Centro de Acústica Aplicada y Evaluación No Destructiva, Consejo Superior de Investigaciones Científicas, Serrano 144, 28006 Madrid, Spain.
J Acoust Soc Am. 2012 Aug;132(2):789-98. doi: 10.1121/1.4733555.
This paper presents theoretical and experimental results on the influence of panel vibrations on the sound absorption properties of thin micro-perforated panel absorbers (MPPA). Measurements show that the absorption performance of thin MPPAs generates extra absorption peaks or dips that cannot be understood assuming a rigid MPPA. A theoretical model is established that accounts for structural-acoustic interaction between the micro-perforated panel and the backing cavity, assuming uniform conservative boundary conditions for the panel and separable coordinates for the cavity cross-section. This model is verified experimentally against impedance tube measurements and laser vibrometric scans of the cavity-backed panel response. It is shown analytically and experimentally that the air-frame relative velocity is a key factor that alters the input acoustic impedance of thin MPPAs. Coupled mode analysis reveals that the two first resonances of an elastic MPPA are either panel-cavity, hole-cavity, or panel-controlled resonances, depending on whether the effective air mass of the perforations is greater or lower than the first panel modal mass. A critical value of the perforation ratio is found through which the MPPA resonances experience a frequency "jump" and that determines two absorption mechanisms operating out of the transitional region.
本文介绍了板振动对微孔穿孔板吸声体（MPPA）吸声性能影响的理论和实验结果。测量结果表明，假设 MPPA 为刚性，薄 MPPA 的吸声性能会产生额外的吸收峰或吸收谷，这是无法理解的。建立了一个理论模型，该模型考虑了微穿孔板和背腔之间的结构声相互作用，假设板的边界条件均匀且保守，并且腔截面的坐标可分离。该模型通过阻抗管测量和背腔板响应的激光测振扫描进行了实验验证。从理论和实验上表明，空气-结构相对速度是改变薄 MPPA 输入声阻抗的关键因素。耦合模式分析表明，弹性 MPPA 的前两个共振是板-腔、孔-腔或板控制的共振，这取决于穿孔的有效空气质量是否大于或小于第一面板模态质量。发现了一个穿孔比的临界值，超过该值，MPPA 的共振会经历频率“跳跃”，并确定了在过渡区域外起作用的两种吸收机制。
