An anisotropic magneto-mechanical model of ferromagnetic materials for the magnetic memory testing method

Abstract

The metal magnetic memory (MMM) method shows great potential in the early damage evaluation of ferromagnetic materials. The MMM signal is affected by the environmental magnetic field because of the magneto-mechanical coupling effect. For instance, the effect of the environmental magnetic field is connected with the angle between the environmental magnetic field and the detected structure, which is referred to as the angle effect. This paper aims to explore the angle effect on the MMM method under the weak magnetic field. An anisotropic nonlinear magneto-mechanical constitutive relationship is proposed based on the magnetic domain theory and the approach law. Compared to the existing model, the present constitutive relationship in this paper can predict the stress-magnetization curve of ferromagnetic materials under the combined action of the loading stress and the environmental magnetic field with different directions. Based on the present constitutive relationship, an anisotropic nonlinear magneto-mechanical model of the MMM method is established, and then the angle effect is discussed in detail. The prediction of the anisotropic nonlinear magneto-mechanical model shows a good agreement with experimental data. The proposed model can clarify the reasons for some complex phenomena of the MMM signal, and thus help in the practical application of the MMM method.