基于变密度法的水声隔声超材料拓扑逆向设计  

Inverse topological design of underwater sound insulation metamaterials based on a density-based method

作　　者：王洋 赵宏刚[1,2] 杨海滨 王超[1,2] 刘家玮 郁殿龙[1,2] 温激鸿[1,2] WANG Yang;ZHAO HongGang;YANG HaiBin;WANG Chao;LIU JiaWei;YU DianLong;WEN JiHong(College of Intelligence Science and Technology,National University of Defense Technology,Changsha 410073,China;Laboratory of Science and Technology on Integrated Logistics Support,National University of Defense Technology,Changsha 410073,China)

机构地区：[1]国防科技大学智能科学学院,长沙410073 [2]国防科技大学装备综合保障技术重点实验室,长沙410073

出　　处：《中国科学：技术科学》2023年第8期1360-1371,共12页Scientia Sinica(Technologica)

基　　金：国家自然科学基金重大项目(批准号:11991032);国家自然科学基金面上项目(批准号:52171327)资助。

摘　　要：低声阻抗超材料在水下环境中可以被视为声学软边界,并且在水声隔声方面具有重要应用前景.然而,设计出能够有效阻隔低频水声声波(<1000 Hz)的低声阻抗超材料仍然面临挑战.本文基于变密度法,对具有90°旋转对称性的低声阻抗超材料开展拓扑逆向设计,得到了一类具有中心四边形框架附着变截面韧带拓扑特征的声学超材料,其声阻抗只有水的1/40~1/30.有限元仿真揭示了超材料在薄厚度约束下(41 mm)能够在200~1000 Hz低频宽带范围内实现高效的水声隔声,平均隔声量大于19 dB.进一步等效参数分析发现,通过改变超材料方位角,能够产生纵波速度远小于横波速度的新颖物理现象.慢纵波速度使得超材料获得更低的等效声阻抗,从而进一步实现低频宽带水声隔声性能.本文的工作有望为低频宽带水声隔声超材料设计提供一种新的思路.Metamaterials with low acoustic impedance can be regarded as acoustic soft boundaries in water and have potential applications in underwater sound insulation.However,designing low acoustic impedance metamaterials capable of insulating low-frequency underwater sound is challenging.This work proposes a new class of low acoustic impedance metamaterials with 90°rotational symmetry based on a density-based inverse design method.The topology of metamaterials shows a square frame at the center connected with ligaments of variable cross-sections.The acoustic impedance of the metamaterials is only 1/40‒1/30 times that of water.For a thin layer of 41 mm,the finite element method reveals that the sound transmission is reduced by over 19 dB from 200 to 1000 Hz on average.Further analysis of the effective parameters shows that,unlike traditional materials,the longitudinal wave speed of metamaterials is less than the transverse wave speed.The slow wave speed ensures the metamaterial has a low acoustic impedance,thereby realizing underwater sound insulation in a low and broad frequency range.This work provides a new avenue for designing metamaterials with low-frequency and broadband underwater sound insulation.

关 键 词：声学超材料 低频水声隔声 低声阻抗 慢波速 负泊松比 

分 类 号：TB34[一般工业技术—材料科学与工程]