Metastructure based broadband structural stealth with material-structure-function integration

Broadband microwave absorption is difficult to be realized in traditional coating form as multiple electromagnetic resonances are difficult to be generated even with dielectric-magnetic loss composites. Narrow absorption band confines the practical usage of the novel electromagnetic nano composites. Herein, the structural stealth concept is proposed to overcome the narrow-band absorption problem with the effect carrier of metastructure. The gradient honeycomb metastructure (GHM) was designed and optimized with module stack large mutation genetic algorithms. The structural design, fabrication, experimental verification and parameter adjustment were included in the closed loop with material-structure-function integration. Multiple resonance effects were introduced in the gradient designs. GHM achieved −10 dB absorption bandwidth in 1.92–17.6 GHz and three deep absorption peaks were introduced by three layers of electromagnetic resonant honeycomb. Broadband absorption in oblique incidence from 30° to grazing angle 85° was achieved to overcome the oblique absorption degeneration problems of traditional nano lossy composites. The structural mechanical performance was high with the maximum equivalent tensile strength of 108.6 MPa and the maximum flexural load of 0.873 kN. The results showed the importance of structural stealth with material-structure-function integration to design metastructure for broadband microwave absorption, which provided a promising approach to achieve broadband microwave absorption.