声学黑洞原理的双层加筋板⁃腔系统降噪研究

Noise reduction of a double-layer stiffened plate-cavity system based on acoustic black hole principle

双层加筋板在现代交通运输工具中被广泛应用,这类结构的声振抑制问题一直是难点。声学黑洞(ABH:Acoustic BlackHole)作为一种新型的波操纵技术,为结构振动噪声控制提供了新思路。提出将ABH应用于双层加筋板中,开发有良好机械特性,特别是能实现减振降噪的结构。设计含有ABH的双层加筋板⁃腔系统,搭建实验平台并在点载荷激励下进行效果测试。结果表明截止频率以上腔体的宽频噪声可降低1.5~8 dB。基于有限元方法建立耦合数值模型,多角度量化了系统的动力学特性,分析揭示了ABH在腔室降噪中具有增加系统阻尼和降低内壁板和声腔的耦合强度的双重物理机制。针对降噪效果欠佳的低频段,提供优化设计方案,拓宽有效频率,实现了全频带的控制。进一步验证了复杂载荷作用下ABH双层加筋板⁃腔声振系统的减噪普适性。

The double-layer stiffened plate is widely used in modern transportation,The noise and vibration problems caused by such structures are still problems that people concerned.However,traditional control methods are difficult to meet the develop⁃ment needs of modern equipment due to their large additional weight,low reliability and narrow effective frequency band.Acoustic black hole(ABH),as a new type of wave manipulation technology,provides new ideas for vibration and noise reduction in the equipment.In this paper,ABH is applied to a double-layer stiffened plate to develop a structure with good mechanical properties,especially to reduce vibration and noise.A double layer stiffened plate-cavity system with ABHs is designed,and an experimental platform is built to test the effect.The results show that the broadband noise of the cavity can be reduced by 1.5~8 dB above cut-off frequency.A coupled numerical model is established based on finite elements,and the physical mechanism behind noise reduc⁃tion is analyzed by quantifying the dynamic characteristics of the system from multiple angles.It can be seen that the ABH effect has dual characteristics in noise reduction,that is,increasing the damping of the system and reducing the coupling strength between inner-plate and cavity.Furthermore,the optimized design schemes are provided for the low frequency with poor noise reduction,widen the effective frequency and realize the control of the full-band.Finally,the universality of the noise reduction under complex loads is verified and analyzed.