Magnetostrictive Deformation Research Articles

Wearable Magnetoelectric Stimulation for Chronic Wound Healing by Electrospun CoFe2O4@CTAB/PVDF Dressings.

Magnetoelectric stimulation is a promising therapy for various disorders due to its high efficacy and safety. To explore its potential in chronic skin wound treatment, we developed a magnetoelectric dressing, CFO@CTAB/PVDF (CCP), by electrospinning cetyltrimethylammonium bromide-modified CoFe2O4 (CFO) particles with polyvinylidene fluoride. Cetyltrimethylammonium bromide (CTAB) serves as a dispersion surfactant for CFO, with its quaternary ammonium cations imparting antibacterial and hydrophilic properties to the dressing. Electrospinning polarizes polyvinylidene fluoride (PVDF) molecules and forms a fibrous membrane with flexibility and breathability. With a wearable electromagnetic induction device, a dynamic magnetic field is established to induce magnetostrictive deformation of CFO nanoparticles. Consequently, a piezoelectric potential is generated on the surface of PVDF nanofibers to enhance the endogenous electrical field in the wound, achieving a cascade coupling of electric-magnetic-mechanical-electric effects. Bacteria and cell cultures show that 2% CTAB effectively balances antibacterial property and fibroblast activity. Under dynamic magnetoelectric stimulation, the CCP dressing demonstrates significant upregulation of TGF-β, FGF, and VEGF, promoting L929 cell adhesion and proliferation. Moreover, it facilitates the healing of diabetic rat skin wounds infected with Staphylococcus aureus within 2 weeks. Histological and molecular biology evaluations confirm the anti-inflammatory effect of CTAB and the accelerated formation of collagen and vessel by electrical stimulation. This work provides insights into the application of magnetoelectric stimulation in the healing of chronic wounds.

Research on the Magnetostrictive Characteristics of Transformers under DC Bias

Direct current (DC) bias leads to increased vibration and noise in transformers. One of the main causes is the magnetostrictive effect of the transformer core. To address this phenomenon of magnetostriction, firstly, a transmission line model (TLM) of a single-phase transformer under DC bias is developed using transmission line theory and Jiles–Atherton (J–A) ferromagnetic hysteresis theory, taking into account the winding copper loss, core eddy current loss, and leakage effect. Secondly, the time-domain simulation of the single-phase transformer based on the Newton–Raphson iterative method is carried out, and the magnetostriction characteristics of the transformer under different DC and its variation law are analyzed. Finally, the results show that the DC bias results in magnetostrictive distortion and vibration acceleration curve distortion, the left and right wings of the magnetostrictive butterfly curve are no longer symmetrical, the slope of the vibration acceleration image increases significantly, and the degree of distortion is positively correlated with the magnitude of the DC. In addition, the peak values of the magnetostrictive deformation and vibration acceleration become larger under DC bias, leading to an increase in the vibration and noise of the transformer. The research object of this paper is the single-phase transformer, and the research method can also be applied to the study of three-phase transformers.

Effect of Al and La Doping on the Structure and Magnetostrictive Properties of Fe73Ga27 Alloy

The changes of microstructure, magnetostriction properties and hardness of the Fe73Ga27-xAlx alloy and (Fe73Ga27-xAlx)99.9La0.1 alloy (x = 0, 0.5, 1.5, 2.5, 3.5, 4.5) were studied by doping Al into the Fe73Ga27 and (Fe73Ga27)99.9La0.1 alloy, respectively. The results show that both the Fe73Ga27-xAlx alloy and (Fe73Ga27-xAlx)99.9La0.1 alloy are dominated by the A2 phase, and the alloy grains are obvious columnar crystals with certain orientations along the water-cooled direction. A proportion of Al atoms replaced Ga atoms, which changed the lattice constant of the alloy, caused lattice distortion, and produced vacancy effects which affected the magnetostriction properties. La atoms were difficult to dissolve in the matrix alloy which made the alloy grains smaller and enhanced the orientation along the (100) direction, resulting in greater magneto-crystalline anisotropy and greater tetragonal distortion, which is conducive to improving the magnetostriction properties. Fe73Ga24.5Al2.5 alloy has a saturation magnetostrictive strain of 74 ppm and a hardness value of 268.064 HV, taking into account the advantages of saturated magnetostrictive strain and high hardness. The maximum saturation magnetostrictive strain of the (Fe73Ga24.5Al2.5)99.9La0.1 alloy is 115 ppm and the hardness is 278.096 HV, indicating that trace La doping can improve the magnetostriction properties and deformation resistance of Fe-Ga alloy, which provides a new design idea for the Fe-Ga alloy, broadening their application in the field of practical production.

A magnetostrictive self-powered biosensor based on Au-BaTiO3-FeGa & PDMS

Piezoelectric flexible sensors have been used to detect biomolecules such as sweat and glucose because of their passive, simple structure and high sensitivity. This paper proposes a novel flexible piezoelectric Au-BaTiO3-FeGa & PDMS biosensor in which magnetostrictive deformation amplifies the surface stress generated by biomolecules combining on the thin film. The modification process of bovine serum albumin (BSA) binding with the sensor was initially determined by the first principles approach. Then, the sensing mechanism was verified by finite-element simulation. Based on the simulation results, flexible Au-BaTiO3-FeGa & PDMS biosensors were prepared, modified, and measured. The structure, modification, and detection of the sensors were analyzed by digital microscopy, Fourier transform infrared spectrometry (FTIR), atomic force microscopy (AFM), and scanning electron microscopy (SEM). The responses of the biosensors detecting different BSA solution concentrations under magnetic fields were then investigated. Experimental results indicate that the biosensor has the highest sensitivity under a magnetic field of 30 mT.

Effect of magnetoelastic interaction on the thermal expansion of the trigonal crystal FeBO3

Iron borate FeBO3 – a trigonal antiferromagnet with weak ferromagnetism – was used as a model object for experimental and theoretical studies of thermal expansion. X-ray diffraction analysis indicated that the character of the thermal expansion changes significantly when passing through the Néel point. In the magnetically ordered state below the phase transition temperature, the thermal changes in the crystal lattice parameters are additionally affected by magnetostrictive deformations. A theoretical model was developed that allows interpreting experimental data and determining the magnetoelastic constants using X-ray diffraction analysis. Temperature dependences of some of the magnetoelastic constants of iron borate were determined, and the hitherto unknown constants were found. These data are essential to describe various phenomena associated with magnetoelastic interactions in magnetically ordered materials.

Strain transfer in ferroelectric-ferrimagnetic magnetoelectric composite

We show that electrically poled ferroelectric matrix considerably enhances the localized magnetostrictive deformations in a ferroelectric-ferrimagnetic composite. Magnetostrain measurements performed on Dy-free and Dy-modified $\mathrm{Bi}\mathrm{Fe}{\mathrm{O}}_{3}\text{\ensuremath{-}}\mathrm{Pb}\mathrm{Ti}{\mathrm{O}}_{3}$ (BF-PT) ferroelectric ceramics revealed no measurable macroscopic strain in poled and unpoled Dy-free nonferromagnetic specimens. Dy-modified BF-PT, on the other hand, exhibit ferrimagnetic dysprosium-iron garnet (DyIG) as precipitates and exhibit a macroscopic strain of \ensuremath{-}4 ppm in the poled state. Despite the small (6%) volume fraction of DyIG, the macroscopic strain in Dy-modified BF-PT is almost 50% of the strain of pure DyIG. Our results suggest that the amplification of the localized magnetostrictive deformation in the ferrimagnetic islands by the neighboring ferroelectric regions is caused by the magnetostrictive stress-induced motion of ferroelectric-ferroelastic domains of the poled ferroelectric matrix.

An improved magnetostriction model of silicon steel considering the saturated magnetic domain wall movement

To obtain the deformation characteristic of silicon steel with yoke clamping applied under an alternating magnetic field, a stress-dependent magnetostriction model of silicon steel must be constructed. Due to the magnetic domain’s rotation and the magnetic domain wall movement with stress applied, the material’s magnetostrictive deformation will reverse and saturate in both magnitude and direction. Therefore, the saturated magnetic domain wall movement effect must be considered in the stress-dependent magnetostriction model. Firstly, a hysteresis stress-dependent magnetostriction model based on the Jiles-Atherton (J-A) model and Zheng-Liu (Z-L) model is proposed. Then, the magnetostrictive deformation curves of the non-oriented silicon steel with external stresses are measured. The magnetic field and deformation parameters that control the saturated magnetic domain wall movement are extracted and applied to the model. Finally, the magnetostrictive loops with the magnetic field under varying stress are obtained based on the proposed model. The proposed model’s effectiveness and accuracy are verified by comparing the measurement results with the simulation results.

Analysis of vibration forces of magnetic origin acting on tank walls of power transformer

The aim of this paper is to present the impact of the leakage flux on magnetic shunts and tank walls of power transformers from vibrational point of view. The experimental studies of the large power transformers show that tank vibrations and the resulting acoustic emission at load condition are significantly higher than at no-load condition. The paper presents 3D finite elements model in electromagnetic domain used for the analysis of magnetic forces applied to shunts at rated short circuit state which are the origin of tank vibration. The main finding of the work is that forces equivalent to the magnetostriction deformation of the shunt interior are comparable with magnetic forces resulting from the stray field and applied to the shunts’ surface.

Features of Surface Morphology and Magnetic Properties of Sm<sub>0.5</sub>R<sub>0.5</sub>Fe<sub>2</sub> (R = Tb, Gd) Compounds

A comprehensive study of the structure and phase composition, magnetostrictive and magnetic properties of the (Sm0.5R0.5)Fe2 (R = Gd, Tb) compounds was performed. The effect of partial replacement of samarium by gadolinium and terbium on the microstructure of the surface, the temperature of phase transitions, the magnitude of magnetostrictive deformations and magnetization was studied. Using atomic force and magnetic force microscopy, the surface topology at the micro and nanoscale was established, and information on the magnetic domain structure at room temperature was obtained.

New elements within finite element modeling of magnetostriction phenomenon in BLDC motor

AbstractReluctance forces are the main cause of vibration in electrical machines. The influence of magnetostriction is still the matter of controversy. In the article, program Ansys (typical for finite element method) was used to analyze stator deformation due to magnetic forces (Maxwell and magnetostriction) for the different boundaries and different methods by taking into account the windings in the mechanical model. Different parameters of numerical model are important factors affecting the level of magnetostriction deformation.

Magnetostrictive Anomalies of Rare Earth Laves Phases with Morphotropic Phase Transition

In the recent years, a number of pseudo-binary RT2 Laves phases with morphotropic phase transitions, i.e., systems of compounds having a morphotropic phase boundary in the phase diagram, have attracted special attention in the process of searching for compounds with high or, on the contrary, almost zero magnetostriction values. In this work, we study the magnetic and magnetostrictive properties of multicomponent systems based on compounds Tb0.2Dy0.8 – xGdxCo2 and Tb0.2Dy0.8 – xGdxCo1.9Al0.1, in which a morphotropic phase transition is observed when dysprosium is replaced by gadolinium. A relationship between the temperature behavior, the sign and magnitude of magnetostrictive deformations, and the type of cubic lattice distortion of the studied Laves phases is revealed. In the region of magnetic phase transitions, the magnetocaloric effect is investigated.

Measurement of thin film magnetostriction using field-dependent atomic force microscopy

Measurement of thin film magnetostriction is a challenging task, as magnetostrictive material deformations in parts per million, in conjunction with materials at small dimensions, require high precision, often with dedicated set-ups, for reproducible results. We have developed a novel approach employing a commercial atomic force microscope (AFM) with attached electromagnets. Magnetostriction measurements are demonstrated on 50–500 nm thick Fe81Al19 films sputter deposited directly on high aspect ratio commercial AFM micro-cantilevers. A magnetostrictive deflection of the cantilever bimorph translates into a deflection force acting in a contact mode measurement, which is interpreted and recorded as a change in height. For determination of the magnetostriction coefficient λs, we have developed a modified version of the equation for the magnetostrictive deflection of a cantilever bimorph by Guerrero and Wetherhold, taking into account long-range attractive forces acting during contact mode AFM measurements in air. The sub-atomic precision of the AFM, combined with the widespread availability of all components and the simple set-up, makes the measurement of magnetostriction on films of just a few tens of nanometers thickness easily accessible.

Strain-mediated propagation of magnetic domain-walls in cubic magnetostrictive materials

The role played by magnetoelastic effects on the properties exhibited by magnetic domain walls propagating along the major axis of a thin magnetostrictive nanostrip, coupled mechanically with a thick piezoelectric actuator, is theoretically investigated. The magnetostrictive layer is assumed to be a linear elastic material belonging to the cubic crystal classes $$\bar{4}$$3m, 432 and m$$\bar{3}$$m and to undergo isochoric magnetostrictive deformations. The analysis is carried out in the framework of the extended Landau–Lifshitz–Gilbert equation, which allows to describe, at the mesoscale, the spatio-temporal evolution of the local magnetization vector driven by magnetic fields and electric currents, in the presence of magnetoelastic and magnetocrystalline anisotropy fields. Through the traveling-wave transformation, the explicit expression of the key features involved in both steady and precessional regimes is provided and a qualitative comparison with data from the literature is also presented.

Negative Thermal Expansion and Spontaneous Magnetostriction of Nd2Fe16.5Cr0.5 Compound**Supported by the National Natural Science Foundation of China under Grant Nos 50871074 and 61474082, the Henan Agricultural University Start-up under Grant No 20190703Y00005.

The structural, thermal expansion, and magnetic properties of the Nd2Fe16.5Cr0.5 compound are investigated by means of x-ray diffraction and magnetization measurements. The Nd2Fe16.5Cr0.5 compound has a rhombohedral Th2Zn17-type structure. There exists a small negative thermal expansion resulting from a spontaneous magnetostriction in the magnetic state of the Nd2Fe16.5Cr0.5 compound. The average thermal expansion coefficient is −1.06 × 10−6/K in a temperature range 299–394 K. The spontaneous magnetostrictive deformation and the Curie temperature are discussed.

Магнитострикционные аномалии редкоземельных фаз Лавеса c морфотропным фазовым переходом

Оver recent years in the process of searching for compounds with high or almost zero magnetostriction values, a number of pseudo-binary Laves RT2 phases with morphotropic phase transitions are attracted particular attention. That is, systems of compounds with a morphotropic phase boundary in the phase diagram. In this paper, the magnetic and magnetostrictive properties of multicomponent systems of compounds Tb0.2Dy0.8-хGdxCo2 and Tb0.2Dy0.8-хGdxCo1.9Al0.1 in which a morphotropic phase transition is observed when replacing dysprosium with gadolinium have been studied. A relationship between the temperature behavior, the sign and magnitude of magnetostrictive deformations, and the type of distortion of the cubic lattice of the studied Laves phases is revealed. In the region of magnetic phase transitions, the magnetocaloric effect was investigated.

Negative Thermal Expansion of the Dy2Fe16Cr Compound**Supported by the National Natural Science Foundation of China under Grant Nos 50871074 and 61474082.

Structural, thermal expansion, and magnetic properties of the Dy2Fe16Cr compound are investigated by means of x-ray diffraction and magnetization measurements. The Dy2Fe16Cr compound has a hexagonal Th2Ni17-type structure. There exists a negative thermal expansion resulting from a strong spontaneous magnetostriction in the magnetic state of the Dy2Fe16Cr compound. The average thermal expansion coefficient is −0.794 × 10−5/K in the temperature range 292–407 K. The spontaneous magnetostrictive deformation and the Curie temperature are discussed.

Magnetostrictive patch sensor system for battery-less real-time measurement of torsional vibrations of rotating shafts

Real-time uninterrupted measurement for torsional vibrations of rotating shafts is crucial for permanent health monitoring. So far, strain gauge systems with telemetry units have been used for real-time monitoring. However, they have a critical disadvantage in that shaft operations must be stopped intermittently to replace telemetry unit batteries. To find an alternative method to carry out battery-less real-time measurement for torsional vibrations of rotating shafts, a magnetostrictive patch sensor system was proposed in the present study. Since the proposed sensor does not use any powered telemetry system, no battery is needed and thus there is no need to stop rotating shafts for battery replacement. The proposed sensor consists of magnetostrictive patches and small magnets tightly bonded onto a shaft. A solenoid coil is placed around the shaft to convert magnetostrictive patch deformation by shaft torsional vibration into electric voltage output. For sensor design and characterization, investigations were performed in a laboratory on relatively small-sized stationary solid shaft. A magnetostrictive patch sensor system was then designed and installed on a large rotating propulsion shaft of an LPG carrier ship in operation. Vibration signals were measured using the proposed sensor system and compared to those measured with a telemetry unit-equipped strain gauge system.

Magnetocaloric effect and magnetostrictive deformation in Tb-Dy-Gd-Co-Al with Laves phase structure

The influence of partial substitution of Co by Al atoms on the magnetocaloric and magnetostrictive properties of the multicomponent Tb-Dy-Gd-Co compounds with a Laves phase structure was investigated. The samples were obtained by arc melting using of high-purity rare-earth metals. The crystal structure of Tb0.2Dy0.8-xGdxCo2-yAly (x = 0.3, 0.4, and 0.5; y = 0 and 0.1) compounds was monitored by powder X-ray diffraction. The magnetostriction and the magnetocaloric effect in external magnetic field up to 12 and 18kOe, respectively, were studied in wide temperature range. The Curie temperature of Al-content compounds increases by an average of 20K, while the magnitudes of the magnetocaloric effect and the magnetostriction slightly decrease.

Magnetic characterization of ODS-Eurofer steel: Remanent magnetization and magnetostriction behavior

Oxide dispersion strengthened ODS-Eurofer steel is a promising candidate for structural applications in future nuclear fusion reactors. Samples of 9Cr-ODS-Eurofer steel were cold rolled up to 80% thickness reduction and annealed up to 1350°C for 1h. The microstructural changes of the annealed samples were followed by magnetic measurements taken at room temperature. In comparison with the coercive field (Hc), the remanent magnetization (Mr) and longitudinal magnetostriction (λlong) behaviors can be explained only if we assume some interaction between pinning sites and residual stresses in the material. It was found that Hc, Mr, λlong, and hardness display the same trend. At the expected fusion DEMO reactor operating conditions (around 650°C and maximum magnetic field of 6T), the magnetostrictive deformation would not surpass 15ppm (15μm in 1m).

Stress analysis of magnetically controlled reactor

To provide technique references for vibration reduction of magnetically controlled reactors (MCRs), stress, which is the inherent reason of vibration and noise, should be investigated. Stresses in reactor cores are produced due to the magnetostriction deformation of silicon steel and electromagnetic force between the core discs. So far, stress analysis on reactor cores was based on one-way coupled numerical method, which did not consider the influence of the stress on magnetic properties of the core material. Thus, multi-group magnetization and magnetostriction characteristics curves of silicon steel under different tensile stresses are measured firstly to support the computation. From the experiment results, it can be seen that magnetic properties of silicon steel change with stress. Then an electromagneto-mechanical two-way coupled numerical model for MCRs considering magnetostrictive effect and electromagnetic force effect is proposed. Stress distribution of MCR cores under the combination excitation of the sinusoidal wave current and different direct currents are calculated. From the computed results, it can be seen that a larger direct current has greater influence on MCRs vibration, which provides a theory basis for further analysis of vibration and noise reduction.