Design And Performance Analysis Of Multi-Stable Piezoelectric Cantilever Energy Based On Magnetic-Mechanical Coupling

The vibration and noise reduction of the vehicle is of great significance for improving the comfort of the vehicle.The vibration and noise reduction of a vehicle usually refers to the conversion of vibration energy into other forms of energy dissipation,such as thermal energy.Collecting and storing the converted energy or powering microelectronic devices such as on-board MEMS sensors has become a hot issue for scholars.Among the commonly used vibration energy collectors（electromagnetic,electrostatic and piezoelectric）,the piezoelectric vibration energy harvester has attracted much attention due to its simple structure,environmental protection and high efficiency.Piezoelectric vibration energy absorbing device is a linear resonator that can only be effective in a narrow frequency band（<2Hz）in a low frequency environment,while the mechanical vibration in the environment is a random vibration that exists in a wide frequency band.Therefore,it is necessary to study low frequency and large bandwidth piezoelectric energy harvesters.The nonlinear energy harvester can capture energy in a wide operating frequency band.In this paper,a multi-stable piezoelectric energy absorbing device using magnetic force to generate nonlinear stiffness is proposed.The energy-displacement function of the energy harvester system is established and the steady-state characteristics of the multi-stable piezoelectric energy harvester are analyzed.Based on the steady-state characteristic analysis,the design of a multi-stable piezoelectric energy harvester that meets specific performance requirements is completed.Finally,the finite element analysis method and experiment were used to verify the power generation performance of the multi-stable piezoelectric energy harvester.The main research work of this paper is as follows:（1）A new configuration of piezoelectric multi-stable energy harvester based on double parallel beams is proposed.A numerical analysis model of the new energy harvester was established,and the correctness of the analytical model was verified by the finite element method.（2）The influence parameter analysis and optimization of the piezoelectric energy harvester were carried out.The energy-displacement function of the system is derived.Based on the obtained energy-displacement function,the effects of structural parameters on the steady-state characteristics of bistable,tristable and four-stable systems are analyzed.Based on the analysis results,the number of magnetic blocks and the arrangement position of magnetic blocks of the energy harvester structure are optimized and the new configuration of the optimal bistable,tristable and four-state piezoelectric cantilever type of energy harvesters is obtained.The adaptation environment of three kinds of energy harvesters is given.The analysis results show that:as the horizontal distance d increases,the potential depth of the bistable piezoelectric energy trap decreases,and the two steady-state positions are close to the origin.It shows that the energy required to cross the barrier during the vibration process is reduced,and it is easier to generate large inter-well vibrations across the bistable,but the amplitude of the large vibration across the barrier will increase with the increase of the horizontal spacing d.reduce.As the vertical spacing d₁ increases,the system potential well depth decreases,and both steady-state positions are far from the origin,indicating that the energy required to pass the beam across the barrier is reduced,and it is easier to generate large inter-well vibrations across the bistable state,and The amplitude of the large vibration across the barrier will increase and for tristable and quad-stable multi-stable piezoelectric traps,an increase in the number of steady-states can increase the spacing between boundary steady states,thereby increasing the amplitude of the vibration between the wells.（3）For the test and verification of the double parallel beam piezoelectric energy harvester,a test platform for vibration test was built and experimental test pieces were fabricated.The white noise random excitation was used to test the power generation performance of the multi-stable piezoelectric energy harvester under low excitation amplitude and high excitation amplitude.Both the analysis results and the experimental results show that the multi-stable piezoelectric energy harvester has better power generation performance than the traditional piezoelectric energy harvester.