Browse Topic: Magnetic materials

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Design and Optimization of an External Rotor Permanent Magnet Motor with a Three-Segment Non-Uniform Halbach Array2026-99-01537/31/2026
To further enhance the performance of the drive unit motor, a novel three-segment non-uniform Halbach array magnetic pole structure is proposed, which is applied to an external rotor permanent magnet motor with magnetic pole optimization. First, the overall motor design is carried out according to the requirements, determining the fundamental parameters of the motor. Then, four common magnetic pole structures—conventional arc-shaped, three-segment, Halbach array, and three-segment non-uniform Halbach array—are analyzed. A finite element analysis model of the motor is established for electromagnetic analysis, comparing the air-gap flux density, torque, and torque ripple of the four magnetic pole structures. Finally, optimized parameters for the stator and rotor tooth shapes are determined, and an optimization model is established. The NSGA-II algorithm is employed to optimize the stator and rotor tooth shapes. After optimization, the motor maintains its torque output while reducing torque ripple by 50%, effectively improving its performance.
Zhao, Changle, Yang, Liu
Preparation and Characterization of Glycerol-Based Fe3O4 Magnetic Fluids2026-99-02447/31/2026
To optimize the preparation protocol and tribological performance of glycerol-based Fe^3O^4 magnetic fluids, three hybrid agitation systems—(i) chemical co-precipitation coupled with magnetic stirring (H+C), (ii) chemical co-precipitation coupled with mechanical stirring (H+J), and (iii) chemical co-precipitation integrated with mechanical plus ultrasonic agitation (H+J+C)—were systematically investigated with respect to their influence on the physicochemical characteristics and lubricating behaviour of the resulting magnetic nanoparticles. Relative to the H+C and H+J protocols, the H+J+C protocol effectively suppressed intermediate agglomeration, yielding a 15 % increase in Fe^3O^4 productivity and a 15 % reduction in the full-width at half-maximum of the particle-size distribution. A binary surfactant system composed of oleic acid and citric acid achieved complete surface passivation, producing nanoparticles with a saturation magnetization of 59.2 emu g^–1. Under a magnetic flux density of 0.0341 T, tribometric evaluation revealed that the friction coefficient of the fluid prepared via the H+J+C route decreased to 0.041, corresponding to reductions of 7.1 % and 22 % relative to the H+J and H+C counterparts, respectively, thereby demonstrating superior tribological performance. The present work furnishes an experimental foundation for the rational design of high-performance magnetically responsive lubricants and the optimization of magnetic-fluid synthesis protocols.
Hu, Rui, Zhong, Shihao, Xu, Chunxia, Chen, Binhua, Liu, Yang
Research on Magnetic Measurement and Evolution Characterization of Fatigue Damage in Ferromagnetic Materials2026-99-16517/24/2026
To address the detection and monitoring needs of fatigue damage in ferromagnetic materials, this paper proposes a nondestructive testing method based on the evolution of magnetic hysteresis characteristics. By constructing a hysteresis loop measurement system, the variation patterns of coercivity (Hc) in Q235 steel specimens under cyclic loading were investigated, revealing three-phase characteristics of fatigue damage: the initial linear growth phase (N ≤ 8,000), the rapid rise phase (8,000 < N ≤ 12,000), and the stable oscillation phase (N > 12,000). Experimental results demonstrate that the relationship between coercivity and damage degree (D) can effectively characterize the processes of crack initiation, propagation, and instability, with significant inflection points observed at D = 0.6 and D = 0.8. The quantitative model based on coercivity provides a novel method for early warning and condition assessment of fatigue damage, offering advantages such as non-contact operation and high sensitivity. This study provides theoretical foundations and technical support for the health monitoring of engineering structures.
Chen, Li, Ding, Keqin
Nonconvex Quadratic Programming Problem for Ship Magnetic Dipole Array Model2026-99-05877/10/2026
The magnetic field modeling methodology for ships based on magnetic dipole arrays demonstrates heightened sensitivity to input data. When addressing overdetermined systems characterized by numerous variables and constrained measurement points, the coefficient matrix frequently develops pathological ill-conditioning, leading to solution divergence and compromised result accuracy. This research reformulates the ship magnetic field inversion challenge as a non-convex quadratic programming problem, employing the Successive Convex Approximation (SCA) algorithm as the computational solver. Rigorous comparative validation was performed against conventional stepwise regression algorithms and experimental datasets acquired from scaled ship model measurements. Results substantiate that while the modeling precision of the SCA algorithm remains comparable to that achieved by stepwise regression methods, SCA exhibits demonstrably superior solution stability. This enhanced robustness positions SCA as a more reliable computational framework for critical naval applications, particularly in high-fidelity ship magnetic signature modeling and rapid detection/localization of magnetic targets in marine environments.
Chen, Hao, Pan, Xun
Optimization of a Halbach array as NVH Mitigation Technique in a Yokeless and Segmented Armature Axial Flux Machine2026-01-07547/1/2026
This paper presents the optimization of a Halbach magnet array applied to an axial flux machine (AFM) in a 12-pole, 18-slots yokeless and segmented armature (YASA) topology, evaluated in the torque–speed characteristics diagram. AFMs offer significant advantages in terms of compact design and high torque density compared to other permanent magnet machine topologies. However, noise, vibration, and harshness (NVH) performance is strongly influenced by cogging torque, electromagnetic torque ripple, and tooth forces. While Halbach magnet arrays are well established in high-performance radial flux machines, only limited research has investigated their influence in AFMs. A Halbach array concentrates magnetic flux on one side of the magnet arrangement, leading to increased air gap flux density and a strongly reduced need of a back iron yoke under the magnets. By using a Halbach array, the magnetic field distribution in the air gap becomes more sinusoidal, thereby reducing harmonic components. Previous studies have primarily focused on further torque enhancement or mass reduction through the elimination of back iron. Given that AFMs already exhibit high torque and power density, the objective of this paper is the reduction of NVH factors such as cogging torque, torque ripple amplitudes and tooth forces while minimizing the required magnet mass and maintaining the specified performance criteria. In the optimization process, in addition to the segmentation of the pole and transition magnets, the magnet height as well as the required thickness of the back iron yoke are optimized. For the design and optimization of the Halbach array, two-dimensional (2D) and three-dimensional (3D) finite-element (FE) models are combined with surrogate modeling techniques. In addition to the impact on torque ripple, further potential benefits of the Halbach configuration, including improvements in efficiency and reductions in overall motor weight, are analyzed and discussed.
Müller, Karsten, Schulz, Fabian, Bremer, Martin, Burkhardt, Yves, De Gersem, Herbert
A High-Sensitivity and High-Throughput Inductive Sensor for Abrasive Particle Detection Using Rectangular Coils2026-99-07575/15/2026
The analysis of wear particles within machinery lubricants constitutes a critical methodology for assessing equipment health and enabling the early identification of potential failures. However, conventional inductive abrasive particle sensors typically exhibit lower detection sensitivity compared to other sensing technologies, limiting their practical application in precision condition monitoring. To address this limitation, this paper introduces an inductive abrasive particle sensor with enhanced sensitivity and throughput, employing rectangular coils, together with a custom-designed signal conditioning circuit. The sensor features two symmetrically arranged rectangular excitation coils and two symmetrically arranged rectangular sensing coils, with their respective axes mutually perpendicular. This unique spatial configuration not only ensures strong magnetic field intensity within the detection region but also significantly enhances magnetic field utilization efficiency. The sensing coils are connected in a differential output configuration to improve the common-mode rejection ratio, thereby enhancing the sensor's immunity to environmental interference. Furthermore, a specifically designed compensation circuit effectively counteracts the inherent unbalanced output of the probe, ensuring stable sensor operation. Subsequent the signal conditioning circuit successfully extracts weak particle signals from the sensor output while effectively suppressing noise interference and improving the signal-to-noise ratio. This paper also develops a comprehensive mathematical model for the proposed sensor, providing theoretical validation of the structural superiority. Experimental results reveal that the sensor can reliably detect ferromagnetic particles as small as 130 μm and non-ferromagnetic particles as small as 184 μm within a flow conduit of 7.2 mm equivalent diameter, maintaining high sensitivity while providing substantial flow throughput of 4.88 L/min.
Jiang, Ziyang, Qian, Min, Huang, Honglian, Lu, Yanlu, Zhang, Junjian, Pan, Chengliang
Effective Prediction of the Mechanical Properties of Glue-Laminated Motor Stator Core with Consideration of Glue Disposition2026-01-01774/7/2026
This study presents an effective predictive methodology for determining the mechanical properties of glue-laminated motor cores, with explicit consideration of glue disposition, including bonding pattern, configuration, location, and coverage. In laminated stator cores, glue bonding and stacking processes jointly govern the mechanical integrity of the lamination stack. Practical production bonding schemes are typically nonuniform and localized, leading to spatial variations in stiffness and to locally anisotropic, orthotropic material behavior. These effects influence both the in-plane and through-thickness stiffness of the stator core. They can significantly affect the accuracy of structural simulations, such as NVH responses of high-speed traction motors and e-drive systems. Given the constituent material properties of the electrical steel laminations and the glue, this work distinguishes the governing mechanisms underlying the equivalent core properties. The in-plane stiffness is primarily controlled by the stacking factor, which statistically characterizes the glue contribution in the axial direction. In contrast, out-of-plane properties (e.g., elastic modulus and shear modulus in the stack direction) are determined jointly by the glue’s axial thickness contribution and its in-plane spatial distribution. To capture these coupled effects, an enhanced homogenization framework is developed using a representative volume element (RVE) formulation implemented through finite element analysis (FEA). The laminated structure is represented as an equivalent orthotropic material, enabling directional stiffness variation induced by nonuniform bonding and lamination material. Parametric simulations establish quantitative relationships between macroscopic core properties and glue configuration, bonding pattern, and stacking factors. A closed-form analytical solution is also derived for simplified cases to support verification. The predicted effective properties show good agreement with experimentally correlated values from production cores, and with analytical solutions under simplified bonding assumptions as well. The proposed methodology enables practical inclusion of glue-disposition effects in early-stage predictive models, thereby improving the fidelity of laminated motor-core NVH assessments and generic structural analysis.
Nie, Zifeng
Advancing Sustainable Electric Vehicles: A Simulation-Driven Study on Rare Earth-Free Motors and Battery Technologies2026-01-02424/7/2026
The increasing adoption of electric vehicles (EVs) introduces critical vulnerabilities associated with dependence on rare earth elements used in traction motors and battery systems, impacting supply chain stability, environmental sustainability, and cost scalability. This investigation focuses on simulation-optimized rare earth-free EV propulsion components, including induction-based and wound rotor electric motors employing ferrite and iron-nitride magnetic materials, in combination with lithium iron phosphate (LFP) battery chemistry recognized for enhanced safety and extended cycle life. An integrated multi-physics simulation framework coupled with targeted experimental validation is employed to evaluate efficiency, thermal behavior, and durability of the proposed motor–battery systems. The optimized configurations demonstrate automotive-grade performance, with motor efficiencies ranging from 90–96% and LFP batteries retaining over 84% of nominal capacity after 5,000 charge–discharge cycles. Simulation predictions exhibit strong correlation with experimental measurements within ±5%, confirming model fidelity. The findings indicate that rare earth-free propulsion systems and LFP batteries can meet EV performance and safety requirements while significantly reducing reliance on critical materials, supporting sustainable EV development.
Saraswat, Shubham, Vishe, Prashant
Advancement in Analytical Characterization of NBR: Py-GC-MS as an Alternative to NMR for Acrylonitrile Quantification2026-26-05461/16/2026
Nitrile Butadiene Rubber (NBR), known for its superior resistance to hydrocarbon oil, low gas permeability, and excellent thermal stability, finds extensive use in seals, O-rings, conveyor belts etc. Importantly, these performance attributes are chiefly governed by acrylonitrile content in NBR. Analytical characterization of raw NBR is relatively straightforward using conventional techniques such as elemental analysis (CHNS) and liquid state 13C NMR. In contrast, the analysis of vulcanized NBR presents considerable challenges due to its crosslinked structure, which renders it insoluble in most organic and inorganic solvents, thereby restricting direct molecular-level analysis. While solid-state 13C NMR is an established technique for structural characterization in rubber vulcanizates, its high-cost curbs routine industrial analysis. In this study, Pyrolysis-Gas Chromatography-Mass Spectrometry (Py-GC-MS) technique has been explored as a robust, precise, cost-effective alternative. Quantitative determination of acrylonitrile (ACN) content in vulcanized NBR, covering a compositional range of 15% to 52% is carried out using Py-GC-MS. For sequence distribution of ACN units, liquid-state 13C NMR, is utilized exclusively for soluble, uncured NBR. The absolute ACN content values thus obtained serve as reference standards for validating the Py-GC-MS method, enabling robust quantification across both raw and cured material forms.
Samanta, Rajyasree, Ghosh, Debojit, Anjana, Kanhaiya, Sen, Amit, Guria, Biswanath, Chanda, Jagannath, Samui, Barun, Ghosh, Prasenjit, Mukhopadhyay, Rabindra
Experimental Research on MFL Detection Technology for Corrosion Damage of Prestressing Tendons in Bridges2025-99-020312/23/2025
Corrosion of prestressed tendons endangers the safety of bridges, but until now, there has been no effective method to solve the problem of detecting corrosion damage in prestressed tendons of concrete beams. To address this, a magnetic flux leakage detection experimental apparatus for corrosion damage in prestressed tendons based on the principle of magnetic flux leakage inspection has been developed. Using this apparatus, magnetic flux leakage tests were conducted on prestressed tendons after electrochemical corrosion, and the results were compared with simulation analysis to conduct a comparative study. In the experiments, the influence of corrosion severity, corrosion width, and the effect of stirrups on the characteristics of the magnetic flux leakage signals were studied. Magnetic signal feature values were extracted, and a quantification neural network model for corrosion damage was established, which is used to quantify the degree of corrosion damage in prestressed tendons. The research results show that the model can predict corrosion rates with an accuracy of 93.58% and predict corrosion widths with an accuracy of 90.30%. This method effectively reduces the influence of external factors on the determination of corrosion rates and widths in prestressed tendons during experimental analysis, thereby improving the precision of quantifying corrosion damage identification in prestressed tendons.
Wang, Peng, Gao, Min, Dong, Lei, Zhu, Junliang
E-Motor Thermal Management Using 2D-3D Coupling2025-28-022511/6/2025
In the electrical machines, detrimental effects resulted often due to the overheating, such as insulation material degradation, demagnetization of the magnet and increased Joule losses which result in decreased lifetime, and reduced efficiency of the motor. Hence, by effective cooling methods, it is vital to optimize the reliability and performance of the electric motors and to reduce the maintenance and operating costs. This study brings the analysis capability of CFD for the air-cooling of an Electric-Motor (E-Motor) powering on Deere Equipment's. With the aggressive focus on electrification in agriculture domain and based on industry needs of tackling rising global warming, there is an increasing need of CFD modeling to perform virtual simulations of the E-Motors to determine the viability of the designs and their performance capabilities. The thermal predictions are extremely vital as they have tremendous impact on the design, spacing and sizes of these motors.
Singh, Bhuvaneshwar, Tirumala, Bhaskar, Badgujar, Swapnil, HK, Shashikiran
Arcing Simulation for Automatic Transfer Switches using In-House UDF2025-28-028411/6/2025
Automatic transfer switches (ATS) play an important role in the providing uninterrupted power to various applications like data Centre, hospitals etc. They can be connected between two utility sources, two gensets or a combination of them. It operates when one of the sources to which the load is connected is not available or the preferred source is up. While they do their job smoothly, they internally see harsh conditions. When an active source disconnects, an arc is generated between the contacts. The arc forms when the current jumps through the small air gap breaking it into ions and electrons at very high temperatures, typically above 10000K. This arc needs to be quenched quickly to avoid damage to the contacts and current carrying conductors. This paper throws light on an in-house methodology that is developed using the commercial tool Ansys Fluent. The physics of arc consisting of flow, thermal and electromagnetic fields are modelled. This paper includes the simulation of arc propagation along with the moving arm and effect of arc roots formed at the arc chute plates that help in quenching the arc. When the arc gets in contact with the splitter plates the plasma sheath layer gets formed. This results in a voltage drop across both sides of plates. A mechanism is devised in house to model this effect of arc roots and validate using the available literature. When the current is flowing through the air it generates a magnetic field which causes the movement of the arc. For introducing this effect User defined scalars are used to incorporate the governing equation for magnetic field and User Defined Function (UDF) is used to calculate the magnetic field. The simulation results are validated with test.
Gaikwad, Nikhil Ravindra, Badhe, Vivek
Multi-Criteria Decision-Making for Magnetorheological Fluid Selection in Automotive Brakes05-19-03-002011/4/2025
Magnetorheological brakes based on MR technology are being investigated for their potential use for automotive purposes. Among the design decisions, the selection of an appropriate MR fluid for the brake application remains an unexplored key issue. This article proposes an MCDM-based framework comprising analytic hierarchy process (AHP) and technique for order of preference by similarity to ideal solution (TOPSIS) to select an appropriate MR fluid for the automotive brake application. Three commercially available MR fluids from Lord Corporation (MRF-122EG, MRF-132DG, and MRF-140CG) are assessed against six criteria, viz. density, temperature range, yield stress, viscosity, magnetic saturation limit, and solid content. Considering all the criteria, the AHP ranked MRF-140CG highest, while TOPSIS chose MRF-122EG. Excluding the temperature range, both methods converged on MRF-122EG as the optimal choice. The proposed framework can be used for the MR fluid selection problem of other MR devices as well.
Powar, Kanhaiya, Patil, Satyajit
Development of High-Efficiency, Fully Recyclable eMotors for Light Mobility Applications Produced in the EU2025-32-009811/3/2025
This article presents a new generation of electric motors developed for light mobility and industrial applications. The motor range is based on synchronous reluctance technology using non-rare-earth permanent magnets. Three continuous power levels have been developed: 2, 4 and 6 kW. The challenges related to that motor range is their high continuous performances (cooled by natural convection) under nominal 48V, and reparability easiness without adding complexity. These motors stand out thanks to their competitive manufacturing cost and peak efficiency above 94%, which is a remarkable performance for this power and torque class. A prototype of a 6 kW continuous power has been produced and benchmarked. The experimental test showed a high level of correlation with the simulation calculation.
CISSE, Koua Malick, Milosavljevic, Misa, Mallard, Vincent, Valin, Thomas, De Paola, Gaetano
Flexible Metal-Free Magnetic Gel for Soft RoboticsTBMG-5411911/1/2025
Soft robots, medical devices and implants, and next-generation drug delivery methods could soon be guided with magnetism — thanks to a metal-free magnetic gel developed by researchers at the University of Michigan and the Max Planck Institute for Intelligent Systems in Stuttgart, Germany.
3D Printed Smart Pen Helps Diagnose Parkinson’sTBMG-5415911/1/2025
Researchers have developed a smart, self-powered magnetoelastic pen that could help detect early signs of Parkinson’s by analyzing a person’s handwriting. The highly sensitive diagnostic pen features a soft, silicon magnetoelastic tip and ferrofluid ink — a special liquid containing tiny magnetic particles.
Fiber Optic Sensing TechnologiesTBMG-5392110/1/2025
Known as FOSS (for fiber optic sensing system), NASA’s patented, award-winning technology portfolio combines advanced sensors and innovative algorithms into a robust package that accurately and cost-effectively monitors a host of critical parameters in real time. These include position/deformation (displacement, twist, rotation), stiffness (bending, torsion, vibration), operational loads (bending moments, shear loads, torques), strength/stress (pressure/fatigue, breakage prediction), and magnetic fields (cracks or other flaws in safety-critical metal structures) for structural health monitoring applications. In addition to monitoring the structure of a tank, FOSS is capable of sensing the tank’s inventory, including amounts, temperatures, and stratification.
Bio-Magnets for DoD Applications2025-01-04859/16/2025
Magnetotactic bacteria (MTB) are capable of biomineralizing crystalline single domain magnetic oxides and sulfides. MTB perform this synthesis inside of well-defined chambers attached to their cell wall called magnetosomes. Magnetosomes are phospholipid vesicles which assemble in chains inside MTB and allow the magnetic oxides to align into a self-assembled bar magnet inside the bacteria. These nano-scale bar magnets allow MTB to align with the earth’s magnetic field allowing the bacteria to thrive in natural aqueous environments as they live in a microaerophilic environment called the oxic/anoxic zone. This presentation will focus on progress regarding using these bio-synthesized magnetic particles for Department of Defense applications.
Allen, Mark A., Jahnke, Justin P., Beyer, Frederick L.
A Novel 5kW Ruggedized Integrated Hybrid Generator System (RIHGS)2025-01-05009/16/2025
This study provides an overview of the 5 kW Ruggedized Integrated Hybrid Generator System (RIHGS) developed by Enginuity Power Systems for the U.S. Army. Designed to replace three existing generator models (MEP-531A, MEP-831A, and RMP-1030A), the RIHGS features; variable-speed load following (1 to 5 kW output at 120/208V), multi-fuel capability (JP8 and Diesel #2), liquid-cooled permanent magnet motor, silicon-carbide power electronics with a bidirectional inverter, software-based controls for efficient operation, thermal management-focused enclosure design. Experimental results confirm the system maintains normal operating temperatures at full power. When using JP8 fuel, engine performance remained stable at 3000 RPM and matched Diesel #2, though fuel economy declined at lower speeds. Compared to the RMP-1030A, the RIHGS improved fuel efficiency by 4.6% on a weighted load factor. Additionally, it demonstrated fast transient load responses (<1 sec) when stepping up from 1 to 5 kW. This generator combines efficiency, adaptability, and advanced technology to enhance field power solutions for military operations
Zoldak, Philip, Schimmels, Philipp, Harman, Andrew, Brooks, Ian, DeMaggio, Phillip, Rosenberger, Kelly
Preliminary Multi-Physics Modelling and Characterization of a Magneto-Rheological Brake2025-01-03479/15/2025
Magneto-Rheological Fluid (MRF) is a smart material used in several applications for its ability to switch from fluid behaviour to solid-like conditions if a magnetic field is present. The dependency of viscosity on magnetic field makes this fluid suitable for braking system of electric vehicles, thanks to its high controllability and response time in the whole operative range. The main parameters that influence the behaviour of the fluid, and so the braking action of the system, are magnetic field and rotational velocity. In general, the variable physical properties make it complicated to simulate the system and its behaviour in different operating conditions. Therefore, it is usually necessary to build a physical prototype to experimentally verify the response of the braking system at different driving conditions. This paper presents the development of a virtual model of Magneto-Rheological Brakes (MRB) whose validity is extended to different driving conditions. This can be accomplished by creating two coupled model, an electro-magnetic and a fluid-dynamic, using respectively Ansys Electronics Desktop 2D Maxwell and Ansys Fluent. Both the models are validated by comparing the magnetic flux density and the braking torque obtained from the experimental test campaign of the braking system prototype at different coil currents. The simulation and experimental results present a good correlation and allow to evaluate a wide range of operative and driving conditions of the braking system. The validation allows to use the developed simulation methodology to design and to adapt the braking system to any other specific application.
De Luca, Elena, Imberti, Giovanni, de Carvalho Pinheiro, Henrique, Carello, Massimiliana
What Materials for an Electrical Motor with a High-Power Density?2025-24-01269/7/2025
The rapid development of electric mobility leads to improve the performance of all the powertrain components. There is still a high need to maximize their efficiency for autonomy reasons, but weight and volume are critical parameters for automotive, aeronautic or train applications. This paper focuses on electrical machines, especially the permanent magnet synchronous axial flux motors (PMSAFM) which offer advantages in terms of power density and volumetric electromagnetic torque. The paper proposes a panorama of solutions for designing such a motor, with an application case to 100 kW – 10000 rpm, and an objective of 12 kW/kg at steady state. Obtaining such a power density can be obtained by optimizing the design, by boosting the current, using a high DC voltage, choosing a high-performance electrical steel and adapted permanent magnets, etc). For the PMSAFM topologies several configurations can be considered, and the authors show that a double rotor PMSAFM surface-mounted magnets configuration leads to the best power density. Different cooling technics are described. Then, magnetic materials as FeSi or FeCo steel are analyzed, as well as the impact of the process on the magnetic circuit performance, especially how rolling the laminations can drastically modify the permeability and iron losses. The authors describe the different permanent magnets configurations, and the influence of their segmentation on the losses. The last part is dedicated to the insulated windings, especially those able to work at high temperature, up to 350°C.
Lecointe, Jean-Philippe, Hebri, Mohamed, Bauw, Grégory, Fawaz, Sara, Duchesne, Stéphane, Zito, Gianluca, ABDELLI, Abdenour, ARSLANE, Idir
Design of a High-Speed Pure Synchro-Reluctant Machine with Asymmetrical Poles for Automotive Applications2025-24-01299/7/2025
In this article, the authors present the various choices made to design a magnet free and directly recyclable pure synchro-reluctant (Pure-SynRel) machine with asymmetrical poles operating at a maximum speed of ~21,000 rpm dedicated to automotive. This project focused on identifying design levers and optimizing the magnetic circuit to address three well-known challenges of this topology that limit its application as an automotive traction machine. These challenges include: maximizing the power factor to reduce inverter rating and cost, minimizing sources of NVH (noise, vibration, and harshness) and torque ripples, and ultimately maximizing efficiency to bridge the performance gap with magnet-based technologies (PMaSynRel). The sizing of stator components—such as the choice of winding (concentric or distributed, full or fractional pitch, round or hairpin wire)—and rotor components (e.g., the number of pole pairs, shape, and number of barriers) are explained. Additionally, the optimization methods and mechanical solutions employed to achieve maximum speed are detailed. A machine with symmetrical poles was firstly designed, with torque ripples of 24% which is over the automotive acceptation levels. Based on this version, an adjacent asymmetrical pole was created, reducing the torque ripple by 56% and limiting the torque drop to 6%. After optimization, the proposed machine generates a maximum torque of 172 N.m and 220 kW of maximum power. The torque ripple and power factor at maximum power are 14% and 0.64 respectively. A prototype is currently being built and will be tested on a test bench at IFPEN. The theoretical expectations will be verified and presented in a future paper.
Applagnat-Tartet, Antoine, Milosavljevic, Misa, Delpit, Pierre
Improve Modeling, Control, and Health Monitoring of an e-Motor Applying an Integrated Flux Sensing Array: Concepts and Design2025-24-01259/7/2025
Knowing the magnetic flux inside an electric machine can provide valuable information, as it allows for monitoring the actual behavior of the motor during operation. This leads to more accurate torque delivery and enables prognostic and state-of-health analyses. By integrating Hall-effect sensors inside an e-motor, it is possible to measure the magnetic flux and gain all the benefits from this information, such as accurate torque, rotor position and speed, and magnets' temperature. This paper describes the design of an e-motor with an integrated flux sensing array (ISA), including all surrounding models and software solutions for efficient motor control, integrating health monitoring and failure prevention. The focus is on the analyses performed to estimate the magnetic flux linkage and determine the optimal sensor placement, the control architectures that can benefit from a more accurate flux estimation, and the design of the e-machine to integrate the flux sensors. The aim is to describe the demonstrator developed to compare the benefits of direct motor flux measurement in terms of controllability and to analyze motor behavior under various operating conditions, enabling the estimation of remaining useful life and anticipating failures.
Capitanio, Alessandro, Sala, Giada, Esmaeilnia, Ali, Garcia de Madinabeitia, Inigo, Pastore, Andrea, Tranchero, Maurizio, Franceschini, Giovanni, Saur, Michael
Optimisation of Rotor Skewing of a Yokeless and Segmented Armature Axial Flux Machine2025-01-03117/2/2025
This paper presents an optimisation approach for rotor skewing in a Yokeless and Segmented Armature (YASA) design Axial Flux Machine (AFM) for electric vehicle applications. Torque ripple amplitudes are a critical factor influencing the noise, vibration and harshness (NVH) behaviour of electric motors. The focus of this paper is to reduce the torque ripple amplitudes of the dominant harmonics over the entire torque-speed characteristic of the AFM. The principle of the proposed approach is a segmented permanent magnet configuration of the AFM, where individual magnet segments can be circumferentially shifted to achieve optimal skewing configurations. Initial optimisations are performed using 2D finite element (FE) simulations, modelled as linear motors with multiple slices and different numbers of magnet segmentation. However, the accuracy of the 2D FE results is limited due to the lack of interaction between the individual segments and the insufficient representation of three-dimensional (3D) effects. To overcome these limitations, the optimisation is extended to 3D FE simulations. This 3D optimisation, conducted with five and 20 magnet segments, demonstrates a significant reduction of torque ripple amplitudes across the entire operating range while adhering to predefined constraints. Finally, different optimised skewing configurations are evaluated considering demagnetisation in 3D FE simulations.
Müller, Karsten, Maisch, Hannes, De Gersem, Herbert, Burkhardt, Yves
Tiny Magnetic Robot Can Take 3D Scans from Inside Your BodyTBMG-532316/1/2025
Researchers have developed a tiny magnetic robot that can take 3D scans from deep within the body and could revolutionize early cancer detection.
Electromagnetic and NVH Analysis of PMSM with Eccentricity and Rotor Magnetization Variations2025-01-00475/5/2025
Permanent magnet synchronous motors (PMSM) are among the most promising motors in electric vehicles due to their high torque density and efficiency. This paper is devoted to detailed electromagnetic investigations of permanent magnet synchronous motor, accounting for specific rotor eccentricity and uneven magnetization. A series of simulations are performed for a 90 HP interior PMSM to investigate the changes in the radial and tangential forces when the rotor is perfectly aligned or with static, dynamic, and mixed eccentricities. Besides, the influence of uneven magnetization due to manufacturing, demagnetization, and magnet deterioration is discussed. The forces are then used to load a vibro-acoustic model to evaluate the impact on the noise, vibration, and harshness (NVH) performance and predict the radiated sound power level for the different conditions.
Hadjit, Rabah, Kebir, Ahmed, Felice, Mario
Material Adapted Method for the Repair of Curved Thermoplastic Composite Structures by Induction Welding of Patches2025-01-01655/2/2025
Thermoplastic fiber-reinforced polymer composites (TPC) are gaining relevance in aviation due to their high specific strength, stiffness, potential recyclability and the ability to be repaired thanks to their meltability. To maximize their potential, efficient repair methods are needed to maintain aircraft safety and structural integrity. This article introduces a novel repair technique for damaged TPC structures, involving the joining of a repair patch with induction welding using a susceptor material. The susceptor consists of a material with high electrical conductivity and magnetic permeability and therefore reacts stronger to the electromagnetic field than the composite, even if the composite is carbon fiber based. I. e. the thermal energy is specifically concentrated in the repair area. In this study, the susceptor was placed on the patch and also in the welding zone. The repair process begins by identifying and preparing the damaged area, followed by precise scarfing. Care is taken to ensure that the surrounding material remains intact and that an exact stepped structure is created, which enables an optimal bonding with the patch to be used. The customized patch, which fits perfectly in terms of shape and material to the area to be augmented, is then inserted into the structure. Induction heating melts the thermoplastic matrix to join the patch with the structure using a flexible induction mat. The repair process is monitored using thermocouples to ensure even heat distribution, while pressure is maintained through a vacuum bag. The vacuum bag ensures a uniform pressure distribution even on complex curved structures. This adaptable repair method can handle individual damages. It was tested on flat carbon fiber-reinforced polyphenylene sulfide (CF-PPS) structures, showing repairs with nearly 70 % of the original performance for copper mesh susceptors. Optical tests of the specimens confirmed a bonding zone with minimal defects. Overall, this method offers a material-compatible solution for TPC repair in future aviation, advancing aerospace maintenance and offering significant potential for future industry use.
Geiger, Markus, Glaap, Anton, Schiebel, Patrick, May, David
Revolutionizing High-Performance Computer Memory StorageTBMG-530345/1/2025
Magnets generate invisible fields that attract certain materials. A common example is fridge magnets. Far more important to our everyday lives, magnets also can store data in computers. Exploiting the direction of the magnetic field (say, up or down), microscopic bar magnets each can store one bit of memory as a zero or a one — the language of computers.
Operating Characteristics of an Automotive Adjustable-Field Permanent Magnet Motors with 3D Magnetic Paths and Asymmetric Magnet Arrangement2024-32-00274/18/2025
This paper describes a three-dimensional structure of an adjustable field magnetization permanent magnet (PM) motor and a high-power density rotor structure with asymmetric permanent magnet arrangement for both high torque and high efficiency operation in the high speed and low torque range. 3D-FEA has confirmed that it is possible to achieve both high torque density and adjustable field magnetization. Load testing using the prototype proposed motor confirmed that high motor efficiency can be achieved even during high-speed operation.
Hiyoshi, Yutaro, Doi, Kotaro, Noguchi, Toshihiko
Reducing the Waste of Plating Solution for Magnetostrictive Torque Sensors2024-32-00064/18/2025
The power assist system of an electric bicycle uses a magnetostrictive torque sensor to detect the pedal force based on the magnetic properties of the crankshaft, which change according to stress. Fe–Ni alloy plating is used to coat the surface of the crankshaft with a magnetic film to enhance the magnetostrictive effect. However, the sensor performance decreases as the plating solution degrades, which necessitates replacement of the plating solution. In this study, experiments were performed to investigate how to prevent or mitigate degradation of the plating solution to reduce waste. The amounts of carbon and sulfur in the magnetic film were found to increase with degradation of the plating solution. The carbon derived from organic reducing agents and their decomposition products, and the sulfur derived from stress relievers and their decomposition products. A method was developed for reducing the amounts of carbon and sulfur in the magnetic film, which would help maintain the sensor performance and thus reduce the waste of plating solution.
Ohnishi, Hiromichi
Evaluation of Additively Manufactured Thermoplastic Composite Magnetic Field Shielding for Stepper Motors2025-01-82014/1/2025
As stepper motors become more and more widely used in engineering systems (vehicles, 3-D printers, manufacturing tools, and similar), the effects of their induced magnetic fields present a concern during the packing and orientation of components within the system. For applications requiring security, this is also a concern as the background electromagnetic radiation (EMF) can be captured at a distance and used to reproduce the motion of the motor during operation. One proposed alternative is to use customized non-magnetic plastic shields created using additive manufacturing. Some small studies have been completed which show some effectiveness of this approach but these studies have been small-scale and difficult to reproduce. To seek a more rigorous answer to this question and collect reproducible data, the present study used full factorial design of experiments with several replications. Three materials were used: Polylactide (PLA), PLA with 25% (weight) copper powder, and PLA with 15% chopped carbon fibers. The factors of interest were infill pattern (gyroid, octet, and concentric) and shield wall thickness (10mm, 20mm, and 30mm), while the response used was strength of magnetic field at two distances (100mm and 200mm) from the motor at various angles. A total of 27 different shield designs were manufactured and tested, with a total of 1176 tests being completed. The results showed some effect, both in shielding and in increasing the magnitude of the EMF, but the effect was significantly smaller than what was shown in some previous screening studies suggesting that some previous studies had a lot of noise in the data. The replications showed excellent consistency, showing that the results are reliable. It was concluded that additively manufactured stepper motor shielding can be used effectively in some cases but is likely not the best shielding option for many scenarios in vehicles and similar applications.
Hu, Henry, Patterson, Albert E., Karim, Muhammad Faeyz, Porter, Logan, Kolluru, Pavan V.
NdFeB Magnets Manufactured by Hot Pressing Using Strip-Cast and Melt-Spun Powders2025-01-82174/1/2025
The initial powder used for the manufacturing of NdFeB permanent magnets is usually prepared through rapid cooling, either by melt spinning or strip casting. The powders produced by these two methods are suitable for different applications: while melt-spun powder is a good initial material for bonded and hot-deformed magnets, strip-cast powder is normally used for sintered magnets. To investigate the suitability of using strip-cast powder to manufacture hot-deformed magnets, NdFeB powder prepared by strip casting was hot pressed (without particle alignment) and compared with melt-spun powder prepared under the same conditions (700 °C, 45 MPa, 90 min). Although the processing parameters are the same (pressed in the same mold), the magnetic properties of the magnets made from the two powders are significantly different. Surprisingly, the magnet made from the strip-cast powder (after ball milling) shows comparable magnetic properties to those of isotropic magnets, with coercivity (HcJ) of 1270 kA/m and remanence (Br) of 0.7 T, while that made from the melt-spun powder exhibits much lower properties: HcJ = 480 kA/m, Br = 0.5 T, although the melt-spun powder initially shows much better magnetic properties than the strip-cast powder. Possible reasons for such a difference in magnetic properties are discussed. It was shown that the particle size of the initial powder plays an important role in determining the final magnetic properties of the hot-pressed magnets.
He, Youliang, Song, Shaochang, Walsh, Dan, Bernier, Fabrice, Mozharivskyj, Yurij, Peng, Philip
Aluminum Foil for Sandwich ConstructionAMSA81596A (Current)3/27/2025
This specification covers the requirements of uncoated aluminum alloy foil for core materials required for structural sandwich construction.
AMS D Nonferrous Alloys Committee
Development of Composite PCM To Enhance Heat Transfer Rate with the Addition of Nanoparticles in Thermal Energy Storage2025-28-00232/7/2025
This paper explores the augmentation of thermal conductivity in paraffin wax through the incorporation of aluminum oxide (Al2O3) and copper oxide (CuO) nanoparticles, leading to the development of composite phase change materials (PCMs). The objective is to enhance heat transfer rates, crucial for various energy storage applications including industrial waste heat recovery and solar thermal energy storage. Differential Scanning Calorimetry (DSC) testing was employed to experimentally investigate the thermal properties of the resulting nanocomposite PCM. The experimental results reveal that the nanocomposite PCM, composed of 96.14% paraffin wax, 2% aluminum oxide, and 1.6% copper oxide, exhibits 1.35 times increase in heat transfer rate compared to conventional paraffin wax. The integration of nanoparticles into the PCM matrix, facilitated by a magnetic stirrer at 50oC for 4 hours, results in uniform distribution and improved grain morphology, as evidenced by SEM images. Moreover, the composite PCM demonstrates superior performance, surpassing paraffin wax by 1.35 times durin g heating and 1.5 times during cooling, while maintaining similar peak temperatures. The normalized enthalpy of the composite PCM exceeds that of paraffin wax by 1.25 times, highlighting enhanced energy storage capacity. The significant enhancements in thermal conductivity and phase change behavior are attributed to the presence of aluminum oxide and copper oxide nanoparticles. Notably, an optimized composition comprising 96.15% paraffin wax, 2.15% aluminum oxide, and 1.7% copper oxide Considered by mass demonstrates a delicate balance between improved thermal properties and material stability. This study underscores the immense promise of nanoparticles – enhanced composite PCMs as a transformative solution for enhancing thermal energy storage efficiency, with implications for sustainable energy technologies. The results shows that the thermal conductivity improved by 48% and the enthalpy increased by 25%.
Tarigonda, Hariprasad, Kumar, YB Kishore, Kala, Lakshmi K, R L, Krupakaran
Comparison of Matrix-Torque-Component Machines with Regular IPMs for New-Energy Vehicles2025-01-70501/31/2025
New-energy vehicles (NEVs) are gaining increasing attention as global efforts focus on reducing carbon emissions and dependence on fossil fuels. The motor drive system, a core technology of electric vehicles, has become a prominent research focus in both academia and industry. This paper investigates a novel matrix-torque-component machine (MTCM) that has been proposed for use in electric vehicles in recent years. First, the paper introduces the topology and torque generation mechanism of MTCM and IPMs. For comparison, an MTCM and a detailed model of the Toyota Prius 2010 interior permanent magnet machine (IPM) are developed. The torque capacity, loss distribution, and operational performance are then compared sequentially. Results indicate that the torque-generating capacity of the MTCM is higher than that of the IPM. Additionally, the MTCM performs better in low-speed, high-torque ranges. Therefore, the MTCM shows promising application potential in electric heavy-duty trucks and as a replacement for IPMs in dual-motor architectures.
Sun, Pengcheng, Jia, Shaofeng, Yang, Dongxu, Liang, Deliang
Design and Optimization of Low-Budget Yokeless and Segmented Armature Electrical Machine2025-01-70551/31/2025
This paper designs a low-budget yokeless and segmented armature (YASA) axial flux permanent magnet synchronous machine, which replaces some of the PMs attached to the rotor with silicon steel plates. For the purpose of checking the effectiveness of the proposed machine, the equivalent magnetic circuits of the typical and proposed YASA machines are first compared and analyzed, and then the models of the two machines are constructed and simulated. The results prove that the proposed YASA machine significantly reduces the quantity of permanent magnets compared to the typical machine. In addition, the thickness of the machine rotor disc has been reduced by optimizing the machine, which both enhances the power density and reduces the volume of the machine. Finally, the rotor-stator magnetic pulling force of the machine is simulated and analyzed, and the results prove that the proposed machine can operate stably.
Li, Tao, Wang, Bitan, Diao, Chengwu, Zhao, Wenliang
Weighting-Factorless PTC Strategy Based on Voltage Vector Angle2025-01-70581/31/2025
The predictive torque control strategy is a very commonly used model predictive control strategy. At present, the research prospects of PTC in motor control are broad, but there are still certain limitations in the industrial application of PTC. In traditional prediction torque control, due to the inconsistent units of electromagnetic torque and stator magnetic flux, weight factors need to be introduced to balance the control effects of the two. However, due to the cumbersome and time-consuming process of determining weight factors, it is not conducive to industrial promotion. In order to solve the problem of weight factors, this paper studies a new torque prediction control strategy based on stator flux vector angle that can avoid weight factors on the basis of traditional torque prediction control. The overall process of the new strategy is to first derive the relationship between the angle between the stator voltage vector and the stator magnetic flux vector and the electromagnetic torque and stator magnetic flux based on the mathematical model of the permanent magnet synchronous motor, establish a corresponding prediction model, and then determine the cost function through the new prediction model to eliminate weight coefficients. Finally, the effectiveness of the proposed weighting-factorless PTC strategy is verified through actual experiments.
Zhang, Dongdong, Huang, Yasong, Du, Annan, Lin, Xiaogang
Inductance Characteristics of the Axial-Radial Hybrid Excitation Motor with Fractional Slot Centralized Winding2025-01-70561/31/2025
The inductance parameter is important for the flux regulation performance of the hybrid excitation motor, and the axial structure leads to the change in the inductance parameter of the axial-radial hybrid excitation motor (ARHEM). To clarify the inductance characteristic of the ARHEM with different winding construction and the mutual coupling effect between the axial excitation and permanent magnet excitation on the inductance. Firstly, the structure of the ARHEM is presented. Secondly, the self and mutual inductance characteristics of ARHEM are analyzed using the winding function method. Then, the influence of the axial excitation structure on the armature reaction field and saliency ratio of ARHEM. On this basis, the mechanism of the mutual coupling, between the axial excitation and permanent magnet field under different excitation currents on the main air gap magnetic field, and the inductance of ARHEM with fractional slot are revealed.
Fu, DongXue, Zhao, Hewei, Wu, Qimin, Yuan, Chunwei, Wang, Dong, Qiu, Hongbo
Nickel-Iron Alloy, Magnetic, Bars, Rods, Tubing, and Forgings 50Ni - 50FeAMS7718J (Current)1/22/2025
This specification covers a magnetically soft nickel-iron alloy in the form of bars, rods, forgings, mechanical tubing, and forging stock.
AMS E Carbon and Low Alloy Steels Committee
Nickel-Iron Alloy, Magnetic, Sheet and Strip 50Ni - 50Fe Annealed, Forming GradeAMS7717F (Current)1/22/2025
This specification covers a magnetically soft nickel-iron alloy in the form of sheet and strip.
AMS E Carbon and Low Alloy Steels Committee
Nickel-Iron Alloy, Magnetic, Sheet and Strip 50Ni - 50Fe Stamping Quality, Half-Hard TemperAMS7719F (Current)1/22/2025
This specification covers a magnetic nickel-iron alloy in the form of sheet and strip.
AMS E Carbon and Low Alloy Steels Committee
Spiral Ladder-Inspired Tool That Allows Precision Control of Light Direction and PolarizationTBMG-523101/1/2025
Photonics is the study of the generation, detection, and manipulation of light waves in the form of photons. One interesting property of light is polarization, defined by its electric and magnetic fields oscillating in any direction perpendicular to the direction of propagation. This oscillation is not restricted to one plane. Circular polarization occurs when light waves have electric fields that follow a spiral trajectory along the direction of propagation.
Deployed Electromagnetic Radiation Deflector ShieldTBMG-523251/1/2025
Spaceflight outside of the Earth’s protective magnetic field is dangerous from a cosmic radiation perspective. Inside Earth’s magnetic field, where the manned International Space Station (ISS) orbits, the radiation encountered is minimal and almost all is deflected by our planet’s magnetic fields. However, outside that protective shield, the Sun’s solar wind (high energy radiation, solar energetic particles or SEPs) consisting of protons, electrons, alpha particles, and plasmas continuously bombards the spacecraft for the months or years of spaceflight.
Magnetic Particles, Fluorescent Wet Method, Oil Vehicle, Aerosol PackagedAMS3046J (Current)12/5/2024
This specification covers one type of fluorescent magnetic particles in the form of a mixed, ready-to-use suspension in an odorless, inspection oil vehicle and packaged in aerosol cans.
AMS K Non Destructive Methods and Processes Committee
Electrochemical Sensors Based on Enzyme-Linked Immunosorbent AssayTBMG-5175410/1/2024
Improvements in trace biological molecule detection can have significant impact on healthcare, food safety, and environmental safety industries. Detection of trace biological molecules can be critical to the diagnosis of early onset of diseases or infections. Researchers at NASA Ames Research Center developed an electrochemical, bead-based biological sensor based on Enzyme-Linked Immunosorbent Assay (ELISA) combining a magnetic concentration of signaling molecules and electrochemical amplification using wafer-scale fabrication of microelectrode arrays.
Magnetic Refrigeration at Room Temperature: A State-of-the-Art Review2024-28-00779/19/2024
Magnetic cooling technology, grounded in the magnetocaloric effect, is a significant area of study given its immense potential to address escalating energy demands and environmental issues posed by current technologies. Investigations into magnetic cooling systems encompass engineering endeavours and materials research. Magnetic refrigeration at room temperature represents a cutting-edge, high-efficiency, and eco-friendly technology. Despite its current developmental stage, it exhibits immense potential for practical applications and appears to be a viable alternative to conventional vapor compression methods. This review primarily focuses on the applications and materials research aspect of these studies, offering insights into the latest advancements in the field.
Meduri, Sunil, Challa, Krishna, Ponangi, Babu Rao
Designing Safer, Higher-Performance Lithium BatteriesTBMG-511808/1/2024
A Columbia Engineering team has published a paper in the journal Joule that details how nuclear magnetic resonance spectroscopy techniques can be leveraged to design the anode surface in lithium metal batteries. The researchers also present new data and interpretations for how this method can be used to gain unique insight into the structure of these surfaces.
Harmonic Injection Method for NVH Optimization of Permanent Magnet Synchronous Motors Considering the Structural Characteristics of the Machine2024-01-30157/2/2024
Noise, vibration and harshness (NVH) is one of the most important performance evaluation aspects of electric motors. Among the different causes of the NVH issues of electrical drives, the spatial and temporal harmonics of the electrical drive system are of great importance. To reduce the tonal noise of the electric motors induced by these harmonics, harmonic injection methods are applied in many applications. However, a lot of existing researches focus more either on improving the optimization process of the harmonic injection parameter settings, or on the controller design of the harmonic injection process, while the structural dynamic characteristics of the motor are seldom considered. A lot of literature shows that the harmonic injection strategies can more effectively influence the mode 0 (M0) radial forces than the higher spatial orders, so it is more efficient to apply such methods at the frequencies/orders where the effect of mode 0 forces are dominant with respect to the surface vibration or acoustics of the motor. In this paper, a guideline is proposed for the design and optimization of current harmonic injection strategies, where a 2-dimensional linear transfer function is computed to quantify the contributions of different force modes and it is used as the reference for the harmonic injection control settings. The proposed method is tested and validated with the multi-physics co-simulation of a finite-element model for an interior permanent magnet synchronous motor (IPMSM), where the influence of the inverter and pulse width modulation (PWM) are also considered and analyzed. The simulation results show that the proposed scheme can effectively reduce the surface vibration (~1.5dB) at the chosen sensor location without deteriorating the torque output performance of the IPMSM model.
Fu, Tongfang, Xu, Zhipeng, Günther, Marco, Pischinger, Stefan, Böld, Simon
On-Skin Wearable Bioelectronic Device Uses Breathable, Stretchable MaterialTBMG-509166/1/2024
A team of researchers at the University of Missouri have made a significant breakthrough in their ongoing development of an on-skin wearable bioelectronic device. Zheng Yan’s lab, which specializes in soft bioelectronics, recently added an important component to the team’s existing ultrasoft, breathable and stretchable material. The key feature: wireless charging — without batteries — through a magnetic connection.
Self-Powered Sensor for Harvesting Magnetic EnergyTBMG-508446/1/2024
MIT researchers have developed a battery-free, self-powered sensor that can harvest energy from its environment. Because it requires no battery that must be recharged or replaced, and because it requires no special wiring, such a sensor could be embedded in a hard-to-reach place, like inside the inner workings of a ship’s engine. There, it could automatically gather data on the machine’s power consumption and operations for long periods of time.
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