Development of Eddy Current Testing System Using HTS-SQUID on a Hand Cart for Detection of Fatigue Cracks of Steel Plate Used in Expressways

作者：Tsukamoto Akira; Hato Tsunehiro; Adachi Seiji; Oshikubo Yasuo; Tsukada Keiji; Tanabe Keiichi

来源：IEEE Transactions on Applied Superconductivity, 2018, 28(4): 1601505.

DOI：10.1109/TASC.2018.2795614

• HTS-SQUID
• eddy current testing
• fatigue crack
• steel plate
• excitation coil
• current dipole

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.

• 出版日期2018-6