Wilcox Paul D, Lowe Michael J S, Cawley Peter
Department of Mechanical Engineering, University of Bristol, Bristol, BS8 1TR, UK.
IEEE Trans Ultrason Ferroelectr Freq Control. 2005 Dec;52(12):2370-83. doi: 10.1109/tuffc.2005.1563281.
Planar coil electromagnetic acoustic transducers (EMATs) are investigated for the excitation and detection of Lamb waves in nonferromagnetic metallic wave-guides. Such EMATs are attractive for certain applications due to their omni-directional sensitivity to wave modes with predominantly in-plane surface displacement, such as the So Lamb wave mode. A model is developed that enables the modal content of the radiated Lamb wave field from a transmitting EMAT to be calculated, and the output voltage from a receiving EMAT to be predicted when a Lamb wave mode is incident on it. The predictions from this model are compared with experimental data obtained from 12 different EMATs tested on a 5-mm thick aluminum plate, and good agreement is obtained. The model then is used to analyze the different effects that contribute to the overall Lamb wave modal sensitivity of an EMAT. The relationship between coil geometry and wavelength is examined.
研究了平面线圈电磁超声换能器（EMAT）用于非铁磁金属波导中兰姆波的激发和检测。这种EMAT对于某些应用具有吸引力，因为它们对主要具有面内表面位移的波模式具有全向灵敏度，例如So兰姆波模式。开发了一个模型，该模型能够计算发射EMAT辐射的兰姆波场的模态内容，并预测当兰姆波模式入射到接收EMAT上时其输出电压。将该模型的预测结果与在5毫米厚铝板上测试的12个不同EMAT获得的实验数据进行比较，得到了良好的一致性。然后使用该模型分析对EMAT整体兰姆波模态灵敏度有贡献的不同影响。研究了线圈几何形状与波长之间的关系。
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