Simulation And Experiment Of Piezoelectric Energy Harvester With Bending And Torsion Coupled

With the fast development of integrated circuit technology and MEMS?Micro Electro Mechanical Systems?technology,how to convert the vibration energy in the environment into electrical energy has attracted the attention of researchers.The piezoelectric energy harvester has been studied extensively for its high output voltage and power density,etc.It has a simple structure which is easy to miniaturize and is not requiring an external power supply.Nowadays,the research on the piezoelectric energy harvester mainly focuses on the type of bending vibration mode,but its frequency may remains at a low and small-bandwidth range.A report shows that with the introduction of torsion,the second-order modal rate of the system will be reduced drastically and then achieve the purpose of widening the frequency-capture range practically.Therefore,it is valuable to research the piezoelectric energy harvester with the bending-torsion coupled vibration model.In addition,some reports indicate that it can increase the output voltage of the bending vibration mode piezoelectric energy harvester by using the width division method,whichchange the mono-spar construction into a double one.However,the application of width division method in the bending-torsion coupled vibration mode piezoelectric energy harvester is still questionable.To conclude,it is worth tostudy the bending-torsion coupled vibration mode piezoelectric energy harvester with the single-cantilever beam structure and the modified double-cantilever beam structure.The contents of this thesis are as follow:?1?PZT-5H piezoelectric material was selected as a piezoelectric vibrator for its high d31 coefficient.The bending-torsion coupled vibration mode piezoelectric energy harvester with double-cantilever beam structure,single-cantilever beams-offset type and mass asymmetric distribution type were designed and prepared.The experimental test system were also constructed.?2?The structures of the bending-torsion coupled vibration mode piezoelectric energy harvester with single-cantilever beam-offset type and mass asymmetric distribution type were optimized by using the ANSYS FEA?Finite Element Analysis?Software.The optimized parameters of the harvester with single-cantilever beam-offset type are:m*=1,L₁=27 mm,L₂=22 mm;The optimized parameters of the harvester with mass asymmetric distribution type are:L₁=L₂=22 mm,m*=4.The strain clouds of the single cantilever beam structure piezoelectric energy harvester with bending-torsion coupled vibration mode and bending vibration mode were compared in the simulation software.And change in the displacement of end mass was analyzed.The variations of the output voltage and power with frequency were analyzed under different loads by the experimental system test and simulation software modeling.Comparing the first two modal frequency,The two cantilever single beam bending and twisting structures respectively increase the bandwidth of the captive energy system by 117%and 171%.?3?The structures of the bending-torsion coupled vibration mode piezoelectric energy harvester with double-cantilever beam was optimized by using the ANSYS FEA Software.The optimized beam spacing is:d=6 mm,the mass ratio m*=9.The influence of the geometrical parameters on the output performance was analyzed by the finite element method for the harvester.The output voltages of the harvester with the single-cantilever beam and the double-cantilever beam were compared by the experiment test system and the simulation model.When the resistance R is 100 K?,the output voltage of the two-beam system is increased by 23.6%in the first-order mode and 13.1%in the second-order mode compared to the single-beam system.