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magnetic force without gap

In Flux I want to compute the attraction force of an electromagnet over another piece that is in contact. I know doing it if there is an airgap region (a surface in Flux 2D) between both, but I don't know doing it if there is real contact. I have tried doing it using a line region (type "air gap region") assigned to the line separating both parts but the computation of the magnetic force gives error.

So, is there any way to compute the magnetic force between two pieces that are in contact?

Thank you

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Flux

v2020.0

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fzidat

Hello;

Using airgap line region should be ok in advanced mode. If you are using the last version of Flux, you can go on the option from the supervisor, and use the advanced mode.

Once this is done, you can open your Flux 2D project, put airgap line region between the magnet and the iron part. After solving you can compute the magnetic force on the magnet.

Regards

Imanol E. P.

Thank you very much. It works.

Just one doubt. It seems that the force on the magnet is not correct because it is much lower in the model with airgap line region (344 N with 5e-7 mm airgap) than in the model with true airgap region (1610 N with 5e-3 mm airgap). However, the magnetic force in the airgap line region is 3320 N, which seems coherent with the 1610 N when airgap is 5e-3 mm. Therefore, shall I compute the magnetic force in the line region instead of in the magnet?

fzidat

Hello;

You are welcome !

I do not understand the comparison, you have different airgap one is 5E-7mm dhe otherone 5E-3mm.

Is it possible to have a look on your Flux project?

Regards

Imanol E. P.

Hello;

You are welcome !

I do not understand the comparison, you have different airgap one is 5E-7mm dhe otherone 5E-3mm.

Is it possible to have a look on your Flux project?

Regards

Hello:

Attached you can find a picture showing the simulated system's models and I try to explain myself better.

I want to know the attraction force on the lamination when it is at different distances from the electromagnet, from 0.2 mm until full contact. When there is no contact, I use the model on the left, which has an airgap region associated to the geometric surface between the lamination and the electromagnet. In this model, the force is 1620 N when the airgap is 5e-3 mm, as shown in the curve Force vs airgap.

When there is contact, I use the model on the right side, which has an airgap line region associated to the geometric line between the lamination and the electromagnet. In this model, the force is 340 N no matter the thickness of the airgap line region. As this is not coherent with the 1620 N of the model 1 at 5e-3 mm, I get the force on the airgap line region, which is 3300 N. Plotted this value in the curve Force vs airgap, it seems coherent with the curve trend from 5e-3 mm and above, because magnetic force quadratically decreases with the distance. But I am not sure if getting the force on a the airgap line region makes sense.

Model comparison_True airgap vs Line Airgap.png

fzidat

Hello Imanol;

Sorry for the late answer, it looks that the two models are different, the width of the pink region seems to be bigger than the one with line region.

in addition to that, you have to compute the forces on one of the magnetic regions surrounded by air, and not on the airgap line region.

Is it possible to have your project ?

Regards

Imanol E. P.

Hello Farid:

The two models are only different in the airgap, the rest of geometry (including the pink region you refer to) is exactly the same in both models. It looks different simply because of the different zoom.

With respecto to the force computation, in Model 1 (true airgap region) I calculate the force in the lamination, which is surrounded by air as you say. However, in Model 2 (real contact, line airgap region), computing the force in the lamination gives apparentely wrong result because it is much lower than in Model 1 with larger airgap. I just showed the force in the airgap line region because its value is more coherent with the one I would expect looking at the force curve versus airgap length in model 2.

I attach both models without mesh nor results. With them they occupy 2.3 MB and 107 MB.

Best regards

EM_20210324_noMesh_ForAltair.FLU.zip

EM_contact_20210324_noMesh_ForAltair.FLU.zip

fzidat

Hello Imanol;

I took some time to analyse the projects you sent. And i also more simplified you project in order to understand better the issue.

So in your case it seems that using line region lead to wrong results in terms of value and direction.

Please have a look on the attached PDF. In parallel to my answer, i added this issue to our R&D team so they will investigate more.

Anyway, in 2D i advise you to display the real airgap.

Best regards

Read_Me.pdf

Imanol E. P.

Thank you very much, Farid.

Looking at your advise for 2D, I wonder:

1) Flux 3D does not have this issue?

2) What do you suggest to compute the force in 2D when there is real contact?

fzidat

You are welcome !

1- In 3D you will use airgap face region instead of lines. You may have the same issue again in your case (for many other cases we did not observed this issue).

2- When this a real contact, there is no magnetic force. There is magnetic force only when there is an airgap. In 2D you still have the possibility to display this airgap. in the example i used here the airgap was 10µm.

Regards

Imanol E. P.

Thank you, Farid. Nothing more from my side. I just hope that the failure in the example I sent you and you have investigated is clarified.

Best regards

fzidat

You are welcome Imanol !