Wall Thinning Assessment for Ferromagnetic Plate with Pulsed Eddy Current Testing Using Analytical Solution Decoupling Method

The wall-thinning measurement of ferromagnetic plates covered with insulations and claddings is a main challenge in petrochemical and power generation industries. Pulsed eddy current testing (PECT) is considered as a promising method. However, the accuracy is limited due to the interference factors such as lift-off and cladding. In this study, by decoupling analytic solution, a feature only sensitive to plate thickness is proposed. Based on the electromagnetic waves reflection and transmission theory, cladding-induced interference is firstly decoupled from the analytical model. Moreover, by using the first integral mean value theorem, interferences of insulation and the lift-off are decoupled, too. Hence, the method is proposed by calculating Euclidean distances between the normalized detection signal and normalized reference signal as the feature to assess wall thinning. Its effectiveness under various conditions is examined and results show that the proposed feature is only sensitive to the ferromagnetic plate thickness. Finally, the experiment is carried on to verify this method practicable.

MAGNETIZATION AND INHOMOGENEOUS MAGNETOELECTRIC EFFECT IN A NANO-SIZED TWO-LAYER FERROMAGNETIC FILM WITH A COMBINED UNIAXIAL AND CUBIC ANISOTROPY IN LAYERS

A numerical study of the magnetization reversal of a two-layer exchange-coupled ferromagnetic plate of finite dimensions, which has a combined uniaxial anisotropy (of the "easy axis" type for the upper layer and «easy plane» for the lower one) and cubic anisotropy with orientation [111]. It is shown that, in the presence of cubic anisotropy, the ground state of magnetization turns out to be uniform in the plane of the film. However, there is discontinuity at the interface between the film layers. This inhomogeneity can lead to the appearance of electric polarization due to the magnetoelectric effect. The electric polarization vector in this case lies in the plane of the film. Its modulus increases with increasing cubic anisotropy. In addition, with an increase in cubic anisotropy, a hysteresis of electrical polarization is observed.

Nonlinear vibration behavior of a carry current ferromagnetic beam plate under magnetic fields and thermal loads

In order to study the magnetoelastic instability and natural frequency of a ferromagnetic plate under a magnetic field, different magnetic force models are considered. In the present study, considering more realistic assumptions, new equations for the study of the vibrational behavior of ferromagnetic beam plates carrying the electric current in the magnetic field are presented by employing the theory of Eringen and Maxwell relations. Conclusively, the effects of magnetic traction and thermal fields created by electric current and eddy currents are taken into account. The coupled nonlinear differential equations of the system are separated by the Galerkin method and solved numerically. The numerical results are compared with the results in the literature, and the effect of different parameters on the vibration characteristics of the soft ferromagnetic beam plate is investigated. The results show that the components of the force that are created by magnetic tractions, as well as the assumption of thermal couplings, can significantly change the vibrational behavior of the plates. Also, by increasing the intensity of the electric current and the magnetic field, the amplitude of the oscillations of the plate is increased and instability occurs for certain values of these parameters in the system.