Sound Transmission Analysis by Holography on Plates

本文研究的问题是声音在不同形式的板中的传播特性，如边界条件和板的形状。本研究采用的方法是用全息法观察板的振动模式，并用有限元法计算分析板的透射特性。从全息观察可以得出以下结论：弹性支撑边缘可以被认为是简支撑边缘和固支边缘之间的条件，可以用边界约束参数来量化。在此基础上，提出了一种基于振动模态估计辐射声功率的全息方法；这种估计对讨论板的共振声传输特性是有用的；通过与声强测量结果的比较，验证了该估计方法的近似性。在这里，这些观察是在板上进行的，明矾…更多的是铝和钢，矩形平面形状和圆柱形弯曲形状。，有弹性支撑边和固定边。一般来说，即使板的形状太复杂，无法用现有的其他振动传感器测量来分析，也可以用全息术来详细分析，而不影响板本身的振动。需要一些新的分析方法来从理论上支持全息观测得出的结论。针对这一问题，提出了一种平板声传输特性的计算分析方法。它基于有限元法，可以处理各种板的问题。通过这些观察和计算分析，研究了圆柱弯曲板在环形频率下具有优于平板的隔声性能；发现圆柱弯曲板的这种特性是由模的辐射效率特性引起的。少

The problem treated in this study is that of the sound transmission characteristics through plates with various kinds of form such as the boundary conditions and the shape of a plate. The method used in this study is the observation of plates' vibrating modes by holography, and the computational analysis on plates' aound transmission properties by finite element method. From the holographic observation, the following are concluded that the elastically supported edges, considered to be the condition between simply supproted edges and clamped edges, can be quantified by the boundary restrain parameter. Additionally, a holographic method is developed to estimate the radiated acoustic power from the plates' vibrating modes; this estimation is useful in the discussion on the resonant sound transmission characteristics of plates; the approximation of the estimating method is examined in comparison with the acoustic intensity measurement. Here, these observations are performed on plates, alum … More inum and steel, rectangular flat shape and cylindrical curved shape., with elastically supproted edges and fixed edges. Generally speaking, even if the form of a plate is too complicated to be analysed by other existing measurements using vibration sensors, it can be analysed by holography in detail without affecting the plate's own vibration. Some new analysing method is needed to support the conclusions derived from the holographic observations theoretically. A computational analysing method on sound transmission characteristics of plates is developed to meet with the problem. It is based on finite element method, and it can treat the problem on various kinds of plates. With these observations and computational analysis, the characteristics of cylindrical curved plates are investigated to have superior sound insulating properties to those of flat plates under the ring frequence; this characteristics of cylindrical curved plates are found to be caused by the characteristics of the modes' radiation efficiency. Less