# Ansys Structural- Symmetry BC Problem

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April 8, 2014, 14:34
Ansys Structural- Symmetry BC Problem
#1
New Member

Mudassir
Join Date: Apr 2014
Location: Pakistan
Posts: 11
Rep Power: 8
Hi,
I am doing a structural analysis on a very basic geometry, Its a Cylinder(Crucible or Glass like geometry), i am Doing this analysis on Half of the geometry and trying to apply the symmetry conditions to accomodate for the rest of the geometry. The problem is , When i fix(FIXED Support) the Bottom Face (Base of the crucible) i get symmetric results, But when the bottom is "Frictionless Support" the results show that it is not behaving like a Cylinder, it means that the symmetry is not working fine? Can anyone please help in this matter?

Image-1: Symmetry Face.

Image-2,3[File: "7-deform","7-stress"] : Results with Bottom Fixed (Show Symmetric Behaviour)

Image-4,5[file name "Deform","Stress"] : Results with Bottom as Frictionless Support(Doesnt seem to be symmetric)

Thanks!
Attached Images
 2-Symmetry.PNG (38.6 KB, 9 views) 7-Deformation.PNG (42.6 KB, 8 views) 7-Stress.PNG (37.8 KB, 7 views) deform.jpg (21.9 KB, 9 views) stress.jpg (22.4 KB, 10 views)

 April 17, 2014, 02:07 #2 New Member     Florin Gheorghe Join Date: May 2013 Location: England Posts: 24 Rep Power: 9 Hello Mudassir, I understand that you get different results using different boundary constraints. I think the problem is not the symmetry BC, but the way you applied the constraints on the bottom. Can you elaborate on the way you applied the loads? __________________ Best regards, Florin

 April 17, 2014, 09:13 #3 New Member   Mudassir Join Date: Apr 2014 Location: Pakistan Posts: 11 Rep Power: 8 Thanks Florin, I just got this problem solved, but i am having some other problem now, May be you can help in that too. I am doing stress analysis as yo can see above, I need GUIDANCE regarding Meshing of this. What type of mesh should i use? How to assure the mesh quality, and that results are near to what would be actually, Etc Etc. Can you help? Thanks again! Mudassir

 April 23, 2014, 05:35 #4 New Member     Florin Gheorghe Join Date: May 2013 Location: England Posts: 24 Rep Power: 9 Hello Mudassir, I would use hexa elements; make sure the midside nodes are on; you can switch the on in global mesh settings, advanced. Make sure you have at least 3 elements on the thickness; to do this you can impose a proper the size of elements on the body. After the analysis is done, I recommend to do a convergence study, to be sure that you results have converged. __________________ Best regards, Florin

 Tags ansys, mechanical, structural, symmetry bc