Research Of Vibration Energy Harvesting By Right Angle Compound Cantilever Beam Based On Piezoelectricity

With the rapid development of low-power wireless electronic devices,how to provide power for these micro-electronic equipment has also drawing the researcher's attention.At present,the wireless electronic devices use battery-powered,but the traditional chemical battery life is limited,in some occasions there are more difficult to replace the drawbacks.It is imperative to seek new methods to supply energy.Vibration mechanical energy can be found in the surrounding environment,if can be used as a potential alternative to energy,then you can once and for all to solve the dependency issues on the external power supply of microelectronic devices.This thesis first discusses varieties of energy sources and energy recovery methods.Secondly,the thesis introduces the energy recovery of piezoelectric vibration and the research achievements and present situation at home and abroad in recent years,then the various optimization methods and their reference are get summarized.The vibration energy recovery based on the piezoelectric effect in these methods has many advantages of high energy density,simple structure,no electromagnetic pollution and easy miniaturization.Then,based on the constitutive equation of the piezoelectric material and the basic theory of the vibration mode,the electromechanical conversion mechanism of the piezoelectric vibration energy harvesting is analyzed,and the theoretical expression of the cantilever structure output power is obtained.The factors influencing the output power are discussed.Based on the above analysis,we proposed the modeling and simulation and structural optimization of the proposed right angle compound cantilever beam.The modal simulation of the first four order vibration mode and the strain distribution are extracted by using the finite element method through the ANSYS software.On this basis,the first-order natural frequency of the structure is 23.121Hz,and the third-order natural frequency is 67.898Hz.We also conducted a harmonic response analysis of the structure,in the 1?100Hz excitation frequency range,every 1Hz sweeping,the load selected is sinusoidal vibration excitation,and ignoring the vibration damping.The frequency response of the strain on the piezoelectric ceramic on the root of the straight beam is shown by the natural frequency.Then,the influence of the size of the loaded mass,the length of the auxiliary beam and the thickness of the auxiliary beam on the resonant frequency of the right angle compound cantilever are discussed in order to guide the physical production of the right angle compound cantilever in the experimental test.Then,based on the above research basis,the fabrication process of right angle compound cantilever beam is described in detail.In addition,its voltage frequency response and power output performance are tested,and compared with the traditional cantilever beam,the validity of the simulation analysis is verified.The results show that the maximum output power can reach 3.4mW under the excitation of sinusoidal vibration with the maximum acceleration of 0.08g,compared with 2.2mW of the traditional cantilever beam.The proposed performance of the right angle compound cantilever beam is better than that of the traditional cantilever beam under the same excitation condition.In summary,the research of this thesis is helpful to reduce the volume of piezoelectric vibration energy recovery device and improve the conversion efficiency of the system.It is very important to realize the independent energy supply for micro-sensors and other devices.