微穿孔薄板耦合共振吸声机理研究与宽带吸声结构优化设计

Microperforated absorber has a decent low-frequency sound absorption performance, and it has become an important practical method of noise control engineering. As the absorption bandwidth of the resonance structure is often narrow, the further expansion of its application is sometimes limited. This project proposes systematic research on microperforated absorber to establish the optimum design of the low-frequency wideband microperforated absorber. This work contains three sections: A theoretical model of microperforated absorber with variable aperture is first proposed on the basis of preliminary studies of microperforated absorber with variable cross-section. The design principle to smoothly broaden the sound absorption bandwidth could be established. The second exploratory work is to study the multiple coupling effect of the microperforated thin panel vibration and panel-cavity, aperture-cavity sound absorption mechanism. An accurate statistical energy-analytical hybrid model is built, then the optimum parameters design of multiple resonance absorption is obtained. Based on the above work, active noise control and active structural acoustic control method is introduced separately to the variable aperture microperforated absorber and panel resonance microperforated absorber. The difficulty of target selection in the existing microperforated absorber active control methods could be overcome. Then the new formation of active and passive hybrid control microperforated sound absorption structure could be put forward. With these exploratory work, the design of low-frequency broadband absorbers can be greatly broadened. This study provides solid foundations of developing new low-frequency broadband sound absorbers.

微穿孔板吸声体由于具有良好的低频吸声性能，已成为实际应用中一项重要的噪声控制手段，但由于这种基于共振原理的吸声结构往往有效作用带宽较窄，导致其应用范围难以进一步拓展。本项目将针对微穿孔吸声结构进行系统的研究，旨在建立低频宽带吸声结构的最优设计方案。本项研究分为三个部分：在已有变截面微穿孔板的研究基础上，建立变孔径微穿孔板吸声结构的理论模型，确定实现吸声结构有效频带平稳拓宽的参数设计原则；同时深入研究微穿孔薄板中板、板-腔和孔-腔多重共振吸声机制及其耦合作用，通过建立准确的杂交统计能量-解析模型，获得实现多重共振吸声的最优参数设计方案；针对变孔径微穿孔板和微穿孔薄板吸声结构，分别引入有源声和有源力控制，克服现有吸声材料主动控制中目标函数选择的困难，形成新的主-被动混合控制吸声结构。本项目的研究成果可大大拓展微穿孔板吸声结构的设计思路，为开发新的宽带薄层吸声结构奠定基础。

微穿孔板吸声体具有良好的低频吸声性能，但由于基于共振原理有效作用带宽较窄，导致应用范围难以拓展。本项目针对微穿孔板吸声结构进行系统研究，旨在建立低频宽带吸声结构的最优设计方案。通过四年的研究取得了以下主要研究成果：.1、以微穿孔板理论、电声等效电路原理为基础，建立了孔径变化、微孔不同分布范围和变截面微穿孔板吸声的理论模型。研究发现，当孔径成正态分布和平均分布时，微穿孔板的吸声峰和吸声带宽略有减小；随着微孔分布范围的逐渐缩小，穿孔板的共振频率向低频方向移动；渐变型和阶梯型变截面微穿孔板，大孔端贡献不明显，小孔端起主导作用。.2、考虑轻薄材料的特点，建立了纺织纤维材料及微孔软膜天花材料吸声的理论模型。研究表明：选择合适的材料流阻和表面密度，超薄纺织纤维材料可以实现宽频高效吸声；针刺微孔膜能够有效增加结构的吸声系数及带宽。.3、建立考虑声致振动时，三层微穿孔板的吸声的理论模型，数值分析了声致振动对微穿孔板吸声性的影响。研究发现，考虑声致振动时，三层微穿孔板吸声体的低频吸声性能有所降低，高频吸声性能变化不大。随着微穿孔板质量密度的增加，考虑声致振动时的三层微穿孔板吸声体的吸声性能曲线逐渐接近未考虑声致振动的情况。.4、建立了复合微穿孔板结构的理论模型，研究了微穿孔板结合薄膜单元、复合背腔微穿孔板结构，微穿孔板镶嵌亥姆霍兹共振器的复合结构的声学特点。结果表明：增加薄膜单元后，微穿孔板的吸声性能明显改善；复合背腔结构能很好的改善微穿孔板吸声结构的低频段吸声性能；镶嵌亥姆霍兹共振器后，在低频段引入了额外的吸声峰。.5、建立了声学超材料的理论模型，研究了薄膜型和磁力负刚度型声学超材料的声学性能。研究表明：薄膜型声学超材料具有良好的低频隔声性能；负刚度能够降低背腔的刚度，降低吸声共振频率。.本项研究拓宽了微穿孔板结构的设计思路，为开发新的宽带薄层吸声结构奠定基础，具有重要的理论意义和工程价值。