This study evaluates the key factors impacting on multi-mode conversion of microwave when applying microwave NDT to bent pipe inspection. Mathematical derivation demonstrates the dependence of multi- mode conversion due to a bend on three factors: the ratio of bending radius to pipe’s diameter, the bend angle and the frequency normalized with the cut-off frequency of an arbitrary mode. To verify the deducting results, numerical simulations were conducted to evaluate multi-mode conversion of bent pipe adopti...
英字タイトル:
Evaluation of general applicability of microwave NDT to pipes with a bend focusing on mode conversion

This study evaluates the applicability of a nondestructive testing method using microwaves to the long-range inspection of a pipe with a bend. Experimental verifications were performed using four 1 m pipes, with an inner diameter of 23 mm, connected with flanges and a 90-degree bend. The experimental verifications confirmed clear reflections due to artificial wall thinning, simulated by a short pipe with an inner diameter larger than 23 mm, even when the wall thinning was situated directly below the ben...

This paper introduces the recent progress in the development of a microwave nondestructive testing method, aiming at the rapid and long-range inspection of a pipe, in the authors’ group. ...
英字タイトル:
Development of a nondestructive testing method using microwaves to the rapid inspection of pipes

In this study, a new signal-processing method was developed to improve the precision of locating flaw’s position using microwave NDT. The previous processing method is available only for the single-mode microwave, which causes the noise generation in the case that multi-mode microwaves propagate in a metal pipe. In order to reduce the noise, the reflections caused by the propagation of unintended modes were extracted and deducted from the original signal. The result showed the less noise intensity and highe...
英字タイトル:
Precision Improvement of a Method to Predict the Flaw Location on an Inner Surface of a Metal Pipe Using Multiple-mode Microwaves