›› 2015, Vol. 24 ›› Issue (3): 30301-030301.doi: 10.1088/1674-1056/24/3/030301

• GENERAL • 上一篇    下一篇

Inverse problem of pulsed eddy current field of ferromagnetic plates

陈兴乐, 雷银照   

  1. School of Automation Science and Electrical Engineering, Beihang University, Beijing 100191, China
  • 收稿日期:2014-09-20 修回日期:2014-10-14 出版日期:2015-03-05 发布日期:2015-03-05
  • 基金资助:
    Project supported by the National Defense Basic Technology Research Program of China (Grant No. Z132013T001).

Inverse problem of pulsed eddy current field of ferromagnetic plates

Chen Xing-Le (陈兴乐), Lei Yin-Zhao (雷银照)   

  1. School of Automation Science and Electrical Engineering, Beihang University, Beijing 100191, China
  • Received:2014-09-20 Revised:2014-10-14 Online:2015-03-05 Published:2015-03-05
  • Contact: Chen Xing-Le E-mail:chenxingle@yeah.net
  • Supported by:
    Project supported by the National Defense Basic Technology Research Program of China (Grant No. Z132013T001).

摘要: To determine the wall thickness, conductivity and permeability of a ferromagnetic plate, an inverse problem is established with measured values and calculated values of time-domain induced voltage in pulsed eddy current testing on the plate. From time-domain analytical expressions of the partial derivatives of induced voltage with respect to parameters, it is deduced that the partial derivatives are approximately linearly dependent. Then the constraints of these parameters are obtained by solving a partial linear differential equation. It is indicated that only the product of conductivity and wall thickness, and the product of relative permeability and wall thickness can be determined accurately through the inverse problem with time-domain induced voltage. In the practical testing, supposing the conductivity of the ferromagnetic plate under test is a fixed value, and then the relative variation of wall thickness between two testing points can be calculated via the ratio of the corresponding inversion results of the product of conductivity and wall thickness. Finally, this method for wall thickness measurement is verified by the experiment results of a carbon steel plate.

关键词: pulsed eddy current electromagnetic field, inverse problem, ferromagnetic plate, wall thickness measurement

Abstract: To determine the wall thickness, conductivity and permeability of a ferromagnetic plate, an inverse problem is established with measured values and calculated values of time-domain induced voltage in pulsed eddy current testing on the plate. From time-domain analytical expressions of the partial derivatives of induced voltage with respect to parameters, it is deduced that the partial derivatives are approximately linearly dependent. Then the constraints of these parameters are obtained by solving a partial linear differential equation. It is indicated that only the product of conductivity and wall thickness, and the product of relative permeability and wall thickness can be determined accurately through the inverse problem with time-domain induced voltage. In the practical testing, supposing the conductivity of the ferromagnetic plate under test is a fixed value, and then the relative variation of wall thickness between two testing points can be calculated via the ratio of the corresponding inversion results of the product of conductivity and wall thickness. Finally, this method for wall thickness measurement is verified by the experiment results of a carbon steel plate.

Key words: pulsed eddy current electromagnetic field, inverse problem, ferromagnetic plate, wall thickness measurement

中图分类号:  (Classical electromagnetism, Maxwell equations)

  • 03.50.De
02.30.Zz (Inverse problems) 81.70.Ex (Nondestructive testing: electromagnetic testing, eddy-current testing) 41.20.-q (Applied classical electromagnetism)