Atherton Model Research Articles

An Optimized Measurement Method for Magnetic Properties of Permalloy Sheet Under Demagnetization

Generally, a permalloy sheet is applied as the major shielding material for weakening the environmental magnetic field interference in a field of high-precision measurement. The demagnetization for a permalloy sheet determines its shielding performance; therefore, an enhanced method for measuring the magnetic properties under degaussing excitation is proposed in this paper. The excitation apparatus and a feedback control system are designed for regulating the B curve of a permalloy sheet as the desired amplitude and waveform. Furthermore, a method for applying degaussing excitation is proposed and the corresponding measurement approach under such magnetic conditions is investigated. Finally, the dynamic Jiles–Atherton model is combined with a finite element method (FEM) algorithm for applying the tested data to the residual magnetic field calculation of a scaled-down model. The agreement between the calculated and tested remanence distribution indicates that the proposed measurement method is reliable and applicable.

Refinement of the magnetic composite model of type 304 stainless steel by considering misoriented ferromagnetic martensite particles

We improved a magnetic composite model that combines the Jiles−Atherton model and Eshelby’s equivalent inclusion method to consider misoriented martensite particles. The magnetic permeability of type 304 stainless steel were analyzed by using both experimental data on the orientation distribution of type 304 stainless steel specimens and the improved model. We found that the model is able to qualitatively explain the variation of permeability with the orientation angle and orientation distribution, an effect that depends on the direction of the excitation magnetic field.

A nonlinear magneto-thermo-elastic coupled hysteretic constitutive model for magnetostrictive alloys

This paper presents a general hysteretic constitutive law of nonlinear magneto-thermo-elastic coupling for magnetostrictive alloys. The model considered here is thermodynamically motivated and based on the Gibbs free energy function. A nonlinear part of the elastic strain arising from magnetic domain rotation induced by the pre-stress is taken into account. Furthermore, the movement of the domain walls is incorporated to describe hysteresis based on Jiles–Atherton's model. Then a set of closed and analytical expressions of the constitutive law for the magnetostrictive rods and films are obtained, and the parameters appearing in the model can be determined by those measurable experiments in mechanics and physics. Comparing this model with other existing models in this field, the quantitative results show that the relationships obtained here are more effective to describe the effects of the pre-stress or in-plane residual stress and ambient temperature on the magnetization or the magnetostriction hysteresis loops.

Numerical determination of Jiles‐Atherton model parameters

PurposeThe purpose of this paper is to propose a robust method to estimate the parameters of Jiles‐Atherton model of ferromagnetic hysteresis by fitting the model to symmetrical hysteresis loops. The performance of the method is evaluated by both theoretical and experimental data.Design/methodology/approachJiles‐Atherton model with five parameters describes the hysteretic behaviour of ferromagnetic materials. To calculate the model parameters, the most common data displaying the hysteresis features are the hysteresis loops stimulated by symmetrical steady state excitations, e.g. sinusoidal sources. Using the characteristic equations at specific points on these hysteresis loops, the Jiles‐Atherton model parameters can be determined by curve fitting and numerical optimized iteration.FindingsPracticality and robustness were not well considered by the conventional parameter estimation method: the initial curve starting from demagnetization is not always available and a direct iterative algorithm to solve the characteristic equations is sensitive to the initial values of the iteration and the evaluation order of the equations because of two main reasons. The first one is that the basic equation group has non‐unique solutions, which is caused by the nonlinearity of the characteristic equations and the fact that there are more unknown quantities (i.e. five model parameters) than the equations available; the second reason is the multimodal feature of the problem, which means that there are many local minima for the iteration algorithm to be trapped in. So curve fitting around the loop tips is proposed before numerical iteration. The goal is to make the initial values, particularly saturation magnetization Ms, not far away from the desired solution to increase the possibility of converging to a physical result. The optimized iterative method with the enhanced ability to avoid local minima and find global roots is then applied to obtain the model parameters.Originality/valueThe proposed method overcomes the difficulties of the other techniques which assume zero remanence. It is also robust as it is guaranteed to converge to physical solutions. The method can facilitate further development and it formed the preliminary basis of our earlier work, where the variation of the Jiles‐Atherton model parameters with different magnetic field strengths was investigated and applied to the simulation of transformer inrush current.

Evaluation of the parameters of a magnetic hysteresis model

This paper presents a method based on use of a measurement system in order to significantly reduce the time taken and to improve the accuracy in evaluating parameters of the Jiles–Atherton's model of magnetic hysteresis. The steps of the proposed method: (a) data acquisition from the experimental hysteresis loop of the magnetic material under test, (b) evaluation of the model's parameters. In order to highlight the method's effectiveness, the results of experimental tests are also given.

A convenient method to compute parameters of Jiles and Atherton model for ferrite materials

The algorithm for computation of parameters of soft ferrite to simulate it with the Jiles and Atherton model is presented. The algorithm tries to reconstruct initial magnetization curve of the ferrite using very few data taken from catalogue of ferrites. The algorithm is illustrated by parameters extraction for a commercially available ferrites.