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A positive magnetostrictive single layer (CoFe) and top-pinned spin-valve structure with positive magnetostrictive free (NiFe) and pinned (CoFe) layers were deposited on flexible polyethylene terephthalate film to investigate the changes in the magnetic properties in flexible environments, especially with a repetitive bending process. It was found that the stress, applied by repetitive bending, changes significantly the magnetic anisotropy of both layers in a single and spin-valve structure depending on the direction of applied stress. The changes in magnetic anisotropy were understood in terms of the inverse magnetostriction effect (the Villari effect) and the elastic recovery force from the flexibility of the polymer substrate. Repetitive bending with tensile stress transverse (or parallel) to the magnetic easy axis was found to enhance (or reduce) the magnetic anisotropy and, consequently, the magnetoresistance ratio of a spin-valve. The observed effects of bending stress in this study should be considered for the practical applications of electro-magnetic devices, especially magneto-striction sensor. [ABSTRACT FROM AUTHOR]

Results on the analysis of the magnetoelastic and magnetostatic contributions in the total free energy of nearly zero magnetostrictive amorphous glass-coated nanowires prepared by means of rapid solidification are reported. The comparative study shows that both terms have values of the same order. However, the magnetostatic term is the most important one over a wide range of dimensions, being responsible for the domain structure formation and for the overall magnetic behavior of the investigated nanowires, which mainly consists in the appearance of an axial magnetic bistability. Even in the thinnest samples, the magnetostatic contribution is essential, in spite of an important magnetoelastic one, too. Calculated results agree with the experimental hysteresis loop data. The results are a key for understanding and controlling the magnetization processes in these novel nanowires. [ABSTRACT FROM AUTHOR]

We develop high power magnetostrictive vibration power generator for battery-free wireless electronics. The generator is based on a cantilever of parallel beam structure consisting of coil-wound Galfenol and stainless plates with permanent magnet for bias. Oscillating force exerted on the tip bends the cantilever in vibration yields stress variation of Galfenol plate, which causes flux variation and generates voltage on coil due to the law of induction. This generator has advantages over conventional, such as piezoelectric or moving magnet types, in the point of high efficiency, highly robust, and low electrical impedance. Our concern is the improvement of energy conversion efficiency dependent on the dimension. Especially, force factor, the conversion ratio of the electromotive force (voltage) on the tip velocity in vibration, has an important role in energy conversion process. First, the theoretical value of the force factor is formulated and then the validity was verified by experiments, where we compare four types of prototype with parameters of the dimension using 7.0 × 1.5 × 50mm beams of Galfenol with 1606-turn wound coil. In addition, the energy conversion efficiency of the prototypes depending on load resistance was measured. The most efficient prototype exhibits the maximum instantaneous power of 0.73W and energy of 4.7 mJ at a free vibration of frequency of 202 Hz in the case of applied force is 25 N. Further, it was found that energy conversion efficiency depends not only on the force factor but also on the damping (mechanical loss) of the vibration. [ABSTRACT FROM AUTHOR]

Iron is a well-utilized material in structural and magnetic applications. This does not mean, however, that it is well understood, especially in the field of magnetostriction. In particular, the rhombohedral magnetostriction of iron, λ111, is anomalous in two respects: it is negative in sign, in disagreement with the prediction of first principles theory, and its magnitude decreases with increasing temperature much too rapidly to be explained by a power law dependence on magnetization. These behaviors could arise from the location of the Fermi level, which leaves a small region of the majority 3d t2g states unfilled, possibly favoring small internal displacements that split these states. If this view is correct, adding small amounts of Co to Fe fills some of these states, and the value of λ111 should increase toward a positive value, as predicted for perfect bcc Fe. We have measured the magnetostriction coefficients (λ111 and λ100) of pure Fe, Fe97Co3, and Fe94Co6 single crystals from 77K to 450 K. Resonant ultrasound spectroscopy has been used to check for anomalies in the associated elastic constants, c44 and c'. The additional electrons provided by the cobalt atoms indeed produced positive contributions to both magnetostriction constants, λ111 and λ100, exhibiting an increase of 2.8 × 10-6 per at.% Co for λ111 and 3.8×10-6 per at.% Co for λ100. [ABSTRACT FROM AUTHOR]

This paper presents two-dimensional magnetostriction of electrical steel sheet under vector magnetic characteristic. In conventional measurement method using Single Sheet Tester, the magnetic flux density, the magnetic field strength, and the magnetostriction have been measured in one direction. However, an angle between the magnetic flux density vector and the magnetic field strength vector exists because the magnetic property is vector quantity. An angle between the magnetic flux density vector and the direction of maximum magnetostriction also exists. We developed a new measurement method, which enables measurement of these angles. The vector magnetic characteristic and the two-dimensional magnetostriction have been measured using the new measurement method. The BH and Bλ curves considering the angles are shown in this paper. The analyzed results considering the angles are also made clear. [ABSTRACT FROM AUTHOR]

The spin configuration and spontaneous magnetostriction λ111 of TbxDy0.92-xNd0.1(Fe0.8Co0.2)1.93 (0.20⩽x⩽0.60) alloys have been investigated. The easy magnetization direction (EMD) at room temperature was observed towards the (111) axis when 0.40⩽x⩽0.60, accompanied by a rhombohedral distortion with large spontaneous magnetostriction coefficients λ111, which increases from 1640 ppm for x=0.40 to 1900 ppm for x=0.60. The strong (111)-oriented pseudo 1-3 particulate composite was fabricated by embedding and aligning particles in a passive epoxy matrix under an applied magnetic field. An enhanced magnetostrictive effect, the large low-field magnetostriction, λa, as high as 480 ppm at 3 kOe, was obtained for the sample of x=0.40, in an excess of 75% of its polycrystalline alloy although it only contains 27 vol.% alloy particles. This enhanced effect can be attributed to its low magnetic anisotropy, anisotropic magnetostrictive nature (e.g., λ111 ≠λ100, (111)EMD), chain structure, and the (111)-textured orientation. In addition, we give a direct experimental support that the (111)EMD of particle and the strong (111)-textured orientation are the crucial factors to realize the enhanced magnetostrictive effect in 1-3 particulate composites. [ABSTRACT FROM AUTHOR]

The (Tb0.3Dy0.7Fe1.9)1-x(Tb0.15Ho0.85Fe1.9)x alloys were prepared in an arc furnace under high purity argon. The as-cast samples wrapped in Mo foil were sealed in a silica tube filled with high purity argon and were homogenized at 1000 °C for 1 day and at 950 °C for 5 days. Then, the homogenized specimens with 5mm in diameter and 8mm in length were annealed under the magnetic field of 320 kA/m. The static measurement of magnetostriction (λ//, λ⊥) was made by standard strain gauge, and the magnetization M was measured by a vibrating sample magnetometer. It is found that the main phase of annealed (Tb0.3Dy0.7Fe1.9)1-x(Tb0.15Ho0.85Fe1.9)xalloys is the (Tb,Dy,Ho)Fe2 phase with the MgCu2-type structure. The magnetostriction λ// and magnetization M of (Tb0.3Dy0.7Fe1.9)1-x(Tb0.15Ho0.85Fe1.9)x alloys increases with increasing x from x=0.1 to x=0.3 when H<240 kA/m. The hysteresis becomes small with increasing x when x⩽0.3. For magnetically annealed rod alloys, the magnetostriction markedly increases and reaches 1080 × 10-6> for x=0.3 when H=240 kA/m. [ABSTRACT FROM AUTHOR]

This paper presents a fully coupled, nonlinear electromagnetic-mechanical-thermal model for Terfenol-D devices which include active magnetostrictive materials and passive components. The model includes two parts: (1) a material-level discrete energy-averaged model (DEAM) to describe the magnetomechanical coupling and thermal effect of Terfenol-D and (2) a system-level finite element model formulated in weak form using Maxwell's equations, Newton's law, and heat transfer equations. The objective is to describe the electromagnetic, mechanical, and thermal dynamics of the device. The system finite element model is constructed in COMSOL Multiphysics, and the nonlinear behavior of Terfenol-D is coupled through lookup tables generated by the DEAM. Preliminary results of the output capacity of a Terfenol-D actuator with respect to ambient temperature are presented in terms of blocked force, free displacement, and output power. The blocked force and free displacement decrease by 8.0% and 29.8%, respectively, for a 12A (RMS) excitation current, as the temperature increases from 20 °C to 180°C. One of the key contributions of this study is that it accounts for both the temperature-dependent Terfenol-D properties and the thermal effects of surrounding passive systems. [ABSTRACT FROM AUTHOR]

Magnetostrictive bending cantilevers are applicable for wirelessly measuring physical quantities such as pressure and strain. Exploiting the DE-effect, the resonance frequency of the cantilevers is shifted because of a change in the magnetic biasing field. The biasing field, in turn, depends on the applied pressure or strain, respectively. With a view to the application as a reliable sensor, maximum sensitivity but minimum hysteresis in the biasing field/resonance frequency dependence is preferred. In this contribution, monomorph bending cantilevers fabricated using magnetostrictive Fe49Co49V2 and Metglas 2605SA1 are investigated regarding their applicability for future sensors. For this purpose, the biasing field-dependent polarization of the magnetostrictive materials and bending of the cantilevers are determined. Furthermore, a setup to magnetically bias the cantilevers and determine the bending resonance frequency is presented. Here, the resonance frequency is identified by measuring the impulse response employing a laser Doppler vibrometer. The measurement results reveal that cantilevers made of Fe49Co49V2 possess a distinct hysteretic behaviour at low magnetic biasing field magnitudes. This is ascribed to the polarization and bending hysteresis. Cantilevers fabricated using Metglas 2605SA1 feature a lower resonance frequency shift compared to cantilevers with Fe49Co49V2, which would result in a lower sensitivity of the sensor. However, their resonance frequency hysteresis is almost negligible. [ABSTRACT FROM AUTHOR]

A dc magnetoelectric sensor operating in ac voltage driving mode is developed based on a piezoelectric-magnetostrictive heterostructure having four thickness-polarized Pb(Zr, Ti)O3 piezoelectric plates bonded symmetrically on a length-magnetized Tb0.3Dy0.7Fe1.92 magnetostrictive plate to give an electrically parallel input and an electrically series output. The dc magnetic field sensing in the sensor is evaluated theoretically and experimentally and is found to originate from a unique ac voltage-driven, dc magnetic field-tuned resonance dc magnetoelectric effect in the heterostructure. An interestingly high, linear, and negative ac voltage-controlled dc magnetic field sensitivity of -1.3 mV/Oe/V is obtained in a broad range of dc magnetic field of 0-400 Oe by referencing an ac voltage of ⩽5V peak amplitude and 116 kHz frequency at the input of the heterostructure. [ABSTRACT FROM AUTHOR]

Vibration based power generation technology is utilized effectively in various fields. Author has invented novel vibrational power generation device using magnetostrictive material. The device is based on parallel beam structure consisting of a rod of iron-gallium alloy wound with coil and yoke accompanied with permanent magnet. When bending force is applied on the tip of the device, the magnetization inside the rod varies with induced stress due to the inverse magnetostrictive effect. In vibration, the time variation of the magnetization generates voltage on the wound coil. The magnetostrictive type is advantageous over conventional such using piezoelectric or moving magnet types in high efficiency and high robustness, and low electrical impedance. Here, author has established device configuration, simple, rigid, and high power output endurable for practical applications. In addition, the improved device is lower cost using less volume of Fe-Ga and permanent magnet compared to our conventional, and its assembly by soldering is easy and fast suitable for mass production. Average power of 3 mW/cm³ under resonant vibration of 212 Hz and 1.2G was obtained in miniature prototype using Fe-Ga rod of 2 × 0.5× 7mm³. Furthermore, the damping effect was observed, which demonstrates high energy conversion of the generator. [ABSTRACT FROM AUTHOR]

We have investigated for the first time the combined effect of current and stress on the giant magnetoimpedance characteristics of vanishing-magnetostrictive Co-rich microwires at microwave frequency. As the current-annealed wire is subject to certain tensile stress, one can observe a drastic transformation of field dependence of magnetoimpedance (MI) profiles from smooth shape of a broad peak to deformed shape of a sharp peak with the emergence of a kink on each side. It follows that three different regions-core, inner, and outer shell-have been formed by the combined effect of Joule-annealing, current generated magnetic field, and the tensile stress. A critical field sees a drop of field sensitivity from outer to inner shell and shifts to lower value with increasing annealing current. We successfully adapted our core-shell model to a core-shell-shell model by designating different anisotropy fields for each region to satisfactorily resolve the unique double-curvature shaped peaks in the field derivative MI profiles. [ABSTRACT FROM AUTHOR]

Magnetostrictive behaviors under rotating magnetic fields are investigated for bcc(001) single-crystal films of Fe100-x-Six(x=0, 6, 10 at.%). The magnetostriction observation directions are along bcc[100] and bcc[110] of the films. The magnetostriction waveform varies greatly depending on the observation direction. For the observation along [100], the magnetostriction waveform of all the films is bathtub-like and the amplitude stays at almost constant even when the magnetic field is increased up to the anisotropy field. On the other hand, the waveform along [110] is triangular and the amplitude increases with increasing magnetic field up to the anisotropy field and then saturates. In addition, the waveform of Fe90Si10 film is distorted triangular when the applied magnetic fields are less than its anisotropy field. These magnetostrictive behaviors under rotating magnetic fields are well explained by employing a proposed modified coherent rotation model where the anisotropy field and the magnetization reversal field are determined by using measured magnetization curves. The results show that magnetocrystalline anisotropy plays important role on magnetostrictive behavior under rotating magnetic fields. [ABSTRACT FROM AUTHOR]

Air-coupled ultrasonic excitation is a relatively poorly studied method of nondestructive testing of polymer and composite materials. The combination of noncontact ultrasonic stimulation in conjunction with laser vibrometry can provide an assessment of the quality of the product without external influence on the tested material. This work is devoted to the study of an ultrasound diagnostic system based on the combined use of a noncontact magnetostrictive transducer and scanning laser Doppler vibrometry for nondestructive testing of polymer and composite materials. We believe that such combination can provide sufficient power for rapid detection of defects, while the optimization of the experimental conditions increased the efficiency of testing results. Measurement of the directional diagram of the magnetostrictive transducer has made it possible to determine the features of the radiation of the magnetostrictor in an assembly with a titanium step-type waveguide. [ABSTRACT FROM AUTHOR]

The acoustically driven spin-wave resonance in a phononic-crystal cavity is numerically investigated. The designed cavity enables confinement of gigahertz vibrations in a wavelength-scale point-defect structure and sustains a variety of resonance modes. Inhomogeneous strain distributions in the modes modify the magnetostrictive coupling and the spin-wave excitation susceptible to an external-field orientation. In particular, a monopole-like mode in the cavity having a near-symmetrical pattern shows a subwavelength-scale mode volume and can provide a versatile acoustic excitation scheme independent of the field-angle variation. Thus, the phononic-crystal platform offers an alternative approach to acoustically control the spin-wave dynamics with ultrasmall and inhomogeneous mode structures, which will be a key technology to integrate and operate large-scale magnomechanical circuits. [ABSTRACT FROM AUTHOR]

Asynchronous machines are omnipresent in automated production systems, due to their robustness and ease of use. These electric motors, however, also concede faults (e.g. short-circuit between turns) leading to unplanned stoppages. Defects with their effects are reflected in the magnitudes of the motors, mainly in flux, current, speed and torque. Our research work in this article presents a contribution of a new approach to the fault tolerant control. This simple and efficient method based solely on the measurement of the electrical energy applied by the magnetostrictive material requires expert knowledge in the field of intelligent materials. In this work, our method is focused on an additive term in the backstepping control that is based on the error of the current during the appearance of the default and the energy recovered by magnetostrictive sensors and the adaptive gain of the Kalman filter. This method improves the performance of backstepping control to maintain the operation despite the appearance of defects. The target is to ensure a minimum performance level of the drive system that is malfunctioning. The obtained results have provided useful information on multiple electrical malfunctions and show the overall performance of this complementary methodology for the fault tolerant control. [ABSTRACT FROM AUTHOR]

A force-driven kinetic energy harvester, designed to be excited with impulse-like mechanical loads, is presented. Energy harvesting is a promising technique to feed wireless sensor networks. The proposed device exploits three rods of Galfenol and has been modeled through FEM COMSOL Multiphysics with nonlinear fully coupled characteristics. They consider the general behaviors of magnetostrictive materials and are compatible with thermodynamics. The preliminary results of the time-domain simulations, with an impulse-like force applied, have been compared with experimental results showing a good agreement. Moreover, the proposed nonlinear modeling has shown better performances with respect to software built-in magnetostrictive models. At the same time, further modeling improvements seem to be needed in the future to better fit the harmonic content of the free evolution of the device. [ABSTRACT FROM AUTHOR]

• An optical fiber weak magnetic sensing system based on Michelson interferometer is proposed. • A new improved phase-generated carrier demodulation algorithm. • Suitable for optical fiber interference weak signal demodulation. • The sensing unit support frame was fabricated using 3D printing. The detection of weak magnetic fields is integral to applications in geophysical monitoring, biomagnetism, and remote sensing. This paper presents a new sensing unit structure and signal demodulation algorithm for optical fiber weak magnetic sensing system. The system uses a strip-ring sensing unit structure that combines magnetostrictive effects with optical fibers through 3D printing technology. This integration facilitates the conversion of magnetostrictive displacement into optical phase. An improved Phase Generated Carrier (PGC) algorithm is employed to demodulate the phase information, enhancing the signal to noise ratio (SNR) by 4.33 dB compared to the traditional PGC algorithm, and achieving a phase resolution of 29.51 µrad/Hz1/2 at 500 Hz. Experimental results demonstrate that the suggested sensing system can detect a minimum magnetic field of 140 nT, with an AC magnetic field phase resolution of 15.78 nT/Hz1/2 at 500 Hz. The demodulation sensitivity reaches 1.87 × 10−6 rad/nT under a magnetic field of 140–1400 nT. The capability of the proposed system demonstrated great potential as an efficient approach for detecting weak magnetic signals in many practical applications. [ABSTRACT FROM AUTHOR]

Delta-E effect sensors are based on magnetoelectric resonators that detune in a magnetic field due to the delta-E effect of the magnetostrictive material. In recent years, such sensors have shown the potential to detect small amplitude and low-frequency magnetic fields. Yet, they all require external magnetic bias fields for optimal operation, which is highly detrimental to their application. Here, we solve this problem by combining the delta-E effect with exchange biased multilayers and operate the resonator in a low-loss torsion mode. It is comprehensively analyzed experimentally and theoretically using various kinds of models. Due to the exchange bias, no external magnetic bias fields are required, but still low detection limits down to 350 pT / Hz at 25 Hz are achieved. The potential of this concept is demonstrated with a new operating scheme that permits simultaneous measurement and localization, which is especially desirable for typical biomedical inverse solution problems. The sensor is localized with a minimum spatial resolution of 1 cm while measuring a low-frequency magnetic test signal that can be well reconstructed. Overall, we demonstrate that this class of magnetic field sensors is a significant step towards first biomedical applications and compact large number sensor arrays. [ABSTRACT FROM AUTHOR]

In this study, a giant magnetostrictive ultrasonic transducer was designed with Terfenol-D as the active material. The influence of different Terfenol-D rod structures on the performance of the giantmagnetostrictive transducerwas investigated. Finite element analysis was used to analyze the dynamics of the theoretical giant magnetostrictive transducer and to validate the design. Eddy current losses were simulated for Terfenol-D rods of various structures using finite element analysis in ANSYS Maxwell. Two different Terfenol-D rods were then fabricated with either slices along the axial direction or slit along the radial direction, then the impedance and amplitude of the magnetostrictive ultrasonic transducer composed of the two Terfenol-D rods were measured. The results suggest that sliced Terfenol-D rods can suppress eddy currents more effectively, resulting in higher energy conversion efficiency; therefore, the Terfenol-D rods of small giant magnetostrictive transducers should be sliced along the axial direction to suppress eddy currents, whereas radial slits should be adopted for the rods of large giant magnetostrictive transducers to ensure integrity of the Terfenol-D rod and avoid adverse effects on the vibration performance of the giant magnetostrictive transducer that are caused by cutting the rods. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Electric current sensors are widely utilized in high-frequency power and electronic circuits which spread over numerous industries. Here, a current sensor based on the high-Q whispering gallery mode optical capillary microresonator filled with Terfenol-D nanoparticles is experimentally demonstrated. The device shows a peak AC current sensitivity of 5.285 μA Hz−1/2 with a corresponding high accuracy of 0.0009%. It possesses a wide detection frequency bandwidth of approximately 12 MHz and exhibits good linearity, enabling for partial discharge signals detection. [ABSTRACT FROM AUTHOR]

Magnetostrictive amorphous ribbons are widely used in electronic article surveillance as well as for magnetoelastic sensors. Both applications utilize the fact that the ribbons' resonant frequency can be read out remotely by applying external magnetic AC fields. This paper proposes a magnetomechanical model to simulate the dynamics of such ribbons. The goal was to only use general material properties as input parameters, which are usually denoted in the data sheet of amorphous metals. Thus, only the magnetization curve at zero stress has to be gained via measurement. The magnetization under stress is calculated thereof. The equation of motion for a longitudinally oscillating ribbon is derived and coupled to Maxwell's equations for magnetostatics. The fully coupled initial value problem is solved simultaneously by a finite difference approach. The model is validated by comparing calculated and measured resonant frequencies of various amorphous ribbons, which turned out to be in good agreement. When slightly adapting single material properties from the data sheet, the match is almost perfect. The model is then used to calculate the local magnetic and mechanical properties inside static and vibrating ribbons. These local distributions can be directly linked to the field dependence of the resonant frequency and its higher harmonics. [ABSTRACT FROM AUTHOR]

Because the performance of giant magnetostrictive materials (GMMs) can vary at different temperatures, the positioning accuracy of a giant magnetostrictive actuator is affected by heat. In this work, a new simplified control strategy under compulsory water cooling is proposed to maintain a constant GMM temperature. Based on this strategy, a coupled turbulent flow field and temperature field finite element model is created for a GMM smart component. The model is simulated using COMSOL Multiphysics software version 5.3. Through simulations, the temperature field distribution of GMM smart components is analysed under different drive input currents and cooling water flow rates. Based on the obtained simulation results, a GMM intelligent component temperature control device is constructed. The experimental results are in good agreement with the simulation results; a thermostatic control effect is achieved in the thermostat of the giant magnetostrictive rod. Thus, the proposed temperature control strategy is proven effective via simulations and experiments. [ABSTRACT FROM AUTHOR]

The magneto-mechanical effect combines the magnetic field and stress σ, making it an important approach for detecting stress concentration and microscopic failure in electrical machines. Alloy sheets as Fe-Si3% used in mechanical structures are subject to the effect of both magnetic and mechanical constraints, but the effects of a mechanical stress on this type of alloy are not widely considered. In previous work, a theoretical approach was proposed, which was obtained by incorporating, in the classical effective field model given by Jiles-Atherton (JA), the effect of an equivalent stress demagnetizing field denoted Hdϭ. Presence of this parameter explains the asymmetry in the change of magnetization under the conditions of tensile and compressive stress. Stress concentration affects all properties of the material. The intermolecular interaction inside the sheet defined by the classical domain coupling factor α is one of more parameters which is affected and need to be modeled. This paper proposes to elaborate a new model based on the merits of the previous approach. An accurate model denoted αeff is thus developed. The evolution of αeff and the magnetostrictive behaviors are simulated at an average frequency f = 50 Hz under tensile stresses. The obtained results are compared with some reported ones; the tendency is shown to be in concordance with those published. [ABSTRACT FROM AUTHOR]

In this work we present a detailed study on the magnetostrictive contribution to Poisson ratio for samples under applied mechanical stress. Magnetic contributions to strain and Poisson ratio for cubic materials were derived by accounting elastic and magneto-elastic anisotropy contributions. We apply our theoretical results for a material of interest in magnetomechanics, namely, galfenol (Fe1-xGax). Our results show that there is a non-negligible magnetic contribution in the linear portion of the curve of stress versus strain. The rotation of the magnetization towards [110] crystallographic direction upon application of mechanical stress leads to an auxetic behavior, i.e., exhibiting Poisson ratio with negative values. This magnetic contribution to auxetic behavior provides a novel insight for the discussion of theoretical and experimental developments of materials that display unusual mechanical properties. [ABSTRACT FROM AUTHOR]

Here, in order to calibrate the magnetostrictive liquid-level meter in situ, a set of in-situ calibration device for magnetostrictive liquid-level meter is designed. The structure and working principle of the device are described, and the experimental test and error analysis are carried out for the parts of the in-situ calibration device. Finally, according to the modern instrument and error theory, the accuracy of the calibration device is assessed, and the field calibration experiment of magnetostrictive liquid level gauge is carried out. The theoretical analysis and field experiment results show that the calibrated device can meet the in-situ calibration requirements of the magnetostrictive liquid-level meter with a range of 0–6 m and a precision of 1 mm.

High-speed electric machines operate at tens of thousands of revolutions per minute. The rotor and stator cores experience high-frequency electromagnetic fields. While the magnetic characteristics are available at 50/60 Hz, magnetic characteristics are required over a wide range of frequency due to variable speed operation of high speed motor. In this article, tests are carried out on ferromagnetic alloys over a frequency range of 1 Hz to 5 kHz and flux densities ranging from 0.1 to 2 T. The materials considered include the widely used M36 and 65C600 laminations. In applications where the rotor speed and shaft temperature are high, solid core rotors are more viable than laminated ones. Furthermore, the application requires that the shaft and active magnetic parts of the rotor be made of a single material. Hence, EN353 and EN8 are the prospective rotor materials considered. An extensive experimental study on the magnetic characteristics of these materials over a wide frequency range is reported in this article. The flux density variation over the core length at different frequencies is analyzed using finite element analysis. The results include B-H curves, static magnetisation curves, and power loss curves. The loss curves are useful to evaluate the loss density in the magnetic material at different frequencies and for various values of peak flux densities. These experimental data are essential for the analysis, design, and performance evaluation of high-speed electric machines. [ABSTRACT FROM AUTHOR]

This paper presents a quasi-3D electromagnetic analysis of the multi-pole magnetization BLDC motor. The permanent magnet (PM) of a multi-pole magnetization BLDC motor has several poles in a magnet. The polar separation section of the multi-pole PM is implemented through the magnetization pattern function. The analysis model of this study, as the outer rotor type, has two 3D structures: the PM overhang and housing-integrated rotor core. Because the 3D analysis is time consuming, 3D structures are corrected to 2D analysis model. The PM overhang is corrected by considering the magnitude of magnetic energy, and the housing-integrated rotor core is corrected by considering the radial direction flux of the rotor core. Finally, the corrected 2D analysis model of a multi-pole magnetization BLDC motor is verified experimentally. [ABSTRACT FROM AUTHOR]

Here, in order to calibrate the magnetostrictive liquid-level meter in situ, a set of in-situ calibration device for magnetostrictive liquid-level meter is designed. The structure and working principle of the device are described, and the experimental test and error analysis are carried out for the parts of the in-situ calibration device. Finally, according to the modern instrument and error theory, the accuracy of the calibration device is assessed, and the field calibration experiment of magnetostrictive liquid level gauge is carried out. The theoretical analysis and field experiment results show that the calibrated device can meet the in-situ calibration requirements of the magnetostrictive liquid-level meter with a range of 0–6 m and a precision of 1 mm. [ABSTRACT FROM AUTHOR]

The frequent accident due to external short circuit of lithium-ion batteries in electric vehicles have prompted people to develop sensing technology to achieve early warning. However, the limited space and high temperature in highly integrated lithium-ion battery packs present significant challenges for current sensors to achieve external short circuit monitoring with high structural flexibility and heat resistance. In this study, a piezoelectric elastomer is designed and blended with magnetostrictive ferric tetroxide to prepare the LMPE/Fe 3 O 4 magnetoelectric current sensor (LMPE/Fe 3 O 4 MCS). The amorphous structure and low modulus of the piezoelectric elastomer enable the LMPE/Fe 3 O 4 MCS to exhibit large deformability over 50 % elongation, and the non-ferroelectric LMPE and ferric tetroxide with high Curie temperature offer the LMPE/Fe 3 O 4 MCS with high heat resistance over 150 °C. Meanwhile, the excellent interfacial interaction between the piezoelectric elastomer and the ferric tetroxide eliminates stress transfer loss between the interface, presenting outstanding magnetoelectric response and excellent linearity (>0.99) with current sensitivity of 5.975 mV A−1. The LMPE/Fe 3 O 4 MCS can achieve real-time monitoring and early warning for external vibration and short circuit during the charging and discharging process of lithium batteries, which shows promising solutions for the safety improvement of electric vehicles. • LMPE and Fe 3 O 4 were combined to prepare magnetoelectric current sensor MCS. • The MCS is obtained with self-powered, heat resistant, cost-effective, etc. • The MCS can achieve real-time monitoring and early warning for ESC. • The MCS has potential for electric vehicle battery safety applications. [ABSTRACT FROM AUTHOR]

The diode is used as the detection unit to receive the millimetre-wave signal directly. A circuit is made with an operational amplifier OP27 to amplify the signal. The magnification of the OP27 circuit is stable at 100

A partitioned stator-flux reversal (FR) permanent magnet machine (PS-FRPMM) is a new combination of a stator PM machine and a magnetically geared machine and has the specifications of both machines in terms of robust structure and torque density. In this paper, a comprehensive 2-D analytical model is developed for PS-FRPMM based on subdomain technique. The presented model has the capability to accurately and quickly investigate the effects of design parameters on the machine performance. The 2-D analytical model is evaluated on two case studies with 12 stator teeth and 10 rotor poles, and 18 stator teeth and 13 rotor poles, with four different magnetization patterns. The influences of various design parameters such as the rotor slot width, slot opening width, and the segment ratio of the PMs in the two-segment magnetization pattern have been investigated on the quantities, such as the instantaneous torque, torque ripple, unbalanced magnetic force (UMF), and electromotive force (EMF). For evaluating the presented analytical model, the 2-D finite element method (FEM) with and without saturation effects has been used. The comparative study between the analytical and numerical models shows good agreement. Finally, a 3-D FEM has been used, and the results of the 2-D analytical model and 3-D FEM are compared in terms of the accuracy and computational time. The results show that the presented model has lower computational time compared to the 2-D and 3-D FEM, while its accuracy is acceptable under different circumstances, such as saturation. [ABSTRACT FROM AUTHOR]

One of the best vibration control methods using smart actuators are semi-active approaches which are as strong as active methods and need no external energy supply such as passive ones. Compared with piezoelectric-based, magnetostrictive-based control methods have higher coupling efficiency, higher Curie temperature, higher flexibility to be integrated with curved structures and no depolarization problems. Semi-active methods are well developed for piezoelectrics but magnetostrictive-based approaches are not as efficient, powerful and well known as piezoelectric-based methods. The aim of this work is to propose a powerful semi-active control method using magnetostrictive actuators. In this paper a new type of semi-active suppression methods using magnetostrictive materials is introduced which contains an equipped vibrating structure with magnetostrictive patches wound by a pick-up coil connected to an electronic switch and a capacitor. The novelty of the proposed damping method is switching on the coil current signal using mentioned switch and capacitor, which is briefly named SSDC (synchronized switch damping on capacitor). In this paper, the characteristics of the semi-active pulse-switching damping technique with magnetostrictive materials are studied and numerical results show significant damping for almost all types of excitations. [ABSTRACT FROM AUTHOR]

One of the main cause of acoustic noise from iron core in electrical machines is magnetostriction. However, good reproducibility of magnetostriction measurement cannot be expected due to its ppm-order value. To measure the magnetostriction accurately, it is required to clarify principal factors affecting the measurement accuracy. In this paper, a high-resolution method of measuring magnetostriction by means of an open-type single sheet tester equipped with double laser Doppler vibrometers is investigated. It is revealed that the odd components of a magnetostriction waveform should be removed as noises because the reproducibility of odd harmonic components is low. To improve the reproducibility, the friction between a test specimen and a support plate installed under the specimen should be reduced. Furthermore, it is demonstrated that the developed measuring system can be also applied to magnetostriction measurement of Fe-based amorphous sheets. [ABSTRACT FROM AUTHOR]

WC-Ni composite coatings were fabricated on Ti-6Al-4V alloy substrates by laser cladding under high frequency micro-vibration. The microstructure, phase composition, microhardness and wear resistance of the cladding coatings were investigated by X-ray diffractometer (XRD), scanning electron microscope (SEM), energy disperse spectroscope (EDS), microhardness tester and friction and wear testing apparatus, respectively. The high frequency micro-vibration produced by a vibration exciter system made of magnetostrictive materials was used to assist laser cladding of nickel composite coatings. The effects of high frequency micro-vibration on the microstructure and properties of the cladding coatings are investigated. The results showed that high frequency micro-vibration promoted the formation of W 2 C and (Ti, W)C during the laser cladding process. Alloying carbide with rich tungsten is uniformly distributed in eutectic (Ti) Ni solid solution under the vibration frequency of 556 Hz, with some new W 2 C phases generated in the composite coating. In addition, at the bonding interface, the number of coarse dendrites is continuously reduced and that of fine grains is gradually increased. Appropriate increase of vibration frequency contributes to the refinement of the grains. The vibration makes the coating microstructure more uniform, which helps to reduce the microhardness fluctuation in the cladding coating. With the help of the fine-grained hard phase, the microhardness of the cladding coating is enhanced by the vibration. By choosing appropriate vibration parameters, high frequency micro-vibration helps to decrease the friction coefficient and wear loss of the composite coating. • Laser cladding WC-Ni coatings are obtained under high frequency micro-vibration. • Appropriate increase of vibration frequency is helpful to refine the microstructure. • The performance of the WC-Ni composite coatings are improved by the vibration. [ABSTRACT FROM AUTHOR]

Torque measurements are used in a number of controls applications, but indirect coupling, size, and the quality of commercially available sensor materials can limit their utility. Here, a compact magnetostrictive torque sensor is made by electrodeposition of Fe1–xGax (0.1

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The magnetostrictive inkjet printhead (MagJet), an example of the 1-D magnetostrictive actuator (MA), consists of one MA, a nozzle, a chamber, and a fluid inlet. The mathematical estimation tells that the droplets are not likely to be made due to the inverse of Ohnesorge number less than one. The experimental results, however, show that the MagJet ejects the high viscosity fluid up to 1000 cP at room temperature. The magnetostrictive motor (MagMotor), an example of the 2-D MA, is composed of one Terfenol-D rod, one toroidal coil, one solenoid coil, a stator, a rotor, and housing. The experimental results show that the MagMotor rotates successfully up to 60 rpm, and about an arbitrary axis. [ABSTRACT FROM AUTHOR]

The present study shows fabrication of electronic resistor by means of inexpensive inkjet printing method on the photonic paper substrate at room temperature. The objective of this work is to demonstrate the feasibility of the inkjet printed resistor with different resistance values for the application of electronic devices. Inkjet printing process is performed using magnetostrictive inkjet printhead designed by our laboratory which use a magnetostrictive material, Terfenol-D rod as an actuation mechanism. For printing resistor component on the photonic paper substrate, we use two functional inks: one is the silver nanoparticle ink, which is used to make conducting layer, the other one is poly (3,4-ethylene dioxythiophene): poly (styrene sulfonate) (PEDOT:PSS) ink, which is used to make resistive layers. The resistivity of the printed resistor is altered with different resistance values with respect to the printing layers, different ink formulations, and length of the resistor line. An electronic circuit is sketched and tested using fabricated resistor component. The printed resistor with various resistance values provides an important building block for low cost, printed electronic circuit application. From these results, we can show that magnetostrictive inkjet printhead has a potential to fabricate electronic devices. [ABSTRACT FROM AUTHOR]

In this paper, a vibrational drilling tool using a magnetostrictive torsional transducer is designed and fabricated. The torsional transducer is a hollow cylinder, which is made up of "2 V permendur." Passing an alternating current through the material creates a variable circular magnetic field and exciting a coaxial coil with a direct current generates a constant axial field in the material. According to the Wiedemann effect, the magnetic domains of the material rotate helically in the direction of the external field and cause a shear strain in the material. To utilize the maximum torque and amplitude of the transducer as well as to maintain the transducer's resonance conditions, a wave transmitter is designed to connect the transducer to a drill bit. The dimensions of the vibrating tool are calculated theoretically and verified by the finite element software of COMSOL. Friction couplings are designed to connect the transducer, wave transmitter, and the drill bit. This torsional drilling tool is used for drilling of aluminum workpieces. The tests show that torsional vibrations reduce the required drilling torque by 60% in comparison to conventional drilling. In addition, usage of the torsional vibrations has the effect of the chip breaking, improving the accuracy of the hole size by 55.4%, and reducing the drilling surface roughness by the percent of 25.3% in comparison to conventional drilling. [ABSTRACT FROM AUTHOR]

This paper presents a theoretical and experimental study on high-frequency (>5000 Hz) output characteristics of the giant magnetostrictive transducer (GMT) at varied operating conditions. Based on the Jiles–Atherton model, Maxwell’s equations, Newton’s law, and Fourier’s heat transfer equation, a nonlinear electromagnetic–mechanical–thermal multi-field coupled finite element model for GMT is established. The output displacement amplitude of the magnetostrictive rod and the acceleration of vibrating horn at the GMT device are measured and analyzed at varied exciting amplitude of ac magnetic field and frequencies (from 5600 to 7000 Hz). The frequency dependences of permeability and magnetoelastic coupling coefficient obtained from the experimental results are used in revising the model parameters. These output characteristics analysis results can provide theoretical and experimental guidance in the optimization of structural design and precise controlling for high-frequency GMT system. [ABSTRACT FROM AUTHOR]

The stator vibrations of a bearingless synchronous reluctance motor are investigated with simulations. The influence of the Maxwell stress tensor and magnetostriction on the stator vibrations is studied at different operational conditions. An energy-based magnetomechanical model of iron core is implemented and the influence of the magnetostriction in the iron core on the stator vibrations is further investigated and compared with the case where the magnetostriction is not modeled. The objective of the research is to find out how the stator vibrations can be used to detect the off-center rotor position. The results show that a single frequency component is not able to assess this phenomenon but a combination of two components makes it possible. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Highlights • Development of 1–2 type BaTiO 3 /CoFe 2 O 4 magnetoelectric thin films. • Synthesis of individually free-standing TiO 2 nanotubes via Ti anodizing. • Hydrothermal conversion of BaTiO 3 from TiO 2 nanotubes. • Dense filling of CoFe 2 O 4 in an interspace between BaTiO 3 nanotubes. Abstract In this study, individually free-standing piezoelectric nanotubes-based magnetoelectric thin films were synthesized by complexation of one-dimensional (1D) BaTiO 3 as the piezoelectric phase, and CoFe 2 O 4 as the magnetostrictive phase. Particularly, the individually TiO 2 free-standing nanotubes were developed onto a Ti substrate via metal anodizing to obtain a high standing stability of 1D piezoelectric structure and a filling volume of magnetostrictive phase, simultaneously for fabrication of magnetoelectric thin films. After BaTiO 3 perovskite conversion from the TiO 2 nanotubes, an enough volume still remains for sufficient self-filling of CoFe 2 O 4 between the BaTiO 3 nanotubes. Finally, BaTiO 3 /CoFe 2 O 4 magnetoelectric films were found to exhibit a dense structure being suitable for strong magnetostriction-mediated piezoelectric voltages. The structure design, based on individually free-standing nanotubes, would be feasible for flexible magnetoelectric devices such as health monitoring sensors, energy harvesters, and memory devices. [ABSTRACT FROM AUTHOR]

Tb–Dy–Fe–Co thin films grown on Si 100 substrates at different substrate temperatures viz., room temperature, 300, 400 and 500 °C were investigated for structural, microstructural, magnetic and magnetostrictive properties. Grazing incidence X-ray diffraction studies showed presence of amorphous structure for the as-deposited film. Structural studies further indicated formation of (Tb,Dy)2(Fe,Co)17 and Fe–Co phases for the films grown at higher substrate temperatures. Magnetization measurements displayed presence of strong in-plane magnetic anisotropy for all the films. In addition to this, formation of out-of-plane magnetic anisotropy co-existing with in-plane magnetic anisotropy was noticed for the films grown at higher substrate temperatures. Accordingly, magnetic force microscopy studies indicated a strong out-of-plane magnetic contrast for the films grown at higher substrate temperatures. The magnetostriction estimated from tip deflection measurement was found to be negligibly small for the film grown at intermediate temperature viz., 300 °C. However, with subsequent increase in substrate temperatures the magnetostriction was found to increase. The presence of strong out-of-plane magnetic anisotropy co-existing with in-plane components was found to be detrimental for the development of magnetostriction. [ABSTRACT FROM AUTHOR]

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It is shown theoretically that applying magnetic fields can modulate the strength of ionic bonds on the surface of a ferroelectric film via field-induced strains from a magnetostrictive substrate. The ionic bonds form between oppositely charged polyelectrolytes that are bonded to the ferroelectric surface via the Coulomb interaction. The calculations show that applying a magnetic field can tune the activation energy of bond dissociation up by ∼50% or down to zero. This large modulation results from the high sensitivity of ferroelectric surface polarization to strain variation near ferroelectric phase transitions, which occur in epitaxial BaTiO3 films at experimentally accessible residual strains. Our results suggest an opportunity for tailoring the ionic bond strength on ferroelectric surfaces both statically and dynamically via strain engineering. [ABSTRACT FROM AUTHOR]

This paper presents the vibration analysis and results of an induction motor through two kinds of magneto-mechanical coupling methods. The computation results are validated by comparing them with the vibration measurements of the motor. The role of both the magnetic forces and magnetostriction are examined and distinguished based on their contribution to the vibration behavior of the machine. It was found that the pole pair number of an induction machine can affect the way the vibrations caused by magnetostriction and magnetic forces either add up or oppose each other. [ABSTRACT FROM AUTHOR]