| 1. |
- Benbouzid, M. E. H., et al.
(författare)
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Dynamic modelling of giant magnetostriction in Terfenol-D rods by the finite element method
- 1995
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Ingår i: IEEE transactions on magnetics. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9464 .- 1941-0069. ; 31, s. 1821-1824
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Tidskriftsartikel (refereegranskat)abstract
- As a contribution to the development of methods for the design and the analysis of devices based on giant magnetostrictive materials, a model for the simulation of the dynamic behaviour of the nonlinear magnetoelastic medium is presented. The coupled magnetic, magnetoelastic and mechanical equations that describe the magnetostrictive problem are solved by means of the finite element method. The thin sheets bending principle (surface splines) is used to introduce in the simulation the nonlinear properties of giant magnetostrictive materials, obtained by static characterizations
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| 4. |
- Bergqvist, A., et al.
(författare)
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A thermodynamic representation of pseudoparticles with hysteresis
- 1995
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Ingår i: IEEE transactions on magnetics. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9464 .- 1941-0069. ; 31, s. 3539-3541
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Tidskriftsartikel (refereegranskat)abstract
- A method of expressing pseudoparticles with hysteresis within a context of irreversible thermodynamics is investigated. The state of a pseudoparticle is uniquely determined by its magnetization and its evolution is governed by entropy maximization. Hysteresis appears if the free energy is a nonconvex function of magnetization. The vectorial nature of magnetization and dependence on rate are accounted for in a systematic manner. Some basic properties are derived for quasistatic processes. In particular, it is found that in the scalar case, the magnetization is a monotonically increasing functional with respect to field and that for quasistatic processes, this implies the wiping-out property
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| 11. |
- Engdahl, Göran, et al.
(författare)
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Experimental study of magnetic slurries regarding magnetic properties
- 1996
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Ingår i: IEEE Transactions on Magnetics. - : IEEE. - 0018-9464 .- 1941-0069. ; 32:5, s. 5109-5111
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to assess the basic magnetic properties of a mixture composed of a commercial lubricant and soft magnetic iron particles, where the particle content is significantly higher than in conventional magnetic fluids, due to the fact that the particles verge on the sedimentation level. This so called magnetic slurry can, then, be regarded as a highly ductile magnetic conducting material for tentative use in a magnetic circuit that can change shape under operation. The high particle content results in high saturation field densities that extend the application field towards electric power engineering. This paper, therefore, focuses on properties like relative permeability, losses, the Q-factor and the efficiency for the power frequencies 50 and 400 Hz. It shows that the relative permeabilities are low (below 10). The values of the efficiency and the Q-factor decrease considerably above 0.5 T. That limits the application of the studied slurry in electric power engineering. In such applications, the powder properties must be improved
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| 15. |
- Engdahl, Göran, et al.
(författare)
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Statistical modeling of magnetic and magnetostrictive properties due to domain wall motion
- 1999
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 85:8, s. 5190-5192
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Tidskriftsartikel (refereegranskat)abstract
- Statistical mechanics is employed to derive magnetic and magnetostrictive bulk properties of soft magnetic materials dominated by domain wall motion. The material is divided into an ensemble of volumes with uniform magnetization, each one much smaller than a typical domain but much larger than one atom. The energy for such a volume element is assumed to consist of an internal energy: the interaction with the external magnetic field and a mean field interaction with the surrounding medium. The volume fractions of discrete mesoscopic magnetizations in the medium are derived from Boltzmann statistics. The bulk magnetization is the weighted average of the mesoscopic values. Magnetostriction is treated in a similar way. Calculations are compared with two-dimensional measurements on grain-oriented silicon #x2013;iron. #xa9; 1999 American Institute of Physics.
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| 16. |
- Holmberg, P., et al.
(författare)
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An approach to model electromagnetic transients in a coil
- 1995
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Konferensbidrag (refereegranskat)abstract
- The design of transformers and explosive magnetic flux compression generators will be more successful and competitive if impinged electromagnetic transients can be modelled accurately. Such a model should consider eddy currents, skin effect, charge storage, moving geometry and magnetic and dielectric materials, which can be nonlinear and hysteretic. For very fast transients, the finite speed of light has to be considered. Often it is of interest to connect the model to an external system. This paper presents an approach with all these possibilities. It is reminiscent of the equivalent circuit approach, but is more general
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| 18. |
- Holmberg, P., et al.
(författare)
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Modelling and design of a set-up for studies of transients in coils
- 1996
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Konferensbidrag (refereegranskat)abstract
- The authors argue that the design of transformers and generators will be more successful and competitive if the response of the windings to impinged electromagnetic transients can be better understood. This paper presents a test set-up where the electromagnetic wave propagation along a coil can be studied. Voltage and current probes with bandwidths of 100 MHz are used. The set-up is modelled by coupled surface current elements and coupled surface charge elements. The skin-depth is considered by means of a Cauer circuit. The simulations are compared to the experimental results
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| 23. |
- Stillesjo, F, et al.
(författare)
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A magnetic and mechanical evaluation of a force outlet design in magnetostrictive actuators
- 1998
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Konferensbidrag (refereegranskat)abstract
- A crucial problem in the design of magnetostrictive actuators is to obtain the combined function of its force outlet regarding its mechanical power transmission and achieving a uniform magnetization of the active material. In this paper, a suggested solution to this problem is evaluated by means of mechanical and magnetic finite element calculations. The principle design comprises a magnetic pole consisting of two laminated soft magnetic pieces, with the laminates in each piece perpendicular to each other. Moreover, one of the pieces is wedge-like in order to create a feasible “bend-over” of the magnetic field lines into the active material and to create a stiff force outlet similar to a solid one. Some realizations of the concept are also discussed
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