Finite Element Analysis Of Piezoelectric Energy Harvesting For Variable Cross-section Cantilever Beam Based On Bending-torsion Coupling

With the development of science and technology and the continuous improvement of people’s living standards,low-energy portable electronic devices and wireless sensor networks are becoming more and more popular.Piezoelectric energy capture device has become a major driving force for the development of MEMS due to its advantages such as convenient micro-structure,long service life and high overall output power.Piezoelectric energy capture device uses the piezoelectric effect of piezoelectric materials（positive piezoelectric effect and inverse piezoelectric effect）for energy conversion and provides energy for MEMS.In order to develop a simple and efficient piezoelectric energy capture device,scientists have designed a large number of different structures and optimized them to adapt to different vibration environments.At present,the optimization of the piezoelectric energy capture is mainly from the perspective of improving the energy capture efficiency and broadening the frequency band.Has been reported literature in bending vibration system is introduced into the reverse games can effectively broaden the original system of captive band,its principle is to use the original system after the bending vibration of the movement and introducing twisting movement phase coupling is introduced into reverse movement makes the crankle coupling system can make the original bending vibration system of the second order modal closer,which is suitable for the external environment of multiple frequency change.Reducing the stiffness of the structural system is conducive to improving the energy capture efficiency of the piezoelectric energy capture device.In this regard,it has been reported that the variable cross-section cantilever beam,compared with the rectangular cantilever beam,not only reduces the stiffness of the structural system to achieve the purpose of improving the energy capture efficiency,but also saves the required materials.Secondly,it has been reported that segmenting the rectangular main beam of the flexural vibration system can reduce the damping of the system and improve the capture energy efficiency.However,there is no literature report about the introduction of torsional motion and the width segmentation of the variable section cantilever beam.Therefore,in this paper,the variable section cantilever beam is introduced into the bending-torsion coupling system and the width segmentation method is carried out.My key work contents are as follows:（1）This paper designed a based on the variable cross-section cantilever beam bending torsional coupled piezoelectric prisoner can implement,on this basis,by introducing twisting motion in different ways and design the structure of the two different（quality block offset structure and beam offset structure）,secondly,based on the idea of width of the segmentation method of the variable cross-section cantilever beam piezoelectric captive double beam can is divided into variable cross-section cantilever piezoelectric prisoner can implement.（2）Using the principle of torsional motion caused by asymmetric structure,the flexural and torsional coupling piezoelectric energy capture device（mass block bias and beam bias）for single cantilever beam with variable cross-section is designed.The mass block bias and beam bias are simulated and analyzed by finite element software respectively.Geometrical and finite element models of mass block bias and beam bias are designed and established by using finite element software.Displacement analysis and stress analysis are carried out to verify that the material selected in this paper meets the yield strength requirements of the material.Within a certain range,the ratio of mass blocks on both sides of the main beam,the length L of the main beam,the thickness of piezoelectric layer t _P,the external load resistance R_Land the right beam L₂of the main beam of the bias beam of the single cantilever beam with variable section are analyzed by single factor.（3）Based on the idea of width segmentation method,geometric models and inite element models of mass block bias and beam bias of the two-beam cantilever with variable section are designed and established.Secondly,displacement analysis and stress analysis are carried out by using the finite element software to verify that the selected materials of the structure meet the requirements of the yield strength of the materials.Based on the geometric parameters of the single factor analysis method,the simulation analysis of the variable cross-section cantilever double beam quality block offset structure on both sides of main girder of the ratio of the mass m^*,girder short edge width d b₂,double beam spacing and external load resistance R_Laffect the performance of the prisoner can double beam with variable cross-section cantilever beam offset structure beam length L₂,different thickness of base layer ts and different external load resistance R_Lon the properties of the prisoner can influence.Finally,the energy harvesting performance of single beam and double beam with variable cross-section cantilever mass block bias and beam bias structure is compared.