Novel NDI by Use of Magneto-Optical Film

For horizontal magnetization to the surface of a specimen, two large magnetic domains occur in the area of a crack due to the detection of the vertical component of the leakage magnetic field using a MO film. This leads to a lower density of the domain walls in the crack area in comparison with the...

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Bibliographic Details
Published inTransactions of the Japan Society of Mechanical Engineers Series A Vol. 64; no. 619; pp. 825 - 830
Main Authors LEE, Jinyi, SHOJI, Tetsuo, MINKOV, Dorian, ISHIHARA, Michiaki
Format Journal Article
LanguageJapanese
Published The Japan Society of Mechanical Engineers 1998
Subjects
Defect Detection
Domain Wall
Image Processing
Laser
Magneto-optical Film
Nondestructive Inspection
Notch
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Summary:For horizontal magnetization to the surface of a specimen, two large magnetic domains occur in the area of a crack due to the detection of the vertical component of the leakage magnetic field using a MO film. This leads to a lower density of the domain walls in the crack area in comparison with the no crack area. Considering that the intensity of the incident or the reflected light is affected when it passes through a domain wall, the optical permeability changes in the area of the crack. The use of a laser as a light source allows to perform a remote sensing by detecting of a brighter area corresponding to a crack and a darker area corresponding to its surroundings which is based on the behavior of the optical permeability. This paper introduces a novel NDI method using a MO film and a laser, which allows to detect cracks far away from the specimen. The method utilizes AC and DC magnetization and variation of the domain wall density and optical permeability inside the MO film.
ISSN:0387-5008
1884-8338
DOI:10.1299/kikaia.64.825