Research on the influence law of geomagnetic field on magnetic signals and compensation modeling

Abstract

To study the influence law and mechanism of the geomagnetic field on magnetic signals in the process of magnetic memory testing, the linear scanning detection results of defective specimens with three different initial magnetization strengths (0 A/m, −70 A/m, 105 A/m) along the horizontal and vertical directions in the geomagnetic field ambient are analyzed and discussed. The result shows that the magnetic signals in the defect-free region only change in amplitude with the change of detection angle, and have no effect on the overall shape of the magnetic signal curve; the characteristic parameters Sm and Km of the peaks of the magnetic signals in the defective region show a corresponding relationship with the measurement angle in the horizontal detection. The initial magnetization strength of the specimen itself affects the change rule of the defective characteristic peaks. The mechanism analysis reveals that the extracted magnetic signals are affected by the combination of the geomagnetic field, the induced magnetic field of the specimen itself, and the leakage magnetic field. Finally, aiming at the problem that the geomagnetic field will change the topography of the defect peaks along different detection orientations, a geomagnetic compensation model is proposed for the barrel-shaped equipment when performing circumferential scanning detection, which can reduce the interference of the geomagnetic field aberration on the detection results, to prevent the misjudgment and omission of the specimen’s defect location.