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Input files
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MagForce.MIN, MagForce.PIN, MagForce.DAT, MagForceField.png
MagForcePerMag.zip
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Description
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The example illustrates techniques for magnetic force calculation with PerMag. The geometry is the same as the example Magnetic levitation equilibrium. A set of magnetic coils interacts with a metal drive plate. In this example, we assume one of two conditions: 1) the field is turned on rapidly compared to the field penetration time into the plate and then remains constant or 2) the plate is a superconductor. In both cases, the plate acts as a field excluder with current distributed over a very thin layer on the surface. The example illustrates two solution techniques: 1) modeling a field exclusion region by assigning a small value of relative magnetic permeability (MuR is much less than unity) and 2) find an accurate value of force on an object with sharp corners by surrounding it with a diagnostic region.
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Results
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The figure shows the coils, the plate (gray), the diagnostic region (tan) and lines of magnetic induction. The plate is assigned a relative magnetic permeability MuR = 1.0E-06 and the diagostic region has MuR = 1.0. The plate excludes the magnetic field and, as a result, feels a strong repulsive force from the coil.
Surface integrals
Region status
RegNo Status Name
======================================
1 External AIR
4 Internal DIAGNOSTIC
5 Internal PLATE
Quantity: FzSurf
Normal integral: 2.938052E+01
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Comments
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The upward force of 29.381 N is 28 times higher than the time-averaged force in the levitation example for two reasons:
- The magnetic field has a steady value rather than an AC variation, accounting for a factor of 2.
- In the levitation example, the field penetrates the aluminum disk. Therefore, the difference in magnetic pressure between the top and bottom of the plate is much smaller.
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