Research On The Effect Of Adhesive Layer On The Electromechanical Property Of Cantilever Piezoelectric Harvester

Piezoelectric harvester is a kind of intelligent structure which converts the mechanical energy in the environment into electrical energy through the electromechanical coupling effect of piezoelectric materials.The commonly cantilever-type piezoelectric harvester based on the resonant capture modes is made by bonding the piezoelectric layer to the elastic layer by an adhesive.Generally,the maximum stress of the piezoelectric sheet is produced at the front of the piezoelectric sheet.What's more,in the case of high-order vibration,the cantilever beam will appear deformation of the inflection point,and some parts appear the tensile deformation,while some parts appear the compression deformation.If the piezoelectric layer is full of cantilever beam,the two parts of the charge generated offset each other,so that energy efficiency will be reduced.Therefore,the piezoelectric sheet is generally laid on the root of the deformed elastic layer to trap a large amount of energy,rather than a resilient layer.Due to the inconsistency between the geometrical parameters and material parameters of the piezoelectric layer and elastic layer,the stress of the adhesive layer is prone to distributing unevenly during the process of deformation transferring in elastic layer and greater stress concentration is prone to appearing at the free end while the elastic layer of the harvester vibrates with the environment vibration.The ultimate voltage output of the piezoelectric harvester is then affected.Therefore,it is necessary to find out the influence of adhesive layer on the energy output.Based on the basic model of cantilever piezoelectric harvester,the two-parameter model is used to simulate the bonding layer,and the governing equations of the cantilever-type piezoelectric traps are established based on the distributed parameter model.When the excitation frequency is given,the governing equations are transformed into the characteristic equation with the wave number as the characteristic value,and the 12 characteristic modes are obtained by solving the equation.The modal linear superposition,boundary and connection conditions can give the solution of the problem.In addition,through the three-dimensional finite element analysis,combined with previous experimental results,compared with each other to verify.After the theoretical correctness is verified,this paper also studied the elastic layer,adhesive layer and piezoelectric layer's material parameters and geometric parametersThis paper is divided into five chapters:the first chapter states the background and significance of this research;the second chapter introduces the theory and method of this study;based on the theory of two-parameter model,the third chapter establish the controlling equation of piezoelectric harvester considering the effect of interfacial stress,then the analytical solutions of piezoelectric voltage output are put forward,the voltage output obtained by theoretical analyzition in the third chapter is verified by the results of finite element simulation in ANSYS,and then compared to the traditional voltage output with no consideration on the effects of the adhesive layer interfacial stress.In the fourth chapter,the influences of parameters,such as thickness and elastic modulus of adhesive layer,laying length,thickness and elastic modulus of piezoelectric layer,thickness and elastic modulus of elastic layer,on the voltage output is analyzed and discussed in detail.The stress state of the adhesive layer in the representative state is observed as well.And finally the changing laws are then summed up.The fifth chapter reviews and summarizes the preceding articles,and prospects the future feasible research.The design and analysis of the piezoelectric harvester are provided with a more accurate theoretically support through the theoretical exploration in this paper.