Magnetostrictive Vibration Research Articles

Vibration-Based Scour-Detection for Bridge-Piers Using a Self-Powered Magnetostrictive Vibration Sensor

Vibration-Based Scour-Detection for Bridge-Piers Using a Self-Powered Magnetostrictive Vibration Sensor

Nonlinear Model for Magnetostrictive Vibration Energy Harvester Considering Dynamic Forces

Nonlinear Model for Magnetostrictive Vibration Energy Harvester Considering Dynamic Forces

Characterization of magnetostrictive bi-stable rotational vibration energy harvester with integrated centrifugal effect

Rotational machinery is a common presence in dust still production, and the occurrence of operational failures in components like engines and turbine blades necessitates effective measures. To solve this challenge, remote structural health monitoring using energy harvesting and wireless sensors has been widely employed to realize self-powered sensing. This study proposes a magnet-induced bi-stable rotational energy harvester (REH), which utilizes the centrifugal effect to broaden the effective frequency bandwidth, enabling efficient energy harvesting in complex environments. A comprehensive mathematical model has been established to facilitate the dynamic characteristics of the bi-stable system, taking into account the centrifugal effect. The theoretical results demonstrate that the gap distance of magnetic configuration has great effects on the bi-stable system. Additionally, the centrifugal effect decided by the centrifugal radius and rotational speeds also affects the stable high-energy orbit oscillations. Furthermore, experimental results indicate that the proposed REH can effectively operate within the frequency range of 230–290 rpm, with a maximum RMS voltage of 780 mV and corresponding power of 4.35 mW. These findings validate the performance of the bi-stable magnetostrictive REH with the centrifugal effect and indicate its potential to effectively address the power supply challenges for wireless sensors. Overall, this study presents a promising solution for enhancing the energy harvesting performance of REH and also provides insights into the design of high-efficiency REH by magnet-induced nonlinearity and the centrifugal effect.

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

Magnetostrictive Vibration Characteristics of Amorphous Alloy Transformer With Three-Dimensional Wound Core

Magnetostrictive Vibration Characteristics of Amorphous Alloy Transformer With Three-Dimensional Wound Core

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.

Evaluation of the incubation period of polymers in cavitation wear by the method of profilometry

The possibility of using profilometry for determining the duration of the incubation period of polymeric materials upon their testing for cavitation wear is considered. Six polymeric materials were tested for cavitation wear: plexiglass, fluoroplastic, low-pressure polyethylene, caprolon, Thordon SXL polymer, and epoxy compound. All the polymers were tested in fresh water kept at 20 ± 3°C, using an ultrasonic magnetostrictive vibrator, the vibration frequency and amplitude of the device horn butt were 22 kHz and 28 μm, respectively. The distance between horn butt and the butt-end surface of the cylindrical polymer sample was set at 0.50 mm. The samples were periodically weighed during testing, the roughness of their worn surface was evaluated, and sample mass loss and arithmetical mean deviation of the assessed profile of its surface were plotted as a function of the test duration. Like the cavitation wear of metals, the cavitation wear of polymers is also characterized by the presence of an incubation period, during which the separation of the wear particles from the sample surface does not take place yet. It is shown, that determination of the incubation period from the dependence of the mass loss vs test duration distinguishes is rather laborious, and, moreover, is accompanied by large errors due to water absorption. The use of profilometry was proposed to shorten the time and increase the accuracy of the determination of the incubation period of the cavitation wear of polymers. The arithmetical mean deviation of the profile of the surface under study is measures periodically during testing for cavitation wear. The duration of the incubation period is determined using the dependence of the arithmetic mean deviation of the wear surface profile on the duration of the cavitation impact by the abscissa of the point, in which the monotony and(or) smoothness of the dependence (plot) is violated.

Application of electroplated Ni–Fe thick film to magnetostrictive material in vibration power generator

Ni100−xFex (at. %) films of about 37 μm thickness are electroplated on Cu base plates of 50 mm length, 10 mm width, and 300 μm thickness by varying the composition from x = 0 to 99. They are applied to cantilevers in magnetostrictive vibration power generators. The influences of magnetic and magnetostrictive properties of electroplated film on the vibration power generation property are systematically investigated. The films with x = 41–65 show low coercivities of about 4 Oe reflecting the low magnetocrystalline anisotropy constants. Large negative magnetostriction is recognized for the films with x = 0–14, whereas large positive magnetostriction is observed for the films with x = 57–80. The cantilevers are vibrated at the respective resonance frequencies of about 105–115 Hz and with the acceleration of 1.5 G while applying the bias magnetic field in a range of 0–300 Oe along the length direction. The output voltages are detected by using a coil with 8000 turns. Peak voltages higher than 1 V are obtained for the films with x = 61–65 whose coercivities are low and magnetostrictions are large. The present study has shown that an Ni–Fe film not only with large magnetostriction but also with low magnetic anisotropy constant is useful as the magnetostrictive material in vibration power generator.

Method of assessment of cavitation-erosion wear resistance of metals in electrolyte media

The paper considers a method of assessing the cavitation-erosion wear resistance of metals, which can be used to obtain data on the cavitation-erosion wear resistance of materials and coatings in laboratory conditions, which correspond to the data of operational tests. The essence of the method is the intensification of corrosion processes during cavitation-erosive wear of samples on a magneto-strictive vibrator (MSV) with the help of their anodic polarization. The value of the polarization current is found by the values of the coefficient of amplification of the mechanical factor of the destruction of the surface during tests on a magneto-strictive vibrator (MSV) and the data of field tests. Corrosion current in a given environment is found during full-scale tests. To reduce the labor intensity and time of research, operational data is obtained on a specially designed and manufactured installation, which is a simplified version of a hydrodynamic tube (HT). The developed assessment method applies only to corrosive electrolyte environments.

Determination of Critical Stresses in Frozen Soils Under Wave Acoustic Loading

The issues related to the development of permafrost and seasonally frozen soils without their preliminary loosening by various earthmoving machines with active working bodies, magnetostrictive vibrators, that soften dense and frozen soils using acoustic elastic waves, are considered. The analytical studies allowed us to establish the regularities of the process of destruction of frozen soil by active teeth of bucket working bodies, according to which, the formulas for calculating the critical tensile stress and shear resistance were obtained. The research results allow us to determine the main parameters of wave loading for both a single radiation source and a group of "n" in-phase radiation sources. The intensity of the acoustic field from the group of "n" emitters increases in proportion to the number of vibration exciters.

Magnetostrictive Vibration Harvester with a Multistage Amplifier and Its Application in Human Walking Energy Harvesting

In this paper, as a theoretical basis, a foot vibration harvester with a finite support mechanism is proposed based on the Villari effect of magnetostrictive materials and Faraday’s law of electromagnetic induction, where a rod-shaped Terfenol-D is used as a core element for energy conversion, and a multi-stage force amplification mechanism is used as a core mechanical structure. The purpose of the amplification mechanism is to amplify the input force provided to the Terfenol-D rod and increase the output electric power. Moreover, the amplification mechanism is designed based on the bridge amplification structure, microlever amplification structure, and wedge amplification mechanism. A mathematical model of the amplification mechanism was developed using the force analysis and unit stiffness matrix methods, and the size and structure were designed and optimized. The performed simulations yielded an output force amplification ratio of 18.04. Based on the optimization results, a prototype was fabricated, and experiments were conducted. Specifically, experiments on the effect of the bias magnetic field on the harvester’s harvesting capability were performed, and the operating characteristics were tested for one complete cycle. Moreover, the effects of the amplification mechanism and vibration harvester were tested for practical applications. The peak output voltage of the harvester was 397.5[Formula: see text]mV under 100 N excitation, and the output electrical power on a resistive load could reach 3.33[Formula: see text]mW. In the application of the human walking process, the voltage could reach a maximum value of 387.3[Formula: see text]mV. The results of the study initially prove that the designed vibration harvester can stably collect human walking vibration.

Design and Characteristic Analysis of Magnetostrictive Vibration Harvester with Double-Stage Rhombus Amplification Mechanism

Vibration energy harvesting is a new alternative to lithium battery power for low-power devices, attempting to recover wasted or lost vibration energy to generate electricity. Magnetostrictive-based energy harvesting exploits the coupling properties of the Villari and Faraday electromagnetic induction effects to achieve mechanical–magnetic–electric energy conversion. In order to better apply to the actual vibration environment, such as buses, and improve the ability to capture low-frequency vibration energy, a double-stage rhombus vibration energy harvesting device, based on Terfenol-D rods, was developed. By establishing an analytical model of the force amplification ratio of the harvesting device, the design is optimized using the Single-Objective Genetic Algorithm, and the safety and pre-magnetization layout methods are analyzed by Finite Element Analysis. The output characteristics of the prototype, including the output voltage frequency response under low-frequency regular excitation and random excitation, the effect of external resistance, and the vibration energy capture performance under random excitation, are investigated in detail through experiments. The results of the experiments showed that the peak output power of the fabricated prototype was 1.056 mW at 30 Hz operating frequency, the energy harvesting capability reached 41.4 μW/N, and the peak open circuit voltage and output power were 2.92 V and 266 mW, respectively, under random excitation. Practical application test results showed that the peak voltage generated was 1.06–1.51 V when the excitation level was 2.2–4.9 m/s2. The comparative study indicates that the output performance of the proposed double-stage rhombus magnetostrictive vibration energy harvesting system is a great improvement over the proposals of existing literature.

Magnetostrictive biomechanical energy harvester with a hybrid force amplifier

Vibrating energy harvesters, capable of converting mechanical energy into electrical energy, have attracted unprecedented interest in both academia and industry because of their great potential for harvesting energy induced by human activity and energy around the body, and to drive low-power wearable biosensors and electronics, micro-robots, and implantable biomedical devices. In this paper, based on the magnetostrictive inverse effect, we propose a magnetostrictive vibration harvester using Terfenol-D, which generates electrical energy when subjected to human movement. A hybrid force amplification frame is integrated in this harvester to amplify weak biological movements. The detailed mathematical model of the multi-stage force amplification process is established, the hybrid force amplifier is also designed in detail, and its structural dimensions are optimized. The position and form of the bias magnetic field arrangement based on the Terfenol-D harvester is systematically analyzed. The experiment shows that 4.13 V peak voltage and 426.4 mW peak power are generated when the harvester is fully compressed. The output power is 213.16 mW and 371.43 mW at an average acceleration of 2.5 g for slow walking and 4 g for jogging, respectively. The results of this study suggest that the combination of rod Terfenol-D and force amplification mechanisms can be used to design bio-vibrational energy harvester with excellent performance, which is especially suitable for self-powered wearable electronic devices.

Erratum: "Working characteristics of a magnetostrictive vibration energy harvester for rotating car wheels" [Rev. Sci. Instrum. 93, 055001 (2022)

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Fractal Model of Contact Thermal Stiffness

The continuity, self-similarity, and self-affinity of a microscopic contact surface can be described by the Weierstrass–Mandelbrot (W–M) function in fractal theory. To address the problems that the existing normal contact load fractal model does not take into account the effect of thermal stress and is not applicable to the temperature variation in the joint surface of the giant magnetostrictive ultrasonic vibration systems, a fractal model of thermal–elastic–plastic contact normal load fractal is established based on fractal theory. The model is an extension of the traditional model in terms of basic theory and application scope, and it takes into account the effects of temperature difference, linear expansion coefficient, fractal dimension, and other parameters. Finally, the effect of the temperature difference at the joint surface on the normal load of the thermoelastic contact is revealed through numerical simulations. The results show that the nonlinearity of the contact stiffness of the thermoelastic joint surface is mainly related to the surface roughness and the fractal dimension, while the effect of the temperature change on the joint surface properties within a certain range is linear.

Performance of Fe–Ga alloy rotational vibration energy harvester with centrifugal softening

With the development of vibration energy harvesting, sensor nodes for wireless monitoring are being increasingly powered by harvesting vibrations in rotating environments such as car tires and fan blades. Considering the diverse installation positions of vibration energy harvesters on rotating carriers, the centrifugal forces of the cantilever beams exhibit remarkable differences during rotation. Crucial factors for the performance of vibration energy harvesting include the deformation of the harvester cantilever beam, which is affected by the centrifugal force, and the influence of the pre-magnetization field on the Villari effect of specific alloys. We propose a rotational vibration energy harvester based on an Fe–Ga alloy and establish a mathematical model for magnetostrictive vibration energy harvesting by leveraging centrifugal softening. In addition, we perform a systematic theoretical analysis of the factors influencing the harvester performance considering centrifugal softening, rotation radius, and arrangement of the pre-magnetization field. The theoretical findings are verified on a prototype, and the system characteristics are investigated experimentally. The maximum output voltage reaches 3.36 V, and the energy harvesting efficiency reaches 22.86% when the harvester undergoes rotation at 330 r min−1. Moreover, the harvester is applied in a low-power temperature sensor for real-time temperature monitoring, indicating the validity and applicability of the proposed rotational vibration energy harvester. The results demonstrate that an appropriate use of the centrifugal softening and the pre-magnetization field can enhance the energy harvesting efficiency of a harvester operating at a low rotational frequency.

Working characteristics of a magnetostrictive vibration energy harvester for rotating car wheels.

The practice of harvesting vibration energy from machine tools, windmill blades, etc., and converting it into electric energy to power low-power electronic circuits has attracted wide attention from experts and scholars. Abundant vibrations that exist in the moving vehicle can be harvested to power sensors in tire pressure monitoring. In this paper, for the first time, a device is proposed to harvest the rotational vibration energy with the iron-gallium alloy (magnetostrictive material) as the core material. Such a device utilizes the coupling characteristics of Villarreal effect and Faraday electromagnetic effect to convert the vibration energy generated by the moving vehicle into electric energy. Upon completion of the design of the magnetostrictive rotational vibration energy harvester, the influence law of key factors, including substrate material, substrate size, and pre-magnetization field arrangement on the harvesting capability of the device, was studied in detail through experiments. An electric motor and vibration exciter were used to apply varied excitation forms to the harvester, and the output patterns of the harvester under conditions of wheel rotation, road bumps, and random vibration were fully analyzed. In addition, the correlation between the deformation of the cantilever beam and harvester performance was also investigated. The results have shown that at the acceleration of 9.6 g and the rotational speed of 90 r/min, the harvester can reach the output voltage of 1.22 V. Consequently, it demonstrates the feasibility of employing the magnetostrictive harvester to gather rotational vibration energy and provides theoretical guidance for further and deeper research on the harvester.

Parameter optimization of magnetostrictive bistable vibration harvester with displacement amplifier

The vibration harvester can transform the ambient vibration energy into electrical energy for the use of microelectronic equipment. Currently, the introduction of bistable structure in magnetostrictive harvester makes the system have two equilibrium states, thus the output capacity of the system is improved. In order to further improve the working ability and its ability to harvest vibration of magnetostrictive bistable harvester with displacement amplification mechanism, the identification of the key parameters of the magnetostrictive bistable vibration harvester's mathematical model are first proposed in the paper. The accurate values of system damping, electromechanical coupling factor, piezomagnetic coefficient and permeability are obtained. On this basis, bistable structure and displacement amplification mechanism in the harvester are optimized, including the repulsive permanent magnets distance in the bistable structure, mass ratio and stiffness ratio between the bistable structure and the displacement amplification mechanism. Finally, the working ability of the optimized prototype is tested through experiments. The results show that the output voltage and electrical power of the optimized prototype are increased by 2∼4 times and 4∼15 times compared with the unoptimized prototype. Under the excitation amplitude of 7.84 m/s2, the voltage of the optimized prototype reaches 2.96 V, and the electrical power reaches146.032 mW.

Development of a simple resonance frequency tuning method for magnetostrictive vibration energy harvesters

A fine-tuning method of the resonance frequency for a magnetostrictive vibration energy harvester by changing the magnetization state, namely using the ΔE effect of Young’s modulus, is proposed. Adjusting magnetization strength by changing the distance between the magnet for magnetization and the magnetostrictive vibration energy harvester in ten-millimeters revealed to tune the resonance frequency in 0.1 Hz order. A plot of the resonant frequency against the change in the flux density on the magnetostrictive material showed good agreement with a quadratic function approximation. A magnetostrictive vibration energy harvester tuned using this fine-tuning method could generate electricity stably for eleven days, suggesting the possibility of this fine-tuning method for long-term use.