Mechanism Research And Device Design Of Laminated Magnetoelectric Composites

Magnetoelectric(ME)composite is a functional material composed of ferroelectric phase material and ferromagnetic phase material.ME composite has attracted much attention from many scholars because of its remarkable ME effect,which can realize mutual conversion between electric energy and magnetic energy,therefore,it is widely used in sensors,energy harvesters,memory devices,RF antennas and so on.At present,the correlational research on ME composites mainly focus on improving the ME coupling coefficient.But there are few studies on the hysteresis inverse ME effect of ME composites under multi-physical fields.In addition,the research and design work on magnetic field sensor and ME energy harvester are still insufficient.In view of the shortcomings of the above research,this paper carried out the following work:At first,based on the one-dimension nonlinear mechanic-magneto-thermal coupling constitutive equations of magnetostrictive material,combined with J-A hysteresis theory model,and introducing the Weiss molecular field and magnetic energy equation expression,the magnetization equation considering the pinning effect is derived.After that,considering the stress coupling effect of laminated ME composite structure under the applied electric field,and the hysteresis theoretical model of the bi-layer ME composite under the inverse ME effect is obtained.According to the theoretical expression of hysteresis,a 3D finite element simulation model of bi-layer ME composite structure is established,and the validity of the model is verified.On this basis,the hysteresis loop and strain loop under different working conditions are calculated and analyzed by changing the applied electric field,temperature and stress of the model.Secondly,according to the constitutive equations of magnetostrictive materials and piezoelectric materials,and considering the strain-displacement equation,dynamic equilibrium equation and boundary conditions of layered ME composite structure,the simulation model of layered ME composite structures is established by using finite element simulation software.In order to verify the reliability of the model,the simulation results are compared with the experimental results.Subsequently,the geometric configuration and size of layered ME composite structure are changed,the ME respond and DC magnetic field sensitivity of bi-layer structure,tri-layer structure,layered staggered structure,rectangular dumbbell-shaped structure and trapezoidal dumbbell-shaped structure are calculated and analyzed,which can provide guidance for the design of the DC magnetic field sensor.Finally,based on the above simulation model of the tri-layer ME composite structure,the ME coefficient of the nested ring structure and the laminated ring structure are calculated,and the effects of different magnetostrictive materials and piezoelectric materials on the ME coefficients are compared.After that,a vibrating ME energy harvester is designed based on the simulation results of the ring structure.And the core component of the energy harvester is a tri-layer nested ring ME composite structure.Because the energy harvester can convert mechanical energy from external environment to electrical energy output,and has the advantages of simple structure,stable energy supply and no pollution,it can be used in MEMS and self-supply energy devices.