Spatial Propagation Law of Magnetic Memory Signals Detected by Using Magnetic Tomography Method

Abstract

Magnetic tomography is a new and nondestructive testing technology based on the metal magnetic memory method, which can perform noncontact testing outside a pipeline. To identify the type of defect from the characteristics of the magnetic field signal detected by this method, we performed basic research on the propagation mechanism of a magnetic memory signal outside the pipe. In this paper, a magnetic field model of the stress concentration zone was first discussed based on the magnetic dipole theory. A 3-D formulation of the spatial propagation of the magnetic memory signals detected by the magnetic tomographic method was built, based on the Biot–Savart law and the magnetic vector potential. The reliability of the model was verified by comparing the field testing signal with the model-calculated values. The model can well describe the propagation law of the magnetic memory signal for the stress concentration zone generated on the inner wall of a pipeline.

Keywords

• Magnetic tomographic method
• law of magnetic field propagation
• stress concentration zone
• magnetic anisotropy
• magnetic dipole