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Failed to find consistent initial values. Constraint found for variables in different segregated groups.

Posted 2025年4月10日 GMT+8 01:45 Heat Transfer, Studies & Solvers, Structural Mechanics Version 6.0 1 Reply

Srinivasan Ramachandran Materials Science and Engineering
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I got this error while modeling Spark Plasma Sintering mechanism. I tried giving all possible boundary conditions as I could think of. The error pops up only for the solid mechanics part (thermal expansion part]. Some problem with the solid mechanics boundary conditions but am not able to figure where and what. Please give me a hand. I am attaching the mph file below.

Regards Srinivasan

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1 Reply Last Post 2025年4月10日 GMT+8 23:00
Henrik Sönnerlind COMSOL Employee

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Posted: 6 months ago 2025年4月10日 GMT+8 23:00

The problem is that when you use a segregated solver, you cannot have constraints that connect degrees of freedom that are placed in different segregated groups. So that is what you have to look for. A typical case would be if displacement fields in solid mechanics are placed in one group and degrees of freedom belonging to rigid domains are placed in another group.

Constraints across different physics fields are uncommon.

Anyway, there are two solutions.
* Place all degrees of freedom that are connected by constraints in the same segregated group (or switch to a fully coupled solver).
* Use weak constraints, rather than pointwise constraints. Weak constraints do not have this limitation.

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Henrik Sönnerlind
COMSOL
The problem is that when you use a segregated solver, you cannot have constraints that connect degrees of freedom that are placed in different segregated groups. So that is what you have to look for. A typical case would be if displacement fields in solid mechanics are placed in one group and degrees of freedom belonging to rigid domains are placed in another group. Constraints across different physics fields are uncommon. Anyway, there are two solutions. * Place all degrees of freedom that are connected by constraints in the same segregated group (or switch to a fully coupled solver). * Use weak constraints, rather than pointwise constraints. Weak constraints do not have this limitation.

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