宽频带薄膜型声学超材料隔声性能研究

Study on Sound Insulation Performance of Broadband Membrane-type Acoustic Metamaterials

针对汽车前围板中低频段隔声性能有待优化对问题,提出一种以“X”形摆臂为中心质量块的薄膜声学超材料结构,使用COMSOL仿真软件中声固耦合模块对其结构整体声传递损失曲线(Sound Transmission Loss,STL)、薄膜表面平均法向位移、等效参数、耦合振动模态以及影响隔声量因素、调控规律进行有限元分析。结果表明:“X”形中心质量块薄膜声学超材料结构具有优异隔声频率带宽及隔声量幅值,带宽接近1332 Hz,隔声量峰值为54 dB;新结构中“X”形摆臂能兼并由四周质量块产生的不连续隔声峰,从而拓宽隔声频带,提高结构整体隔声性能;增大薄膜厚度和预紧力会使STL曲线整体向高频方向移动,增大“X”形摆臂弹性模量仅会使STL曲线第二隔声谷向高频方向产生小范围移动;其与钢板组成的复合结构能有效提高前围板平均隔声量。相关研究拓展了采用薄膜型声学超材料结构进行中低频段噪声治理的工程应用领域。

Aiming at the optimization of the sound insulation performance of automobile front coaming in middle and low frequency band,a membrane-type acoustic metamaterial structure with X-shaped swing arm as the central mass block is proposed.The sound-structure coupling module in COMSOL simulation software is used to analyze the overall sound trans-fer loss(STL)curve,the mean normal displacement of the film surface,the equivalent parameters,the coupled vibration modes and the control law of the factors affecting the sound insulation.The results show that the membrane-type acoustic metamaterial structure with the X-shaped central mass block has excellent sound insulation frequency band bandwidth and sound insulation amplitude,the bandwidth is close to 1332 Hz and the peak value of sound insulation is 54 dB;In the new structure,the X-shaped swing arm can merge the discontinuous sound insulation peaks generated by the surrounding mass blocks,thus widening the sound insulation band and improving the overall sound insulation performance of the structure.The increase of film thickness and preload will make the STL curve shift towards the high frequency side as a whole,while the increase of the elastic modulus of the X-shaped swing arm will only make the second valley of the STL curve move to-wards the high frequency slightly.The composite structure composed of steel plate can effectively improve the average sound insulation of front coaming plate.This study has expanded the engineering application prospect of membrane-type acoustic metamaterial structures in the field of noise control in low and medium frequency bands.