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.

Aircraft composite laminates are susceptible to delamination damage throughout their lifecycle, from manufacturing to in-service operation. The existence of delamination damage results in a significant degradation in structural strength, stiffness, and stability, which can induce early instability and precipitate global failure. Therefore, it is necessary to explore the influence of delamination damage on the mechanical properties of composite laminates. Addressing the material selection for delamination-critical regions in aircraft structures is an imperative research objective. Further analysis is warranted to understand how delamination depth affects the mechanical behavior of composite structures. Therefore, four kinds of carbon fiber reinforced epoxy resin matrix composites were selected for single delamination damage and impact damage (gradient delamination damage). Quasi-static compression, low-velocity impact and compression after impact tests were carried out to compare the compressive residual strength of four composite laminates with delamination damage. Combined with finite element simulation, the influence trend of delamination depth on the compression performance of composite laminates is explored, and the reason for this trend is analyzed. The results show that compared with the unidirectional prepreg, the selection of high strength fabric prepreg in delamination-critical regions of the aircraft structure will bring better results, and the maximum compressive residual strength can be increased by 118.31%. Additionally, different delamination depths will lead to the bearing capacity of composite laminates determined by different sub-plates. The influence of delamination damage on the compressive properties of aircraft composite laminates has been discussed in depth, which provides a research basis for the damage tolerance design of aircraft composite structures.