Hierarchical Hybrid Radar Absorber Design Realized by Carbon Fiber Arrays and Honeycomb

Hierarchical structure design can improve the structural efficiency of lightweight sandwich structures, and the potential for multifunctional design is also considerable. By constructing fishbone-shaped Carbon Fiber Reinforced Plastic (CFRP) arrays onto the grid walls and introducing Absorbent Honeycomb Sandwich Structure (AHS) as its small-scale configuration, Hierarchical Grid Hybrid Absorber (HGHA) is proposed. By deriving the equivalent models of absorbent honeycomb, its Electromagnetic (EM) and mechanical properties are decoupled. The high relative permittivity and dielectric loss of AHS, combined with the local strong E-filed excited by the CFRP arrays, broaden the absorption band towards lower frequency and significantly reduce the reflection loss (RL), respectively. After optimization, HGHA achieves broadband (2–18 GHz), wide-angle (0–60°), and efficient (average [Formula: see text]) EM wave absorption. Furthermore, honeycomb provide efficient lateral support for the grid walls, changing its failure mode from elastic buckling to plastic microbuckling. Thus, the specific compressive strength and specific energy absorption of HGHA is improved by 99.3% and 173%, respectively, compared to grid sandwich structure. It demonstrates that HGHA is competitive among radar absorbing structures and composite sandwich structures, providing a novel solution for the lightweight, high-efficiency, and multifunctional design of aircraft structures.