Electromagnetic Force Research Articles

Electromagnetic forces and their finite element computation

AbstractThis paper introduces the concepts of differential geometry that are necessary to establish a systematic definition for electromagnetic forces by means of a natural thermodynamic approach. It is shown that standard electromagnetic force formulae used in finite element computational electromagnetism are particular instances of that general approach. Finally, the paper offers a complete conceptual framework, as well as a mathematical toolbox, to derive electromagnetic force formulae for multi‐physics finite element models with complex materials.

Modeling of nonequilibrium effects in a compressible plasma based on the lattice Boltzmann method

A magnetohydrodynamic lattice Boltzmann method (MHD-LBM) model for a 2D compressible plasma based on the finite volume scheme is established. The double distribution D2Q17 discrete velocities are used to simulate the fluid field. The hyperbolic Maxwell equations, which satisfy the elliptic constraints of Maxwell's equations and the constraint of charge conservation, are used to simulate the electromagnetic field. The flow field and electromagnetic field are coupled to simulate a compressible plasma through the electromagnetic force and magnetic induction equations. Four typical cases, the Taylor vortex flow, strong blast, Orszag–Tang vortex, and one-dimensional Riemann problems, are simulated to validate the MHD-LBM model for a compressible plasma. It is found that shock waves widely exist in a compressible plasma, and strong nonequilibrium effects exist around each shock wave. The quantitative simulation for the Brio–Wu problem demonstrates that this model can easily obtain the physical characteristics of nonequilibrium effects at sharp interfaces (shock waves and detonation waves). The magnetic fields can affect the magnitudes to which the system deviates from its equilibrium state. The viscosity can increase the magnitudes to which the system deviates from its equilibrium state. Compared with existing compressible MHD, these results for nonequilibrium effects can provide mesoscopic physical insights into the flow mechanism of a shock wave in a supersonic plasma.

Forces, Hierarchy, Unification

Force or energy is both a relationship and a pulse between objects (relational physics). Based on this idea, I have succeeded in unifying the gravitational and electromagnetic forces, as well as the strong and weak forces, using the same framework. Through this verification work, I have also been able to determine the radius and mass of the neutrino. In my deep consideration of the background of the formation of the weak and strong forces, I also succeeded in unifying alpha and beta decay by combining radioactive decay with the vision of the pulse.

Axial vibration characteristics analysis of transformer windings based on magnetic‐structural coupling correction model

AbstractDue to the strong coupling effect between the internal magnetic field and the structural field of the transformer, the magnetic‐structural coupling should be considered in axial vibration process of the winding short‐circuit impact. A 110 kV transformer is taken as the research object. Firstly, the vibration modal characteristics of the transformer are calculated using the classical axial vibration model, and the spatial distribution of the leakage magnetic flux density of the iron core window is obtained based on the image method, which is used as the basis for calculating the excitation electromagnetic force. With the consideration of the non‐linear mechanical characteristic of the pad, the dynamic stiffness equation is analysed and established and the magnetic‐structural coupling correction model is constructed. Finally, the winding vibration amplitudes obtained respectively by the classical model, the magnetic‐structural coupling model, and the magnetic‐structural coupling correction model considering the dynamic stiffness are compared. The results show that, compared with the classical model, the vibration amplitude increment with the magnetic‐structural coupling correction model is less. The dynamic stiffness will hinder the vibration intensification. The magnetic‐structural coupling correction model can provide a more accurate calculation scheme for the winding vibration characteristic analysis.

Increasing Light-Induced Forces with Magnetic Photonic Glasses

In this work, we theoretically and experimentally study the induction of electromagnetic forces in an opal-based magnetic photonic glass, where light normally impinges onto a disordered arrangement of SiO2 spheres by the aggregation of Fe3O4 nanoparticles. The working wavelength is 633 nm. Experimental evidence is presented for the force that results from forced oscillations of the photonic structure. Finite-element method simulations and a theoretical model estimate the magnetic force volumetric density value, peak displacement, and velocity of oscillations. The magnetic force is of the order of 56 microN, which is approximately 500-times higher than forces induced in dielectric optomechanical photonic crystal cavities.

Characteristic Analysis of Electromagnetic Force in an HTS Field Coil Using a Performance Evaluation System

A performance evaluation system (PES) can experimentally test the structural stability and magnetic field effects of HTS coils against high magnetic fields and electromagnetic forces before mounting the HTS coils on a large-capacity rotating machine. This paper deals with the characteristic analysis of electromagnetic force in an HTS field coil for a 10 MW Class HTS Wind Power Generator using PES. Based on the designed 10 MW class HTS wind power generator, the HTS coils are manufactured and installed in the PES by a support structure, which is designed considering the electromagnetic force (torque) and heat loads in the HTS coil. To check the stress and deformation in the support structure caused by the electromagnetic force generated from the coil, strain gauge sensors were attached to the support structure and measured under full-load conditions. As a result, the maximum magnetic field and electromagnetic force are 2.8 T and 71 kN, respectively. Compared to the analysis results, the magnetic field and generated electromagnetic force in the HTS coil were the same under no-load and full-load conditions. These results will be effectively used to study and fabricate high magnetic field coils for HTS applications, as well as the PES being fabricated.

Nonlinear free vibration analysis of the rectangular conductive elastic plate in magnetic field based on homotopy perturbation method

AbstractThis article tries to investigate the nonlinear free vibrations of the rectangular conductive elastic plate in uniform magnetic fields under the classic plate theory considering nonlinear strain‐displacement. The formulation of the governing equations integrates the electromagnetic forces arising from the motion of the plate. The nonlinear motion equations are dimensionless, which takes the effect of in‐plane inertia into account. The equations are solved by the Galerkin method and homotopy perturbation method (HPM). The effectiveness of the solution is verified. According to the solutions by HPM, the effects of the initial conditions, length‐to‐thickness ratio, and magnetic induction intensity on the nonlinear free vibrations behavior of conductive elastic plates are discussed.

Experimental investigation on magneto-convective flows around two differentially heated horizontal cylinders

Liquid metal buoyant flow around two differentially heated horizontal cylinders in the presence of a uniform vertical magnetic field is investigated experimentally. While magneto-convection in pipes or ducts has been studied theoretically and experimentally in recent years, data for heat transfer at immersed obstacles are rare and, to our knowledge, detailed experimental investigations on this fundamental magnetohydrodynamic problem do not exist. In the present work, two horizontal cylinders inserted into an adiabatic rectangular cavity filled with gallium–indium–tin are kept at constant temperatures to establish a driving temperature gradient in the surrounding liquid metal. The buoyancy-driven flow, quantified by the Grashof number $Gr$ , is varied in the range ${10^{6} \leq Gr \leq ~5\times 10^{7}}$ . With increasing magnetic field, expressed via the Hartmann number $Ha$ , different flow regimes are identified from measurements for $0 \leq Ha \leq ~3000$ . The effect of the electromagnetic force primarily consists in suppressing turbulence and damping the convective flow. The heat transfer is quantified in terms of the non-dimensional Nusselt number $Nu$ , and its dependence on $Gr/{Ha}^{2}$ , which is identified as the important group governing the flow, is discussed.

Strength and Plasticity Synergistic Enhancement Mechanism for AZ31B Magnesium Alloy Using Electrically Assisted Electromagnetic Forming

Few independent slip system causes poor formability of magnetic alloys at room temperature. Electromagnetic forming (EMF) is a high‐rate forming method, which improves formability of magnetic alloy. However, conventional EMF weakens energy utilization, and reduces strength and plasticity of formed parts. In this work, a novel electrical assisted electromagnetic forming (EAEMF) is proposed to improve energy utiization and properties of AZ31B alloy. nergy utilization of EAEMF is 100% higher than that of EMF under same height limit, which is due to the greater temperature and electromagnetic force acting on the sheet during EAEMF. Moreover, average tensile strength, yield strength, and elongation of the EAEMF specimen are 7.5%, 6.7%, and 50% higher than those of the EMF‐produced sample, respectively. This is because EAEMF promotes grain refinement, induces more twins and dislocations, which is beneficial for enhancing strength and plasticity. Particularly, twin density of EAEMF sample increased by 70%, grain size decreased by 26.6% owing to dynamic recrystallization. In addition, EAEMF weakened basal texture, increased deformation region and more uniform plastic deformation, provided more interfaces to accommodate disocations, which ensured the increase of plasticity. Therefore, this study proves the feasibility and superiority of EAEMF, providing new prospect for improving property of magnesium alloy parts.

Numerical and experimental research on the hydro-electromagnetic levitation micropump

Micropump is the core component of the microfluidic systems. However, most mechanical micropumps are using the traditional contact bearings that are troubled by wear-out failure. Hydraulic levitation, which can make the rotating components levitate without any solid-solid contact, provides efficient solution to this long-standing challenge. Nevertheless, the current hydraulic levitation technology must utilize micron microgroove structure to produce thrust forces, therefore enlarging the assemble difficulty and manufacture cost. Alternatively, a novel kind of hydro-electromagnetic levitation micropump (HELP) without grooved thrust bearing is designed in this study. Taking advantage of the coupling behavior between the electromagnetic force and hydraulic force, the rotor of the HELP can levitate in the working fluid in all directions. Thereafter, the mechanisms of levitation forces formation are elucidated by the simulations of fluid flow and motor. Results indicate that the levitation bearing can provide sufficient load capacity in all working conditions, especially in high speeds. Based on the hydro-electromagnetic levitation principle, the HELP prototype is manufactured, whose overall size is as large as a coin, but can output the hydraulic performance of over 3160 mL/min and 90.5 kPa at 20000 RPM, which is several times over other micropumps. To verify the rotor levitation performance, the levitation trajectory test benches are built on the basis of laser displacement sensors. Results prove that the designed HELP can levitate stably in all directions at all rotational speeds. The proposed levitation micropump may be an excellent choice for powering the liquid cooling systems with high performance and high reliability.

Novel multi-layer field shaper in electromagnetic manufacturing process technology of tube joining for uniform deformation

Electromagnetic joining technology is widely utilized in assembling tubular components due to its ability to exert uniform magnetic pressure. To augment this pressure, a field shaper structure has been introduced. However, the conventional design may impair the uniformity of deformation, particularly at the seam. This study presents a novel multi-layer field shaper (MLFS) to enhance deformation uniformity. The performance of the MLFS was evaluated and optimized through experimental trials and simulation analysis. The results showed that MLFS achieved a 300 % increase in minimum deformation with a 56 % reduction in the aspect ratio, demonstrating that our design effectively balances efficiency with deformation uniformity. The magnetic cubic decay formula could fit the simulation data well with R2 higher than 0.999. MLFS was found to enhance uniformity by creating a more even magnetic field that decreased the curvature near the plastic hinge. Compared to altering the interlayer thickness, adjusting the interlayer angle can further enhance uniformity. When the rotation angle is 60°, the radius range can be further reduced by 32.5 %, 39.0 %, and 12.2 % at energy levels of 27 kJ, 30 kJ, and 33 kJ, respectively. The above results indicate that by designing and optimizing MLFS, sufficiently large and uniform electromagnetic forces were obtained.

Simulating Noise, Vibration, and Harshness Advances in Electric Vehicle Powertrains: Strategies and Challenges

This study examines the management of noise, vibration, and harshness (NVH) in electric vehicle (EV) powertrains, considering the challenges of the automotive industry’s transition to electric drivetrains. The growing popularity of electric vehicles brings new NVH challenges as the lack of internal combustion engine noise makes drivetrain noise more prominent. The key to managing NVH in electric vehicle powertrains is understanding the noise from electric motors, inverters, and gear systems. Noise from electric motors, mainly resulting from electromagnetic forces and high-frequency noise generated by inverters, significantly impacts overall NVH performance. This article details sources of mechanical noise and vibration, including gear defects in gear systems and shaft imbalances. The methods presented in the publication include simulation and modeling techniques that help identify and solve NVH difficulties. Tools like multi-body dynamics, the finite element method, and multi-domain simulation are crucial for understanding the dynamic behavior of complex systems. With the support of simulations, engineers can predict noise and vibration challenges and develop effective solutions during the design phase. This study emphasizes the importance of a system-level approach in NVH management, where the entire drivetrain is modeled and analyzed together, not just individual components.

Electromagnetic–Structural Finite Element Analysis of Copper and Aluminum Windings in Power Transformers under Short-Circuit Conditions

Electromagnetic forces can lead to the structural failure of power transformers due to extreme loading conditions, vibration, and/or fatigue. Therefore, studying the nature and the magnitude of these forces is a key task in the design and failure analysis of such important equipment. Keeping this issue in mind, this work aims at conducting a numerical analysis in order to evaluate the mechanical stresses and displacements of windings in power transformers due to the action of electromagnetic forces. With this purpose, a finite element model is developed considering electromagnetic and mechanical effects assuming short-circuit conditions. The study compares the cases employing copper and aluminum windings with header tap, in different temperatures. The model developed in this work is verified against analytical solutions. The numerical calculations allow for performing a detailed analysis in terms of the distribution of both displacements and stresses along the windings, which is of great relevance for identifying critical structural points and avoiding structural failure. Overall, the obtained results demonstrate that the finite element model is a useful tool for the structural design of power transformers that allow for investigating and optimizing key aspects before manufacturing.

Heat and mass transfer behavior in CMT plus pulse arc manufacturing

The metal transfer mode, temperature distribution, flow behavior, and microstructure characteristic in the process of cold metal transfer plus pulse (CMT+P) arc manufacturing were investigated by the in-situ observation and numerical simulation. A novel coupling model for droplet-pool interaction under the CMT+P arc was established, along with a new heat source model that considered Marangoni forces on droplets. These innovations provided significant insights into the heat and mass transfer mechanisms in the CMT+P hybrid arc manufacturing process. The results show that the droplets generated by the CMT+P hybrid arc exhibited a mixed transfer mode: short-circuit transfer in the CMT period and projected transfer of one droplet per pulse during the pulse period. The short-circuit transfer was more stable than the projected transfer, attributed to the smooth transfer of droplets to the molten pool through the liquid metal bridge, dominated by surface tension and Marangoni forces. The main energy of the molten pool was provided by droplets, which had a dominant ability to melt the substrate. However, the liquid metal bridge in the CMT period slowed down the heat transfer to the molten pool and had significant oscillating and stirring effects. During the pulse period, the droplet was accelerated and projected transfer by gravity and electromagnetic force. After solidification, the microstructure exhibited an alternating distribution of columnar and equiaxed grains from the bottom-up in the monolayer deposited layer, with a deflected fusion interface towards the scanning direction. At the top of the deposited layer, coarse columnar grains were distributed obliquely or laterally, inhibiting the growth of equiaxed grains and forming a distinct boundary with the equiaxed grains below.

Magnetic Field Driven Dynamic Reorganization of Electrocatalytic Interface for Sustainable Enhancement in Oxygen Evolution

Hydrogen with high calorific content (150 MJ/kg) and environment-friendly combustion product (H2O) becomes the alternative fossil fuel. Catalytic electrolysis of water is one of the attractive routes for generating H2. Energy-efficient and cost-effective electrolytic production of H2 has predominantly focused on lowering the overpotential for water splitting process by developing newer non-Pt group-based catalysts.This work demonstrates a new direction towards sustainable oxygen evolution reaction (OER) by exploiting the fundamental interplay of electromagnetic forces. Introducing an external magnetic field (Hext = 100 mT) perpendicular to the heterogeneous electrocatalytic interface produces an unprecedented increase in rate of electrocatalytic OER in phosphate buffer with pH=7. Such electromagnetic catalysis is achieved with metal phosphides (NiCoP and NiCoFeP) with different morphology, leading 2.5 fold increase in the OER current density and concomitant lowering of overpotential by 10% (Hext = 100 mT). Thereby, 50% lowering of charge transfer resistance (Rct) is achieved. This is substantiated by the lowering of the Tafel slope (by 5%) in the presence of Hext. Thus, we report two important observations influenced by the magnetic field: (a) direct effect of magnetic field on the catalyst surface to reduce the charge-transfer resistance, (b) spin-dependant OER process to get influenced under magnetic field and (c) indirect effect of magnetic field to sustain the magneto-electrocatalytic enhancement even after removing the magnetic field. The time-scale of magnetic relaxation is million times higher than conventional spin-lattice relaxation events in para/ferromagnetic systems. Such long-term stability of magnetized states is predominantly proposed to be originating from the NiCoP and NiCoFeP interface. So, we attribute the long-lived states to be additionally contributed from the volumetric expansion and active site expansion of the catalyst upon magnetization. Catalyst interface is arising due to the dendritic structure of catalyst. Such synergism of magnetization, is expected to increase the applicability of magneto-electrocatalysis as a more sustainable electrocatalytic approach towards a hydrogen-driven economy. Figure 1

Magnetic controlled arc welding technology: a review

PurposeThe purpose of this study is to optimize and improve conventional welding using EMF assisted technology. Current industrial production has put forward higher requirements for welding technology, so the optimization and improvement of traditional welding methods become urgent needs.Design/methodology/approachExternal magnetic field assisted welding is an emerging technology in recent years, acting in a non-contact manner on the welding. The action of electromagnetic forces on the arc plasma leads to significant changes in the arc behavior, which affects the droplet transfer and molten pool formation and ultimately improve the weld seam formation and joint quality.FindingsIn this paper, different types of external magnetic fields are analyzed and summarized, which mainly include external transverse magnetic field, external longitudinal magnetic field and external cusp magnetic field. The research progress of welding behavior under the effect of external magnetic field is described, including the effect of external magnetic field on arc morphology, droplet transfer and weld seam formation law.Originality/valueHowever, due to the extremely complex physical processes under the action of the external magnetic field, the mechanism of physical fields such as heat, force and electromagnetism in the welding has not been thoroughly analyzed, in-depth theoretical and numerical studies become urgent.

In situ X-ray imaging of α-Al(FeMn)Si grain evolution during solidification of an Al-Si alloy with electromagnetic stirring

During the solidification of aluminum alloys with high iron concentrations in conjunction with electromagnetic stirring, the electromagnetic force induces movement of precipitated intermetallic grains containing iron. This force is assumed to cause macrosegregation of such compounds, although the movement process is complex due to the additional effects of melt flow on growth kinetics. The present work used in situ X-ray imaging to obtain insights into the macrosegregation process induced by electromagnetic stirring. This imaging was employed to observe the evolution of primary intermetallic α-Al(FeMn)Si grains during the solidification of an Al-10Si-2Fe-2Mn alloy in the presence of a rotating magnetic field. The α-Al(FeMn)Si grains were found to be uniformly distributed in the horizontal direction of the alloy without electromagnetic stirring but tended to congregate at the periphery of the specimen with stirring. In situ X-ray imaging confirmed that electromagnetic stirring also promoted growth of α-Al(FeMn)Si phase grains from the periphery into the center of the alloy. The α-Al(FeMn)Si phase at the sample periphery comprised a single grain, indicating that stirring led to dendrite growth. These observations together with ex situ crystallographic analyses demonstrated that macrosegregation in an Al-10Si-2Fe-2Mn alloy solidified with electromagnetic stirring resulted from grain coarsening of the α-Al(FeMn)Si phase at the sample periphery.

Enhancing the cryogenic performance of superconducting magnet encapsulation resins with hyperbranched polymers: A molecular dynamics simulation and experimental study

Epoxy resin (EP) plays a crucial role in safeguarding superconducting magnets. One of the major concerns related to its usage is its inherent susceptibility to cracking under cryogenic temperatures and the strong electromagnetic forces experienced during the operation of superconducting magnets. In this study, we utilize molecular dynamics (MD)simulation and cryogenic experiments to conduct a comprehensive investigation aimed at gaining a profound understanding of the cryogenic toughening mechanism in hyperbranched polymers-toughened (HBPs) EPs. Five different crosslinking models of EP composites were established by MD simulations. The performance parameters obtained from the MD simulation calculations are highly consistent with the experimental results, which included the glass transition temperature, coefficient of thermal expansion, mechanical properties, free volume and atomic mean square displacement. Moreover, the relationship between structural changes and properties of the MD models was investigated. This research method provides a new avenue of exploration for superconducting magnet encapsulation resin materials.

Arc behavior and droplet transfer characteristics during oscillating laser-arc hybrid welding of 2024 Al alloy based on Zr-core-Al-shell wire

A novel zirconium (Zr)-core-aluminum (Al)-shell wire (ZCASW) combined with oscillating laser-arc hybrid welding (O-LAHW) process was employed for the welding of aluminum alloy 2024 (AA2024). The arc stability and characteristics, droplet transfer behavior and weld formation were systematically investigated. The results show that electrical signal waveform determines wire feeding rate, which affects the welding stability and weld quality. The increment in wire feeding rate increases magnetic field intensity and narrows arc cross-sectional area, which leads to arc contraction. The oscillating laser increases arc width and arc area, thereby expanding the conductive channel and greatly improving conductive ability of hybrid plasma, which promotes interactions between plasmas and helps to droplet transfer. Meanwhile, owing to the melting points differences between Zr wire and Al wire in ZCASW filler material, the melting rate of outer Al wire is larger than that of central Zr wire during welding, thereby resulting in two kinds of droplet transfer modes, and electromagnetic force and metal vapor reaction force strongly influence droplet transfer behavior. The oscillating laser improves the weld quality, which is deteriorated due to the appearance of spatters as wire feeding rate increases. When 1 m/min wire feeding rate is selected, a perfect formation is obtained. The current study offers insight into the formation mechanism of high-quality weld and welding stability during O-LAHW of AA2024 combined with ZCASW filler material.

A hybrid physics-informed machine learning approach for time-dependent reliability assessment of electromagnetic relays

Electromagnetic relays (EMRs) are intricate micro-electromechanical systems characterized by nonlinear behavior and coupling effects between electromagnetic and mechanical forces. Accurately modeling degradation and assessing reliability are crucial yet challenging tasks for ensuring their safe and efficient operation. Current data-driven methods for degradation modeling and reliability assessment often neglect the known physical knowledge regarding EMRs, leading to inaccuracies in modeling and assessment outcomes when data is incomplete. While physics-informed machine learning (PIML) approaches offer a potential solution, common regression models like Gaussian processes (GP) and long short-term memory (LSTM) suffer from underfitting and overfitting, respectively. To address these issues, we presents a hybrid PIML approach for time-dependent reliability assessment based on the emerging variational autoencoder (VAE) framework. This approach combines the advantages of GP-based methods that enable probabilistic representation with deep neural network-based methods that are more flexible and computationally efficient. Finally, we validate our proposed approach using real-world engineering data, demonstrating its superior accuracy and computational efficiency compared to state-of-the-art methods.