Magnetostriction Curves Research Articles

A one-step fabrication method of flexible magnetostrictive fiber ribbon based on Fe50Co50 alloy and its characteristics study

Magnetostrictive materials are widely used in sensors, actuators and micro-nano electronics because of their excellent performance. However, traditional rigid magnetostrictive materials are difficult to adapt to the flexible and deformable structure of flexible electronic devices. In order to solve the deformation, sensing and control problems in the field of flexible electronics, a one-step new method of is proposed to deposit Fe50Co50 fiber ribbons with reciprocated and loop structures on flexible substrate. Helmholtz coil is designed to test the magnetostrictive positive effect ability of Fe50Co50 ribbon, and its magnetostrictive strain curve is analyzed. Furthermore, frequency domain characteristics of Fe50Co50 ribbon are tested, and the influence of externally driving magnetic field on elastic layer materials and resonance output characteristics is analyzed. The experimental results show that Fe50Co50 ribbon exhibits good low-frequency magnetic field characteristics. And free end displacement of Fe50Co50 ribbon based on loop structure, under 12 mT alternating magnetic field and 134 mT bias magnetic field, reaches a peak-to-peak value of 870 μm for first-order resonance, and 320 μm for second-order resonance. This verifies that Fe50Co50 ribbon possesses the expected properties that magnetostrictive materials should have, and innovatively breaks through the technical bottleneck of manufacturing flexible micro-nano magnetostrictive energy exchange components.

Study on magnetostrictive properties of oriented silicon steel sheet under different working conditions

Accurate measurement of magnetostriction is the basis for calculating the vibration of silicon steel laminated core. In this paper, a laser magnetostriction measurement system (MST500) is used to study the magnetostriction characteristics of silicon steel under sinusoidal, third harmonic, and DC bias magnetization. The magnetostrictive butterfly curves, time domain waveforms, and spectrum diagrams of silicon steel sheets under different excitations are compared and analyzed. The effects of different operating conditions on the magnetostrictive properties of silicon steel sheets were studied and analyzed, mainly including amplitude and spectrum analysis. Finally, the magnetostrictive peak to peak curves under different operating conditions were extracted, providing a data basis for the core vibration of power equipment.

Research on multi-scale hysteresis constitutive model of giant magnetostrictive materials considering multi-field coupling

The magnetization and magnetostrictive strain of giant magnetostrictive materials exhibit a complex nonlinear trend under the coupling of multiple fields, including magnetic field, temperature field, and prestress field. To enhance prediction accuracy, we propose a three-dimensional magnetic-thermal-force coupled nonlinear multi-scale hysteresis vector model. This model is derived from the principles of thermodynamics and continuum mechanics, taking into account the interactions among magnetic domains, grains, polycrystals, and macroscopic scales. It combines the volume-averaging principle of magnetic domain microscopy with the generalized Jiles-Atherton hysteresis model. The predicted hysteresis magnetization and magnetostrictive strain curves obtained from this model are in good agreement with experimental results. By analyzing the predicted hysteresis magnetization and magnetostrictive strain under different conditions, we demonstrate that our proposed model can comprehensively describe the effects of temperature and prestress on the multi-field coupled hysteresis behaviors of giant magnetostrictive materials. Moreover, it provides theoretical guidance for both macroscopic and microscopic optimization in designing active devices incorporating super magnetostrictive materials.

Huge magnetostriction in superconducting single-crystalline BaFe1.908Ni0.092As2

The performance of iron-based superconductors in high magnetic fields plays an important role for their practical application. In this work, we measured the magnetostriction and magnetization of BaFe1.908Ni0.092As2 single crystals using pulsed magnetic fields up to 60 T and static magnetic fields up to 33 T, respectively. A huge longitudinal magnetostriction (of the order of 10–4) was observed in the direction of twin boundaries. The magnetization measurements evidence a high critical-current density due to strong bulk pinning. By using magnetization data with an exponential flux-pinning model, we can reproduce the magnetostriction curves qualitatively. This result shows that the magnetostriction of BaFe1.908Ni0.092As2 can be well explained by a flux-pinning-induced mechanism.

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.

Significant magnetoelectric enhancement of composite films of CoZnxFe2-xO4 particles and poly (vinylidene fluoride-trifluoroethylene) for AC magnetic sensors

Polymer-based magnetoelectric (ME) nanocomposites exhibit a low ME effect and high bias field at room temperature, which severely limits their application in flexible wearable sensors. To overcome these obstacles, Zn-doped magnetic nanoparticles of CoZnxFe2-xO4 (x = 0, 0.1, 0.2, and 0.3) were prepared by an auto-combustion method in this work. The obtained magnetostrictive curves imply that Zn element doping can improve greatly the piezomagnetic coefficient of magnetic nanoparticles, and among the tested materials, CoZn0.1Fe1.9O4 has the largest piezomagnetic coefficient. Composite films of poly(vinylidene fluoride-trifluoroethylene) and CoZn0.1Fe1.9O4 (P(VDF-TrFE)/CoZn0.1Fe1.9O4) were prepared by spin coating. The maximum ME voltage coefficient of P(VDF-TrFE)/CoZn0.1Fe1.9O4 composite film with a filler weight concentration of 10 wt% is 87.9 mV cm−1 Oe−1 with a bias field of 1050 Oe and a resonance frequency of 46 kHz, which is the highest value reported in the literature of 0–3 type polymer-based ME composite films at present. To evaluate the composite films for application in magnetic sensors, the ME output voltage was measured at a bias field of 1050 Oe with increasing AC magnetic field, demonstrating a good linear relationship with linearity of 0.999. These results indicate that the piezomagnetic coefficient of magnetic materials is an the important factor for the great enhancement of the ME voltage coefficient. This work provides a new approach for the synthesis of more effective polymer-based ME nanocomposites for potential applications in smart wearables.

Signature of spin-triplet exciton condensations in LaCoO3 at ultrahigh magnetic fields up to 600 T

Bose-Einstein condensation of electron-hole pairs, exciton condensation, has been effortfully investigated since predicted 60 years ago. Irrefutable evidence has still been lacking due to experimental difficulties in verifying the condensation of the charge neutral and non-magnetic spin-singlet excitons. Whilst, condensation of spin-triplet excitons is a promising frontier because spin supercurrent and spin-Seebeck effects will be observable. A canonical cobaltite LaCoO3 under very high magnetic fields is a propitious candidate, yet to be verified. Here, we unveil the exotic phase diagram of LaCoO3 up to 600 T generated using the electromagnetic flux compression method and the state-of-the-art magnetostriction gauge. We found the continuous magnetostriction curves and a bending structure, which suggest the emergence of two distinct spin-triplet exciton condensates. By constructing a phenomenological model, we showed that quantum fluctuations of excitons are crucial for the field-induced successive transitions. The spin-triplet exciton condensation in a cobaltite, which is three-dimensional and thermally equilibrated, opens up a novel venue for spintronics technologies with spin-supercurrent such as a spin Josephson junction.

The magneto-mechanic hysteresis model for giant magnetostrictive materials based on the magnetic domain theory

In the paper, a magneto-mechanic hysteresis model for giant magnetostrictive materials is suggested by considering the effect of the domain rotation and domain wall motion on the magnetization process under prestress and the applied magnetic field. The coercive force, which is magneto-mechanic dependent, is proposed instead of a pinning constant in the Jiles–Atherton model. The model can well predict the characteristics of a magnetization-applied field curve and magnetostrictive strain-applied field curve shown in the experiment, especially the “overturn phenomenon” under different compressive prestresses. Furthermore, the effect of the microstructure parameter, such as the ratio of the domain wall thickness to the internal stress wavelength, the amplitude of internal stress, the ratio of the domain wall thickness to the inclusion radius, and inclusion consistency, on coercive force under applied prestress can also be described by the model. The comparison between the results predicted by the model and experiment shows that the model is suited for a wide-ranging applied magnetic field.

The Vector Electromagnetic Vibration of Magnetically Controlled Reactor Considering the Vector Hysteretic Magnetostriction Effect

Magnetically controlled reactors (MCRs) are widely used as reactive power compensation equipment owing to their favorable properties of smoothly adjusting their inductance value through dc bias. However, the dc bias and the rotational magnetization at corner and T-joint areas make the cores of MCRs saturated, resulting in high magnetostriction and vibration. Thus, the electromagnetic vibration analysis of MCRs must consider the vector hysteretic magnetostriction effect. In this article, a vector hysteretic magnetostriction model of silicon steel is proposed by combining the quadratic domain rotation model with the vector inverse Jiles–Atherton model firstly. Then, based on the measured magnetization and magnetostrictive characteristics curves of silicon steel, the model’s parameters are optimized by velocity controllable particle swarm optimization (VCPSO). Finally, the vector hysteretic magnetostriction model is combined with the finite element method (FEM) to simulate the vector vibration characteristics of MCR under dc bias. The simulation results show that the vector property of electromagnetic vibration and magnetic field at the T-joint area is higher than that at other areas. And the MCR vibration test results are consistent with the simulation results, which verify the accuracy of the proposed model in simulating electromagnetic vibration.

Theoretical and experimental study on optimum operational conditions of a magnetostrictive force sensor

Terfenol-D, as a giant magnetostrictive material, is used to fabricate different force sensors. In these sensors, bias magnetic field and mechanical pre-stress are applied to improve the sensor’s characteristics. The present paper proposes the optimum values of the above operational conditions to reach maximum sensitivity and linear measuring of the sensor. Initially, a sensor’s model based on coupled piezomagnetic equations is developed and affective parameters on the output voltage are recognized. An experimental setup is fabricated and used to obtain magnetization and magnetostriction curves of Terfenol-D at different mechanical pre-stresses to study the parameters. Analyzing the experimental curves, the sensor's effective parameters, including magnetostriction constant, magnetic permeability, and their variation with axial stress, are calculated and imported to the model. Hence, the sensor's sensitivity and linear measuring range are obtained at different values of bias magnetic field and mechanical pre-stress and optimum values considering the external force’s amplitude are introduced. The maximum sensitivity factor is 0.004515 mV/Ns−1 which obtained at mechanical pre-stress of 6.89 MPa and bias magnetic field of 25kA/m. In these conditions the linear measuring range of the sensor is 260–500 N. To validate the model, the results are compared with previously reported experimental results, and the minor errors show the precision of the model and experimental investigation.

Magnetostriction studies on transition metal substituted cobalt ferrite

Structural, magnetic and microstructural properties of transition metal (TM) substituted cobalt ferrite Co0.9TM0.1Fe2O4 (where TM = Ti, Cr, Mn, Ni and Cu and Zn) were investigated. The present study shows marked dependence of the magnetostriction on the concentration of the substituted transition metal ions for Cobalt in CoFe2O4. The magnetic characteristics of the prepared compositions such as coercivity, anisotropy constant and saturation magnetization changed significantly on transition metal substitution. The present study shows the way to tune the anisotropy of cobalt ferrite by effective substitution of other transition metal ions for Co which subsequently affects the stress sensing performance by changing the slope of the magnetostriction curve. Apart from the magnetic properties the microstructure can also be effectively modified by substitution of other transition metal ions. Only 10% substitution of cobalt showed drastic influence on magnetostriction and slope of magnetostriction curve. The composition with 10% nickel Co0.9Ni0.1Fe2O4 exhibited maximum slope for the magnetostriction curve of −53.7 ppm/Oe, along with reasonably high magnitude of strain of 186 ppm making it a suitable for exploring stress sensing applications.

Numerical Calculation of Vibration Characteristics of Transformer Core under Inter-harmonics

In this paper, a numerical model that can simulate the vibration of the transformer core under arbitrary inter-harmonic excitation is established. On this basis, the influence of interharmonics on core vibration is studied. First, based on the multi-physics coupling software, by deriving the differential equations of the physical fields, a coupling model of the circuit, magnetic field and solid mechanics is established. Then the magnetostriction curve is used to calculate the magnetic flux density and vibration displacement of the transformer core model under power frequency sine and interharmonic excitation. The work of this paper lays a theoretical foundation for studying the vibration problems of power transformers and other equipment under inter-harmonics.

Features of magnetostriction in carbon steels

Magnetostriction of the tempered 60G steel in the magnetic field of a solenoid is studied. A technique is proposed for dividing magnetostriction into components, namely those induced by the displacement of interdomain boundaries and those caused by the mechanism of rotation of spin magnetic moments. The dependences of the magnetostriction components on the tempering temperature of the hardened steel are constructed. This contributes to an increase in the effectiveness (accuracy) of evaluating elastic stresses in a steel structure by magnetoelastic methods. The essence of the technique lies in the application of the Langevin function to describing the experimental magnetostriction curves of the tempered 60G steel.

Self-Similarity in Magnetostrictive Materials: An Experimental Point of View

Magnetostrictive behavior is characterized by a complex coupling between magnetic and mechanical quantities. While this behavior can be quite easily exploited for both actuation and sensing or energy conversion purposes, the complex hysteresis interaction between magnetization and magnetic field and mechanical stress and strain is hard to model. Nevertheless, magnetic and magnetostrictive experimental curves are quite self-similar, assuming stress as self-similarity parameter. The quantification of this concept would help modeling. Here, this concept is quantified and experimentally confirmed over different types of magnetostrictive samples.

A Longitudinal Mode Guided Wave Transducer With the Ring Permanent Biased Magnet Based on Magnetostrictive Effect for Large Diameter Bridge Cables

The existing yoke magnetizers can be used for large diameter bridge cable detection, but cannot provide the optimal bias magnetic field due to the repulsion of the polarities arranged in the circumferential direction, which reduces the energy conversion efficiency of the magnetostrictive longitudinal mode guided wave transducer. A magnetostrictive longitudinal mode guided wave transducer with the ring permanent biased magnet is provided to improve energy conversion efficiency for large diameter bridge cables. Firstly, a ring magnetizer for the axial magnetization is proposed, which inspired by the structure of the yoke magnetizer and the adjustable bias magnetic field generated by the solenoid coil. Then, the specific transducer with the ring magnetizers is designed for PES(C) 7-127 cable. Based on the magnetostrictive coupling coefficient curves and magnetization curve of the cable steel wire, the finite element models verify that the magnetization effect of the ring magnetizer is better than the yoke magnetizer for PES(C) 7-127 cables. Furthermore, the structural parameters of the ring magnetizers are optimized based on magnetization strength and magnetization uniformity. Finally, the improved efficiency of the transducer is verified by experiments. The energy conversion efficiency of the transducer is increased by 43.65% at the transmitting side, 4.76% at the receiving side, 48.41% at the both sides. Besides, the weight of the ring magnetizers is 19.85% lower than the yoke magnetizers.

Optimisation design of double-column multi-gap reactor core structure for noise reduction

The noise from a double-column multi-gap reactor is very loud and should be controlled. Based on different gap configurations, the gap configuration design schemes of the double-column multi-gap reactor to noise reduction are proposed. According to the positions of the gaps, the 20 gaps of the actual reactor are simplified into five gaps. Then, 31 reactor finite element simulation models are constructed respectively according to the gap position or length. A three-dimensional (3-d) electromagnetic–mechanical weak-coupled model is used to study the average surface vibration velocity of each reactor core simulation model with different gap configurations. The 3-d anisotropy of magnetisation curves (BH curves) and magnetostriction curves of laminated Grain-oriented steel plates are considered. Some gap configuration design schemes are proposed on the basis of the results of simulations. Two double-column multi-gap reactor models are used for comparative testing. The test results show that the gap configuration design schemes can reduce the sound power level of the reactor by about 6.836 dB. Finally, gap configuration design schemes for noise reduction of a double-column 20-gap reactor are proposed.

Near-zero magnetostriction in magnetostrictive FeCo alloys

Soft magnetic metallic materials are the key components in generators, motors and transformers. The Curie temperatures of currently used soft magnetic metallic materials limit their applications in high-temperature environments. In this work, we tuned the bcc/fcc ratio through modifying the Co content, thus obtaining near-zero magnetostriction and improved soft magnetic properties in the magnetostrictive system Fe100-xCox (70≤x≤93) alloys with high Curie temperature. With the increase of Co content, we observed the evolution of three crystal structures from bcc to fcc and three types of magnetostriction curves, ∧-type, ∨-type and M-type, which can be well interpreted by the domain-switching model. The optimum composition Fe20Co80, corresponding to the coexistence of bcc & fcc phases, exhibits magnetostriction of -3 ppm, a coercive field of 0.18 kA/m and saturated magnetization of 183 Am2kg−1. Our study provides an effective route to design magnetic functional materials with zero magnetostriction.

Investigation of Piezomagnetism in Nickel Ferrite

Applications of magnetostrictive materials, such as sensors and energy-harvesting devices, generally involve the use of the dynamic deformation, i.e., the piezomagnetic effect, induced by an exciting magnetic field H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ac</sub> . However, this effect is rarely measured directly but commonly approximated by the strain derivative ∂λ/∂H, which is deduced from the quasi-static magnetostrictive curve. In this article, we propose an investigation of the piezomagnetic effect in nickel ferrite by directly measuring the dynamic magnetostriction under various exciting fields using a dynamic strain-gauge setup. These values are compared with the strain derivative in order to disclose the limitations thereof. In addition, the magnetoelectric effect is measured in a ferrite/PZT bilayer and compared with the calculated magnetoelectric coefficient based on an analytical model. When the dynamic magnetostrictive coefficients are integrated into the calculation, good accuracy is found with experimental values, whereas it is not the case for calculated coefficients based on the strain derivatives. The findings of the present study highlight the importance of accurately characterizing the piezomagnetic effect in magnetostrictive materials in order to optimize their performances in dynamic applications.

Structural design and performance evaluation of FeCo/epoxy magnetostrictive composites

A class of FeCo/epoxy magnetostrictive composites is prepared in this study to explore the effect of the structural design of composites on the magnetostrictive properties. The experiments are divided into two groups according to the shape of the FeCo wires: to fabricate the FeCo/epoxy magnetostrictive composite, one experimental group uses twisted FeCo wires while the other uses straight FeCo wires. An experiment on harvesting bending-energy is conducted for these two groups to analyze the effect of the residual stress stemming from the twisted structure on domain rotation or wall movement. By considering the magnetization and magnetostrictive curves, this work provides insights into the mechanism responsible for the improvement in magnetostriction of the magnetostrictive composite due to the effect of structural design. This study offers another concept of structural design differing from modification of the composition to improve the magnetostriction of the magnetostrictive composite. Meanwhile, this work also avoids reduction of the magnetostriction due to the discontinuous magnetostrictive powder and fiber that occurs in certain traditional magnetostrictive composites.

Origin of large magnetostriction in palladium cobalt and palladium nickel alloys: Strong pseudo-dipole interactions between palladium–cobalt and palladium–nickel atomic pairs

The origin of the large magnetostriction in palladium cobalt and palladium nickel alloys was investigated. Density functional theory calculations based on the Korringa–Kohn–Rostoker Green function method with the coherent potential approximation revealed that alloying with palladium results in increased magnetization of cobalt and nickel atoms. Also, anomalous magnetization of palladium atoms occurs simultaneously. Employing calculated spin and orbital angular momenta of the atoms, magnetostriction was discussed based on the two-spin model for disordered alloys. Under the assumption that the pseudo-dipole interaction is proportional to the orbital and total angular momenta, the experimental magnetostriction curves can be reproduced. The estimated contributions of each atomic pair to magnetostriction revealed that the large magnetostriction at the palladium-rich side originates from the strong pseudo-dipole interactions between 4d and 3d transition metal atoms, namely, palladium–cobalt and palladium–nickel atomic pairs.