Study On High Performance FDTD Method For Simulating Anisotropic Fiber Reinforced Composite Structures And Their Applications

Recently,carbon fiber reinforced polymer(CFRP)materials,due to their high strength,light weight,and easy to be fabricated,have been widely used for the design of aircraft cabin,ship shell and missile shell,etc.However,the conductivity of CFRP is much lower than that of the traditional metal materials.Thus,it is of great significance to study the shielding effectiveness(SE)of CFRP for further electromagnetic protection design of many objects.There are two major problems in computing the SE of CFRP using Finite-Difference Time-Domain(FDTD)method:one is the anisotropic properties of CFRP and the other is the multi-scale features resulted from its thin thickness.This thesis is focused on the study of high performance FDTD method for simulating anisotropic fiber reinforced composite structures,and its research and academic contributions are summarized as follows:(1)The homogenization method is used to homogenize the complex CFRP material properties,and a set of equivalent electromagnetic parameters is extracted and discussed.Then,some equations are derived to calculate reflection coefficient,transmission coefficient and shielding effectiveness of the CFRP.(2)An embedded thin-layer model is proposed based on sub-gridding boundary conditions.In this model,the anisotropic CFRP thin layer is equivalent to an 1-D structure and embedded between the neighboring 3-D grids of FDTD.Further,it combines with the quasi-l-D C-N FDTD method to compute the fields inside the thin layer,where the time step is independent of the fine mesh.Under such circumstances,much computational resource can be saved during simulation.The embedded thin-layer model is integrated into the massive parallel computing program JEMS-FDTD,and numerical examples are given to show the accuracy and high efficiency of the developed program.(3)The effects of different layers of CFRPs,fiber orientation angles,and polarization states of the incident wave on the SE of single-sided CFRP cavity are investigated.Then,the SE results of the all-sided CFRP cavity are given.Finally,by simulating the SE of CFRP-based aircraft gate,missile shell,and aircraft cabin,both capability and application of the JEMS-FDTD integrated with the embedded thin layer model are illustrated and discussed.