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Apply constraints to material model's parameters in MCalibration


wldeng
Posts: 2
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(@wldeng)
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Joined: 4 months ago

Hi Jorgen,

I wonder if there is a way to apply inequality constraints to material model's parameters in MCalibration during data fitting. For example, considering the Mooney-Rivin model, the Drucker stability condition requires that 

C10 + C01 > 0.

I looked up the forum and only found this page for applying Parameter Connections (equality constraints). 

Thanks!

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wldeng
(@wldeng)
Joined: 4 months ago

New Member
Posts: 2
Posted by: @wldeng

Hi Jorgen,

I wonder if there is a way to apply inequality constraints to material model's parameters in MCalibration during data fitting. For example, considering the Mooney-Rivin model, the Drucker stability condition requires that 

C10 + C01 > 0.

I looked up the forum and only found this page for applying Parameter Connections (equality constraints). 

Thanks!

I guess the way to apply the inequality constraints, such as C10 + C01 > 0, is

put '-C10' in the lower bound for parameter 'C01'???

 

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Jorgen
Posts: 3924
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(@jorgen)
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Joined: 2 years ago

There are 2 ways to do that. The first is to use an equation-based constrains on the parameters. In this case I used a "penalty" value of 10 and the step-function to impose the inequality constraint. This approach is similar to a Lagrange multiplier.

Another approach is to set a fitness weight for the Drucker stability. That can be specified for each load case.

/Jorgen

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