Localization of notches with Lamb waves.
Localization of notches with Lamb waves.
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用兰姆波定位凹口。
DOI：
10.1121/1.1593058
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发表时间：
2003
影响因子：
2.4
通讯作者：
L. Jacobs
中科院分区：
文献类型：
--
作者：
Rüdiger Benz;M. Niethammer;S. Hurlebaus;L. Jacobs
利用时频表示(TFR)分析了多模频散兰姆波与凹口的相互作用，并作为相关技术定位凹口的基础。该实验程序使用一个激光光源和一个双探头激光干涉仪来产生和检测缺口平板中的兰姆波。激光超声的高保真、宽频带、点状和非接触的特性是这项研究成功的关键，这使得在实验上测量瞬时兰姆波成为可能，而没有任何频率偏差。用一种特殊的TFR--重新分配的谱图来解析板的各个模式的色散曲线，然后由重新分配的谱图计算出板的慢度-频率表示(SFR)。通过将陷波视为附加(第二)源，使用SFR自动识别每个Lamb模式的反射和传输贡献。然后，这些结果被用来发展对入射兰姆波与缺口的相互作用的定量理解，从而帮助识别模式转换。最后，基于对兰姆波散射的理解，发展了两种互补的自动定位技术。
A time-frequency representation (TFR) is used to analyze the interaction of a multimode and dispersive Lamb wave with a notch, and then serves as the basis for a correlation technique to locate the notch. The experimental procedure uses a laser source and a dual-probe laser interferometer to generate and detect Lamb waves in a notched plate. The high fidelity, broad-bandwidth, point-like and noncontact nature of laser ultrasonics are critical to the success of this study, making it possible to experimentally measure transient Lamb waves without any frequency biases. A specific TFR, the reassigned spectrogram, is used to resolve the dispersion curves of the individual modes of the plate, and then the slowness-frequency representation (SFR) of the plate is calculated from this reassigned spectrogram. By considering the notch to be an additional (second) source, the reflected and transmitted contributions of each Lamb mode are automatically identified using the SFRs. These results are then used to develop a quantitative understanding of the interaction of an incident Lamb wave with a notch, helping to identify mode conversion. Finally, two complementary, automated localization techniques are developed based on this understanding of scattering of Lamb waves.