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Input files
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IronBody.OTL
MagneticClamp.MIN, MagneticClamp.GIN, MagneticClamp.BAT, MagneticClamp.SCR
Download MagneticClamp.zip
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Description
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The hardened police detective kills time on the stakeout running the divorce through his mind like a tape loop. Suddenly, the lime green 82 Datsun streaks by. He hits the siren, slams a flashing light on the top of his car and takes off...
Everybody thinks about the plot, but what about the magnetic clamp? Will the flasher fall off crashing though the junkyard? This example addresses the issue. The clamp is a steel frame with four N35 neodymium magnets. A plastic base keeps the clamp from adding more scratches to the vehicle. The goal is to calculate the force as a function of the base thickness. A primary function of this example is a demonstrate how to set up automatic control of an extended set of runs.
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Results
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The graph shows the results of force calculation. The values of |B| are low enough to justify the assumption of fixed MuR for the steel. |
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Comments
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The example demonstrates some useful Magnum techniques. The force is calculated by taking an integral of the Maxwell stress tensor over a surface in contact with air surrounding the magnet assembly. For high accuracy, the assembly is surrounded by a diagnostic region with MuR = 1.0. The calculation of field values is performed over a simple surface rather than the complex shapes of the assembly parts. The MagView script file MagneticClamp.SCR automatically sets up the surface integral with the diagnostic region defined as internal and air set as external. Generation of the graph data was carried out automatically under control of the file MagneticClamp.BAT with the following steps:
- A single calculation was defined using the Create task button of FPController.
- The file MagneticClamp.MIN was modified to include a pass parameter to set the displacement of the steel substrate.
- The batch file was modified to a) run the mesh generator with a sequence of displacements, b) to recalculate the field and c) to run MagView with the analysis script as a pass parameter.
- The file MagneticClamp.SCR included the Append option in the Output command so that data from all runs was written to the same file.
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