Experimental investigation on bend-region crack detection using TE₁₁ mode microwaves

ABSTRACT

This study experimentally investigates the efficacy of TE₁₁ mode microwaves in detecting bend-region cracks. Three types of bends with different dimensions were deployed in a 3 m piping system and then tested, with an axial or circumferential slit machined at different angular positions to simulate a crack. The TE₁₁ mode microwaves were excited using self-designed TE₁₁ mode microwave probes and utilised for crack detection. The experimental results show clear reflection peaks at the bend position, demonstrating the feasibility of applying TE₁₁ mode microwaves in the detection of bend-region cracks. Furthermore, the peak location of reflection is in accordance with the angular position of the slit. The findings also indicate that the peak amplitude of reflection is affected by the factors of mode conversion of microwaves at a bend. In addition, the experimental results also manifest an excellent signal-to-noise ratio to both two types of slits, suggesting that the microwave NDT is a powerful tool for bend-region inspection.

KEYWORDS:

• Non-destructive testing (NDT)
• metal pipe
• mode conversion
• bend
• microwave probe

Acknowledgements

This study was partially supported by the Grant-in-Aid for JSPS fellows (No. 18J20649). The authors would like to thank Mr. Takao Nagaya, who is affiliated with the School of Engineering of Tohoku University, for his assistance in the mechanical fabrication. The first author is supported by the China Scholarship Council (CSC).

Disclosure statement

The authors have no potential conflicts of interest to disclose.

Additional information

Funding

This work was supported by the Japan Society for the Promotion of Science [18J20649].