Finite element modelling of non-linear magnetic circuits using Cosmic NASTRAN

The general purpose Finite Element Program COSMIC NASTRAN currently has the ability to model magnetic circuits with constant permeablilities. An approach was developed which, through small modifications to the program, allows modelling of non-linear magnetic devices including soft magnetic materials, permanent magnets and coils. Use of the NASTRAN code resulted in output which can be used for subsequent mechanical analysis using a variation of the same computer model. Test problems were found to produce theoretically verifiable results

Radiation and temperature effects on electronic components investigated under the CSTI high capacity power project

The effects of nuclear radiation and high temperature environments must be fully known and understood for the electronic components and materials used in both the Power Conditioning and Control subsystem and the reactor Instrumentation and Control subsystem of future high capacity nuclear space power systems. This knowledge is required by the designer of these subsystems in order to develop highly reliable, long-life power systems for future NASA missions. A review and summary of the experimental results obtained for the electronic components and materials investigated under the power management element of the Civilian Space Technology Initiative (CSTI) high capacity power project are presented: (1) neutron, gamma ray, and temperature effects on power semiconductor switches, (2) temperature and frequency effects on soft magnetic materials; and (3) temperature effects on rare earth permanent magnets

Study on the Production of Bonded Magnet NdFeB and Polyvinyl Butyral

bonded magnet is composite magnet material made by mixing magnetic powder with non-magnetic binder. The process in manufacturing bonded magnet NdFeB made by mixing powder of neodymium iron boron (NdFeB) commercial type MQP-B with a polyvinyl butyral powder using a glass beaker. The comparisons of variation in composing NdFeB magnets powders with a binder of PVB (% weight) are 98:2, 96:4, 94:6 and 93:7 of 8 grams from total mass of the sample. After mixing the powder, it is molded by using a compression molding method with 8 tons pressure for 20 minutes at curing temperature 1600C. The molded samples are conducted by characterizing the physical properties which include measurement of density, microstructure analysis using SEM-EDX and magnetic properties which include measurement of the magnetic field strength using a Gaussmeter and hysteresis curve using VSM. The result of the study shows that the addition of and binder PVB in bonded magnet NdFeB causes a decrease in the density and magnetic field strength. The best result of density and magnetic field in the manufacture of bonded magnets is obtained by the addition of 2 % binder of 5.66 g/cm3 and strong magnetic field of 1862.4 G. the score of Mr = 72.86 emu/g, Ms = 103 emu/gram, Hc = 8.490 KOe and BHmax = 5.1 MGOe was obtained on the addition of PVB 2 %

Use of magnets for reversible restoration in sculpture. The case of the Virgen de los Desamparados in Valencia (Spain)

[EN] In this paper, we present the use of a magnetic system for restoring a real piece of art: the Virgen de los Desamparados sculpture (1954) by the Valencian sculptor Silvestre d'Edeta (Valencia, Spain). This sculpture is made of artificial stone reinforced with iron rods in the matrix and, before the intervention, showed a high degree of degradation due to various physical, chemical and biological processes causing internal strain, cracks and fragmentation. Several non-destructive imaging techniques (photography, photogrammetry, digital radiography and 3D virtual reconstruction) have been used to study the original status of the artwork. The materials to produce the prosthesis to restore the sculpture, and the procedure to attach them with magnets and various adhesives, have been addressed in this study. Different theoretical models and simulations have been developed to help the restorer to select the most appropriate magnets and their optimal position. The restoration returns legibility to the piece by restoring the missing head-hair-crown section. (C) 2018 Elsevier Masson SAS. All rights reserved.Rodríguez-Rodríguez, M.; Ruiz-Gómez, S.; Pérez-García, L.; Mas-Barberà, X. (2018). Use of magnets for reversible restoration in sculpture. The case of the Virgen de los Desamparados in Valencia (Spain). Journal of Cultural Heritage. 31:215-219. https://doi.org/10.1016/j.culher.2018.01.005S2152193

Three-Dimensional Field Solutions for Multi-Pole Cylindrical Halbach Arrays in an Axial Orientation

This article presents three-dimensional B field solutions for the cylindrical Halbach array in an axial orientation. This arrangement has applications in the design of axial motors and passive axial magnetic bearings and couplers. The analytical model described here assumes ideal magnets with fixed and uniform magnetization. The field component functions are expressed as sums of 2-D definite integrals that are easily computed by a number of mathematical analysis software packages. The analysis is verified with sample calculations and the results are compared to equivalent results from traditional finite-element analysis (FEA). The field solutions are then approximated for use in flux linkage and induced EMF calculations in nearby stator windings by expressing the field variance with angular displacement as pure sinusoidal function whose amplitude depends on radial and axial position. The primary advantage of numerical implementation of the analytical approach presented in the article is that it lends itself more readily to parametric analysis and design tradeoffs than traditional FEA models

Performance Evaluation of Novel Rare Earth Free Magnets Based Motors for Electric Vehicle Applications

Electrical Vehicles (EVs) are regarded as an effective solution in a world where environmental protection along with energy crises is gaining higher attention. Permanent Magnet Synchronous Machines (PMSMs) are considered significant competitors for EVs amongst the other varied motor drives. Owing to their higher efficiency, higher output power to volume ratio, and higher torque to current ratio, they are regarded as a feasible option in several sorts of applications like wind turbines, along with EVs. For higher-performance applications, Permanent Magnet (PM) motors with Rare-Earth (RE) magnets are pondered as one of the best candidates. Conversely, replacing the Rare-Earth (Neodymium-iron-boron) in EVs with lesser or even no RE alternatives is the most critical concern in PM owing to their limited along with the unstable supply of RE elements. Therefore, to eliminate the usage of RE magnets as well as to identify the finest alternative materials, which assure lower cost along with mass production in manufacturing industries, various permanent magnetic materials are examined here with different PMSM designs for EVs applications. Manganese Aluminide (MnAl), Ferrite, Tetrataenite (L10FeNi), Iron Nitride (Fe16N2) and Nanocomposite magnetic materials are the varied magnetic materials utilized for evaluation. For varied magnetic materials, the simulation outcomes are obtained regarding the variations in cogging torque, average torque, efficiency, along with magnet mass. On analogizing RE with various magnetic materials, it was established that a higher performance was attained by replacing RE magnets with substitute magnetic material; in addition, it also proves to be highly effective. It is observed that although their electromagnetic performance of the various materials is similar, iron nitrade has an excellent demagnetization withstand capability. Finally, in contrast to the interior V type with rare earth magnets, iron nitrade and MnAl magnet machine can attain better torque development with high efficiency

Operation of a low-power Hall thruster: comparison between magnetically unshielded and shielded configuration

International audienc

Applying high‐throughput computational techniques for discovering next‐generation of permanent magnets

The uncertainty in rare‐earth market resulted in worldwide efforts to develop rare‐earth‐lean/free permanent magnets. In this paper, we discuss about this problem and analyse how advances in computational and theoretical condensed matter physics could be essential in the development of a new generation of high‐performance permanent magnets via high‐throughput computational technique for material design. Additionally, we show that an adaptive genetic algorithm based methodology could be a useful tool for finding new magnetic phases. In particular, we apply such approach to Fe0.75Sn0.25 compound recovering well‐known experimental results and also finding new low‐energy magnetic metastable structuresNOVAMAG project, under Grant Agreement No. 686056, EU Horizon 2020 Framework Programme for Research and Innova-tion (2014-2020). Authors also acknowledge the Spanish Super-computing Network (RES) and CESVIMA for providing super-computational resources under Ref. QCM-2016-2-003