The Model of a Surface Flaw and the Calculation of the Topography of Its Magnetic Field for Normal Magnetization by an Alternating Field. A Quasi-Stationary Case

Abstract

A surface flaw model is proposed. The model describes the magnetic field topography Hd for normal magnetization by an alternating field Hω of frequency ω. It is shown that Hd can be presented as two cofactors: one cofactor describes a dependence of the topography on coordinates x, z and parameters of a flaw (depth h, opening width 2b), and another cofactor describes its dependence on the electrophysical properties of a tested material containing the surface flaw (specific conductivity σ, and the relative magnetic susceptibility μ). Transition from the magnetostatic field of a flaw ω = 0 to a quasi-stationary field for magnetization under an alternating field H0s of frequency ω is carried out using the model proposed for the magnetic field of a surface flaw under normal magnetization.