Magnetic Force Measurements Research Articles

Smartphone-based measurement of magnetic force and demonstration of Newton’s third law of motion

Smartphone-based measurement of magnetic force and demonstration of Newton’s third law of motion

Thermal evolution of low-temperature magnetic texture modulation in fept thin films by direct visualization

Patterns of ferroic domains and domain walls are being intensively studied to implement new logic schemes. Any technological application of such objects depends on a detailed understanding of them. Using low-temperature magnetic force measurements (10–300 K), the evolution of ferromagnetic stripes on equiatomic FePt thin films is thoroughly analyzed. Since FePt is known to develop a transition from in-plane homogeneous magnetization to stripe domains upon varying its thickness, multiple samples are studied demonstrating the well-established reduction upon thickness decrease and a non-trivial dependence on temperature. Moreover, the room-temperature uniform distribution of the pattern evolves into a distorted one upon temperature cycling. Finally, dissimilar stripe patterns are obtained upon reducing and increasing temperature indicating the states are dependent on the history of applied stimuli rather than the parametric conditions.

Very strong levitation force and stability achieved with a large MgB2 superconductor disc

This rapid communication highlights a remarkable achievement obtained with a 120 mm diameter large cylindrical MgB2 bulk: the measurement of magnetic levitation forces up to 700 N at 20 K, levitation being stable up to levitation forces exceeding 400 N. The investigated sample, which has one of the largest dimensions reported in the literature, was fabricated using the unconventional spark plasma sintering technique. This method is known as one of the most efficient methods for producing dense MgB2 samples. This breakthrough holds significant potential for advancing high-performance levitation systems and superconducting applications, including high-speed transportation systems and magnetic bearings.

The possible effect of surface barriers on the magnetic levitation of cylindrical superconductors

Abstract Superconducting magnetic levitation force measurements on large field cooled cylindrical MgB2 bulks with different diameters and thicknesses are reported. For these experiments, a special set-up permitting one to measure forces up to 500 N was used. In contradiction to previous measurements, the obtained force hysteresis cycles could not be reproduced with the analytical mean field model proposed by Bernstein et al (2017 Supercond. Sci. Technol. 30 065007). The failure of the model has been attributed to surface barriers effects which were not taken into account in the model. This last one was accordingly modified in order that the measured force cycles could be reproduced. Contrary to most other models describing surface barriers effects, the modified model suggests that above a threshold field anti-vortices and not vortices enter the superconductor. This behaviour is related to the storage by the superconductor of the mechanical work done by the operator. In addition, it has turned out that the threshold field is a decreasing function of the critical surface current density of the samples. As a consequence, the surface barriers effects occur only if this quantity and the critical current density are large enough. Otherwise, the internal magnetic field of the superconductor could be computed and was seen to be a decreasing function of the thickness of the superconductors.

Ferromagnetism of concrete

Studying the intrinsic properties of concrete is essential for addressing various aspects of concrete structure design, material selection, and sustainability. In this study, a suspended strong magnetic torsion balance device was designed and constructed to investigate the ferromagnetic properties of concrete specimens and their constituent materials. It was found that sand and cement generally exhibit ferromagnetic properties, while aggregates do not possess ferromagnetic properties. Analysis using powder X-ray diffraction (XRD) and chemical experiments confirmed that the ferromagnetic material in sand and cement is elemental iron. A simplified calculation formula for the magnetic force between concrete specimens and an external magnetic field was derived. Three sets of specimens were designed and fabricated for experimental exploration of ferromagnetic properties and magnetic force measurements. The experimental results demonstrate that plain concrete possesses measurable ferromagnetic properties. The magnetic force of concrete initially experiences a rapid decay followed by a gradual leveling off as the distance (from the magnetic field source to the concrete surface) increases. The decay rate approximately follows a fourth-power relationship with distance. Under a loading condition with an applied magnetic field intensity of 0.2 T, the optimal measurement range for ferromagnetic force in concrete is between 0.02 m and 0.05 m.

Strong Influence of Pressure on the Magnetic Properties of MgB2 Bulk Superconductors

The influence of the pressure on the magnetic and superconducting properties of polycrystalline MgB2 bulks was studied. Bulk MgB2 samples were prepared using conventional in-situ solid state reaction and hot-pressing methods. The structural and electromagnetic properties of MgB2 samples were studied by using x-ray diffraction (XRD), scanning electronic microscope (SEM), magnetic hysteresis (M-H) and magnetic levitation force (Fz, Fx) measurements. XRD measurements proved high quality of MgB2 bulks with only small traces of MgO impurity phase. The zero-field Jc value reached 240 kA/cm2 for MgB2 sample produced by hot-press while 23 kA/cm2 for MgB2 sample produced by conventional in-situ at measurement temperature of 25 K. The max. levitation force values were obtained as 11.60 N and 15.42 N for MgB2 bulk samples produced by in-situ and hot-press methods at 25 K, respectively. All these magnetic measurements result indicate that pressure acts like driving force for manufacturing highly dense and high levitation capability MgB2 bulk superconductors.

Nondestructive evaluation of carburized layer depth in furnace tubes of Cr35Ni45NbMA using magnetic field distortion and magnetic attraction force measurement methods

The ability of magnetic field distortion (MFD) and magnetic attractive force (MAF) sensors to detect both the inner and outer carburized layers of the furnace tube was investigated in the study. They were employed for quantitative nondestructive evaluation of carburized layer depth in furnace tubes of Cr35Ni45NbMA. It was found that the carburized layer on the outer surface had the dominant effect on the responses of MFD and MAF sensors compared to the carburized layer on the inner surface. Parabolic dependency of the responses of MFD and MAF sensors on the carburized layer at the outer surface was concluded. The accuracy of the proposed sensors was verified by experiments. It was found that MFD sensor was more suitable for the detection of the outer carburized layer of furnace tube than MAF sensor, while PSD obtained by MAF could be used for qualitative evaluation of the depth of inner carburized layer.

An adjustable low frequency vibration isolation with high-static-stiffness low-dynamic-stiffness property using a novel negative stiffness element

A vibration isolator with a novel negative stiffness element (NSE) configured with two electromagnetic springs in parallel was proposed in this study. The electromagnetic force and stiffness model of NSE was built based on the Ampere current model and filament method, the effect of configuration parameters on the negative stiffness was investigated in detail. The linear negative stiffness principle was proposed based on the impact of height difference on the nonlinear component sign of the negative stiffness, and the linear negative stiffness parameter design strategy for NSE was also developed. The isolator prototype was fabricated with the parameter design result, and the correctness of modeling and principle for linear negative stiffness were validated by magnetic force measurement. A series of experiments under different coil currents and vibration amplitude was conducted. The results show that high-static-stiffness and low-dynamic-stiffness property of the isolator is realized, the resonant frequency is 3.85 Hz with the coil current is 1A is reduced by up to 58.5% compared with the resonant frequency when coil without energized, the isolation bandwidth has been stretched and can be adjusted by coil current and performance has been significantly improved also. In addition, the isolator is stable and the performance is not deteriorator under different vibration amplitudes.

Study of magnetic force between the two magnets for the torque and speed evaluations of rim-driven motor

A new quasi-Coulomb relation between magnetic force vs distance, magnetic flux density, and magnetic pole area is proposed in this paper based on the empirical analysis on the magnetic force vs distance measurements. A simple device is designed and fabricated to measure the repulsive/attractive magnetic force between two magnets. The measurement results show that the relationship between the magnetic force and distance is similar to Coulomb’s electrostatic law, but the attraction is greater than the repulsion. The magnetic force is proportional to the integral of the magnetic flux density with the areas of the magnetic pole. This quasi-Coulomb relationship is useful to evaluate the torque and speed of a rim-driven motor, which plays an important role in electrified propulsion in green aviation technology.

Safety and image quality at 7T MRI for deep brain stimulation systems: Ex vivo study with lead-only and full-systems.

Ultra-high field MRI at 7 T can produce much better visualization of sub-cortical structures compared to lower field, which can greatly help target verification as well as overall treatment monitoring for patients with deep brain stimulation (DBS) implants. However, use of 7 T MRI for such patients is currently contra-indicated by guidelines from the device manufacturers due to the safety issues. The aim of this study was to provide an assessment of safety and image quality of ultra-high field magnetic resonance imaging at 7 T in patients with deep brain stimulation implants. We performed experiments with both lead-only and complete DBS systems implanted in anthropomorphic phantoms. RF heating was measured for 43 unique patient-derived device configurations. Magnetic force measurements were performed according to ASTM F2052 test method, and device integrity was assessed before and after experiments. Finally, we assessed electrode artifact in a cadaveric brain implanted with an isolated DBS lead. RF heating remained below 2°C, similar to a fever, with the 95% confidence interval between 0.38°C-0.52°C. Magnetic forces were well below forces imposed by gravity, and thus not a source of concern. No device malfunctioning was observed due to interference from MRI fields. Electrode artifact was most noticeable on MPRAGE and T2*GRE sequences, while it was minimized on T2-TSE images. Our work provides the safety assessment of ultra-high field MRI at 7 T in patients with DBS implants. Our results suggest that 7 T MRI may be performed safely in patients with DBS implants for specific implant models and MRI hardware.

Conceptual design of magnetic force control system using wedge mechanism

This paper presents a conceptual design and proof-of-concept to control magnetic force using a wedge mechanism. The concept starts with the general knowledge that magnetic force is inversely proportional to distance. A magnetic model is generated consisting of a permanent magnet (PM), two magnetic flux paths, two wheels, and a steel plate. This model is subjected to formulate a mathematical relationship between the movement of the PM and a magnetic force exerted onto the steel plate. A 3D simulation has been conducted to verify the effectiveness of the developed mathematical model. The comparison between the mathematical and simulation models is likely to be fair. The next is to design a wedge mechanism which is composed of two wedges, a trenching plate, and a stepping motor. Finally, the proof-of-concept is placed on a magnetic force measurement and subjected to experiments. The result shows that the changes in the magnetic force according to the PM movements are 84.5% with simulation and 80.1% with the experiments, respectively. It can be concluded that the proposed concept is effective in reasonably controlling the magnetic force.

Compensation of Magnetic Force of an Electromagnet for Compression Mode Characterization of Magnetorheological Elastomers

Compression mode characterizations of magnetorheological elastomers (MREs) involve challenges associated with compensating for the magnetic force generated by electromagnets. Different series of magnetic force and flux measurements were performed in order to establish a general systematic methodology for compensating for the magnetic force. In this regard, an optimal design of a UI-shaped electromagnet was realized to facilitate measurements of the force under controlled magnetic flux density up to 1 T. Results revealed notable phase and magnitude differences between the measured static and dynamic magnetic forces, which are found to be mainly dependent on magnetic flux density and frequency. A simple and powerful compensation model was proposed to accurately predict the magnetic force for the entire range of flux density and excitation conditions considered. The proposed model is experimentally validated, and then employed to identify viscoelastic force of an isotropic MRE. Results revealed maximum errors in equivalent stiffness and damping constants of the MRE in the orders of 90% and 163%, respectively, without compensation. The proposed methodology provides a framework for accurate characterization of MREs in the compression mode.

Effect of Gd211 Addition on the Vertical Levitation Force of Gd123 Superconductors

We investigated the microstructure and magnetic properties of Gd123:Gd211 = 1-y : y (y = 0.0, 0.1, 0.2, 0.3, 0.4 and 0.5) bulk superconductors with the diameter of 13 mm and thickness of 5 mm fabricated by melt-textured method. The vertical levitation force between melt-textured bulk superconductors and a permanent magnet is measured at 30, 40, 50, 60, and 77 K under zero-field-cooling (ZFC) and field-cooling (FC) regimes by Magnetic Levitation Force Measurement System (MLFMS). The phase and microstructures properties of all samples are determined by SEM (Scanning Electron Microscope). The measurements of superconducting characteristics showed that the maximum vertical levitation forces of the Gd01 sample were noted as 3.04, 2.30, 1.53, 0.91 and 0.16 N at the temperatures of 30, 40, 50, 60 and 77 K, respectively. The present results perform that a high-performance good-quality GdBCO can improve from laboratory conditions to technological applications for large scale levitated system.

Oscillographic modeling of characteristics of magnetic materials

The question of using an oscilloscope to measure the characteristics of magnetic materials using computer simulation techniques is considered. The work is used in the training of specialists in metrology, carried out by the department of information-measuring equipment of the National Technical University ‟Igor Sikorsky Kyiv Polytechnic Institute” in the specialty ‟Metrology and information-measuring equipment”. The bachelor’s program contains the course “Methods and Measuring Instruments”, which includes learning of methods and measuring instruments for electrical, magnetic and non-electrical quantities.Characterization of magnetic materials is made by various methods. One of them is a method with using an oscilloscope. The method of indirect measurement of magnetic induction and coercive force by integrating a secondary electromotive force is used. The method allows to estimate the maximum intensity and induction of the sample, the absolute and relative magnetic permeability, residual induction and coercive force, that is convenient for students, allows remote execution of laboratory practical work.The task of creating a computer workshop was solved by using the LabVIEW software package. A simulation model, a measurement experiment technique, and a procedure are described.The use of computer technology in the training of specialists has allowed to acquire the skills of visual observation of the dynamic magnetic loop of the test sample on the screen of the oscilloscope, to determine the main characteristics of the test material by the loop of the dynamic cycle, as well as, if necessary, to perform laboratory work remotely and to provide the opportunity to use this course while training the specialists in other specialties.

An analysis on the relation between the seed distance and vertical levitation force for the multi−seeded YBCO using the modified advanced frozen image (MAFI) and experimental methods

The higher magnetic levitation force and related stiffness values are very important for Maglev and magnetic bearing applications. Also, larger superconducting surface area is needed for continuous and larger magnetic mediums with different geometries and dimensions in real scale industrial applications of superconducting systems. In this study, the cylindrical YBCO superconductors were fabricated by top−seeded melt growth (TSMG) method in single and two−seeded forms with different seed distances and then the magnetic force and stiffness measurements were carried out by three axes magnetic force measurement system in different cooling heights (CH) of 20 mm and 75 mm. Additionally, a new analytical method, based on the magnetic dipole approximation, is proposed to calculate the levitation force in this study, named as Modified Advanced Frozen Image Method (MAFI), since although the Advanced Frozen Image Method in literature can calculate the levitation force with hysteresis, this method does not include the size effect of the superconductor. In the experimental studies, it is seen that the maximum levitation force values obtained by PMG with three PMs (named PMG−1) are more than two times higher than that of obtained with single PM for all samples with different distance of seeds, because of the higher magnetic flux distribution of related PMG arrangement than the single PM. In addition, the maximum magnetic levitation force value firstly increased and then decreased due to current coupling effect weakness by increasing distance of seeds. The calculated analytical levitation force results are not compatible with the experimental results without current coupling effect, but a well agreement is observed when the current coupling effect is taken into account in calculations. Also the MAFI method was tested with different dimensions of superconductors and the obtained results indicated the success of the proposed method. The maximum levitation force values obtained with MAFI method increased with increasing dimensions of HTS and PMs. Thus, one can say that the MAFI method is useful for the levitation force calculations between multi−seeded superconductors and PMGs with different dimensions and for different CHs. As a result, the analytical levitation force values obtained with the MAFI method are agree with the experimental levitation force sufficiently and this method can give fast calculation results without any divergence problem. This method can be thought as an alternative to the numerical calculation methods, having serious divergence problems for much amount and bigger size superconducting samples, therefore it will be useful to clarify bulk superconducting properties as supporter to the experimental studies.

Infiltration effects on (RE) 123 superconductors

We produced RE-123 infiltrated by Sm123 superconductors by the melt growth method. The samples have been investigated in terms of X-ray diffraction (XRD) analysis, AC susceptibility, levitation force, and a magnetic stiffness calculation. The X-ray diffraction analysis showed that the Sm123 and Y123 phases were insufficiently grown at the selected sintering temperature of 1040 °C. The transition temperature of the IP Sample is 94.28 K from the AC Susceptibility (at 1 KHz and 4 Oe applied AC field) measurement. The magnetic stiffness was calculated using our newly designed vertical magnetic levitation force measurement system. It has a Nb-Fe-B permanent magnet (∼0.5T) at 77 K with the Zero Field Cooled process. The magnetic stiffness was calculated using the data of the levitation force. The descending experimental results showed that the most significant F0was contained in the sample I5 (F0 = 9.034 N) and the largest constant b value was determined in the sample IP (b = 0.3320 mm−1). But in the ascending results, the most significant F0 is 8.604 N, and the largest constant b is 0.3047 mm−1, both calculated in the IP sample. Considering the oxygen content effects on the magnetic stiffness, one can infer that it has been positively affected by an increase in the Sm123 infiltration. These results indicatethat the produced samples could be applied to bearing systems, magnetic sensors and other technological applications.

Lorentz Force Velocimetry using a bulk HTS magnet system

Design of the Lorentz Force Flow-meter (LFF-meter) for weakly-conducting and slow-flowing fluids, e.g., glass melts, place stringent requirements on the magnetic field generation and force measurements. In the scope of the Research Training Group “Lorentz Force Velocimetry (LFV) and Lorentz Force Eddy Current Testing”, a LFF-meter considers: first - a magnetic field source, where NdFeB permanents magnet system is replaced with a bulk high-temperature superconductors (HTS), which promise higher flux densities (> 1 T) and thus higher output force resolution; second - a high-precision force measurements, where electromagnetic force compensation weighing balance (EMFC) setup is replaced with torsion balance based system (TFMS), which claims an increase of the force resolution up to 1 nN. Furthermore, in order to raise the issue of the limiting total mass (which is always an issue for high-precision force measurements), the bulk HTS and TFMS are merged within the cryostat. This work discusses LFV experiments, calculations and numerical simulations, where a magnetic field is generated by the bulk HTS.

A novel method for calculating and measuring the second-order buoyancy experienced by a magnet immersed in magnetic fluid

The phenomenon whereby an object whose density is greater than magnetic fluid can be suspended stably in magnetic fluid under the magnetic field is one of the peculiar properties of magnetic fluids. Examples of applications based on the peculiar properties of magnetic fluid are sensors and actuators, dampers, positioning systems and so on. Therefore, the calculation and measurement of magnetic levitation force of magnetic fluid is of vital importance. This paper concerns the peculiar second-order buoyancy experienced by a magnet immersed in magnetic fluid. The expression for calculating the second-order buoyancy was derived, and a novel method for calculating and measuring the second-order buoyancy was proposed based on the expression. The second-order buoyancy was calculated by ANSYS and measured experimentally using the novel method. To verify the novel method, the second-order buoyancy was measured experimentally with a nonmagnetic rod stuck on the top surface of the magnet. The results of calculations and experiments show that the novel method for calculating the second-order buoyancy is correct with high accuracy. In addition, the main causes of error were studied in this paper, including magnetic shielding of magnetic fluid and the movement of magnetic fluid in a nonuniform magnetic field.

Magnetoactive elastomer as an element of a magnetic retina fixator

We explore the possibility of creating an effective retinal fixator on the basis of magnetoactive elastomers (MAEs) and systems of permanent magnets. MAEs consist of silicone elastomer matrix with embedded magnetic iron microparticles. We study theoretically and experimentally magnetic forces acting between MAE samples and permanent magnets in various configurations. The theoretical model is based around classical magnetostatics and Maxwell equations with different parameters accounting for peculiarities of the material and the setup. Approximation of the experimentally measured magnetization curves for MAE samples was used to find input parameters for the theoretical model. To test the model, we conducted a series of experimental measurements of magnetic forces accompanied by model predictions for the system of one cylindrical magnet and a cuboid MAE sample. Calculated dependences of the average pressure arising from magnetic interactions on the distance between the closest faces of MAE samples and a permanent magnet are in a good agreement with the experimental data. The proof on concept for smaller magnetic systems required for eye surgery includes data for 10 magnets configuration and a thin MAE band. This research demonstrates high prospects of using MAE as an element of a magnetic fixator for treatment of complicated retinal detachments.

Direct measurement and microscale mapping of nanoNewton to milliNewton magnetic forces

This paper describes the direct measurement and mapping of magnetic forces/fields with microscale spatial resolution by combining a commercial microforce sensing probe with a thin-film permanent micromagnet. The main motivation of this work is to fill a critical metrology gap with a technology for direct measurement of magnetic forces from nN to 10’s of mN with sub-millimeter spatial resolution. This capability is ideal for measuring forces (which are linked to magnetic field gradients) produced by small-scale magnetic and electromagnetic devices including sensors, actuators, MEMS, micromotors, microfluidics, biomedical devices. This new measuring technique is validated by comparison of measured forces from small permanent magnets with the analytical models.