Detection of small cracks using high-Tc SQUIDs in an unshielded environment

J. T. Jeng, H. E. Horng, H. C. Yang

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

In this study, we utilized high-Tc rf SQUIDs to detect microcracks in metallic samples in an unshielded environment. The environmental noise in the SQUID was suppressed by using a first-order electronic gradiometer. The samples under investigation were excited by ac magnetic fields applied by a differential excitation coil. A technique utilizing the differential defect field was adopted to analyse the defect field from the crack. It was found that the crack is detectable for the crack width down to micrometres. In addition, the defect field is not a function of the crack width when it is much less than the size of the excitation coil. Finally, the SQUID nondestructive evaluation (NDE) system that was built was also applied to detect small cracks due to fatigue.

Original languageEnglish
Pages (from-to)416-420
Number of pages5
JournalSuperconductor Science and Technology
Volume15
Issue number3
DOIs
Publication statusPublished - 2002 Mar 1

ASJC Scopus subject areas

  • Ceramics and Composites
  • Condensed Matter Physics
  • Metals and Alloys
  • Electrical and Electronic Engineering
  • Materials Chemistry

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