I was really surprised that I got the decision letter of acceptance from NDT E International only two days later than the acceptance of another submission from IJAEM. What a nice week!
Crack is a common defect in pipe system. Our previous study on detecting cracks using microwaves only considered the penetrating slit with large width. This is different from the real cracks with extremely small width. As real cracks to be detected usually do not penetrate pipe walls, evaluating their penetration effects on microwave NDT signals is necessary.
This study investigated the effect of crack size parameters on the microwaves’ reflection by both simulations and experiments. The feasibility of microwaves to detect narrow circumferential and axial cracks was discussed using experimental results. In addition, the influence of pipe wall penetration was also studied in experiments.
Title: Evaluation of the applicability of microwave nondestructive testing to crack detection on a pipe inner surface (マイクロ波非破壊検査法の配管内面割れへの適用性評価）
Abstract: This study explores the applicability of microwave nondestructive testing to detecting a metal pipe’s inner crack. Three-dimensional finite element simulations were conducted to study the inspectability of cracks using microwaves in different modes and the dependency of the reflection characteristics of microwaves on crack size. The simulation results showed that microwaves in the TM01 and TE01 modes can detect circumferential and axial cracks, respectively. The positive relationship between crack size and intensity corresponding to the reflected microwaves was obtained in simulations and then verified by experiments. In both simulations and experiments, the axial crack length showed a small influence on the results, especially for shallow crack detection. In the experiments, circumferential and axial cracks with a width of 0.3 mm were detected using microwaves. The experimental results revealed that signal amplitudes decreased when a slit penetrated a pipe wall, probably due to a microwave leakage.