber torsional actuator • b. Tube actuators and its composite

  4. a. Discovery of torsional actuation discovery

  5. Experimental measurement Static response of voltage Resonance image of the prototype actuator’s free end. Test setup Dynamic response of frequency C. L. Pan, Z. H. Feng, et al., "Small torsional piezoelectric fiber actuators with helical electrodes,“ Applied Physics Letters, vol. 92, p. 012923, 2008.

  6. Application—Impact piezoelectric motor Rotor Piezoelectric fiber motor Bulk piezo cylinder moter

  7. Impact piezoelectric motor Impact response of the fiber motor Impact response of the bulk motor W. X. Han, Z. H. Feng, et al., "An impact rotary motor based on a fiber torsional piezoelectric actuator," Review of Scientific Instruments, vol. 80, p. 014701, 2009.

  8. Impact piezoelectric motor

  9. Miniature optical scanning mirror • Fora 15 mm length fiber: • Torsional vibration, 0-30 kHz bandwidth, 0.2° amplitude • Longitudinal vibration, 0-50 kHzbandwidth, 1μmamplitude It consists of cantilevers, hinges, and mirror. Designed structure

  10. Principle of 2-D scanning

  11. Fabrication and test

  12. Results Measured vertical frequency response of the prototype scanners. C. L. Pan, Z. H. Feng, et al., "Miniature orthogonal optical scanning mirror excited by torsional piezoelectric fiber actuator," Sensors and Actuators A: Physical, vol. 165, pp. 329-337, 2011.

  13. b. Piezoelectric scanners used in SPM Side view and top view of a piezoelectric tube AFM: Atomic Force Microscope SPM: Scanning Probe Microscopy Voltage driving for getting x direction displacement

  14. Multitube actuators Advantages: 1.Much more accurate actuation can be achieved by deliberate arrangement of the four tubes. 2. Multitube structure has better performances under certain conditions. (a) single-tube actuator, (b) four-tube actuator. Piezoelectric tubes with film electrodes on their outer and inner surfaces can be used to compose multitube actuators. The actuator of four piezoelectric tubes can substitute the traditional single-tube actuator.

  15. Experiments The trace of a distinct point on the actuator’s moving head. The end surface of the four-tube actuator.

  16. Miniature tubular centrifugal piezoelectric pump • The mechanical structure of a prototype pump. • (b) The photograph of the prototype pump. The structure of the centrifugal pump using wobbling motion of a metal tube to push the liquid out. Y. T. Ma, Z. H. Feng,et al., "Miniature tubular centrifugal piezoelectric pump utilizing wobbling motion,“ Sensors and Actuators A: Physical, vol. 157, pp. 322-327, 2010.

  17. Experimental measurement 233.2Hz 120Vp-p 2.0kPa Flow rate at different driving frequencies, under 120Vp-p driving voltage and 2.0 kPa backpressure. A maximum flow rate of 7.7ml/min occurs at 232Hz.。 The relationship between the flowrate and backpressure at different driving voltages shows a good linearity. 精密机械与精密仪器系Precision Machinery and Precision Instrumentation

  18. Two-Phase Piezoelectric Motor Structure of the stator: Structure of the prototype motor: Stiffness 2.5N/mm • dimensions of the stator • (b) stator settled on the base. • Sectional drawing • (b) external appearance.

  19. Experimental measurement result Angular speed, output power, and efficiency versus load Angular speed versus driving voltage amplitude. Y. T. Ma, Z. H. Feng, et al., "Two-Phase Piezoelectric Motor Using a Multiple-Tube Structure actuator,“ Japanese Journal of Applied Physics, vol. 48, Sep 2009.

  20. 2. Piezoelectric Transformer

  21. Radiator heightens power densityof piezoelectric transformers For a specific PZT-5H sample considered, this material can handle 330 W/cm3 at 100 kHz in theory. However, the maximum output power density of current PTs is typically less than 30 W/cm3 Construction and dimensions of proposed piezoelectric transformer operating in contour-extensional vibration mode W. W. Shao, Z. H. Feng,et al., "Radiator heightens power density of piezoelectric transformers,“ Electronics Letters, vol. 46, p. 1662, 2010.

  22. Photograph of the prototype device • PT: Roughness Ra 0.2 μm. • copper plate： Dimensions：32×25×1 mm3 Roughness Ra of 0.02 μm • A layer of grease pad thickness 0.23 mm insulation and transfer heat. • A spring with a stiffness of 1 N/mm is attached to a bolt；a thread pitch of 0.5 mm to supply variable pressing force .

  23. Results of test When the input voltage increased to 150 Vpp, the temperature rise of the free PT increased rapidly over 30 ºC and then continued up to a higher value. The characteristics of PT became quite unstable. Based on this research, it is hoped to make metal-cased piezoelectric transformers, which will have wide application potential in many fields.

  24. 3. Precision Control of Piezoelectric Actuators Charge pump controller

  25. Hysteresis of piezoelectric actuators Configuration of the voltage amplifier Piezoelectric actuators hysteresis Configuration of the charge amplifier

  26. Switched capacitor charge pump reduces hysteresis Floating ground Principle of switched charge pump Piezoelectric actuators hysteresis 精密机械与精密仪器系Precision Machinery and Precision Instrumentation

  27. Experimental setup 精密机械与精密仪器系Precision Machinery and Precision Instrumentation

  28. Displacement resonance of piezoelectric stack control with small steps. control with large steps Displacement step is 15 nm

  29. The hysteresis of the voltage and charge drive Charge Voltage 精密机械与精密仪器系Precision Machinery and Precision Instrumentation

  30. The result of the three control methods L. Huang, Z. H. Feng,et al., "Switched capacitor charge pump reduces hysteresis of piezoelectric actuators over a large frequency range," Review of Scientific Instruments, vol. 81, p. 094701, 2010.

  31. Charge pump controller for grounded piezoelectric actuators Schematic charge pump controller for the grounded load

  32. 4. Energy Harvesting

  33. Maximum mechanical energy harvesting strategy for a piezoelement Proposed energy harvesting system using a piezoelectric element. Standard circuit for energy harvesting W. Q. Liu,Z. H. Feng, et al., "Maximum mechanical energy harvesting strategy for a piezoelement," Smart Materials and Structures, vol. 16, pp. 2130-2136, 2007.

  34. Analytical process Proposed cycle for output maximum energy For a fixed material and structure, the system would exhibit a better performance following the use of the control method suggested. This will greatly improve the design of the power generator.

  35. Right-angle piezoelectric cantilever Right-angle cantilever uniform strain distribution of piezoelement 精密机械与精密仪器系Precision Machinery and Precision Instrumentation

  36. Results of test It has been determined that the competence of the right-angle cantilever for energy harvesting under a strain limit is 2 times larger than that of the traditional cantilever. The right-angle cantilever system produces more electrical energy compared to a traditional cantilever. Frequency response for the two devices at sinusoidal vibration amplitude of 2.5 m s−2 . Strain distribution in the surface of PZT element during vibration. J. W. Xu, Z. H. Feng,et al., "Right-angle piezoelectric cantilever with improved energy harvesting efficiency," Applied Physics Letters, vol. 96, p. 152904, 2010.

  37. Piezoelectric Wind-Energy-Harvesting Device with Reed and Resonant Cavity Equivalent circuit Outline drawing of the wind-energy-harvesting device. 精密机械与精密仪器系Precision Machinery and Precision Instrumentation

  38. The device was investigated with a wind speed ranging from 2.8 to 10m/s. An output power of 0.5–4.5mW was obtained with a matching load of 0.46MΩ. The energy conversion efficiency of the device could reach up to 2.4%. Results of test The relationships between output power, the load resistance, and the wind speed. Output power and the energy conversion efficiency with a resistive load 0.46MΩ J. Ji, Z. H. Feng, et al., "Piezoelectric Wind-Energy-Harvesting Device with Reed and Resonant Cavity," Japanese Journal of Applied Physics, vol. 49, p. 050204, 2010.

  39. 5. Other Researches

  40. Signal Conditioning Methods for Piezoelectric Sensors The equivalent circuit of a piezoelectric element linked with a charge amplifier. The equivalent circuit of a piezoelectric sensor linked with a voltage amplifier.

  41. The influence of preamplifiers on the piezoelectric sensor’s dynamic property Experimental setup. W. Q. Liu, Z. H. Feng,et al., "The influence of preamplifiers on the piezoelectric sensor’s dynamic property," Review of Scientific Instruments, vol. 78, p. 125107, 2007.

  42. A High-sensitive Static Vector Magnetometer based on 2D vibration Two Vibrating Coils Reflection method to measure vibration angle Schematic diagram of device configuration The linear range is about 100 μT, which is available in earth magnet detection, navigation, vehicle detection and so on.

  43. Science

  44. High-speed Electrically Actuated Elastomer

  45. Thank You ! 精密机械与精密仪器系Precision Machinery and Precision Instrumentation

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