Learning Forum

[h.smeitink]

Hi all,

I have created a model consisting of an outer ring of twelfth 35*20mm magnets in a circle of diameter 200, with a disc magnet of 5*60mm at a height of 70 mm. As shown below:

(the box next to it is vacuum, and just used to specify a local coordinate system).

I then set up a parametric simulation to increase the disc's height from 40 to 90mm, expecting a decreasing force. But for some reason, the force seems to jump around a lot.

 

 

The same type of effect seems to occur for X, whereas I would expect that it essentially stay 0 since the disc magnet is exactly in the middle of the ring of magnets (it only moves in the Z direction):

I've used the default analysis setup, with the initial mesh settings resolution set to 5. I also made sure that the magnetization direction is upwards/in the Z direction for all magnets.

When I look at the B field plot on some planes, it does look normal to me:

I've used the default NdFe35 material for the disc magnet, and a altered version to get a grade 45 magnet specified this for the ring of magnets:

 

This is my first time using this software, so I'm kind of stuck now as I have no clue what might be causing this. Could somebody perhaps point me in the right direction?

[NA]

Dear @h.smeitink,

Which solver are you using for this case? I’m guessing Magnetostatic solver. This looks like a meshing issue. Since the forces are created due to magnetic fields in the airgap, the airgap should be sufficiently meshed as well. Not only the objects. On the analysis setup window > general tab, you can set a lower percent error (maybe 0.1 would be a good value). If this doesn’t resolve the issue, you can try to create vacuum objects between the main disc and the magnets and set mesh operations on them. We call these dummy objects and their purpose is to refine the mesh in specific areas we need dense mesh. I hope this helps!