Preisach Hysteresis Research Articles

Moving vector Preisach hysteresis model and δM curves

The /spl delta/M curves predicted by the vector Preisach model are analyzed and proved to always be negative. A mean interaction field parallel to the magnetization is added to the model so as to reproduce the positive /spl delta/M curve of barium ferrite particulate media. By using this model in self consistent field computation, the typical overwrite behavior of barium ferrite has been reproduced. Calculated dc-erasure has been found to be more efficient than ac-erasure, which is consistent with experimental results.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Description of magnetic interactions and Henkel plots by the Preisach hysteresis model

The ability of the scalar Preisach model (PM) to describe magnetic interactions and Henkel plots is discussed. It is shown that the random interactions described by the PM switching field distribution p(/spl alpha/,/spl beta/) always have a net demagnetizing-like effect on remanences. The connection between the properties of p(/spl alpha/,/spl beta/) and those of Henkel plots is investigated. In particular, it is shown that, when p(/spl alpha/,/spl beta/)=f(/spl alpha/)f(/spl minus//spl beta/), the remanence law i/sub d//i/sub /spl infin//=1/spl minus/2/spl radic/i/sub r//i/sub /spl infin//, completely independent of f(/spl alpha/), holds. The joint presence of random interactions and mean-field effects is dealt with through the moving PM (MPM), in which an additional field proportional to magnetization acts on each PM elementary loop. The classification of Henkel plots by MPM is discussed. In particular, it is shown that Henkel plots exhibiting both magnetizing-like and demagnetizing-like deviations are a certain indication of the joint presence of random interactions and magnetizing-like mean-field effects. Theoretical predictions are compared with recent Henkel plot measurements on magnetic recording media, superconductors, thin films, hard magnets, and soft magnetic materials.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Periodic solutions of the stefan problem with hysteresis-type boundary conditions

We consider the Stefan problem with Dirichlet boundary conditions depending on a hysteresis functional where the free boundary is involved. We show existence of a positive valueT and existence of aT-periodic solution of the problem, provided the Stefan number is sufficiently small and the hysteresis functional is described by the elementary rectangular hysteresis loop. If in addition the Preisach hysteresis operator is Lipschitz-continuous we prove that every periodic solution must be stationary.

Hybrid boundary-volume Galerkin’s method for solution of magnetostatic problems with hysteresis

This article describes a method for the solution of magnetostatic problems with hysteresis. A time-stepping technique is employed to accumulate field history. At each time step, the magnetostatic problem is formulated using a constitutive law determined from the accumulated history and the vector Preisach hysteresis model. The field problem at each time step is reduced to coupled boundary-volume Galerkin’s forms. The finite-element discretization is used in the interior regions, while harmonic basis functions are used in the exterior regions. A globally convergent iterative technique is proposed for the solution of discretized hybrid boundary-volume Galerkin’s forms. The solution method is illustrated on 2D magnetostatic problems.

Dynamic generalization of the scalar Preisach model of hysteresis

A dynamic generalization of the Preisach hysteresis model is proposed, in which the rate of change of the flux associated with each elementary Preisach loops is not infinite, as in the standard Preisach model, but proportional to the difference between the external field and the loop threshold fields. With this assumption, the shape of the elementary Preisach loops, as well as of the macroscopic hysteresis loops, becomes dependent on the magnetizing frequency f. In particular, it is found that the loop area follows a law of the form C/sub 0/+C/sub 1/ square root f. The model is well suited to applications in the field of power loss calculations in soft magnetic materials.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Physical interpretation of induction and frequency dependence of power losses in soft magnetic materials

A loss model based on a dynamic generalization of the Preisach hysteresis model, in which the standard Preisach algorithm is coupled to an equation for the rate of change of the flux associated with each elementary Preisach loop, is presented. The model is able to predict loss features not explained by previous treatments and provides a general interpretative frame for the study of the connection between power losses and microstructure of soft magnetic materials.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Application of a stress-dependent magnetic Preisach hysteresis model on a simulation model for Terfenol-D

A previously reported simulation model for the highly magnetorestrictive material. Terfenol-D has been extended by implementation of the recently developed stress-dependent magnetic Preisach hysteresis model. The model is based on static measurements of material characteristics combined with equations for the dynamic mechanical and magnetic behavior of the material. As a test of the model the authors have simulated the behavior of a Terfenol-D rod for different load conditions. The results show that the model is able to describe the influence of nonlinearities, eddy currents, and hysteresis on the magnetomechanical transduction process of magnetorestrictive materials.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Computation of Fields in Electromagnetic Systems with Hysteresis

ABSTRACT A quasi-finite element method for calculation of static fields in media with hysteresis is presented in this paper. The proposed method utilizes vector Preisach hysteresis model to describe the material behavior. Time-stepping technique is employed in which the evolution of the electromagnetic system is traced to compute the field history as well as the current value of the field self-consistently. At every step in this technique a boundary value problem is solved by using coupled boundary-volume Galerkin's forms. In this formulation, the solution within the material medium is approximated in terms of finite element basis funtions, while the solution outside the material medium is approximated in terms of harmonic functions. An iterative technique for the solution of the resulting set of nonlinear equations is described. The proposed method is demonstrated on two dimensional electrostatic problems.

Generalization of the vector Preisach hysteresis model

A generalization of the vector Preisach hysteresis model is proposed. This new vector hysteresis model represents a larger class of hysteresis nonlinearities than either the Stoner-Wohlfarth model or the previously developed vector Preisach model. To demonstrate this fact, it will be shown that the Stoner-Wohlfarth model and earlier vector Preisach models are particular cases of the generalized vector Preisach model and can be obtained by specific choices of parameters in the new model.

Preisach model with stochastic input as a model for viscosity

The viscosity phenomenon in hysteretic systems has been traditionally studied by using thermal activation-type models. In this paper, a new approach to viscosity modeling is explored. This approach is based upon the use of the Preisach hysteresis models driven by stochastic inputs. First, the scalar case is discussed, and the obtained results are compared with thermal activation-type models and with some known experimental facts. The paper is concluded by the discussion of the vector models for viscosity.

Superconducting hysteresis and the Preisach model

It is suggested to use the Preisach hysteresis model for the description of superconducting hysteresis. It is shown that the Bean (critical state) model and its further generalizations are very particular cases of the Preisach model. It is also shown that noncyclic hysteresis losses in superconductors can be evaluated by using the Preisach model and experimentally measured first-order transition curves.

Generalized Preisach model of hysteresis — theory and experiment

A new approach to the Preisach hysteresis model is presented. Special attention is focused on the analytical expression of the model function. α-Fe2O3 natural sample is used to demonstrate the model, and the latest findings in the problem of the stability of the Preisach diagram are discussed.

A least squares method for finding the preisach hysteresis operator from measurements

A finite element like least squares method is introduced for determining the density function in the Preisach hysteresis model from overdeterined measured data. It is shown that the least squares error depends on the quality of the data and the best approximations to the analytic density. For consistent data criteria are given for convergence of the approximate density and Preisach operator with increasing measurements.

Comparison of the classical and generalized Preisach hysteresis models with experiments

The authors describe the experimental testing of the accuracy of the classical and generalized (nonlinear) Preisach models of hysteresis. The experiments performed for two typical magnetic tape materials show that both models are about equally accurate when the reversal values of the magnetic field are larger than or equal to coercive field values. However, the generalized Preisach model gives more accurate predictions when the reversal values of the magnetic fields are smaller than the coercive values.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

On Maxwell equations with the Preisach hysteresis operator: The one- dimensional time-periodic case

Energy functionals for the Preisach hysteresis operator are used for proving the existence of weak periodic solutions of the one-dimensional systems of Maxwell equations with hysteresis for not too large right-hand sides. The upper bound for the speed of propagation of waves is independent of the hysteresis operator.

Computation of magnetic field in media with hysteresis

The vector Preisach hysteresis model is employed for the calculation of static magnetic fields in media with hysteresis. A time-stepping technique is used to trace a history of the magnetizing process. At each time step, a magnetization integral equation is employed, and a special technique for the solution of this equation is discussed. Theoretical considerations are illustrated by a numerical example. The attractive features of the model considered are its computational efficiency, ability to describe nonsymmetrical minor hysteresis loops, and the existence of well-developed identification procedures. >

Erasing magnetic recording media

The erasure characteristics of longitudinal magnetic recording media have been explored by correlating measurements and the results of a magnetic recording simulation. The two-dimensional simulation uses the standard self-consistent method with a vector Preisach hysteresis model. Writing NRZI-All-1 patterns with a ferrite head at 1 MHz generates the unerased magnetization pattern. The simulated unerased voltage pulse shapes agree well with experiment. The Fourier harmonics of the readback waveform characterize the recorded signal, and are observed as a function of longitudinally applied dc and decaying ac erase fields. Results from experiment and simulation indicate that dc erase fields, of strength near Hc, enhance even Fourier harmonics of the NRZI waveform by destroying the antisymmetric relationship between successive pulses. The measured superiority of ac erasure is explained by both more rapid approach to demagnetization, and broadening of the transition.

A better scalar Preisach algorithm

A Preisach hysteresis model for the case in which Everett's function, E(H/sub 1/, H/sub 2/), has been defined from measurements of the magnetization change from a turning point H/sub 1/ to the field H/sub 2/. E(H/sub 1/, H/sub 2/) is the integral of the Preisach density function, whose symmetry imposes the relation E(H/sub 1/, H/sub 2/)=E(-H/sub 1/, -H/sub 2/). This is inconsistent with measured first-order curves. The source of the inconsistency is that magnetization changes depend on the state of the medium, not just the most recent turning point as Preisach assumes. A Preisach-like algorithm is proposed that is consistently defined by first-order curves and that predicts magnetization changes based on the state of the medium. The algorithm maintains a turning-point history and predicts closed minor loops, like the traditional model, but also predicts noncongruent minor loops and nonzero initial susceptibility. >

On the integral equation of the vector Preisach hysteresis model

The isotropic vector Preisach model of hysteresis is briefly described and the problem of fitting experimental data by this model is posed in terms of a specific integral equation. A closed form solution to this integral equation is found. The analytical theory is illustrated by a numerical example.

Mathematical models of hysteresis.

A new approach to Preisach's hysteresis model, which emphasizes its phenomenological nature and mathematical generality, is briefly described. Then the theorem which gives the necessary and sufficient conditions for the representation of actual hysteresis nonlinearities by Preisach's model is proven. The significance of this theorem is that it establishes the limits of applicability of this model.