Abstract
We have been developing an HTS-SQUID eddy current testing system using an HTS-SQUID module and external pickup coil made of Bi-2223 tape to investigate the feasibility of nondestructive evaluation of a steel plate paved with asphalt. In this paper, a new excitation coil intended as a current dipole source is designed and evaluated. The current dipole coil can be expected to generate a unidirectional excitation field and exhibit small field decay by distance and, thus, seems suitable for a measurement under a long liftoff condition such as the case for crack detection through an asphalt pavement. It is also found that a strong single peak appears just above a slit hole as a simulated crack by applying the excitation field using a tilted current dipole coil. The developed measurement system was mounted on a hand cart, and successful detection of a 50-mm-long slit hole and its stable operation were demonstrated in a field operation test.
Original language | English |
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Article number | 1601505 |
Journal | IEEE Transactions on Applied Superconductivity |
Volume | 28 |
Issue number | 4 |
DOIs | |
Publication status | Published - Jun 2018 |
Keywords
- HTS-SQUID
- current dipole
- eddy current testing
- excitation coil
- fatigue crack
- steel plate
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Electrical and Electronic Engineering