Finite Element Analysis And Design Of Micro-Wave Absorbing Composites With Frequency Selective Surface

With the development of computers, Finite Element Method (FEM) becomes an effective method in studying and designing the micro-wave absorbing composites with Frequency Selective Surfaces (FSSs). The results could guide design, optimize and improve the experimental data. Thus, with the help of the calculation, the "thin, light, wide, strong" stealthy materials with low cost could be designed, and finally come into practical use. In this dissertation, FSS or Circuit Analogue (CA) is introduced to the design of the micro-wave absorbing composites. Firstly the factors that may affect the capability of micro-wave absorbing are theoretically analysed. Then the influences of the dimension, electromagnetic parameters, thickness and number of layers and cascades of the inductive FSS on the micro-wave absorbing capability are studied based on FEM. Furthermore, the applications of the metamaterial in FSS are primarily explored. Based on the above analysis, we try to design two eligible stealthy materials, one of which has more micro-wave absorbing ratio, and the other of which has more bandwidth. Moreover, based on the experimental results, the electromagnetic parameters of a kind of stealthy materials used in practice are recovered through computation; and the suggestion to improve the materials behavior is presented. Finally, the static and dynamic properties of the cylindrical shell structure with the micro-wave absorbing composites are analysed based on the computation by FEM.The results indicate that the eligible bandwidth and peak value of the micro-wave absorbing composites can be increased and the frequency of the peak value can be modified by introducing the FSS. The FSS composed of semiconductor of nanometer metal instead of common metal has more adjustable parameters. By modifying the semiconductor parameters, micro-wave absorbing composites with better micro-wave absorbing capability could be gained. The results also show that the peak value of the micro-wave absorbing composites can be increased by using metamaterial in the dielectric layer. The dynamic analysis of the structures with the micro-wave absorbing composites shows that the displacement of the first mode is very small, and thus can be neglected. More attention should be paid on the higher modes in practice. The optimization of the structure could be realized by analyzing the results according to the practical conditions. The results of this dissertation are of practical importance to the design of micro-wave absorbing composites and structures.