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首页> 外文期刊>IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control >Air-coupled ultrasonic estimation of viscoelastic stiffnesses inplates
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Air-coupled ultrasonic estimation of viscoelastic stiffnesses inplates

机译：板中粘弹性刚度的空气耦合超声估计

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摘要

Materials characterization by means of megahertz air-couplednultrasound is reported in this paper. In plates of composite laminatesnthe reconstruction of a function closely related to the transmissionncoefficient has been accomplished using leaky guided waves. The spatialnand frequency dependence of the transmitted leaky waves have beennmeasured for a variety of plates, including aluminum-aramid andngraphite-epoxy. These results are based on a general method, developednin this paper, to reconstruct a transmission function experimentallynfrom scans both of receiver position and incident angle. A syntheticnaperture technique is utilized to reduce the measurements by forming anneffective wide-angle focused aperture. This synthetic focused aperturenis obtained experimentally by summing measured signals coherently fornmany transmitter-receiver separations and summing incoherently for manyntransducer angles with respect to the plate normal. These results havenbeen employed to deduce, with high precision, a function related to thenplane-wave transmission coefficient of the plate over the frequency andnangular bandwidths covered by the measurements. Calculation of thisnfunction is demonstrated, and the source of its deviation from thenplane-wave transmission coefficient is explained. The experimentalnresults show good agreement when compared to three-dimensionalntheoretical beam calculations. The high degree of accuracy in thenmeasured transmission function has been exploited to construct annefficient inversion algorithm to estimate the viscoelastic materialnproperties and/or sample thickness
机译：本文报道了通过兆赫兹空气耦合超声进行材料表征的方法。在复合层压板中，已经使用漏导波完成了与透射系数密切相关的功能的重建。对于各种板，包括铝-芳族聚酰胺和石墨-环氧树脂，已经测量了所传输的泄漏波的空间和频率依赖性。这些结果基于本文开发的通用方法，通过对接收器位置和入射角的扫描实验性地重建了传输函数。利用合成孔径技术通过形成无效的广角聚焦光圈来减少测量。这种合成的聚焦光阑是通过将测量信号相干地求和以得到发射机和接收机之间的距离并相对于板法线在许多n个传感器角度上非相干地求和而获得的。这些结果尚未被用来高精度地推导与板在测量所覆盖的频率和矩形带宽上的平面波传输系数有关的函数。演示了该函数的计算，并解释了其与平面波传输系数的偏差来源。与三维理论梁计算相比，实验结果显示出良好的一致性。利用已测量的传递函数中的高精度来构造一种有效的反演算法，以估算粘弹性材料的性质和/或样品厚度

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