| The power demand of lower power-dissipated productions, micro wireless sensorand integrated systems are fast increasing, however, electrochemical batteries aspower sources have many flaws, such as limited lifespan and pollution. On thecontrary, piezoelectric vibration energy harvester has become a hot spot of technicalresearch. Given that hydraulic drive has the advantages of high energy density, lownoise and without impact, fluid is introduced to piezoelectric energy harvester, and apiezo-hydraulic vibration energy harvester (PHVEH) is presented based on solid-fluidcoupling vibration. In this dissertation, finite element simulation, theoretical analysis,design and processing, prototype testing and other methodologies are used to developthe PHVEH. The main research contents are as follows:1. ANSYS software is adopted to analyze the circular PZT disk subjected to auniform load, which is an important component of the PHVEH. Set the parameters forthe FEM simulation, carry out the FEA simulation, and obtain the maximum voltageof circular PZT disk. In order to achieve the maximum electrical energy from PZTdisk generator, the expression involving the maximum voltage is derived. Radiusratio(λ), thickness ratio(β) and material Young’s modulus(ζ) of the PZT disk aredefined in order to investigate the influence of energy generation. The research resultshows that there has the optimum value of radius ratio and thickness ratio for a PZTdisk to maximize performance, which consists of PZT-4and beryllium bronze.Similarly, there is an optimal material Young’s modulus of PZT disk with differentstructure parameters. In the condition of given radius ratio, the material Young’smodulus make the obvious influence on the electrical energy with lower thicknessratio. Using aluminum or beryllium bronze as a substrate materials, the best radiusradio and thickness ratio of the PZT disk are (0.926,0.636) or (0.95,0.745)，and themaximum electrical energy are3.853×10-4J or3.5485×10-4J，respectively． 2. The following section details the structural and principle of the PHVEH, andsimplifies the vibration mechanical model. The theoretical model of PHVEH underharmonic excitation was established utilizing the theory of piezoelectricity,hydromechanics and vibration mechanics. The theoretical expression of the generatedelectrical energy from the PHVEH is derived, and the affecting factors of electricitygeneration are carried out by the expression. Choose amplitude of vibration (H), backpressure (Pb) and the proportion of air (τ) as affecting factors, the frequency responsecurves are drawn under the condition of changing one factor. The affecting factorsleading to the generation performance change are analyzed. The analytical resultsshow that the frequency response curves has peak point (including natural frequencyand maximum electrical energy), which exist in low frequency range. The systemparameters leading to peak point change are also analyzed. For more study of factorsinfluencing electrical energy from the PHVEH, the generated energy is studied bymeans of single factor analysis under the condition of constant excitation frequency.3. In order to prove the feasibility of vibration energy harvesting based onsolid-fluid coupling vibration and the validity of theoretical model, an experimentalPHVEH is processed and fabricated. For testing the power-generation capacity,experimental test systems are constructed. The power-generation capacity is affectedby the external excitation (including vibration frequency and amplitude of vibration)and the system parameters (including back pressure and power-transmitting medium).To find out the influencing rule, the experimental study is investigated. Theexperiment results illustrate the validity of the main conclusions in theoretical analysisand simulation analysis. |
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