Research On Integrated Manufacturing Process And Electromagnetic Camouflaging Performances Of Curved Conformal Metasurface

The design concept of metasurface breaking through the limitation of physical properties of natural materials through artificial structures provides a new way for the development of warship electromagnetic camouflage technologies.Metasurface shows great academic research value and broad engineering application prospect benefiting from the its light structure and flexible electromagnetic wave control ability.However,with the gradual perfection of the basic design theory,manufacturing technologies have become the coming barrier restricting the practical application of metasurface electromagnetic camouflage technologies.To solve these problems,the following works are done in this thesis:Firstly,a fused deposition integrated manufacturing process of metal-polymers heterostructures is proposed,and the high-precision integrated forming of Sn-Bi liquid metal and polylactic acid materials is realized by the interface reinforcing mechanism of hot pressing and microstructure embedment.Aim for the metasurface camouflage functional structures,a trapezoidal illusion metasurface device which can change the reflecting characteristics of objects contour,position and size is designed and fabricated by this process.The maximum generalized RCS reduction of the metasurface device reaches about-14.1 d B in the normal incidence electromagnetic wave.The excellent electromagnetic performance measurement results verify the great potential of the fused deposition integrated manufacturing process in the integrated manufacturing of metasurface heterostructures.Secondly,on the basis of the fused deposition integrated manufacturing process,a thermal programming curved conformal method of heterostructures is established by ingeniously utilizing the different mechanical properties of thermoplastic polymers before and after the glass-rubber state transformation.Combined with the design of the easy-bending metasurface unit cells,an integrated design and preparation of the arched stealth metasurface device with curved surface characteristics is realized,which provides a feasible manufacturing strategy for the surface engineering application of the metasurface functional structure.The measurement results show that the maximum RCS reduction of the metasurface sample reaches about-9.4 d B,and the 3 d B reduction bandwidth is about26.6 %,which strongly proves the effectiveness of the metasurface thermal programming design and fabrication method.Finally,a metal-polymers fused deposition packaging method is proposed,which endows the fused deposition integrated manufacturing process with the ability to manufacture multilayer metal heterostructures.Based on the structure design of dual-wavelength response unit cells,an arched stealth and illusion functional integrated metasurface is designed and fabricated.According to the measurement verification,regardless of the TE polarization or TM polarization,the metasurface sample can achieve stealth and illusion functions at about 4.3to 4.8 GHz and 14.8 to 16.3 GHz,respectively,and the effective incident angle range is extended to 45°.The implementation of curved surface and multi-layer metal-polymers fused deposition composite printing will effectively promote the development and practical process of metasurface electromagnetic camouflage technologies.