Ponschab Michael, Kiefer Daniel A, Rupitsch Stefan J
IEEE Trans Ultrason Ferroelectr Freq Control. 2019 Dec;66(12):1898-1905. doi: 10.1109/TUFFC.2019.2933699. Epub 2019 Aug 7.
Properties of isotropic plates in terms of material constants and thickness are characterized by making use of dispersion characteristics of propagating Lamb waves. A numerical model is inversely optimized in order to match dispersion curves measured by laser vibrometry. This kind of material characterization has gained interest in recent research. Improvements in accuracy and efficiency of the optimization process are therefore important steps toward an industrial application of this technique to nondestructive testing and online monitoring. For this purpose, the use of a fast converging numerical model based on spectral collocation has been found to be well suited. Furthermore, we improved the signal-to-noise ratio by utilizing long-time broadband excitation signals for multimodal excitation of Lamb waves. The wavenumber spectrum up to 2.5 MHz is acquired by measurements with a laser-scanning vibrometer. In order to exploit the information contained in high-order modes, we present an algorithm to match the measured data to the calculated modes during the optimization process, leading to higher accuracy of the estimated model parameters. The characterization results are verified by comparison to measurements with a conventional ultrasonic method.
利用传播的兰姆波的色散特性，根据材料常数和厚度来表征各向同性板的特性。通过对数值模型进行反向优化，使其与激光测振仪测量的色散曲线相匹配。这种材料表征方法在最近的研究中受到了关注。因此，提高优化过程的准确性和效率是将该技术应用于无损检测和在线监测的重要步骤。为此，已发现使用基于谱配置的快速收敛数值模型非常合适。此外，我们通过利用长时间宽带激励信号对兰姆波进行多模态激励，提高了信噪比。使用激光扫描测振仪进行测量，获取高达2.5MHz的波数谱。为了利用高阶模态中包含的信息，我们提出了一种算法，在优化过程中将测量数据与计算模态进行匹配，从而提高估计模型参数的准确性。通过与传统超声方法的测量结果进行比较，验证了表征结果。
