Problem Incompatible constraints on nodes when performing DC Crrent Flow analysis Version 24 / 21

Hengre

Hello

I am facing a problem during performing a DC current flow analysis with Mecway solver.
When I start solver, I get solver error message right in the beginning
"Error: Incompatible constraints on nodes 196457, 196467, 197063-197084, 227807-227829, 424800, 424811, 42483..."



The nodes involved seem to be on faces and edges where I used bonded contact.
here the nodes are on the dark blue part


here they are on the upper green part


Does any one have an idea to get rid of the errors.

Regards

Hengre

One additional question
How many nodes can be handled by the internal solver for DC current flow calculations?

Regards

Victor

That happens when other constraints share the bonded contact's slave nodes. Those could be fixed electric potentials or other bonded contacts. A workaround is to extrude a thin layer from some surfaces and exclude the thin edge of that from one of the bonded contacts. Or you could make that thin strip using split face in CAD.

You can also avoid it by consolidating multiple bonded contacts if possible.

Version 26 is less restrictive here and allows slave nodes to also be master nodes of other bonded contacts so you can avoid the problem in some cases by swapping master/slave surfaces.

The maximum number of nodes for DC current will be greater than static and similar to thermal steady state because its 1 DOF per node. So maybe a couple of million, at a guess.

Victor

Just a guess but your 3rd picture looks like it might be a symmetry boundary. Be aware that symmetry for DC current flow is the default when no boundary conditions are applied so maybe you can remove something from there??

Hengre

Hello Victor,
thank you for your answer. I was able to solve the problem. In the case of picture 2 swapping master/slave surfaces was agood Idea. 3rd picture, I found it was my mistake, because i had a double definition of a contact.
Thank you also for your information about symmetry boundary in connection with DC curent flow.

One more question about node internal heat generation using "Transfer internal heat generation from solution". Is ther any option to calculate the total amount of heat generated in a volume of a part. (Imported values from solution are node values)

Regards

Victor

In the DC current solution, you can use Solution -> Volume integral to integrate power density.

Hengre

Thank you for the last information (volum integral)! Works fine.

I am struggling again with an error message of the Mecway-Solver



It says Error: Element 268788 has incorrect topology. It may be inverted, tangled, flattened or severely distorted. (DC current analysis worked fine without issues) .

When I transfered internal heat generation from solution and make a therm. steady state calculation i'll gett that error. What can I do? How to correct the element? Deleting it did not help, another one popped up.


Regards

Victor

It sounds like a poor quality mesh but such elements are supposed to be indicated with a red "X" visible in wireframe view. Do they show that? If not, could you please send me the file to investigate why they're not being detected?

Hengre

Hello Victor,
I solved the problem doing a remeshing with modified meshing parameters.
But I was only able to find those elements by the searching with element number, didn't see a red "X"