Studies On The Fine Calculation Method Of The Coupled Field In The Piezoelectric Functional Devices

Piezoelectric materials,which can achieve transformation between mechanical energy and electric energy,are often used in the design of piezoelectric functional devices,such as sensors,actuators,energy harvesters,transducers and so on.Because the two forms of piezoelectric functional devices,which consist of piezoelectric layer on dielectric or conductor substrate and dielectric or conductor layer on piezoelectric substrate,are the most common in engineering,it shows great theoretical and engineering values to study on the precise calculation method of electro-mechanical coupling field in the piezoelectric functional devices.This work will much contribute to the fine design and fabrication of the piezoelectric functional devices with high quality.Therefore,the fine calculation method for the electro-mechanical coupling field in the piezoelectric functional devices is searched for in this dissertation.The main achievements include the following three parts.For the piezoelectric function devices which consist of piezoelectric materials,dielectric materials and electrical conductor materials,based on the general solutions of the two-dimensional and three-dimensional governing equations,a series of harmonic functions with undetermined constants are constructed when the piezoelectric functional devices are under the load cases including the two-dimensional normal line force,the line charge,the tangential line force and the three-dimensional normal point force,the point charge,the tangential point force.By substituting these harmonic functions into the two-dimensional and three-dimensional general solutions,respectively,the corresponding Green's function solutions in the piezoelectric functional devices under all above concentrated loads can be obtained,and the undetermined constants can be determined by using boundary conditions,interface continuity conditions and electro-mechanical equilibrium conditions.The calculation results show that this method can be used to obtain the accurate solution of electro-mechanical coupling field in everywhere of the piezoelectric functional devices.It has high precision,high efficiency and high stability,which is the necessary foundation for further work.Based on the obtained Green's function solution and superposition principle,the solutions of the electro-mechanical coupling field in the piezoelectric functional devices which are under an arbitrary electro-mechanical load can be obtained.On this basis,the detailed calculation and analysis are presented for the piezoelectric functional devices under various service loads.Firstly,a concise method is proposedto obtain the electro-mechanical coupling field of piezoelectric functional devices with different layer thickness by just one time of calculation.Because the layer thickness is the most important parameter to determine the reliability and comprehensive service efficiency of piezoelectric functional devices,this method will greatly improves the design efficiency of the piezoelectric functional devices and can very quickly obtain the optimal thickness of layer in the piezoelectric functional devices.Secondly,the contours of the electro-mechanical coupling field components for various piezoelectric functional devices are given to show the use of this method.Some valuable engineering conclusions are presented for the reliability design of piezoelectric functional devices,the sensitivity improvement of piezoelectric sensors,the working efficiency improvement of piezoelectric actuators and the energy capture efficiency enhancement of piezoelectric energy harvesters.Based on the work of this dissertation,the special software for fine calculation of electro-mechanical coupling field of piezoelectric functional devices is presented.This software is easy to be operated.Based on it,the optimal thickness of layer in the piezoelectric functional devices can be quickly obtained.Meanwhile,the contours of the electro-mechanical coupling field components can be output as required.After simple training,this software can be quickly mastered by engineering professionals.And based on this software,a large number of different types of piezoelectric functional devices can be analyzed and designed in engineering.And then,the work of this dissertation can contribute to the engineering applications and create the economic and social benefits.