Improvement of the Dipole Model of a Surface Crack

Dorian Minkov, Jinyi Lee, Tetsuo Shoji

Research output: Contribution to specialist publicationArticle

8 Citations (Scopus)


In the frame of the dipole model of a crack, a new analytical expression is derived for the z component of the intensity of the leakage magnetic field in the vicinity of a right angular parallelepiped surface crack, assuming parabolic distribution along the crack depth of the surface density of magnetic charge at the crack walls (m). This allows calculation of the Hall voltage to be measured by a Hall element outside the specimen in the proximity of a crack that is proportional to the intensity of the leakage magnetic field. Measurements of the Hall voltage distribution are done on specimens in different magnetization conditions containing artificial cracks. Regression is performed for the Hall voltage distribution, which allows determination of the parameters of the parabolic depth distribution of m. It is shown that the depth distribution of m should not be considered constant, although this has always been done. Instead, a linear depth distribution of m can be used for accurate description of the Hall voltage distributions measured, while m is always larger at the crack tip with respect to the crack mouth. The performance of DMC for nondestructive testing based on magnetic methods can be improved by taking into account the precise depth distribution of m.

Original languageEnglish
Number of pages6
Specialist publicationMaterials Evaluation
Publication statusPublished - 2000 May
Externally publishedYes


  • Dipole model
  • Hall element
  • Hall voltage
  • Magnetic dipole
  • Magnetic material
  • RMS error
  • Regression
  • Surface crack

ASJC Scopus subject areas

  • Materials Science(all)
  • Mechanics of Materials
  • Mechanical Engineering


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