Simultaneous enhancement of absorbent honeycomb with EM wave absorption and compressive properties realised by fishbone-shaped carbon fibre insertion

A novel hybrid design method is proposed to improve the Electromagnetic (EM) and mechanical properties of Absorbent Honeycomb Structures (AHS) synergistically. These improvements are achieved by inserting a Glass Fibre-Reinforced Plastic (GFRP) grid core adhered to fishbone-shaped Carbon Fibre-Reinforced Plastic (CFRP) arrays into an AHS. To this end, a Grid-Enhanced Absorbent Honeycomb Structure (GEAHS) is constructed. Further, the equivalent EM parameters of the AHS are investigated to simplify the simulation model and analyse the enhanced mechanism. The results indicate that the CFRP arrays effectively excite the spoof surface plasmon polariton mode at low frequencies, which greatly widens the effective absorption band and improves absorptivity. Through genetic algorithm optimisation, the average EM wave reflectivity of GEAHS within the range of 2–18 GHz is reduced by 58.1% compared to that of an AHS with only one layer of CFRP prepreg added. In addition, the lateral support provided by the honeycomb core to the GFRP grid walls results in a coupling effect. Thus, the specific compressive strength and energy absorption per volume of the GEAHS increase by 64.8% and 173%, respectively, compared to that of the AHS. Comparing the increased EM and mechanical performances with those of other comparable structures reveals that the present design can be applied to multi-functional design fields.