Thin-skin AC field in anisotropic rectangular bar and ACPD stress measurement

K. Chen, F.P. Brennan, W.D. Dover

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)


This paper presents some theoretical and experimental studies on the magnetostrictive anisotropy (stress-induced anisotropy) in a long rectangular steel bar that were recently conducted at the University College London. In order to obtain the thin-skin field in the anisotropic bar, the validity of the general boundary conditions at the interface between the conductor and the exterior (air), which were established in earlier studies for isotropic media, were firstly examined. The thin-skin field solution of Zhou and Lewis for the isotropic bar was then extended to include magnetic anisotropy. Using the extended thin-skin field solution, an electromagnetic stress model has been presented by relating the stress level to a quantity that can be used as a measure of the amount of magnetic anisotropy in the material. For the application of this model, experimental stress measurements on mild steel rectangular bars with different dimensions were conducted based on the Alternating Current Potential Difference (ACPD) technique. The ACPD stress measurement results showed that the theoretical stress model could predict the stress values with the calibration of a magnetic anisotropic parameter.

Original languageEnglish
Pages (from-to)317-323
Number of pages7
JournalNDT and E International
Issue number5
Early online date6 Apr 2000
Publication statusPublished - 31 Jul 2000


  • magnetostrictive anisotropy
  • uniform AC field
  • electromagnetic stress model
  • ACPD stress measurement
  • rectangular mild steel bar


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