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Shock and Vibration
Volume 2014, Article ID 929341, 8 pages
http://dx.doi.org/10.1155/2014/929341
Research Article

Magnetic Flux Leakage Sensing-Based Steel Cable NDE Technique

1School of Civil, Architectural, and Environmental Engineering, Sungkyunkwan University, Suwon, Gyeonggi 440-746, Republic of Korea
2Department of u-City Design and Engineering, Sungkyunkwan University, Suwon, Gyeonggi 440-746, Republic of Korea
3Department of Civil and Environmental Engineering, Sejong University, Seoul 143-747, Republic of Korea

Received 11 December 2012; Accepted 13 April 2013; Published 8 May 2014

Academic Editor: Gyuhae Park

Copyright © 2014 Seunghee Park et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Nondestructive evaluation (NDE) of steel cables in long span bridges is necessary to prevent structural failure. Thus, an automated cable monitoring system is proposed that uses a suitable NDE technique and a cable-climbing robot. A magnetic flux leakage- (MFL-) based inspection system was applied to monitor the condition of cables. This inspection system measures magnetic flux to detect the local faults (LF) of steel cable. To verify the feasibility of the proposed damage detection technique, an 8-channel MFL sensor head prototype was designed and fabricated. A steel cable bunch specimen with several types of damage was fabricated and scanned by the MFL sensor head to measure the magnetic flux density of the specimen. To interpret the condition of the steel cable, magnetic flux signals were used to determine the locations of the flaws and the levels of damage. Measured signals from the damaged specimen were compared with thresholds that were set for objective decision-making. In addition, the measured magnetic flux signals were visualized as a 3D MFL map for intuitive cable monitoring. Finally, the results were compared with information on actual inflicted damages, to confirm the accuracy and effectiveness of the proposed cable monitoring method.