Research on magnetoelastic coupling model based on magnetic dipole theory

In this paper, a theoretical model of a magnetoelastic coupling magnetic dipole is established to analyse the influence of stress on the magnetic signal in magnetic memory testing. Based on the theory of ferromagnetism, the equivalent field strength under the combined action of stress and the magnetic field is determined and a numerical solution for the stress magnetisation of isotropic ferromagnetic materials under a weak environmental magnetic field is obtained. Based on the assumption of a double rectangular crack in a three-dimensional problem for the magnetic signal, a theoretical analysis model of a magnetoelastic coupling-type magnetic dipole is established. Based on the theory of the magnetoelastic coupling magnetic dipole, the influence factors and rules of the magnetic signal are analysed in detail. The theoretical research shows that the solution based on the theoretical model in this paper can explain some basic experimental phenomena and laws in magnetic memory inspection. The magnetic signal of a defect-free plate shows a 'horseshoe shape'. The length, width and height of the plate will affect Hx but have no effect on Hy . In addition, the lift-off value has a great influence on the magnetic signal of the plate. When the two cracks are a small distance apart, the magnetic signal of the plate is the superposition of the magnetic signals of the two cracks. For plates with cracks, the crack size, spacing, external magnetic field strength and stress will affect the magnetic signal of the plate.