Simulation For The Relationship Between Microstructure Of Material And Electromagnetic Field Effect

Material microstructure impact electromagnetic filed effect directly. The practicalengineering experiments have many limitations in the depth and breadth by variousfactors, which include the electromagnetic environmental interference and theinstability of experimental material. With the development of finite element methodand computer technology, and the people can make use of finite element method tosimulate microstructure in order to achieve the goals of the performance-orienteddesign and performance prediction of material microstructure. In this paper, on thebase of visualized simulation for microstructure, finite element software ANSYS isapplied to design the calculation model of electromagnetic field effectiveoperation-space for materials, and calculated electromagnetic field effects of materialsby the Poynting vector method.The electromagnetic field effective operation-space for materials is determinedfrom model length, model size level, thickness of parts, element size, numbers ofelement layer, boundary conditions and load application by the two-port networkalgorithm based on transmission line theory and waveguide structure model. Thecomputer experiments show that the impacts of thickness of the electromagnetic fieldeffective operation-space component parts for electromagnetic field effect are tiny, andthe numbers of element layer is the key of simulation. The reason is that the elementsare carrier of the electromagnetic wave propagation and attenuation, while thegeometry size of model can only reflect the relationship of electromagnetic far-fieldand near-field in finite element simulation.The advantages of two-port network algorithm is not consider the complexelectromagnetic field coupling effect in material itself, and research the influence ofelectromagnetic wave on the external port for the whole material structure, and theresearch process is simplified greatly. However, this algorithm has brought thefollowing disadvantages. Firstly, the reflectivity may be far greater than100%whenthe working frequency arrive at the resonance region of the material structure, which isinconvenient the contrast of the reflectivity, transmittivity and absorptivity. Secondly,it can not calculate multi-angle reflectivity. Thirdly, it can not calculate layeredabsorptivity and layered reflectivity of multilayer composite materials. In order tosolve these problems, a new caculated method is designed in this study,electromagnetic field effects of materials are calculated by the Poynting vector which can characterize the flow direction and magnitude of electromagnetic field energy.The various microstructures of the ferrite materials are designed cooperation withcolleague in our studying team as example. The electromagnetic field effect iscalculated on the ferrite material elements in plane electromagnetic wave by thePoynting vector algorithm, and the problem is solved that the multi-angle reflectivitycould not calculation in similar research. Computer experiments show that: ferritematerial has excellent absorption capacity for plane electromagnetic wave, thenano-particles interpenetrating structure has better absorption capacity than thestructure containing nano-spherical pores of ferrite material. This is mainly determinedby the high resistivity and complex internal structure of the ferrite material.The layered electromagnetic field effect of a simple structure, which is composedthree-layer materials, was calculated by the Poynting vector algorithm. It verified thefeasibility of the algorithm. Then, the layered electromagnetic field effect is calculatedfor the fiber composite material with four structural layers. Computer experimentsshow that the composite material has a low reflectivity in a wide frequency range. Ithas high absorptivity in the low frequency band, and absorptivity decrease with theincrease of working frequency. The absorptivity is stable in about50%when theworking frequency is above40GHz. The electromagnetic field effect is determined bythe fiber weave structure of three-dimensional and the electromagnetic parameters ofmaterial itself. The calculation results of layered electromagnetic field effect for thestructure show that, in the incident plane electromagnetic wave, the electromagneticenergy is mainly concentrated in the previous two structural layers along the directionof electromagnetic wave propagation. This is related to the skin effect of material andworking frequency.In order to definitude in the influence of electromagnetic parameters of thecomposite material’s each phase in the calculation of the electromagnetic field effect,the fiber composite material with four structural layers is research object, usingorthogonal experimental method to research the impact regularity which is the changeof complex electromagnetic parameters against the composite electromagnetic fieldeffect for each phase of the composite material. The results showed that: theabsorptivity is increase and the reflectivity is decrease with the increase of real part ofcomplex electromagnetic parameters, and the influence of the imaginary part ofcomplex permittivity is just the opposite, and the influence of the imaginary part ofcomplex permeability is relatively small. This is related to the basic physicalsignificance of the complex electromagnetic parameters, the real part represent the capacity of electromagnetic energy, the increase of real part indicates that the materialstored energy values increase, so the absorptivity will rise.Finally, in order to obtain high-absorption and low-reflection properties of thecomposite materials in wide frequency band range, we calculated electromagnetic fieldeffect of the fiber composite material with four structural layers by anisotropicelectromagnetic parameters which is related to fiber distribution. The results showedthat: the larger real part of complex electromagnetic parameters of materials in thevertical direction of the electromagnetic wave propagation can obtain a high-absorptionand low-reflection properties in wide frequency band range.Computer experiments and theoretical analysis show that the method ofelectromagnetic field effect simulation is feasible by the Poynting vector algorithm.Research methods solve the problems of multi-angle reflectivity calculation andlayered electromagnetic effect calculation of materials. In addition, research contentshave guiding significance for composite materials design of high absorptivity and lowreflectivity properties in a wide frequency.