基于局域共振编码超表面的低频超宽带水声扩散隐身OA

Underwater acoustic stealth is of great significance for improving the survival and working capabili-ties of underwater devices.A method for underwater low-frequency ultra-wideband acoustic diffusion stealth based on the locally resonant coded metasurface was proposed.Firstly,an equivalent model of acoustic-vibra-tion coupling for locally resonant metasurface elements was established,revealing the mechanical mechanism of an inverted T-shaped fractal structure in modulating the phases of underwater reflected acoustic waves.Then,a collaborative optimization design of the broadband coded elements was carried out based on the genetic algo-rithm.Furthermore,based on the coding theory,the coding sequence of the metasurface with superior diffu-sion performance within the broadband range was optimized.Finally,numerical simulations and experimental tests were conducted for this metasurface.The results show that,the metasurface coding element with an in-verted T-shaped fractal structure can exhibit excellent ultra-wideband phase modulation performance at the deep sub-wavelength scale.The coded metasurface can achieve underwater diffusion stealth in the low broad-band frequency range of 300～1 500 Hz.The experimental results are basically consistent with the simulation re-sults.The research provides a new approach for underwater low-frequency ultra-wideband acoustic stealth.