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Electromagnet modeling in 3D BH curve&relative permeability

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Hi all,
at start let me say I am new in Comsol. I am using v 4.0a AC/DC Magnetic Fields. What I am trying to model is type of a magnetic brake. It`s geometry is very similar to plain electromagnet, consisting out of single cylindrical coil and a single (or mere) solid cylindrical iron (or other materials) solenoid. I have successfully modeled this geometry, defined all parameters and got results in 3D Plot Group 2/Slice 1/Arrow Volume 1/ etc. See attachment.
The thing that troubles me is how to define VARIABLE RELATIVE PERMEABILITY as a B-H curve function. i have modeled this geometry entering a number in relative permeability field but that is not want I want. I want to enter a r. permeability as a B&H curve function for specific material. I have data for B-H curves for materials of interest. I tried to type mu0*(normB/normH) as a equation in material`s relative permeability field and Comsol accepted this but I still do not see how or where to define B-H curve.
The main reason for doing this, correct me if I am wrong, is that I think I should enter relative permeability as a function not as a fixed number in case if I decide to make a solenoid out of two very different materials.
I know I haven`t presented my situation as best as it should, but I think You get the picture.
So, to summarize, should I enter relative permeability for certain material as a fixed number of as a B-H curve function and if so, how to do it?
Thank You all.


7 Replies Last Post 2013年3月20日 GMT-4 08:21
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Hello Aleksandar Poznic

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Posted: 1 decade ago 2013年3月14日 GMT-4 15:11
Hello,
I think I have the same problem of defining a variable relative permeability, how did you solve the problem?
Regards
Wanjiku
Hello, I think I have the same problem of defining a variable relative permeability, how did you solve the problem? Regards Wanjiku

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Posted: 1 decade ago 2013年3月15日 GMT-4 03:22
Hello!

Maybe this one will help:
www.comsol.de/community/forums/general/thread/26751/

Ralf
Hello! Maybe this one will help: www.comsol.de/community/forums/general/thread/26751/ Ralf

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Posted: 1 decade ago 2013年3月17日 GMT-4 06:46

4 Wanjiku:

I have not solve my "problem" jet. I putted comsol`s soft iron (with loses) instead my linear material. This soft iron has all B-H properties that You needs and You can just change existing parameters of it to suits You. It is that simple, :(.
On fortunately, after this I had problems with solvers. Now I do not have an idea how to overcome this problem.
I have realized that I can reduce my model to a simple model of a DC electromagnet with nonlinear material core.
Now I am looking for somebody's comsol 4.0a model of DC electromagnet so I can see where am I doing it wrong.

Best regards.

Sasa.
4 Wanjiku: I have not solve my "problem" jet. I putted comsol`s soft iron (with loses) instead my linear material. This soft iron has all B-H properties that You needs and You can just change existing parameters of it to suits You. It is that simple, :(. On fortunately, after this I had problems with solvers. Now I do not have an idea how to overcome this problem. I have realized that I can reduce my model to a simple model of a DC electromagnet with nonlinear material core. Now I am looking for somebody's comsol 4.0a model of DC electromagnet so I can see where am I doing it wrong. Best regards. Sasa.

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Posted: 1 decade ago 2013年3月17日 GMT-4 08:01
Hello Aleksandar,

I'm currently reviewing your query and installing COMSOL 4.2a. Unfortunately, I don't have a 4.0 version anymore, but I hope we still be able to solve your problem. If you would like to talk further, you can contact me on Skype: Rival-cs.

Kind regards,
Konstantin
Hello Aleksandar, I'm currently reviewing your query and installing COMSOL 4.2a. Unfortunately, I don't have a 4.0 version anymore, but I hope we still be able to solve your problem. If you would like to talk further, you can contact me on Skype: Rival-cs. Kind regards, Konstantin

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Posted: 1 decade ago 2013年3月17日 GMT-4 08:18
Oh no.... :(
Not the 4.2.
You don have it saved somewhere.... long shot, I know.
No problem for Skype, aleksandarpoznic.
But I am not in a position to use it a next few day.

I don`t know how to read Your model. Your solution would be valuable to me.
Is there any chance to get a 4.0a model.....
Oh no.... :( Not the 4.2. You don have it saved somewhere.... long shot, I know. No problem for Skype, aleksandarpoznic. But I am not in a position to use it a next few day. I don`t know how to read Your model. Your solution would be valuable to me. Is there any chance to get a 4.0a model.....

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Posted: 1 decade ago 2013年3月17日 GMT-4 08:36
Don't worry, I think we'll think of something. It will be easier to find the problem when we'll be in touch in skype.
Don't worry, I think we'll think of something. It will be easier to find the problem when we'll be in touch in skype.

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Posted: 1 decade ago 2013年3月20日 GMT-4 08:21
Found the solution for nonlinear material problem and made the User instruction.
Anybody interested?

Please let me know at:

alpoznic@gmail.com
Found the solution for nonlinear material problem and made the User instruction. Anybody interested? Please let me know at: alpoznic@gmail.com

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