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Problem on result when simulate varied force between two permmanent magnet plates
Posted 25 mars 2016, 13:37 UTC−4 Low-Frequency Electromagnetics, Geometry, Modeling Tools & Definitions, Parameters, Variables, & Functions, Studies & Solvers Version 5.2 2 Replies
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Hi,
Currently, I am working on a 3D model of two permanent magnet plates (I have attached model below, the permanent magnet plates have alternating polarity). One permanent magnet plate can move in the direction parallel to the other permanent magnet plate. Now, I want to find relationship between force in motion direction and the displacement. I use AC/DC model for the magnetic field. I also use infinite elements to be the boundary. Basically, I follow the every setting of a tutorial on 3D axial magnetic bearing from COMSOL.
However, the result I have is weird (see the attachment), the plot is not smooth and even the force at 0 displacement is not 0 which should be 0 because of the symmetry. Since I am a beginner on COMSOL, I can't figure out where the problem is from. Can anyone help me on this?
Sincerely,
Xingjian Liu
Currently, I am working on a 3D model of two permanent magnet plates (I have attached model below, the permanent magnet plates have alternating polarity). One permanent magnet plate can move in the direction parallel to the other permanent magnet plate. Now, I want to find relationship between force in motion direction and the displacement. I use AC/DC model for the magnetic field. I also use infinite elements to be the boundary. Basically, I follow the every setting of a tutorial on 3D axial magnetic bearing from COMSOL.
However, the result I have is weird (see the attachment), the plot is not smooth and even the force at 0 displacement is not 0 which should be 0 because of the symmetry. Since I am a beginner on COMSOL, I can't figure out where the problem is from. Can anyone help me on this?
Sincerely,
Xingjian Liu
Attachments:
2 Replies Last Post 29 mars 2016, 09:12 UTC−4
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Posted:
9 years ago
Hi there,
Just taken a look at your model and there are several things to consider. The first thing I would do is to use a 2D planar model with the "mfnc" physics, rather than the 3D model you have with the "mf" interface. (you have no currents in your model, so the formulation used in the mfnc may suit your model better).
Your system can be well simulated in 2D as the airgap (1mm) is significantly smaller than your plate width (125.664mm). End effects will have minimal effect on the result.
By doing this, your mesh can be significantly denser, which will help smooth out the force plot, (you are integrating over a volume and the mesh density needs to be high enough to ensure a good volume integration). At the moment, with no use of symmetry your mesh is far too coarse to obtain smooth results. It also looks as though your force calculation is actually a torque about an axis, is that what you want to calculate?
Your model has no Study node, so cannot see what type of study you are attempting. I would imagine a parametric sweep of one plate moving in the z direction is what you will need to use.
Hope this helps.
Mark
Just taken a look at your model and there are several things to consider. The first thing I would do is to use a 2D planar model with the "mfnc" physics, rather than the 3D model you have with the "mf" interface. (you have no currents in your model, so the formulation used in the mfnc may suit your model better).
Your system can be well simulated in 2D as the airgap (1mm) is significantly smaller than your plate width (125.664mm). End effects will have minimal effect on the result.
By doing this, your mesh can be significantly denser, which will help smooth out the force plot, (you are integrating over a volume and the mesh density needs to be high enough to ensure a good volume integration). At the moment, with no use of symmetry your mesh is far too coarse to obtain smooth results. It also looks as though your force calculation is actually a torque about an axis, is that what you want to calculate?
Your model has no Study node, so cannot see what type of study you are attempting. I would imagine a parametric sweep of one plate moving in the z direction is what you will need to use.
Hope this helps.
Mark
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Posted:
9 years ago
I have created the attached model which should give you what you are after (unless I have misunderstood your requirements).
Hope this helps,
Mark
Hope this helps,
Mark
Attachments: