Jiles-Atherton Theory Research Articles

Magnetic leakage behavior assessment in pipeline stress-concentrated areas using improved force-magnetic coupling model.

Magnetic flux leakage (MFL) technology is remarkable for its capability to detect pipeline geometric deformation and general corrosion defects. However, it cannot characterize the MFL behavior in stress-concentrated areas, thereby greatly challenging the subsequent pipeline maintenance. This study suggests that the MFL characteristics of pipeline in stress-concentrated areas are caused by the combined effect of the face magnetic charge on the deformed end-face and the body magnetic charge of the dislocation stack. In addition, an improved force-magnetic coupling model of the pipeline in stress-concentrated areas is established based on the magnetic dipole model and Jiles-Atherton (J-A) theory. In the verification experiment, the Q235 steel plate is magnetized along the extension direction (axis of the pipeline) through the solenoid coil to obtain the distribution law of the MFL signal in the stress-concentrated area under different excitation intensities. The results show that with the increase in excitation intensity, the deformation of the MFL field signal caused by the end-face of the stress-concentrated area gradually increases to a stable state. Moreover, the internal stress of the MFL field signal generated by the pipe dislocation rapidly increases to a peak value and then decays exponentially to a certain base value. The overall change trend is in good agreement with the calculation results of the established force-magnetic coupling model. Meanwhile, the differentiation research between deformation and internal stress MFL field signals under different magnetic field intensities can provide a reliable theoretical basis for the subsequent accurate identification and quantification of pipeline stress-concentrated areas.

Self-sensing model of low-frequency magnetostrictive composites actuator based on Jiles-Atherton theory

Giant magnetostrictive powder composites (GMPCs) have important applications in electric current sensing, stress sensing, vibration damping, actuation, health monitoring and other fields. Most of the research discussed the actuation or sensing function of GMPCs merely. In this paper, GMPCs based actuator with a self-sensing function is proposed to realize direct measurement of the deformation amplitudes of the actuator in low frequency, through monitoring the voltage signal of the driving circuit. It also means the actuator can be used as a compressive stress and magnetostriction sensor. The self-sensing actuator avoids the dependence on extra sensors for actuation detection, which complements the self-sensing technique in GMPC-based actuators. It is helpful not only in the designing and controlling of self-sensing applications in actuators, but also in expanding the applications of GMPCs in the field of integrated devices.

An improved stress-dependent magnetostriction model of silicon steel based on simplified multi-scale and Jiles–Atherton theory

Due to the magnetic domain movement and energy change under magnetic field and stress applied, the macroscopic magnetic properties and magnetostriction properties of non-oriented (NO) silicon steel are influenced. To present this effect of the magnetic domains’ motion mechanism, a stress-dependent magnetostriction must be modeled. This paper proposes an improved stress-dependent magnetostriction model (I-SDM model) for NO silicon steel based on a simplified multi-scale model. Firstly, the stress-dependent expression of the anhysteretic magnetization, obtained by assuming a six-domain structure and considering the volume fraction of magnetic domain energy, is introduced into the inverse Jiles–Atherton (JA) model. In this way, the stress-dependent hysteresis model is constructed. Then, coupling with the improved quadratic domain rotation model that considers pinning effects, the I-SDM model for NO silicon steel is built. Finally, with the parameters obtained from experimental results, the proposed model under varying stresses is simulated and compared with other models. It shows that the proposed model has the highest simulated accuracy for both λ-H loop and λ-B loop with stress applied.

Low-frequency incremental permeability for the evaluation of deep carburization treatments: Theoretical understanding

Precise evaluation of deep carburization treatments is essential to prevent degradation of high-performance mechanical components. A nondestructive magnetic method called low-frequency incremental permeability testing appears to be particularly suitable for this purpose. This method consists of slowly magnetizing the specimen to be controlled and then superimposing a relatively low-frequency eddy current testing process on the specimen (<2 kHz). The sensor’s coil impedance is monitored along with the magnetization cycle. When plotted versus the magnetic excitation, the impedance produced butterfly-shaped curves that were dependent on the carburization depth. Operating at low frequency increases the scanned layer thickness up to the untreated inner part of the specimen and induces characteristic variations in the butterfly-shaped curves. A model to solve for the indirect relationship between the magnetic properties and the carburization treatment properties is presented in this manuscript. This model combines the Dodd and Deeds analytical expression for a flat sensor coil above a two-layer conductor with Jiles-Atherton theory for consideration of the hysteresis. The magnetic and electromagnetic responses are well considered, providing accurate reconstructions of experimental data. The model predictions reveal magnetic indicators that are highly correlated with the carburization depth and provide optimal conditions for nondestructive testing observation.

Transformer modelling considering power losses using an inverse Jiles-Atherton approach

Power transformers are devices with non-linear behavior due to the saturation of the ferromagnetic core. When modelling such devices, the saturation effect must be taken into account because it greatly affects their performance and efficiency. In this paper, an electromagnetic model for power transformers is proposed and experimentally validated using an electrical T-model coupled with a reluctance network to model the magnetic part. The electrical circuit and the reluctance network are linked by two B–H approaches. The B–H relationships are modelled by the full hysteresis cycle based on the inverse Jiles-Atherton theory and by the initial magnetization curve. The results obtained with the inverse Jiles-Atherton theory model reproduce the magnetic core behavior with more accuracy than the one based on the initial magnetization curve, especially at low load conditions where saturation plays a more prominent role on the no-load current. The proposed model can be applied to other magnetic devices such as inductors for power electronic applications or electromechanical relays, among others.

A transient magneto-mechanical numerical model of a tank based on improved jiles-atherton theory

Magnetic field generated by the ferromagnetic material of underwater detectors varies with seawater pressure, which may affect the accuracy of deep-sea resource exploration. The effect of stress on magnetization is cumulative. In order to accurately simulate the influence of deep-sea pressure on the magnetic field around underwater detectors, it is very important to develop a transient magneto-mechanical numerical model. In this paper, a transient magneto-mechanical coupling model of a tank was developed to obtain the magnetic signal deviation caused by the magneto-mechanical coupling effect. By improving the Jiles-Atherton theory for complex stress and calculating the variation in magnetic field with pressure, the hysteresis effect between magnetization and stress was verified. Under different background magnetic fields, the effect of stress on magnetic field was determined by calculating the magnetic field distribution under different pressures.

Parameter Identification of Displacement Model for Giant Magnetostrictive Actuator Using Differential Evolution Algorithm

Based on Jiles–Atherton theory and the quadratic law, a displacement model for giant magnetostrictive actuators (GMA) has been developed. The Runge–Kutta method is used to solve the nonlinear differential equation of the hysteresis model in a segmented magnetic field. Aiming at the problem that the model parameters are coupled with each other and difficult to estimate, a heuristic intelligent search algorithm-differential evolution algorithm (DE) is employed to implement parameter identification. In order to verify the effectiveness of the algorithm, comparative studies with the genetic algorithm (GA) and the particle swarm optimization (PSO) applied in parameter identification are performed. The simulation results demonstrate that the algorithm has the advantages of requiring few control variables, fast convergence speed, stable identified results, and excellent repeatability. Furthermore, the experimental results demonstrate that the output displacements calculated from the identified model are in great agreement with the measured values. Accordingly, the DE can identify the parameters of a displacement model for giant magnetostrictive actuators with satisfactory accuracy and reliability.

A nonlinear magneto-elastoplastic coupling model based on Jiles–Atherton theory of ferromagnetic materials

As seen in the Jiles–Atherton (J–A) model and its modified form, the linear relationship between the magnetization coefficient and the stress deviates significantly from the experimental results. It is necessary to introduce many parameters that are difficult to obtain or unknown to describe the effect of elastoplastic deformation on magnetization or hysteresis, such as shape coefficient, pinning coefficient, and molecular field coefficient. In this paper, a new nonlinear magneto-elastoplastic model for ferromagnetic materials is established based on the magneto-mechanical coupling effect, and both the sixth-order term of magnetization and the nonlinear equation of the magnetization coefficient are introduced into the magnetostriction equation. In the models established in this paper, the elastoplastic deformation equivalent magnetic field is introduced into the effective magnetic field, and the Frohlich–Kennelly equation is used to describe the anhysteretic magnetization. After comparing the prediction results of different models with the available experimental results, it is observed that the proposed model in this paper exhibits superior prediction ability for magnetostrictive strain, magnetization, and hysteresis phenomena under different stresses. This paper has also analyzed the mechanism of the effect of elasto-plastic loading and residual stress on the hysteresis in different models as well as the differences between them. The determination coefficient of the proposed model in this paper is closer to 1, which is better than the existing models, indicating that it has a better fitting effect and is of great significance to the development of quantitative non-destructive testing technology.

The Research on Anti-DC current Transformer of Dual Iron Core Structure with Air Gap

Current transformer (CT) is wildly used in electrical measurement and relay protection. In order to improve the power system stability in DC bias, the CT performance of anti-DC is necessarily to be enhanced. Based on the Jiles-Atherton theory, the magnetization characteristics of iron core with different air gap was analyzed in this paper. A simulation model was established using the Simulink toolbox, and the ratio error and angle error were investigated in different air gap length. Simulation result shows that the maximum magnetic density of iron core almost stays uncharged with the addition of air gap. Furthermore the slope of magnetization curve decreased, which leads to the increase of iron core saturation current. Current transformer with closed and air gap iron core possesses a stable measurement error in condition of severe DC bias.

DC Bias Characteristics Analysis of CSR of TCT Type in the Thyristor Abnormal Operation State

In order to obtain DC bias characteristics of controlled shunt reactors (CSRs) of thyristor controlled transformer (TCT) type in the thyristor abnormal operation state, a DC bias characteristics analysis model for the CSR based on Jiles-Atherton(J-A) theory is proposed. A single-phase prototype for the CSR is developed and tested. The coil currents and magnetic flux densities of the iron core are calculated in time domain and frequency domain based on the model. The experimental results agree well with the calculated results. The DC bias characteristics of the CSR are analyzed.

Modeling dynamic magnetostriction of amorphous core materials based on Jiles–Atherton theory for finite element simulations

Due to its favorable properties of low core loss and high saturation magnetic flux density, amorphous material is widely used as the core material of low and medium frequency transformers. However, its magnetostriction is much higher than that of grain-oriented sheet steel, a very common material for conventional transformers, resulting in high acoustic noises. This paper proposes a comprehensive model of magnetostriction in amorphous material based on the interdependence between magnetostriction and magnetization by combining the isotropic magnetostriction effect and Jiles-Atherton energy balance theory. Incorporated in coupled magneto-mechanical field calculation, the proposed model can correctly simulate the butterfly loops of magnetostriction, magnetic hysteresis loops and vibration displacements. The theoretical results of magnetostriction characteristic are verified by both single sheet test and the experimental results of amorphous transformer prototype.

Modeling of Magnetic Properties of Magnetorheological Elastomers Using JA Hysteresis Model

Magnetorheological elastomers (MREs) are composite materials that consist of magnetically permeable particles in a nonmagnetic polymeric matrix. Under the influence of an external magnetic field, a reversible deformation change occurs in the mechanical properties of these materials. Due to their coupled magnetomechanical response, these materials have been found suitable for a range of applications including tunable vibration absorbers, sensors, and actuators. Notably, improvement of such devices are prerequisites to efficient energy conversion systems, hence the need to understand further the MRE technology. The Jiles-Atherton (JA) theory takes into consideration the magneto-coupling experienced by effective domains in a magnetic material. Algorithm based on the theory yields five model parameters; saturation magnetization (M <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">s</sub> ), domain density (a), domain coupling (α), loss coefficient (k), and reversibility (c). Using JA theory, model parameters were calculated and linked to the physical attributes of Fe powder and isotropic MRE. The results show that the calculated Ms for the MRE is reasonably related to that of the Fe powder by a factor of the particle's volume fraction used in the MRE. The calculated k, a, and α provided support for the reduced pinning factor, domain density, and increased domain coupling in the MRE due to the changes in the domain structure between the two materials. From the calculated JA parameters, finite-element modeling (FEM) of the MRE hysteresis loop was performed. The analysis showed that the modeled magnetic properties including coercivity, remanence, and coordinates of the hysteresis loop tip vary with geometric position.

An efficient dynamical model of reluctance actuators with flux fringing and magnetic hysteresis

This paper presents an efficient and accurate dynamical model of reluctance actuators, suitable for prediction and control applications. It is a hybrid lumped-parameter state-space model that takes into account the mechanical and electromagnetic dynamics, including eddy currents, flux fringing, magnetic hysteresis and saturation. Special emphasis is placed on the hysteresis model, which is based on the Jiles–Atherton theory. The novel parts of the model – the gap reluctance expression and the modified Jiles–Atherton hysteresis model – are identified, showing that the simulated results fit very well the experimental data. Furthermore, its potential application for control is exemplified with a feedback strategy, in which the design of the controller and observer are based on the proposed dynamical model.

Multiscale modelling of the magnetic Barkhausen noise energy cycles

The magnetic Barkhausen noise (MBN) control is popular for materials characterization and as a magnetic Non-Destructive Testing & Evaluation (NDT & E) method. MBN comes from the erratic and unpredictable magnetic domains motion during the magnetization process. Its correlation to the micro-structural properties is evident. MBN is usually studied through time independent indicators, like the MBNenergy, which is obtained by integrating the square of the MBN voltage signal with respect to the time axis. By plotting the MBN energy as a function of the tangent excitation field H, a hysteresis cycle can be observed. After renormalization, the comparison with the classic induction vs excitation B(H) hysteresis loop provides interesting observations. Similar shapes can be observed if the domain wall contribution is preponderant in the magnetization process. On the contrary, strong differences appear if the magnetization rotation mechanism is stronger. There is no available standard for the exploitation of MBN control devices. Usual procedures rely on rejection thresholds based on empirical relations. In this domain, simulation tools able to refine these thresholds and improve the understanding of the physical behavior are highly desired. In this study, a simulation method combining a multiscale model for the anhysteretic behavior and the Jiles-Atherton theory is proposed to simulate precisely the MBNenergy hysteresis cycles. The use of the multiscale model allows separating the contributions of domain wall motion and magnetization rotation mechanisms. The satisfying simulation results validate the approach and constitute a major step toward a comprehensive simulation tool dedicated to MBN.

A Simulation Model for Narrow Band Gap Ferroelectric Materials

AbstractVarious ferroelectric simulation models have been developed in recent decades in order to study the mechanisms and predict the behaviors of ferroelectrics by simulating their hysteresis loops. Conventional ferroelectrics have wide optical band gaps (&gt;2.7 eV), making them difficult to respond to visible light. Although their ferroelectricity can be affected by higher‐energy radiation like ultraviolet, little attention is paid to the development of their models incorporating light‐dependent factors. However, in recent years, narrow band gap (&lt;2.5 eV) ferroelectrics have been discovered and are increasingly researched. These special ferroelectrics effectively absorb visible light and hence exhibit strongly light‐dependent ferroelectricity, triggering potentially a broad range of applications. Therefore, there is a need to develop a model for these ferroelectrics in order to predict their behavior under visible light. Such a model is also needed to improve the understanding of the interaction mechanisms between light and domains. In this paper, a ferroelectric simulation model based on the Jiles–Atherton theory considering light dependence is developed for the first time, and its accuracy is validated by experiments. The model shows an average error of 7.5% on polarization values compared to experimental results and thus can be employed to reliably predict photo‐induced ferroelectricity.

Research on Ceramic Spindle Loss Based on Ceramic Reverse Magnetic Effect

Ceramic motorized spindle is a multifield, nonlinear, and strong coupling system. The present model ignores the reverse magnetic effect and has a poor accuracy on the loss of the spindle system. In the paper, Park transformation was used to establish the electromagnetic physical model of ceramic motorized spindle. By combining with the Jiles–Atherton theory, an eccentric magnetization model of a ceramic motorized spindle considering reverse magnetic properties was established. Energy consumption parameters were calculated under various working conditions. The influence of ceramic reverse magnetic characteristics on the motorized spindle loss was analyzed and verified by experiments. The results show that the simulation of the ceramic motorized spindle loss model is in good agreement with the experimental results. Compared with the experimental results, the average loss error was 2.1%. Due to the reverse magnetic characteristics, the application of ceramic motorized spindle can help reduce the system loss. The ceramic motorized spindle model provides a theoretical basis for the development of ceramic spindle energy loss and efficiency.

A Dynamic Magnetostriction Model of Grain-Oriented Sheet Steels Based on Becker–Döring Crystal Magnetization Model and Jiles–Atherton Theory of Magnetic Hysteresis

Grain-oriented (GO) sheet steels are widely used as the core material in large power transformers. The strong magnetostriction in GO sheet steels, however, causes undesirable vibrations and acoustic noises, and is difficult to estimate in the design optimization of power transformers. This article proposes a new magnetostriction model of GO sheet steels by combining the Becker-Doring crystal model and the dynamic Jiles-Atherton hysteresis model. Incorporated in the finite-element analysis (FEA), the new model can correctly simulate the butterfly loops of magnetostriction in GO sheet steels. The effectiveness and accuracy of the proposed model are verified by the experimental measurement results on a single sheet sample in a free state with no external stress.

Non-destructive testing on creep degraded 12% Cr-Mo-W-V ferritic test samples using Barkhausen noise

Micro-magnetic non-destructive testing helps in evaluating the mechanical and structural integrity of ferromagnetic components (mostly steel) via local magnetic characterization. As a means of revealing the magnetic domain wall movements, the Barkhausen noise measurement method is a micro-magnetic non-destructive testing method of considerable potential and interest. The Magnetic Barkhausen Noise Energy (MBNenergy) method can be used to reconstruct local hysteresis cycles from Barkhausen noise measurements. These cycles constitute good indicators for understanding the magnetization process and the influence of microstructural and mechanical properties. In this article, the MBNenergy method is employed for evaluating the microstructural changes induced by creep/ageing of high chromium steel subjected to different creep test conditions as stress and temperature. The corresponding magnetic parameters are investigated in relation to precipitations and dislocations. After the experimental analysis, simulations are performed based on the Jiles-Atherton theory for the quasi-static magnetic behavior. This simulation approach yields physically meaningful model parameters that can be analyzed and linked to the sample microstructural characteristics, thereby enabling physical interpretation.

The practical CT transient simulation model based on dynamic tests and its application

AbstractWith the fast development of the modern power system, the current transformer (CT) saturation problem is most serious, causing the measuring error of primary current and the maloperation of protection. This article proposes a CT transient simulation model based on the Jiles–Atherton theory. The key coefficients of the CT model that define the basic magnetizing characteristics are identified based on the practical CT. The dynamic tests are carried out to analyze the saturation characteristics of different CT types, and to verify the accuracy of the CT simulation model. The CT simulation models are then utilized for analyzing two actual maloperation cases. The results prove that the proposed CT simulation model can provide an effective method for analyzing the CT saturation problem. © 2018 Institute of Electrical Engineers of Japan. Published by John Wiley &amp; Sons, Inc.

Modeling plastic deformation effect on the hysteresis loops of ferromagnetic materials based on modified Jiles-Atherton model

Plastic deformation is one of the most important features that affect the hysteresis magnetic properties of steels, because it changes the dislocation density and affects domain-wall movement and pinning. In order to model the effect of plastic deformation on the magnetic properties, the prevailing Jiles-Atherton (J-A) theory is extensively used. However, the J-A models in a series of papers published by Jiles et al. are not completely consistent. As a result, there exists no uniform formula of magneto-plastic model established by different researchers, based on different J-A models, and various versions given by different mathematic expressions of magneto-plastic model often create difficulty in discriminating the accuracies and effectivenesses of the analyzed results. Therefore, it is necessary to establish an accurate and reasonable magneto-plastic model. In this paper, on the basis of magnetization mechanism of ferrimagnet and plastic deformation model, the effects of plastic deformation on the magnetic characteristic parameters adopted in magneto-plastic model, such as dislocation density, pinning coefficient and scaling constant, are analyzed and the relationship between them is first established. Then, by contrasting the fitting formula of the anhysteretic magnetization curve, the energy conservation equation and the effective magnetic field equation established by different researchers, several queries are proposed, and the irrationality and inaccuracy of the existing magneto-plastic model are elucidated, such as the mixing of anhysteresis magnetization and magnetization, the unreasonably regarding the irreversible magnetization energy as actual total magnetization energy. Thus, the energy conservation equation, the effective magnetic field equation and the anhysteretic magnetization equation are modified, and the differential expression of the magneto-plastic model is re-derived finally. Comparing the results calculated by the existing magneto-plastic models with the experimental results, it is seen indeed that a more sharp change of magnetization appears at small plastic deformation, then, the values of magnetization decrease more slowly with the increase of plastic deformation than those from the models respectively proposed by Li Jian-Wei, Leng Jian-Cheng and Wang Zheng-Dao; the saturation magnetization and residual magnetization decrease with the increase of plastic deformation, the coercive force is increased oppositely and the trend to reach the saturation magnetization becomes gentler, which is more exactly consonant with experiment observation than that calculated by the Sablik's model; additionally, the hysteresis loops of the plastically deformed carbon-steel samples calculated by the modified magneto-plastic model are also in better agreement with the experimental results than those from the existing models. Consequently, the modification is effective, and the modified magneto-plastic model is more accurate to simulate the plastic deformation effect on the magnetic property of ferromagnetic material.