A.A. Adly

Preisach modeling of magnetostrictive hysteresis

Preisach‐type models are suggested for the description of strain hysteresis of magnetostrictive materials. It is pointed out that the strain hysteresis has some peculiar properties in comparison with magnetic hysteresis. These peculiarities of strain hysteresis are discussed in detail along with the identification problem for these models.

Using neural networks in the identification of Preisach-type hysteresis models

The identification process of the classical Preisach-type hysteresis model reduces to the determination of the weight function of elementary hysteresis operators upon which the model is built. It is well known that the classical Preisach model can exactly represent hysteretic nonlinearities which exhibit wiping-out and congruency properties. In that case, the model identification can be analytically and systematically accomplished by using first-order reversal curves. If the congruency property is not exactly valid, the Preisach model can only be used as an approximation. It is possible to improve the model accuracy in this situation by incorporating more appropriate experimental data during the identification stage. However, performing this process using the traditional systematic techniques becomes almost impossible. In this paper, the machinery of neural networks is proposed as a tool to accomplish this identification task. The suggested identification approach has been numerically implemented and carried out for a magnetic tape sample that does not possess the congruency property. A comparison between measured data and model predictions suggests that the proposed identification approach yields more accurate results.

Computation of inrush current forces on transformer windings

Inrush currents are frequently encountered during the switching process of transformers. The purpose of this paper is to present an investigation of forces that appear as a result of inrush currents. While both short circuit and inrush transformer situations might seem identical, they vary significantly from the core magnetization viewpoint. Three-dimensional computations have been carried out on a typical single-phase power transformer using the Hopfield neural network energy minimization technique. Results are given in the paper as well as comparison with short circuit forces.

A new vector Preisach‐type model of hysteresis

New isotropic vector Preisach‐type models of hysteresis are introduced. These new models contain additional unknown functions. This presents the opportunity to incorporate more experimental data in the identification process than in the case of previously suggested vector Preisach models, thus leading to more accurate models. The solution of the identification problem is discussed and some results of experimental testing of these models are reported.

Experimental tests of a magnetostrictive energy harvesting device toward its modeling

This paper deals with a recently proposed device for energy harvesting from environmental vibrations, employing a magnetostrictive material. Even if most of the modeling efforts were focused on a linear approach, more complex and nontrivial phenomena are experimentally observed. A sample of such nontrivial behaviors, suggesting the definition of potentially more effective models, is described and discussed in this paper.

Magnetostriction simulation using anisotropic vector Preisach-type models

Magnetic materials exhibiting gigantic magnetostriction, especially Terfenol, are currently being widely used in fine positioning and active vibration damping devices. By involving accurate magnetostriction models during design stages, precision of such devices may be significantly enhanced. In this paper a straight-forward approach that employs anisotropic vector Preisach-type hysteresis models in simulating field-stress effects on magnetic materials is presented. Formation of the proposed model is given and its identification problem is solved. The presented approach has been numerically implemented and numerous digital computer simulations have been performed for Terfenol material. Sample simulation results as well as comparisons with experimentally observed magnetostriction curves are reported in the paper.

New Preisach‐type models of hysteresis and their experimental testing

New Preisach‐type models of scalar hysteresis are discussed and the results concerning experimental testing of these models are given.

Scaling and data collapse in magnetic viscosity

This article presents experimental evidence for scaling and data collapse in magnetic viscosity. It is demonstrated that, by using appropriate scaling, the “bell-shaped” viscosity coefficient curves observed for different temperatures collapse onto one universal curve. This data collapse reveals a self-similar structure of the viscosity coefficient as a function of two variables: magnetic field and temperature.

Magnetization image reconstruction from magnetic force scanning tunneling microscopy images

The problem of magnetization image reconstruction from magnetic force scanning tunneling microscopy images is discussed. The reconstruction problem is reduced to some convolution‐type integral equations and analytical solutions to these equations are obtained by using the standard Fourier transform technique. The theoretical discussion is illustrated with some numerical examples.

Utilizing Anisotropic Preisach-type Models In The Accurate Simulation Of Magnetostriction

Magnetostriction models are being widely used in the development of fine positioning and active vibration damping devices. This paper presents a new approach for simulating 1-D magnetostriction using 2-D anisotropic Preisach-type models. In this approach, identification of the model takes into account measured flux density versus field and strain versus field curves for different stress values. Consequently, a more accurate magnetostriction model may be obtained. Details of the identification procedure as well as experimental testing of the proposed model are given.