Modeling and analysis of magnetic dipoles in weak magnetic field

Abstract

The magnetic leakage field distribution resulting from linear defects of a tube sample in the geomagnetic field is modeled according to the magnetic dipole theory. The formula to compute the normal component of the weak magnetic field is deduced based on the spatial distribution of the magnetic dipole. The shape and characteristics of the zero line (an important criterion for magnetic memory testing) of the normal field is analyzed under different longitudinal magnetizations. Results show that the characteristics of the zero line should be considered when the metal magnetic memory testing method is used to find and locate the defect.

References

1. Anatoli A Doubov. Diagnostics of metal itemsand equipment by means of metal magnetic memoryIn: Proceedings of CHSNDT 7th Conference on NDT and International ResearchSymposiumChinaNon-Destructive Testing Institution. Chinese MechanicalEngineering Society 1999 181187
2. Doubov A A Screeningof weld quality using the magnetic metal memorWelding in the World 1998 41(3)196199
3. Zhang Weimin Dong Shaoping Zhang Zhijing State-of-the-art of metal magnetic memory testing techniqueChina Mechanical Eengineering 2003 10(14)892896(in Chinese)
4. Wan Defu Ma Xinglong Magnetic PhysicsBeijingPublishingHouse of Electronics Industry 1999 (inpress)
5. Zhong Weichang Magneticdipole and magnetic particle inspection-principle of magneticparticle inspectionNondestructive Testing 1990 12(3)6670(in Chinese)
6. Zhong Weichang Why the model of magnetic dipole, but not the model of magnetic domainis used for the research on magnetic testing principleNondestructive Testing 2006 28(2)9495(in Chinese)