Warning on boundary conditions

[tito662]

I m defininf symetry boundary conditions on a structure but Abaqus is giving me the following message on every node at the symetry section and is ignoring the symetry condition
DEGREE OF FREEDOM 3 IS NOT ACTIVE ON NODE 42284 INSTANCE
RAIDISSEUR-1 - THIS BOUNDARY CONDITION IS IGNORED
Can anyone help?

 

[corus]

Is it a 3D problem otherwise in 2D there is no freedom 3.

corus

 

[tito662]

It is a 3D problem...
When i define symetry i have to block translation along direction 3 and rotation around axis 1 and 2(degrees of freedom 4 and 5)...For parts neshed with solid elements:
I have the following message for solid elements:
Degree of freedom 4(or 5) is not active in the model on node...this boundary condition will be ignored..

For the part (meshed with shell) i have the following'
Degree of freedom 3 is not active in the model..

So for solid elements do i have only to restrain displacement along direction 3?
And for the shells i dont define boundary conditions?
Thanks!

 

[dldhdz]

what's the exactly element type you are using then?

 

[Yoman228]

Did you have coupling or tie surface at those nodes?

 

[bassmanjax]

Solid continuum elements like C3D8 do not have rotational dof's, only translational, hence the warning when you try to apply constraints to dof 4& 5.

Not sure about the 'shell' elements though...please post excactly what elements you are using.

Martin

Martin Stokes CEng MIMechE

 

[tito662]

Yes Yomann i have tie surfaces and coupling..
Do u think i have the warnings cause i m trying to constrain nodes which are tied to other constrained nodes due to the tied surfaces?

 

[Yoman228]

I belive that is the case then, as you already tied or coupled the surface, that dof is already be fixed by the tie or coupling.
I personaly excluded that dof in the symmerty node and make the model look more tidy and save the analysis to print out unnessary message, but I think it does not matter in term of the results in either way.
It is a warning not a error, right?

 

[tito662]

Ure right
Thanks for ur help