声学超材料对低频噪声的消声特性

针对低频噪声较难消除的问题,设计了亥姆霍兹共振腔与声学超材料薄膜耦合的消声结构,在利用有限元软件进行屈曲分析薄膜的临界状态得知声学超材料薄膜结构临界失稳力为0.087 N·m,利用COMSOL声固耦合模块研究薄膜形态对传递损失峰值频率的影响。结果表明:薄膜扭转角度由0°增加到30°时,薄膜总体刚度增加,传递损失峰值对应频率向右偏移了30 Hz,变化并不明显。为了扩大频率偏移范围,在扭转30°的基础上,对扭矩棒施加垂直向下的压力,压力由0 kPa增加到2 kPa,薄膜预应力增大,系统刚度增加,使得传递损失峰值向右偏移了170 Hz。最后搭建实验平台,验证了薄膜在扭转时的频率偏移与仿真基本吻合,在不同压力时频率偏移一致,进而可以实现较大范围的低频率噪声控制。为声学超材料的设计和控制提供有效的依据。

The muffling characteristics of acoustic metamaterials to low frequency noise

Aiming at the problem of low frequency noise is difficult to eliminate,the Helmholtz resonator and acoustic metamaterial silencing structure of membrane coupling is designed.The buckling analysis by using finite element software of the critical state of thin-film learned that the critical buckling force of the acoustic metamaterial structure is 0.087 N·m,and the influence of film form on the peak frequency of transmission loss is studied by using the COMSOL acoustic-solid coupling module.The results show that when the torsion angle of the thin film increases from 0°to 30°,the overall stiffness of the thin film increases,and the frequency corresponding to the peak value of transfer loss shifts to the right by 30 Hz,with no obvious change.In order to expand the frequency offset range,a vertical downward pressure is applied to the torque bar on the basis of torsion of 30°.The pressure increases from 0 kPa to 2 kPa,and the membrane prestress increases and the system stiffness increases.As a result,the peak value of transfer loss is shifted 170 Hz to the right.Finally,the experimental platform was built to verify that the frequency offset of the thin film during torsion is basically consistent with the simulation,and the frequency offset is consistent at different pressures,so as to achieve a wide range of low frequency noise control.It provides an effective basis for the design and control of acoustic metamaterials.