Influence of inhomogeneous damping distribution on sound radiation properties of complex vibration modes in rectangular plates
Influence of inhomogeneous damping distribution on sound radiation properties of complex vibration modes in rectangular plates
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DOI：
10.1016/j.jsv.2016.05.009
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发表时间：
2016-09
影响因子：
4.7
通讯作者：
Oliver Unruh;Oliver Unruh
中科院分区：
文献类型：
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作者：
Oliver Unruh;Oliver Unruh
为了减少振动结构发出的噪声，可以使用附加的阻尼处理，例如约束层阻尼或嵌入的弹性体层。为了节省重量和成本，附加阻尼往往被放置在结构的一些关键位置，这导致阻尼的空间不均匀分布。结构阻尼的这种不均匀分布导致复杂振动模式的发生，这些模式不再由纯驻波主导，而是由行波和驻波的叠加主导。复振型的存在引起了关于复振型对声辐射影响的问题，以往对矩形板复振型声辐射的研究表明，随行波方向的不同，结构模态的辐射效率会略有降低或显著提高。这些观察是使用一个简单的非均匀阻尼配置的矩形板，其中包括一个单一的板边界具有较高的结构阻尼比。为了回答关于其他可能的阻尼配置对声辐射特性的影响的问题，本文讨论了由此产生的复杂振动模式的自辐射和互辐射效率。数值模拟用于计算具有不同几何形状和对称性的不同非均匀阻尼配置的复杂结构模态。自辐射和互辐射效率的评估表明，主要是不均匀阻尼分布的对称性影响声辐射特性。特别是非均匀阻尼的非对称分布对所研究的声学指标有很大的影响。所提出的研究还表明，结构模式之间的声交叉耦合，这是描述的相互辐射效率，一般与行波的存在下增加。
In order to reduce noise emitted by vibrating structures additional damping treatments such as constraint layer damping or embedded elastomer layers can be used. To save weight and cost, the additional damping is often placed at some critical locations of the structure, what leads to spatially inhomogeneous distribution of damping. This inhomogeneous distribution of structural damping leads to an occurrence of complex vibration modes, which are no longer dominated by pure standing waves, but by a superposition of travelling and standing waves. The existence of complex vibration modes raises the question about their influence on sound radiation.Previous studies on the sound radiation of complex modes of rectangular plates reveal, that, depending on the direction of travelling waves, the radiation efficiency of structural modes can slightly decrease or significantly increase. These observations have been made using a rectangular plate with a simple inhomogeneous damping configuration which includes a single plate boundary with a higher structural damping ratio. In order to answer the question about the influence of other possible damping configurations on the sound radiation properties, this paper addresses the self- and mutual-radiation efficiencies of the resulting complex vibration modes. Numerical simulations are used for the calculation of complex structural modes of different inhomogeneous damping configurations with varying geometrical form and symmetry. The evaluation of self- and mutual-radiation efficiencies reveals that primarily the symmetry properties of the inhomogeneous damping distribution affect the sound radiation characteristics. Especially the asymmetric distributions of inhomogeneous damping show a high influence on the investigated acoustic metrics. The presented study also reveals that the acoustic cross-coupling between structural modes, which is described by the mutual-radiation efficiencies, generally increases with the presence of travelling waves.