The Multi-Field Coupling Mechanical Behaviors Of Magneto-Electric-Elastic Layered Composite

Magneto-electric materials are a class of functional materials which can convert magnetic energy and electrical energy into mechanical energy and vice versa, and also show good application prospect in many important areas. ME devices or magneto-electric materials usually work together in complex physical environment, which seriously influence the performance of ME materials to a certain extent, will also change the magnetoelectricity conversion efficiency of the ME devices. To research more physical field of ME materials or special physical field effect will be of great importance in the magneto-electric device system design and application, and in the ME materials performance parameter testing. The reliability and sensitivity of ME device is very important, in process of production layered ME composite materials maybe produce interface defect at the interface cohesion restricted by industrial art and technology level, and lead to mechanical stress, which can’t completely eliminate except considering to improve the structure. This thesis is focusing on ME materials, the research works are listed below:Firstly, we have investigated the electro-magneto-thermo-elastic coupling characteristics of a laminated ME plate with consideration of the interfacial layer. Introduced the mechanics of the interface transition layer theory, and using the finite element programming method. The distribution characteristics of the displacements, the electric potentials, stresses, and the magnetic potentials of the laminated ME plate are discussed and displayed. The influence of the interfacial layer thickness and different transition approaches of the material properties of the interfacial layer, the electric potentials, the stresses, the displacements and the magnetic potential of the plate are also studied. The theoretical research results shows that the interfacial transition layer has a very important effect on the distribution of electric potential, the stress and the magnetic potential, especially for the distribution of magnetic potential, these results may be very important in the functional design and the reliability analysis of magnetoelectricity laminated structures.Secondly, three layers of ME composite materials structure simulation model composed of piezoelectric materials (NEPEC6, PZT4) and magneto strict ion materials (CoFe2O4) are built. We have used finite element software ANSYS to simulate the static structural model with the actual conditions in non-uniform temperature field. Using both ends clamped boundary conditions and have a carefully studied the changes of its mechanical and electrical properties, then obtained the specific changing conditions of displacement, stress, electric field and the magnetic field in different layers in Non-uniform temperature field with temperature load. Finally, in this paper, we have introduced displacement potential function method, based on the complexity of interface singularities of the electro-magneto-elastic layered composite structure on the space problem. We also have deduced the general solution of interface singularity of the electro-magneto-elastic composite structure about displacement, stress, electric field and magnetic field.In a word, in this thesis, we study the interface translation layer, uniform temperature field, non-uniform temperature field and interface singularity problem of the electro-magneto-elastic layered composite materials, all results are very useful on the development and applications of ME materials and devices.