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BH Curve as function of normH and T

Posted May 24, 2013, 10:36 a.m. EDT Low-Frequency Electromagnetics Version 4.3b 3 Replies

Nicola Gagliardi
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Hi,
I'm study the induction heating of a billet and I'd like to implement a BH curve as function of normH and the temperature. I have an analytical formula for that where I compute the normB as function of normH and T. This analytical formula is not inverse and I can't invert it. In order to reach that I add a BH curve in the material propriety where I report my formula. when I lunch the solution the software answer that doesn't know normH that in principle should be an input factor. So seems possible to give normB as input and extract normH but not the opposite that it my case. There is something of wrong in my procedure? Can someone help me to solve that problem?

Many Thanks

Best Regards,
Nicola
3 Replies Last Post May 27, 2013, 9:50 a.m. EDT
Jens Krause
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Posted: 1 decade ago May 27, 2013, 6:45 a.m. EDT
If there is really no way to invert the function analytically you might
use Comsol to invert it numerically. This may of may not work in your case:

Use a "dode" physics with variable u and create an algebraic equation in
the domains where the respective material and set it to:

u-f(mf.normB,T)

This will calculate normH for the current value of normB and T and store it into u.
Now you can use u as normH in mf:

Ampere's Law -> Magnetic Field -> Magnetic Field Norm -> User Defined = u

This make your problem highly nonlinear and you might want to set good initial
values.

Good luck,

Jens
If there is really no way to invert the function analytically you might use Comsol to invert it numerically. This may of may not work in your case: Use a "dode" physics with variable u and create an algebraic equation in the domains where the respective material and set it to: u-f(mf.normB,T) This will calculate normH for the current value of normB and T and store it into u. Now you can use u as normH in mf: Ampere's Law -> Magnetic Field -> Magnetic Field Norm -> User Defined = u This make your problem highly nonlinear and you might want to set good initial values. Good luck, Jens
Nicola Gagliardi
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Posted: 1 decade ago May 27, 2013, 8:13 a.m. EDT
Hi,

Please can you help me in the implementation of your solution.
The model is attached.

Many Thanks,
Nicola
Hi, Please can you help me in the implementation of your solution. The model is attached. Many Thanks, Nicola
Jens Krause
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Posted: 1 decade ago May 27, 2013, 9:50 a.m. EDT
Hi,

maybe this will help you for a start. I don't have the time implement the complete
function, but the error message is gone.

You must replace

u*mu0_const*42-ih.normB

by something in the manner

BH_function(u,T)-ih.normB

where BH_function is your expression for the
BH-relationship, in this expression you must use
u for normH


Regards

Jens
Hi, maybe this will help you for a start. I don't have the time implement the complete function, but the error message is gone. You must replace u*mu0_const*42-ih.normB by something in the manner BH_function(u,T)-ih.normB where BH_function is your expression for the BH-relationship, in this expression you must use u for normH Regards Jens

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