Resonance phenomena during reversal magnetization of cylindrical specimens in an inhomogeneous alternating field

Abstract

The physics of magnetic permeability has widely been considered in many textbooks and monographs. They all mainly concern studies of interaction between constant magnetic fields and ferromagnetic materials. However, the interaction between alternating magnetic fields and ferromagnetic materials occurs in practice no less often. This work is devoted to studying the properties of magnetic materials in alternating fields. Cylindrical specimens with a diameter of 8 mm and length of 160 mm have been studied. The specimens were made of different very common steel grades. To study magnetization of cylindrical specimens in a homogeneous field, a specimen is simultaneously magnetized along its whole length, which makes it impossible to study the inertial properties of magnetic materials or magnetic viscosity. Therefore, a scheme that provides magnetization of a specimen in one place and measurements of magnetic permeability in another has been used. In this case, it becomes necessary to carry out measurements in an inhomogeneous field. Furthermore, the magnetizing signal does not act on a measuring coil and is transmitted by means of passing along some path along the studied specimen in order to retain information on the material. A model in which the magnetizing and measuring coils are replaced in turn has been used in the calculations. To solve a direct problem, it is assumed that the signal of a magnetizing turn is given and the signal of a measuring turn should be determined. The inverse problem consists in determination of the components of magnetic permeability at a known signal of a measuring coil that has been experimentally registered. As a result of solution of the inverse problem, the components of complex magnetic permeability can be determined. The scheme of an experimental setup that allows one to measure the complex permeability at a chosen frequency using the corresponding computer program has been considered. The dependence of components of magnetic permeability as a function of the frequency of magnetizing field has been presented. It has been shown that the frequency dependence of magnetic permeability substantially changes with a change in the chemical composition of specimen materials (steel grades).