Magnetostrictive Devices Research Articles

Experimental Characterization of an AC–DC Boost for Energy Harvesting Device Based on Magnetostrictive Materials

Magnetostrictive alloys hold great promise for Energy Harvesting applications due to their inherent durability. However, their implementation often results in usable voltage ranges that fall significantly below common electronic standards like 1.6, 3.3, and 5 volts. Consequently, the utilization of electronic circuits becomes essential to amplify the voltage and enhance energy conversion efficiency. Over the past few decades, numerous conversion techniques have been devised for other intelligent materials, such as piezoelectrics, some of which have even made their way into commercial products. Surprisingly, there is a dearth of specialized techniques, if not a complete absence, tailored to magnetostrictive devices. Among potential solutions, a suitable AC–DC Boost converter stands out as a highly promising candidate for addressing this challenge, but this solution has never been fully characterized. Then, this paper presents thorough experimental validations of such a converter, driven by a real-time Arduino board equipped to measure source time periods and operate under various conditions. We present several cases demonstrating the circuit’s substantial potential for enhancing energy harvesting from magnetostrictive materials.

Reduction in bending stress in magnetostrictive vibration sensor devices using concave-convex spherical contact

Reduction in bending stress in magnetostrictive vibration sensor devices using concave-convex spherical contact

Reduction in bending stress in magnetostrictive vibration sensor devices using concave-convex spherical contact

Reduction in bending stress in magnetostrictive vibration sensor devices using concave-convex spherical contact

Secondary recrystallization of Goss texture in one-stage cold rolled Fe–Ga thin sheets via a large rolling reduction

Preparing Fe–Ga sheets with excellent magnetostrictive coefficients by rolling and annealing methods can greatly promote the development of high-efficiency magnetostrictive devices. 0.3 mm thick Fe–Ga thin sheet was produced by the one-stage large-reduction cold rolling method without intermediate annealing. Trace V and Nb elements addition improves the rolling formability of the Fe–Ga sheet by precipitating a large number of (Nb,V)C particles. The evolution of precipitation, microstructure, texture, and magnetostrictive coefficients in the Fe–Ga sheet was investigated. The microstructure of primary recrystallization is composed of homogenous distribution of fine grains with an average grain size of about 22 μm. The composite inhibitors composed of MnS and (Nb,V)C precipitates with a particle size of 40∼80 nm suppress the matrix grains effectively. The primary recrystallization texture consists of a strong γ texture with a peak at {111}<112> and a relatively strong {114}<481> texture. The secondary recrystallization of Goss grain occurs at the annealing temperature of 900 °C and is completed at 1100 °C by the combined effects of the existing inhibitor and texture. The Fe–Ga thin sheets composed of several millimeter-sized grains of Goss texture accompanied by small grains oriented by {114}<481> were obtained after annealing at 1100 °C, and its measured magnetostriction value is about 238 ppm. The present work proposes a promising routine to produce high-performance Fe–Ga thin sheets.

Design and Optimization of a Boost Interface for Magnetostrictive Energy Harvesting

Magnetostrictive alloys are very promising for Vibration Energy Harvesting applications to supply power to Wireless Sensor Network (WSN) and Internet of Things (IoT) devices, especially because of their intrinsic robustness. Typically, vibration energy sources are random in nature, usually providing exploitable voltages much lower than the electronic standards 1.6, 3.3 and 5 V. Therefore, a Power Electronic Interface (PEI) is needed to improve the conversion to DC output voltage from AC input over a wide range of frequencies and amplitudes. Very few or no conversion techniques are available for magnetostrictive devices, although several have been presented over the years for other smart materials, such as piezoelectrics. For example, hybrid buck–boost converters for piezoelectrics use one or more external inductors with a high-frequency switching technique. However, because of the intrinsic nature of harvesters based on magnetostrictive materials, such energy conversion techniques are proved to be neither efficient nor applicable. An improved AC–DC boost converter seems very promising for our purpose instead. The key feature is represented by the direct exploitation of the active harvester coil as a storage element of the boost circuit, without using other passive inductors as in other switching methods. Experimental tests of such a converter, driven with a real-time operating Arduino controller to detect the polarity of the input voltage, are presented with the aim to assess the potentiality of the scheme with both sinusoidal and impulse-like inputs. Simulations have been performed with LTspice, and the performance and efficiency have been compared with other energy conversion techniques.

The effect of temperature on giant magnetostrictive thin films in high pre-stress environment for sensor application

The high pre-stress environment arises in the manufacturing of amorphous thin films of Terfenol-D through sputtering techniques. The pre-stress thin film of Terfenol-D has been developed due to the mismatch in the thermal coefficient of deposited magnetostrictive film and substrate. In the presence of high pre-stress anisotropic energy has been changed and due to that magnetization and magnetostriction properties of the thin film are affected. A novel three-dimensional hyperbolically generalized constitutive model for giant magnetostrictive materials along with vector generalized Jiles-Atherton hysteresis model was considered for predicting the hysteretic responses precisely under thermo-elasto-magnetic field. The material constants for the generalized constitutive models are taken from calibrated physical and experimental evidence. A non-linear finite element model for the thin films made up of Terfenol-D has been developed for investigating the thermo-elasto-magnetic characteristics, using COMSOL Multiphysics software. The predicted thermo-elasto-magnetic results have been critically analyzed the effect of temperature, the orientation of the applied magnetic field, and in-plane stresses condition. Hence, the present study can be decisive for the development of a more reliable and robust design of magnetostrictive film-based intelligent devices.

К вопросу использования в образовательном процессе разработанного программного обеспечения для исследования акустических трактов магнитострикционных преобразователей перемещений

The article is devoted to the research of the processes arising during the formation, translation and reading of information signals in the acoustic paths of magnetostrictive linear and angular displacement transducers. Mathematical models are given that make it possible to calculate the magnetic fields of annular permanent magnets and those formed by current pulses when they flow in a waveguide medium. To calculate the magnetization of the waveguide, a numerical method was developed that allows taking into account the magnetization of the waveguide material at a previous time. Mathematical models are also given to calculate the parameters of the magnetic flux of the solenoid and the output signal. Mathematical models for calculating permanent magnet magnetic fields, the developed numerical method and mathematical models for the formation of magnetic flux and output signal were implemented in the developed software used in the educational process. The research results, as well as refined and developed methods for calculating magnetic fields and the numerical method can be used to study magnetostrictive devices both at the stage of their design and operation, which reduces their final cost. It should also be noted that the article does not address issues related to the processing of the output signal, which provides opportunities for further research and further modification of the software.

High performance magnetostriction of Fe-Cu-Pd ferromagnetic strain glass:Local chemical ordering induced martensitic nanodomains morphology with low modulus

Large magnetostriction with low saturation magnetic field was recently reported in Fe-Pd ferromagnetic strain glass alloys. Such behaviour is highly desirable for miniaturized sensor and actuator applications. The origin of high performance magnetostriction in Fe-Pd ferromagnetic strain glass is suggested to stem from its martensitic nanodomains. However, the atomic formation mechanism underlying these nanodomains and their associated local crystal symmetry breaking have not been well revealed. Moreover, accumulating experimental results indicate that the nano-structure can lead to a small saturation field but cannot guarantee large magnetostriction. Consequently, the necessary conditions for low field triggered large magnetostriction of Fe-Pd ferromagnetic strain glass alloys still remain unclear. In this paper, the chemistry, structure and transformation properties of the Fe98-xCu2Pdx (x = 28.5 ∼ 31) system are systematically explored to discover the origin of the high performance magnetostriction of ferromagnetic strain glass alloys. We found that the structure of ferromagnetic strain glass consists of local chemical order. This leads to tetragonal martensitic nanodomains with the local crystal symmetry breaking. The local chemical order also induces strong local phonon softening and a low modulus during the strain glass transition. Further investigation shows that the combination of martensitic nanodomains and low modulus are the necessary conditions to achieve both large magnetostriction and a low saturation field, because they can result in small energy barriers for the rotation of nanodomains. These findings provide an effective guideline to design high performance magnetostrictive materials and devices.

High-frequency magnetic energy loss based on J-A model for gallium iron alloy rod under variable stress conditions

Magnetostrictive rods have stress-sensitive properties. They are the core component of high-frequency high-power magnetostrictive sensor and actuator devices. In practical high frequency applications, a certain compressive stress needs to be applied to improve the magnetostrictive coefficient of the material. However, unsuitable operating conditions can lead to increased magnetic energy losses and deterioration of device performance. Therefore, the loss modelling as well as other physical behaviour of the material need to be investigated before designing magnetostrictive devices. This paper builds a test platform for high frequency magnetic properties of magnetostrictive materials. The high frequency magnetic properties of rod gallium iron alloy were measured and analyzed under different exciting conditions (different compressive stress σ, magnetic field frequency f, and magnetic field strength H). Then, based on the experimental data and the classical static J-A model, a high-frequency dynamic model for rod gallium iron alloy taking into account compressive stress was developed. The novelty of the model is that the variation pattern of the J-A model parameters with frequency and compressive stress is obtained by importing the experimental data into a parameter identification program written based on a hybrid particle swarm algorithm. The trend is fitted as a polynomial function of frequency and compressive stress to account for its effect on the magnetic properties of the material. The model can effectively predict the change of high frequency magnetic loss of materials under variable compressive stress conditions. Comparing the calculated values of magnetic energy loss with the measured ones show that the maximum error is 4.37% and the average error is 2.57%, which verifies the accuracy and feasibility of the model.

Vanadium trapped by oblique nano-sheets to preserve the anisotropy in Co–V thin films at high temperature

In this study, oriented nano-sheets generated during the growth of cobalt-rich Co–V and Co–Zn thin films induced a large anisotropy in the magnetic and transport properties. The regular nano-sheets were tilted 52–54 deg. with respect to the substrate plane, ≈ 3.0–4.0 nm thick, ≈ 30–100 nm wide, and ≈ 200–300 nm long, with an inter-sheet distance of ≈ 0.9–1.2 nm. In spite of the different microstructures of the two kinds of samples where the Co–V films were amorphous, whereas the Co–Zn films showed a growth of Zn nanocrystals, the oblique nano-sheet morphology conferred noticeable shape anisotropy to both specimens. This anisotropy resulted in an in-plane uniaxial magnetic anisotropy. The changes in the nano-morphology caused by thermal treatments, and hence in their anisotropic properties, were studied. While the Co–V samples retained or increased their magnetic and transport anisotropies, this anisotropic behavior vanished for the annealed Co–Zn films. High resolution transmission electron microscopy, HRTEM, including chemical analysis at the nano-scale, and the dependence of the anisotropic resistance on temperature allowed to establish the nature and the activation energy spectra of the atomic relaxation processes during heating. These processes displayed a single peak at 1.63 eV for the Co–V and two peaks at 1.67 and 2.0 eV for the Co–Zn. These spectra and their singularities were associated to the changes induced in the nano-morphology of the films by thermal treatments. The Co–V films retained their nano-sheet morphology almost up to 500 ºC; the Co–Zn films lost their nano-sheets at 290 ºC. The thermal stability exhibited by the Co–V films makes them useful for applications in ultra high frequency, optical, magnetostrictive and magneto-electric devices.

Modeling and analysis of the piezomagnetic, electromagnetic, and magnetostrictive effects in a magnetostrictive transducer

A comprehensive model is a basis for adequately understanding the energy conversion mechanism of magnetostrictive materials and guides the design of magnetostrictive devices. This paper established a fully coupled model that fully considered the piezomagnetic effect and the electromagnetic effect in its procedure of energy conversion. The proposed model can accurately predict the output voltage with different excitation levels and illustrate the interaction between physical fields. Based on the established model, we quantify the voltage contributed by the piezomagnetic effect and the electromagnetic effect. After a thorough analysis, we discovered that even though the voltage generation is always dominated by the piezomagnetic effect of the magnetostrictive material, the proportion from the electromagnetic effect will increase moderately with larger excitation levels. In addition, the magnetostrictive effect toward the output performance is also discussed, which proved to lead to a marginal impact on the voltage waveform.

Layer-Dependent Mechanical Properties and Enhanced Plasticity in the Van der Waals Chromium Trihalide Magnets.

The mechanical properties of magnetic materials are instrumental for the development of magnetoelastic theories and the optimization of strain-modulated magnetic devices. In particular, two-dimensional (2D) magnets hold promise to enlarge these concepts into the realm of low-dimensional physics and ultrathin devices. However, no experimental study on the intrinsic mechanical properties of the archetypal 2D magnet family of the chromium trihalides has thus far been performed. Here, we report the room temperature layer-dependent mechanical properties of atomically thin CrCl3 and CrI3, finding that the bilayers have Young’s moduli of 62.1 and 43.4 GPa, highest sustained strains of 6.49% and 6.09% and breaking strengths of 3.6 and 2.2 GPa, respectively. This portrays the outstanding plasticity of these materials that is qualitatively demonstrated in the bulk crystals. The current study will contribute to the applications of the 2D magnets in magnetostrictive and flexible devices.

Variable coefficient magnetic energy loss calculating model for magnetostrictive materials considering compressive stress

The effect of variable compressive stress on hysteresis, eddy-current, and anomalous losses in magnetostrictive materials is investigated by the built magnetic characteristic testing system. Based on experimental results of Terfenol-D and loss separation theory, the trends of loss coefficients of three variables, magnetic frequency f, peak flux magnetic density Bm, and compressive stress σ, are analyzed. The reasons for the change in losses are explained from the point of view of micro-magnetism and physical mechanism. A variable coefficient magnetic energy loss calculating model considering compressive stress is derived using the algorithm of Levenberg–Marquardt and the method of multivariate parametric regression. The experimental and computed results of magnetic energy losses are compared and analyzed under different operating conditions. The analysis results show that the proposed model could well predict the losses under compressive stress at high-frequencies (5–20 kHz). The average error of the computed and experimental results is 5.5%. This research has improving significance in giving theoretical guidance for magneto-mechanical design in the high-frequency operated conditions of magnetostrictive devices.

Shunted magnetostrictive devices in vibration control

Structural vibrations in rotating machinery may lead to imprecise motion control, excessive noise, or even structural damage. Magnetostrictive materials can dissipate unwanted vibrations via hysteresis, eddy currents, and joule heating while exhibiting an electrically-tunable elastic modulus. Harnessing this feature, this article presents a shunted magnetostrictive device that includes an iron-gallium (Galfenol) rod, a permanent magnet array, a flux return path, and shunt circuits. The stiffness tunability and damping of this passive device are measured under a 750 Hz sinusoidal axial compression for resistive, capacitive, and inductive shunt circuits. The effect of eddy currents stiffness and damping is investigated for the first time by comparing results from laminated and solid Galfenol rods. Solid Galfenol produces larger eddy current-based damping, while laminated Galfenol enables larger stiffness variation and total damping. This device demonstrates a power density of 19.83 mW cm−3 for vibration energy harvesting. The frequency-dependent behavior of the shunted device is tested from 5 Hz to 1 kHz for selected electrical loads.

Fabrication, Modeling and Characterization of Magnetostrictive Short Fiber Composites.

Magnetostrictive materials have a wide variety of applications due to their great capability as sensors and energy-harvesting devices. However, their brittleness inhibits their applications as magnetostrictive devices. Recently, we developed a continuous magnetostrictive Fe-Co-fiber-embedded epoxy matrix composite to increase the flexibility of the material. In this study, we fabricated random magnetostrictive Fe-Co short fiber/epoxy composite sheets. It was found that the discontinuous Fe-Co fiber composite sheet has the magnetostrictive properties along the orientation parallel to the length of the sheet. Finite element computations were also carried out using a coupled magneto-mechanical model, for the representative volume element (RVE) of unidirectional aligned magnetostrictive short fiber composites. A simple model of two-dimensional, randomly oriented, magnetostrictive short fiber composites was then proposed and the effective piezomagnetic coefficient was determined. It was shown that the present model is very accurate yet relatively simple to predict the piezomagnetic coefficient of magnetostrictive short fiber composites. This magnetostrictive composite sheet is expected to be used as a flexible smart material.

Investigation on microstructures and phases of Fe-Ga alloy films deposited by magnetron sputtering

Galfenol (Fe-Ga alloy), as a new magnetostrictive materials, has potentially wide applications in magnetostrictive devices. In this work, Fe-Ga alloy thin films were prepared by slice-style target magnetron sputtering and investigations on microstructures and phases of Fe-Ga alloy films were made to explore the relationship of properties and microstructures. The results show that the component of alloy thin film is related to physical properties of the material itself as well as the area ratio of the patch and target. The phase formed in the films in is disorderly A2 phase with face-centred cubic structure. The films prepared by magnetron sputtering exist in the form of polycrystalline with crystallographic texture perpendicular to the film plane. The structure shape of as-deposited specimens present a maze domain with different contrast and resolution and the magnetic domain decreased with the increase of the Ga content. With the increase of the Ga content, the magnetic domains become more and more irregular. Fe-Ga thin film morphology is related to the growth mode of the film. The microstructures of Fe-Ga alloy films can be controlled by magnetron sputtering technology.

Electrical tuning of magnetostrictive applications: Equivalent electromechanical circuit analysis

Electromechanical equivalent circuit models provide an efficient tool for analysis of power flow across multiple physical domains. This work applies this approach to analyze the dynamic behavior of magnetostrictive material-based devices. Here, the unimorph system consists of a magnetostrictive galfenol (Fe-Ga alloy) layer bonded to a non-magnetic flexible metal layer, a pick-up coil wound around the bimetallic strip, and an electrical load. Permanent magnets at both ends of the unimorph provide a magnetic bias. The electrical load, consisting of a resistance and capacitance, is connected to the pick-up coil, such that vibration in the magnetostrictive alloy layer generates electrical energy. From a system point of view, a transformation of the electrical and magnetic elements into the mechanical domain reveals a vibration absorption core structure of the electromechanical system with the appropriate applied electrical load. Experimental results from two different devices are presented and their dynamic behaviors are compared with simulations for purposes of adjustable damping and tunable energy harvesting. Because of the very good agreement between simulations and measurements, the presented network model can be used to predict the performance of magnetostrictive sensors, actuators, energy harvesters, and dampers with a similar structure.

Study of Dynamic Behavior of Magnetostrictively Patterned Flexible Micro-Wings

For the design of magnetostrictive MEMS devices, finite-element modeling (FEM), the determination of the magnetostrictive coefficient, and application examples were examined in this paper. The magnetostrictive coefficients are usually calculated by measuring the bending deflection of the cantilever on which magnetostrictive materials are deposited. In most of the research on the magnetostrictive deposited substrate for the derivation of structural formulas, it is commonly assumed that the flexural rigidities of magnetostrictive materials are negligible because magnetostrictive films are much thinner than substrate materials. In this paper, the effect of magnetostrictive thin film's elastic energy on the magnetostrictive coefficient is investigated. A self-coded and developed finite-element program for magnetostrictive actuators is formulated, where magnetic properties are considered as nonlinear, and elastic properties are assumed as linear. As a result, it is potentially shown that magnetostrictive thin-film micropatterned actuators would be accommodated for targeted actuating behavior through an FEM capability for evaluation and selective micropatterning technique for fabrication.

Comparative study on the magnetostrictive property of cobalt ferrite synthesized by different methods from spent Li-ion batteries

Comparative studies have been made to investigate the influence of different synthesis routes on the structural, microstructural, magnetic and magnetostrictive properties of cobalt ferrite, using spent Li-ion batteries as raw materials. Three routes are proposed in this study, mainly, sol-gel, co-precipitation and microwave assisted hydrothermal methods. X-ray diffraction patterns of the samples confirmed the formation of pure phase cubic spinel structure with Fd-3m space group. It is observed that the synthesis methods have a strong influence on the morphological features of the synthesized cobalt ferrite (CoFe2O4) nanoparticles and the fractured surface of the sintered cylindrical rods. Quantitative analysis, based on X-ray photoelectron spectroscopy, indicated that CoFe2O4 had a mixed spinel structure. Magnetic parameters, such as saturation magnetization and coercivity, showed significant differences that were correlated with the different cation distribution, crystallite size and induced lattice strain. This study provides an alternative way for recovering Co from spent Li-ion batteries. The product of this process (cobalt ferrite) obtained through different methods has different magnetostrictive coefficients and strain derivatives, suggesting the potential application in the field of magnetostrictive sensors or actuator devices.

Non-linear dynamics of the Villari effect in the presence of a non-homogeneous magnetic field

Investigations of systems with an active magnetostrictive element generally assume the presence of an external homogeneous bias magnetic field. This article, however, presents the results of a study investigating a bimorph magnetostrictive-aluminium beam vibrating in a non-homogeneous bias field. By comparing results obtained under different operating conditions of the system, the combined effect of the non-linear beam stress and the non-homogeneous external magnetic field on the dynamics of the Villari phenomenon is determined. The preliminary results prove that the application of non-linear magnetic fields to the magnetostrictive devices ensures the extension of energy harvesting bandwidth of these devices and can be used to improve their control possibilities. A study of time series and hysteresis loops provides more detailed information about the non-linear magnetization and dynamics of the system.