Laboratory of Acoustical Imaging and Sound Control, Delft University of Technology, P.O. Box 5046, 2600 GA Delft, The Netherlands.
J Acoust Soc Am. 2011 Oct;130(4):2035-42. doi: 10.1121/1.3626164.
Flexural waves play a significant role for the radiation of sound from plates. The analysis of flexural wave fields enables the detection of sources and transmission paths in plate-like structures. The measurement of these wave fields can be carried out indirectly by means of near-field acoustic holography, which determines the vibrational wave field from pressure information measured in a plane close to the plate under investigation. The reconstruction of the plate vibration is usually obtained by inverting the forward radiation problem, i.e., by inversion of an integral operator. In this article, it is shown that a pressure measurement taken in the extreme near-field of a vibrating plate can directly be used for the approximate analysis of the dispersive flexural wave field. The inversion step of near-field acoustic holography is not necessarily required if such an approximate solution is sufficient. The proposed method enables fast and simple analysis of dispersion characteristics. Application of dispersion compensation to the measured field allows for visualizations of propagating wavefronts, such that sources and scatterers in the plate can be detected. The capabilities of the described approach are demonstrated on several measurements.
弯曲波在板的声辐射中起着重要作用。弯曲波场的分析能够检测板状结构中的声源和传播路径。这些波场的测量可以通过近场声全息术间接进行，该技术通过测量接近被测板的平面上的压力信息来确定振动波场。板振动的重建通常通过反转辐射问题来获得，即通过反转积分算子来实现。本文表明，在振动板的极近场中测量的压力可以直接用于近似分析色散弯曲波场。如果近似解足够，则不需要近场声全息术的反转步骤。所提出的方法能够快速简单地分析色散特性。将频散补偿应用于测量场，可以可视化传播波前，从而可以检测板中的源和散射体。所描述方法的功能在几个测量中得到了验证。
