Detection of cracks with arbitrary orientations in a metal pipe using linearly-polarized circular TE11 mode microwaves
Detection of cracks with arbitrary orientations in a metal pipe using linearly-polarized circular TE11 mode microwaves
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DOI：
10.1016/j.ndteint.2019.102125
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发表时间：
2019-10-01
影响因子：
4.2
通讯作者：
Hashizume, Hidetoshi
中科院分区：
文献类型：
--
作者：
Chen, Guanren;Katagiri, Takuya;Hashizume, Hidetoshi
这项研究提出了一种利用线偏振圆TE11模微波进行长距离无损检测的方法，能够快速检测金属管内表面的轴向和周向裂纹。根据TE_(11)模微波在管道内表面产生的电流讨论了TE_(11)模微波在裂纹检测中的适用性。在对弯曲引起的模式转换进行理论和数值分析的基础上，设计了一种双弯曲结构模式转换器，用于在具有一定内径的管内传输线偏振TE11模微波。该模式转换器的工作带宽为3.5 GHz，TE11模的转换效率超过90%。采用内径23 mm、全长7m的不锈钢管道进行了实验验证，并引入了一条轴向和一周向缝隙来模拟裂纹。实验结果证实了轴向和周向狭缝的反射，表明TE_(11)模微波可用于裂纹检测。结果还证实了TE11模偏振度与其对沿周向不同取向狭缝的探测灵敏度之间的相关性。此外，通过正交布置模式转换器将TE11模的偏振改变90度，成功地检测出位于不同纵向和周向位置的管内轴向和周向狭缝。
This study proposed a long-range non-destructive pipe inspection approach using linearly-polarized circular TE11 mode microwaves, enabling rapid detection of both axial and circumferential cracks on the inner surface of a metallic pipe. The applicability of the TE11 mode microwaves for crack detection was discussed in the light of the currents induced on the inner surface of a pipe due to the propagation of the TE11 mode microwaves. A dual bend structured mode converter was designed to propagate linearly-polarized TE11 mode microwaves inside a pipe with a certain inner diameter, based on the theoretical and numerical analysis of mode conversion due to a bend. A 3.5 GHz working bandwidth of the mode converter was achieved with a conversion efficiency of the TE11 mode of over 90%. Experimental verification was conducted using stainless-steel pipes with an inner diameter of 23 mm and a total length of 7 m. An axial and a circumferential slit were introduced to simulate cracks. The experimental results confirmed reflections from both the axial and circumferential slits, indicating that the TE11 mode microwaves are applicable to crack detection. The results also confirmed the correlation between TE11 mode polarization and its detection sensitivity toward slits with different orientations along the circumferential direction. Furthermore, the axial and circumferential slits situated at different longitudinal and circumferential locations in the pipe were successfully detected by orthogonally deploying the mode converter to change the polarization of the TE11 mode by 90 degrees.