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Ansys Structural- Symmetry BC Problem

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Old   April 8, 2014, 14:34
Question Ansys Structural- Symmetry BC Problem
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Mudassir
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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
File Type: png 2-Symmetry.PNG (38.6 KB, 9 views)
File Type: png 7-Deformation.PNG (42.6 KB, 8 views)
File Type: png 7-Stress.PNG (37.8 KB, 7 views)
File Type: jpg deform.jpg (21.9 KB, 9 views)
File Type: jpg stress.jpg (22.4 KB, 10 views)
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Old   April 17, 2014, 02:07
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Florin Gheorghe
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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?
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Old   April 17, 2014, 09:13
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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
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Old   April 23, 2014, 05:35
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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.
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