声学超结构低频宽带协同耦合高效吸声机理

Low-Frequency Broadband Synergistic Coupling Mechanism of Acoustic Metamaterials with High Efficiency Absorption

针对传统材料难以有效控制低频噪声的问题,提出了一种膜类带腔声学超结构的低频宽带协同耦合高效吸声机理。这种超结构有多个吸声单元,每个吸声单元由两个铝片组成,铝片固定在空气腔上方的硅胶薄膜上。首先利用有限元软件COMSOL Multiphysics 5.3计算单元胞的吸声特性,确定吸声结构的尺寸和材料参数;然后通过两元胞结构分析振动模态和吸声机理,解决吸声结构窄带的问题,再分析典型结构参数对协同耦合机理和吸声特性的具体影响规律;最后通过多单元的协同耦合,实现整个频率范围内的宽带吸声。仿真结果表明:通过设计多个单元的协同耦合,可以将不同单元之间的吸声峰值相互错开,使结构的吸声系数在整个低频范围内均匀分布,实现200~1 000 Hz范围内连续的吸声宽带,平均吸声系数为80%左右,实现低频大宽带的优异吸声性能。该研究结果可为低频宽带吸声材料的设计提供一种新的思路,在控制振动和噪声方面具有潜在的应用前景。

A low-frequency broadband synergistic coupling mechanism of membrane-type metamaterials with high efficiency absorption is proposed to solve the problem that traditional materials are difficult to effectively control low-frequency noise.This kind of membrane-type metamaterials consists of multiple units,each unit is composed of two aluminum platelets,and each platelet is fastened on a piece of silicone membrane above an air cavity.Finite element software COMSOL Multiphysics 5.3 is used to calculate the absorption characteristics to determine the structure size and material parameters of the cell.Then the vibration mode and mechanism are analyzed by two cells to solve the narrow band.The influence of typical structural parameters on synergetic coupling mechanism and absorption characteristics is discussed.The broadband sound absorption in the whole frequency range is realized via synergetic coupling of multiple units.The simulations show that the absorption peaks of units can be staggered with each other via synergetic coupling of multiple units,so that the absorption coefficient of this structure is evenly distributed in the whole low frequency range,and the continuous broadband in the range of 200-1 000 Hz is obtained.The average absorption coefficient is about 80%,and an excellent absorption performance of low-frequency broadband is achieved.Thus a new idea for the design of acoustic metamaterials with low-frequency broadband absorption is presented.