Ultrathin Underwater Sound-Absorbing Metasurface by Coupling Local Resonance with Cavity Resonance
Jiaming Feng, Qingxuan Liang, Yu Dou, Jingru He, Jin He, Tianning Chen
Abstract
An ultrathin underwater metasurface with low frequency, broadband, high-efficiency absorption, and high-hydrostatic-pressure-resistance performance is proposed based on the integrated principle of local resonance and cavity resonance. The design-parameter complexity is overcome by the global-optimization capability of the genetic algorithm. As a demonstration, an average sound-absorption coefficient of 92.3% at 500--10 000 Hz with an ultrathin thickness of 32 mm is achieved, including more than 99% sound-absorption coefficient at 4670--8630 Hz. In the proposed metasurface, the complex surface impedances of the three subsurfaces provide unique views for the high-efficiency sound-absorption coupling mechanism by the equivalent-circuit model. Further investigation demonstrates that the excellent property of high-efficiency sound absorption is maintained under 4.5-MPa hydrostatic pressure. The proposed metasurface provides more possibilities for underwater noise suppression.