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Rotation
Posted 20 nov. 2012, 12:36 UTC−5 Low-Frequency Electromagnetics, Structural Mechanics Version 4.3 5 Replies
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I am trying to allow the remanent flux density within a magneto-active elastomer (MAE) to rotate with the elastomer as a magnetic field is applied to the material. Within the ampere's law that governs the MAE, I have the following:
Model Inputs-> STP
Material Type/Electric Field/Conduction Current->From Material
Coordinate System->Global CS
And the main section:
Magnetic Field- I'm using remanent flux density
Relative perm- From Material
Remanent Flux Density (Where I believe the problem lies):
X: M*cos(solid.curlUZ/2)
Y: M*sin(solid.curlUZ/2)
Z: 0
I've tried varying rotation between solid.curl and solid.Rot variables. I've attached both a picture(to help clarify visually) and the model. I'm just looking to rotate the remanent flux density with the rotation of the elastomer. Just to be clear, the rotation is about the Z axis (no rotation or displacement in the Z-direction).
Attachments:
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I am not sure how to use Solid's variable to compute the rotation, but you can instead use the frames. In you model, Magnetic Fields is solved in the spatial frame (the "fixed" frame), while you want to define the magnetization as a vector in the X direction in the material frame (the frames that deforms with the material), so that when the material is deformed the magnetization follows the deformation. The transformation matrices between frames are spatial.F and spatial.invF (you can find them in the plot list, under Definitions -> Frame transforms).
To manually specify a "material" remanence in the "spatial" magnetic fields, simply use the matrices to transform your vector. For example, if the magnetization is in the x+ direction, then write Br = {M*spatial.invF11, M*spatial.invF21}, while if it is in the x- direction just prepend a minus sign.
A note on postprocessing: I noticed that you applied a deformation to the Arrow Surface plot. The deformation node acts on the points where the arrows are placed, but it won't affect the vector components. So even if Br is collinear with the material, it will not be shown as such in the plot. If you choose to plot in the spatial frame (in Data Sets -> Solution 1) you don't need to deform by {u,v} to see the deformed position of the body.
--
Andrea Ferrario
Electromagnetics Group
COMSOL AB
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That response was very helpful and I appreciate it. I plan on working on the model tomorrow so I will give that a shot and let you know how it works out.
Regards,
Rob
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I've tried using your method of frame transforms but it describes the variables as unknown when taking the exact variable name from the descriptions under the plots. Perhaps the variables are being used in a way that comsol doesn't recognize?
Again thanks for your help.
Rob
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Please see the attached model.
--
Andrea Ferrario
Electromagnetics Group
COMSOL AB
Attachments:
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This is phenomenal! I input exactly what you did but got the "Unknown variable" color notation on the Ampere's law and didn't think to try to run it. This is great though, exactly what I wanted.
Best regards,
Rob