Journal of Nondestructive Evaluation

, Volume 12, Issue 4, pp 199–207 | Cite as

Crack detection in conducting materials using SQUID magnetometry

  • Ronald R. Gans
  • R. M. Rose


A highly sensitive multichannel SQUID gradiometer, optimized uniquely for spatial resolution, was used to map in two dimensions the magnetic field perturbations from circular holes and thin slots in conducting plates and strips, respectively. Holes as small as 0.75 mm radius in electrically conducting plates were measured directly using a single channel. Edge slots as short as 0.5 mm long in conducting strips were detected, using a multiple-channel measurement method which eliminated the effects from the edge of the strip and the current leads. Clear magnetic signatures from these simulated cracks were measured using low current densities. Numerical computations of the theoretical field distributions are presented which confirm the experimental results. Calculations indicate that much smaller defects should be detectable with an optimization of test parameters.

Key words

Crack detection NDE SQUID magnetometry magnetic methods current perturbation 


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Copyright information

© Plenum Publishing Corporation 1993

Authors and Affiliations

  • Ronald R. Gans
    • 1
  • R. M. Rose
    • 2
  1. 1.Massachusetts Institute of TechnologyCambridge
  2. 2.Materials Science and EngineeringMassachusetts Institute of TechnologyCambridge

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