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load group and constraint group

Posted Apr 6, 2024, 10:03 p.m. EDT 4 Replies

Carl Xu
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What if all constraints are put into load groups as well rather than in constraint groups?

In Stationary analysis there is "define load case" under study extensions. But in time dependent analysis there seems to be nowhere to define load groups. So there is no way to specify different load groups to different study steps?

4 Replies Last Post Apr 11, 2024, 3:33 a.m. EDT
Henrik Sönnerlind COMSOL Employee

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Posted: 7 months ago Apr 8, 2024, 5:33 a.m. EDT

The difference between constraint groups and load groups is that loads only change the right hand side of the system of equations. If you change the set of constraints, you also get a new stiffness matrix. So they are not interchangable. When you can assign a constraint to both a load group and a constraint group, the constraint group is used for turning the constraint on and off. The load group can be used changing, for example, the value of a non-zero prescribed displacement.

Load and constraint groups are only supported by some study types.

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Henrik Sönnerlind
COMSOL
The difference between constraint groups and load groups is that loads only change the right hand side of the system of equations. If you change the set of constraints, you also get a new stiffness matrix. So they are not interchangable. When you can assign a constraint to both a load group and a constraint group, the constraint group is used for turning the constraint on and off. The load group can be used changing, for example, the value of a non-zero prescribed displacement. Load and constraint groups are only supported by some study types.
Carl Xu
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Posted: 7 months ago Apr 9, 2024, 10:09 a.m. EDT

Thank you. So may I confirm that in time dependent analysis load groups aren't supported?

Thank you. So may I confirm that in time dependent analysis load groups aren't supported?
Henrik Sönnerlind COMSOL Employee

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Posted: 7 months ago Apr 10, 2024, 3:51 a.m. EDT
Updated: 7 months ago Apr 10, 2024, 4:06 a.m. EDT

That's correct. It is supported for the stationary types of analysis, that is Stationary and Frequency Domain.

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Henrik Sönnerlind
COMSOL
That's correct. It is supported for the stationary types of analysis, that is Stationary and Frequency Domain.
Carl Xu
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Posted: 7 months ago Apr 11, 2024, 3:33 a.m. EDT

Thank you for the confirmation Dr Sönnerlind

Thank you for the confirmation Dr Sönnerlind

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