Multifunctional composite structures have attracted increasing interest in design of ultra-lightweight for aerospace and marine applications. However, an optimized configuration together with precise theoretical prediction models still is urgently needed. In this work, a novel impedance-type square lattice composite structure (ISLCS) with superior out-of-plane load-bearing capacities and broadband radar absorption characteristics was designed. Two theoretical prediction models were developed for optimizing both mechanical and electromagnetic properties considering the shearing deformation of the Timoshenko beam and the scale effect of the electromagnetic wave frequency. The inherent effect mechanism between unit cell geometries and electromagnetic properties was firstly revealed. An integrated molding technology was adopted to fabricate a series of specimens composed of glass fiber reinforced polymer (GFRP) and resistance material. The reliabilities of the proposed models and simulations were verified by the out-of-plane compression and electromagnetic reflectivity tests. The optimized results revealed an average critical compressive stress of 40 MPa and an absorbing band of 5.4–18 GHz, consistent with the mechanical and electromagnetic simulations and experiments. Further simulations with different structural parameters confirmed the wide application scope and equivalence deduction between unit period and sheet resistance. In sum, this study provides a reference for future multi-objective optimization design of three-dimensional radar absorbing structures (3D-RASs).

多功能复合结构在航空航天和海洋应用的超轻型设计中引起了越来越多的兴趣。然而，仍然迫切需要优化配置以及精确的理论预测模型。在这项工作中，设计了一种具有优异的面外承载能力和宽带雷达吸收特性的新型阻抗型方格复合结构（ISLCS）。考虑到 Timoshenko 梁的剪切变形和电磁波频率的尺度效应，开发了两种理论预测模型，用于优化机械和电磁特性。首次揭示了晶胞几何形状与电磁特性之间的内在效应机制。采用一体成型技术制作了一系列由玻璃纤维增​​强聚合物（GFRP）和电阻材料组成的试件。通过平面外压缩和电磁反射率测试验证了所提出的模型和模拟的可靠性。优化结果显示平均临界压应力为 40 MPa，吸收带为 5.4-18 GHz，与机械和电磁模拟和实验一致。不同结构参数的进一步模拟证实了单位周期和薄层电阻之间的广泛应用范围和等效推导。综上所述，本研究为未来三维吸波结构（3D-RASs）的多目标优化设计提供了参考。