基于局域共振编码超表面的低频超宽带水声扩散隐身

Underwater acoustic stealth is of great significance for improving the survival and working capabilities 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-vibration 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 algorithm. Furthermore, based on the coding theory, the coding sequence of the metasurface with superior diffusion 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 inverted 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 broadband frequency range of 300~1 500 Hz. The experimental results are basically consistent with the simulation results. The research provides a new approach for underwater low-frequency ultra-wideband acoustic stealth.