Measurements of intrinsic magnetic properties of materials from surface inspection (abstract)
- Ames Laboratory, Department of Electrical and Computer Engineering, and Center for NDE, Iowa State University, Ames, Iowa 50011 (United States)
Surface inspection of magnetic properties with a sensor is a useful and practical technique because it gives a rapid and noninvasive measurement and requires minimum material preparation. However, this technique is handicapped by the practical problems of calculating inherent magnetic properties of the material from such a measurement. A transfer function based on the first approximation was developed previously and it worked well when the dimension of the sample was comparable with the inspection head. However, the nonuniform distribution of the magnetic field is an inherent problem and gets more serious when the vertical and lateral dimensions of the test material become comparable with the pole length of inspection head. Therefore, it invalidates the application of first approximation. A more general and practical transfer function is derived in this paper, including the geometry effects of inspection head and test material. This transfer function is based on the surface magnetic charge model and fits well in the situation when the test material has a large dimension. Test results on specimens by direct measurement and measurement from surface inspection will be presented.
- OSTI ID:
- 7071981
- Journal Information:
- Journal of Applied Physics; (United States), Vol. 75:10; ISSN 0021-8979
- Country of Publication:
- United States
- Language:
- English
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