Radar-stealth and load-bearing corrugated sandwich structures with superior environmental adaptability

The engineering design of lightweight multifunctional composite structures is an attractive research subject with enormous potential in the aerospace and marine fields. Nevertheless, the mechanical and electromagnetic performance of variable-curvature structures has been seldom investigated. Herein, a novel multifunctional sinusoidal corrugated sandwich structure with impedance-type frequency selective surface (FSS) is proposed to provide superior out-of-plane load-bearing capacity and broadband microwave stealth performance. A precise theoretical model is proposed to predict the out-of-plane compressive strength of sinusoidal corrugated structures. The model is based on the Timoshenko beam theory and a modified plastic hinge theory, considering the actual stress distribution on the cross-section. The selective laser sintering (SLS) method is employed to fabricate a series of specimens with different structural parameters. The simulation analysis and experimental results suggest that the proposed mechanical model possesses high precision and wide applicability. The proposed multifunctional sandwich structure has an average ultimate compressive strength of 1.106 MPa and broadband microwave stealth (maximum reflectivity of −8.8 dB in 2–18 GHz). Environmental factors are found to have little effect on microwave reflectivity, including out-of-plane compressing (2 dB), frosting (0.5 dB) and holing (0.5 dB). The present study provides an example of broadband microwave stealth and load-bearing structure with superior environmental adaptability.