蜂窝夹芯结构吸波性能的有限元计算分析

Numerical analysis of absorbing property for structural absorbing material (SAM) with honeycomb cores

针对周期性蜂窝夹芯结构型吸波材料的非均匀性,提出采用频域有限元数值仿真和散射参数反演法计算不同构型蜂窝夹芯材料的雷达散射截面(RCS)和反射系数,并探讨了周期性蜂窝夹芯结构中胞元的尺寸效应对结构型吸波材料隐身性能的影响.计算结果表明:对于具有相同体分比的不同构型蜂窝夹芯结构型吸波材料,当胞元尺寸大于工作波长时,夹芯材料的不均匀性导致RCS值变化幅度较大;随着尺寸的缩减,RCS值逐渐减小且变化趋于平缓.但在不同入射方向具有明显的散射特性,而且不同构型蜂窝夹芯结构的反射系数也表现出明显的尺寸效应.研究结果为周期蜂窝夹芯结构型吸波材料的多功能设计提供了计算依据.

In order to explore the effects of inhomogeneity of structural absorbing material （SAM） with periodic sandwich cores on its stealthy property, the frequency-domain finite element numerical computation and the retrieval technique are adopted to evaluate the radar cross section （RCS） and the reflective index of honeycomb cores. And then we compare the RCS and the reflective index of honeycomb cores with the different configurations. The size effect of periodic honeycomb unit cells on the stealthy property is pointed out. To simulate the periodic boundary conditions, the PEC （Perfect Electric Conductor） and PMC （Perfect Magnetic Conductor） are imposed on the unit cells in the different periodic dielectric honeycombs. Moreover, the radar cross section is defined by the ratio of scattering power density and incident wave power density. The reflective index is obtained by the scattering parameter retrieval method. On this basis, the stealth property for structural absorbing material with honeycomb cores is evaluated. Numerical results show that the configuration and size of honeycomb unit cells have the obvious influences on the RCS and reflective index. When there is much difference between the size of honeycomb unit cells and incident wave length, the inhomogeneity of sandwich cores results into the great variation of RCS values. With the size reduction, the RCS values have the gradual variation. However the obvious scattering property appears in the different incident directions The research provides the basis for the analysis of the multifunctional design and application of structural absorbing material with honeycomb cores.