| There are many vibrations with low amplitude and frequency and three-dimensional whose intensity is less than 0.5g and frequency is less than 50Hz in production and life,such as the vibration of bridge buildings,the vibration of pavement and the vibration of trees,etc.These vibration environments store a large amount of mechanical energy,which can be harvested and transformed by a specific harvesting structure.At present,it is generally difficult that the function of three-dimensional and wide-band harvesting are achieved in one structure of the piezoelectric vibration energy harvester developed by scholars at home and abroad.In order to realize the function of organic combination for three-dimensional broadband vibration energy harvesting,a Z-type piezoelectric vibration energy harvester with multi-layer structure is designed.The nonlinear mass is introduced by the Z-type structure to broaden the harvesting frequency band,and the three-dimensional vibration energy harvesting is realized by the longitudinal and lateral instability of the Z-type structure.Firstly,the model of statics and dynamics for Z-type piezoelectric vibration energy harvester is established,and the accuracy of the mathematical model is verified by 3D model simulation in COMSOL.From the static simulation results,it is shown that the end displacement of the beam is the result of the interaction for the coupling moment and the coupling force,which is highly consistent with the prediction results of the mathematical model.From the results of dynamic simulation,it is shown that the larger for number of folded layers,the wider for width and the longer for length,the better for effect of frequency reduction.When the number of folded layers of the beam is 7,the width is 25 mm,the length is 60 mm and the folding angle is 12°,the number of modes within 100 Hz reaches 11,from which the nonlinear characteristics of the low-frequency and multi-mode of the Z-beam is verified.Secondly,the electromechanical coupling simulation and experimental analysis of the Z-type piezoelectric vibration energy harvester are carried out.From the simulation and experimental results,it is shown that when the number of layers of the energy harvester is 7 and the excitation intensity is 0.8g,as many as 4 voltage peaks number is shown in the range of 5-40hz,the maximum voltage is above 16V,and the maximum output power is 0.18mw.The maximum output voltage harvested from the horizontal and vertical acquisition are more than 10V,the number of voltage peaks is more than 5,and the maximum output power is 0.108mw and 0.053mw respectively,from which three-dimensional harvesting function of the Z-type piezoelectric vibration energy harvester are verified.Then,the arrays experiment platform is built to study the array harvesting performance of the Z-type piezoelectric vibration energy harvester.From the experimental results,it is shown that when the number of arrays is 12,the excitation intensity is reduced to 0.2g,90%of the parallel arrays output voltages in the range of 15-40hz are more than 4V,the serial arrays output voltages in the range of 17-40hz are almost more than 5 V,and even the output voltages of 23-33hz are more than 10V.The maximum output power of the parallel arrays is up to 0.864 mW,from which the excellent harvesting performance of the Z-type piezoelectric vibration energy harvester is verified.Finally,the output of Z-type piezoelectric vibration energy harvester arrays is used as the power,and the wireless switch module is selected for the wireless signal transmission test.From the test results it is shown that the maximum transmission distance is more than 50 m,the maximum power supply rate is more than 1 Hz,and the success rate of signal reception is more than 95%,from which the feasibility of array output power for normal power supply of wireless equipment is verified.Figure[93]table[3]reference[84]... |
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