超表面异质结构的熔融沉积复合成形工艺及其电磁伪装性能研究

Research on Fused Deposition Integrated Manufacturing Process and Electromagnetic Camouflaging Properties of Metasurface Heterostructure

超表面异质结构曲面共形电介质基底和金属单元序构的集成制造是阻碍超表面电磁伪装技术向工程化应用方向发展的瓶颈问题。基于3D打印技术设计自由度高、适合复杂结构快速成形的优势,提出一种液态金属与聚合物异质结构的熔融沉积复合成形工艺。在现有聚合物熔融沉积成形(Fused deposition modeling,FDM)工艺的基础上,基于热压-微结构嵌合界面增强机理,实现了熔融Sn-Bi液态金属在聚乳酸(Polylactic acid,PLA)基底上的稳定沉积;进一步优化打印挤出流量和层高等工艺参数,实现了金属线条的可控成形;通过运动指令修正和动态流量补偿的方式,显著提升了熔融沉积复合成形工艺的复杂结构成形能力。最后,利用所提出的液态金属与聚合物熔融沉积复合成形工艺制备了一种梯形超表面电磁伪装结构。电磁测试结果表明,所设计的超表面样品在x极化电磁波垂直入射的条件下最大广义雷达散射截面(Radar cross section,RCS)缩减达到约-14.1 dB,即超表面样品与拟伪装目标的电磁反射特性达到约96.1%的相似度,3 dB缩减(即RCS缩减至50%)带宽约为33.6%,显示出优异的电磁伪装性能。这种液态金属和聚合物的熔融沉积复合成形工艺为曲面共形超表面异质功能结构的集成制造提供了一种有效方法,为推动超表面向工程应用方向发展提供了制造技术支撑。

The integrated manufacturing of curvilinear conformal dielectric substrates and ordered metal unit cells of metasurface heterostructure is a bottleneck problem that hinders the development of metasurface electromagnetic camouflaging technology to engineering application.With the advantages of high design freedom and suitable for rapid prototyping of complex structures by 3D printing technologies,a fused deposition integrated manufacturing process of liquid metal and polymer heterostructure is proposed.Based on the existing polymer fused deposition molding(FDM)process,the stable deposition of fused Sn-Bi liquid metal on the polylactic acid(PLA)substrate is realized by the interface reinforcing mechanism of hot pressing and microstructure embedment.Afterward,the controllable forming of metal lines is realized by optimizing the process parameters such as printing extrusion flow and layer height.And the complex structure forming ability of fused deposition integrated manufacturing process is significantly improved by motion command correction and dynamic flow compensation.Finally,a trapezoidal metasurface electromagnetic camouflage structure is fabricated by the proposed fused deposition integrated manufacturing process of liquid metal and polymer.The electromagnetic measurement results show that the maximum generalized radar cross section(RCS)reduction of the designed metasurface sample is about−14.1 dB at x-polarization in the normal incidence electromagnetic wave,i.e.the electromagnetic reflection characteristics of the metasurface sample and the camouflage target reach about 96.1%similarity,and the 3 dB reduction(i.e.RCS reduced to 50%)bandwidth is about 33.6%,showing excellent electromagnetic camouflaging properties.An effective method is provided by the fused deposition integrated manufacturing process of liquid metal and polymer for the manufacturing of curvilinear conformal metasurface heterogeneous functional structures,which provides manufacturing technology support for promoting the development of metasurface to engineering applications.