Affiliations: [a] Research Center for IT-based Real Time NDT, Chosun University, Gwangju 61452, Korea | [b] Department of Control and Instrumentation Engineering, Graduate School of Chosun University, Gwangju 61452, Korea
Correspondence:
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Corresponding author: Jinyi Lee, Research Center for IT-based Real Time NDT, Chosun University, Gwangju 61452, Korea. Tel.: +82 62 230 7101; E-mail: jinyilee@chosun.ac.kr.
Abstract: This paper presents a nondestructive testing method for bleed air duct tubes in aging aircrafts. The inspection technique is based on eddy current testing. The sensor probe is constructed of a bobbin coil as a magnetic source and a bobbin-type integrated Hall sensor (BIHaS) array to measure the electromagnetic field distribution around cracks on the bleed air duct tube. The BIHaS has many Hall sensor elements arrayed in a circumference that can measure the radial component of the electromagnetic field with high spatial resolution. For example, 45 Hall sensor elements were used for inspection of a bleed air duct tube having an inner diameter of 38 mm. To verify the effectiveness of the proposed system, tests were carried out on artificial cracks in bleed air duct tubes. The system was able to inspect 3 mm long cracks and their length was quantitatively evaluated with 1.57 mm of standard deviation.
Keywords: Control rod, encircling coil, eddy current, sensor array, small-bore piping system, magnetic camera, imaging
