A comparative study between magnetic field distortion and magnetic flux leakage techniques for surface defect shape reconstruction in steel plates

• Published in: Sensors and actuators. A. Physical. Vol. 288; pp. 10 - 20
• Main Authors: Zhang, Jiaying, Liu, Xiucheng, Xiao, Junwu, Yang, Zekun, Wu, Bin, He, Cunfu
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 01.04.2019; Elsevier BV
• Subjects: Comparative studies; Defect shape reconstruction; Defects; Distortion; Ferromagnetism; Finite element analysis; Finite element method; Leakage; Magnetic field distortion; Magnetic fields; Magnetic flux; Magnetic flux leakage; Magnetic scanning imaging; Measuring instruments; Performance evaluation; Reconstruction; Scanners; Scanning; Sizing; Steel plates; Surface defects; Magnetic flux leakage; Defect shape reconstruction; Magnetic field distortion; Magnetic scanning imaging
• ISSN: 0924-4247; 1873-3069
• DOI: 10.1016/j.sna.2019.01.019

Fig. 10 Shape reconstruction of ESD. (a) and (d) are based on normal components of MFL method. (b) and (e) are based on tangential components of MFL method. (c) and (f) are based on MFD method. [Display omitted] •MFD technique cannot detect the subsurface defect in ferromagnetic material.•Precise shape reconstruction of an 8-shaped defect was achieved by MFD.•MFL imaging results have poor performances on defect shape reconstruction. Both magnetic flux leakage (MFL) and magnetic field distortion (MFD) techniques are promising methods for surface defect detection in ferromagnetic components. The two techniques are based on different physical principles. However, their defect sizing and shape reconstruction abilities are seldom comparatively explored. In this study, finite element simulations and experiments were performed to achieve magnetic scanning imaging of a defective plate with both MFD and MFL techniques. First, the curves of voltage extracted from the lines crossing the center of cylindrical-hole defect (CHD) were used to evaluate the performance of several feature parameters in sizing the diameter and the depth of CHD. Second, the profiles of the normalized magnetic scanning imaging results were analyzed with a threshold plane to evaluate the abilities of MFD and MFL on reconstructing the shape of 8-shaped and cross-type through wall defects. Under the condition that the Hall device for measuring both the normal component of MFL and MFD has same lift-off distance as 1 mm, the MFD technique showed the advantages in defect shape reconstruction at the cost of available detection depth as compared with MFL techniques.