Learning Forum

[Ranjan13]

Dear all!

I have a cylindrical structure as shown in the figure below:

[Erik Kostson]

Hi

Use just normal symmetry in the the two quarter faces which should have an axis perpendicular to them - or just fix that displacement along the normal of the face as shown in the video below.

See here for sym.:

Cyclic symmetry you need to have certain mesh (same actually - and using some ways to copy the mesh between the faces) on the cyclic faces which you do not have since it is an import.

All the best

[Ranjan13]

Hi Erik Thanks for the prompt response! I tried to implement the normal symmetry in my model. But I am facing a problem in selecting the face from my lattice structure using both Geometry and Named Selection options. Using the face selection feature in the Geometry selection, it is selecting the whole volume instead of a face. The Named Selection option is not giving me the list of the faces from the structure which I imported from nTopology for applying boundary conditions (As shown in the below image):
Could you please tell me how can I select the faces from the gyroid lattice? I have imported the lattice as an Abaqus input file from nTopology along with the name selected faces.
Thanks a lot in advance!
Regards Ranjan

[Erik Kostson]

Can you please show your imported lattice model inside the mechanical
UI (just want to see how it looks) and also show the named selection FACESET1 and 2.

thank you

Erik

[Ranjan13]

Hi Erik Here it is:
Imported model
FACESET 1:
FACESET 2:
Thanks a lot!
Regards Ranjan

[Erik Kostson]

No worries.
To be honest these part or at least the named selections are not very similar with each (different amount of nodes in each face and distribution) other which one would expect, so something is strange - in the software you use to generate the lattices I would start with these faces being completely planar so it does not curve them, because a symmetry plan should be flat to make life easy. Once this is done (flat symmetry faces) then:
So try to add a Displacement boundary condition (BC) as shown in the image below, and then restrain the displacement (set it to 0) in the direction perpendicular to these symmetry faces (just as shown in the video above in the previous post). You need like in the video of course to have 2 Displacement BC, one for each symmetry plane.



All the best

Erik

[Ranjan13]

Hi Erik I did create a more planar surface in the external model and imported it to Ansys mechanical for applying the symmetry conditions. But unfortunately, it is still not showing in the drop-down list under the named selection feature. Please find below the surfaces I imported from nTopology:
FACESET 1:
FACESET 2:
I am using version 2021 R2 on my laptop. I have also checked in my friend's laptop (version 18.1), but still facing the same problem.
Thanks a lot!
Regards Ranjan

[Erik Kostson]

Please read through my post carefully - we can not use symmetry so do this instead which is equivalent to a symmetry condition:
So add a Displacement boundary condition (BC) as shown in the image below, and then restrain the displacement (set it to 0) in the direction perpendicular to these symmetry faces (just as shown in the video above in the previous post). Finally you need to have 2 Displacement BC, one for each symmetry plane.
So use displacement
Also search the internet to understand what a symmetry BC is (just restrains degrees of freedom that are/move perpendicular to the symmetry plane - so for 3D elements either UX,UY, or UZ) - see this video for a simple example:
Thank you
Erik

[Ranjan13]

Hi Erik Yeah understood it now. Thanks a lot for the guidance! By using displacement in place of symmetry the only drawback I think is we can't see the full model after getting the results for the quarter model. Please let me know if there is a way to see the full model with all the results.
Thanks a lot in advance!
Regards Ranjan

[Erik Kostson]

Hi

That is very good.

Yes, we can not see the full model in the results with displacement (as we said though symmetry on nodal named selections does not work with the imported external model).

All the best

Erik

[Ranjan13]

Thanks a lot, Erik for your valuable time and guidance!!
Best Regards Ranjan