[ANSYS Meshing] Mesh of concentric cylinders with hole

DDL · May 17, 2016, 09:05

Hi there!
My geometry consists of two concentric cylinders, with the outer one having a thick slot on the top (like a moneybox) at a certain distance from the sides.
Can you help me obtaining a good mesh? I just have to make a linear static mechanical analysis (a simple bending test) so it will be a stress concentration near the slot, and I want the mesh to be good there.
I tried at first with an automatic mesh, but the problem is the inner cylinder has no defects; this means the elements are very different in the contact points (outer surface of the inner cylinder and inner surface of the outer one).

Thank you for your help!

Steffen595 · May 19, 2016, 01:11

make a sweep. (mesh->insert mesh method -> sweep) Less cells and faster (especially helpful in academic with cells limit).
If you split the culindric surface at certain angles like a pie. If you do the inner and outer tube same angles, the cells will line up.
Then split the pipe solid where the slot is, do automatic mesher just there, with curvature and proximity. Then wou will get a fine mesh around the slot, where its critical

DDL · May 19, 2016, 05:57

Quote:

Originally Posted by Steffen595

If you split the culindric surface at certain angles like a pie. If you do the inner and outer tube same angles, the cells will line up.

Do you mean before extruding? I tried splitting in 4/8 equal parts and extruding them separately, obtaining 4-8 solids to mesh, but the result was not so good.

Quote:

Originally Posted by Steffen595

Then split the pipe solid where the slot is, do automatic mesher just there, with curvature and proximity. Then wou will get a fine mesh around the slot, where its critical

I'll try it, thank you. Before doing it, I expect the elements around the slot to be different from those in the same position in the inner cylinder (because there's no slot there). Couldn't it be a problem?At the same time I'm creating three solids in this way, when I tried before writing here I had problems in the connections of these solids. With "problems" I mean the elements where the connection is, which I suppose have to show some continuity.

Than you very much for your help!

Steffen595 · May 19, 2016, 06:15

no, dont solit the solids. Split the surfaces, in your CAD. Or if Design modeller can do that, do it there. I am not using DM, CAD is more convenient.
The mesh cells of both walls dont have to match, pretty impossible. But if you make a sweep with angles and the same number od separations they become quite close.
The slot will have finer mesh and this has to be so, because there happens the most. Id you have CAD wit FEA, can do some qick simulation there.

DDL · May 25, 2016, 08:13

Using the "Proximity and curvature" command my mesh has too many elements, I have to reduce them drastically. Is there a way to do it just for one solid and not for all of them? I choose the automatic method near the slot, and the sweep in the other two solids (on the left and on the right of the slot). But the "proximity and curvature" is selected on the general settings of the meshing.

DDL · May 25, 2016, 10:00

What I'm noticing is that using "Proximity and Curvature" I obtain a mesh which doesn't change if I add the sweep control, or an automatic method, or whatever. What am I missing?

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May 19, 2016, 01:11		#2
Steffen595 Senior Member Join Date: May 2012 Location: Melbourne Posts: 161 Rep Power: 13	make a sweep. (mesh->insert mesh method -> sweep) Less cells and faster (especially helpful in academic with cells limit). If you split the culindric surface at certain angles like a pie. If you do the inner and outer tube same angles, the cells will line up. Then split the pipe solid where the slot is, do automatic mesher just there, with curvature and proximity. Then wou will get a fine mesh around the slot, where its critical

May 19, 2016, 06:15		#4
Steffen595 Senior Member Join Date: May 2012 Location: Melbourne Posts: 161 Rep Power: 13	no, dont solit the solids. Split the surfaces, in your CAD. Or if Design modeller can do that, do it there. I am not using DM, CAD is more convenient. The mesh cells of both walls dont have to match, pretty impossible. But if you make a sweep with angles and the same number od separations they become quite close. The slot will have finer mesh and this has to be so, because there happens the most. Id you have CAD wit FEA, can do some qick simulation there.

May 25, 2016, 08:13		#5
DDL New Member Join Date: May 2016 Posts: 4 Rep Power: 9	Using the "Proximity and curvature" command my mesh has too many elements, I have to reduce them drastically. Is there a way to do it just for one solid and not for all of them? I choose the automatic method near the slot, and the sweep in the other two solids (on the left and on the right of the slot). But the "proximity and curvature" is selected on the general settings of the meshing.

May 25, 2016, 10:00		#6
DDL New Member Join Date: May 2016 Posts: 4 Rep Power: 9	What I'm noticing is that using "Proximity and Curvature" I obtain a mesh which doesn't change if I add the sweep control, or an automatic method, or whatever. What am I missing?