Electromagnetic waves in the microwave and millimeter-wave frequency range are used in non-destructive testing and structural health monitoring applications to detect material defects such as delaminations, cracks, or inclusions. This work presents a sensing concept based on guided electromagnetic waves (GEW), in which the waveguide forms a union with the structure to be inspected. Exploiting ultra-wideband signals a surface defect in the area under the waveguide can be detected and accurately localized. This paper presents numerical and experimental GEW results for a straight waveguide focusing on the detection of through holes and cracks with different orientation. It was found that the numerical model qualitatively replicates the experimental S-parameter measurements for holes of different diameters. A parametric numerical study indicates that the crack parameters such as its orientation and width has a significant influence on the interaction of the incident wave with the structural defect. On top, a numerical study is performed for complex-shaped rectangular waveguides including several waveguide bends. Besides a successful damage detection, the damage position can also be precisely determined with a maximum localization error of less than 3%.

中文翻译：

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用于金属板损伤检测和定位的引导电磁波：数值和实验结果

微波和毫米波频率范围内的电磁波用于无损检测和结构健康监测应用，以检测分层、裂纹或夹杂物等材料缺陷。这项工作提出了一种基于导电磁波 (GEW) 的传感概念，其中波导与要检查的结构形成一个联合体。利用超宽带信号，可以检测并准确定位波导下方区域的表面缺陷。本文介绍了直波导的数值和实验 GEW 结果，重点是检测不同方向的通孔和裂纹。发现数值模型定性地复制了实验小号- 不同直径孔的参数测量。参数数值研究表明，裂纹的方向和宽度等参数对入射波与结构缺陷的相互作用有显着影响。最重要的是，对包括几个波导弯曲的复杂形状的矩形波导进行了数值研究。除了成功检测损伤外，还可以精确确定损伤位置，最大定位误差小于 3%。