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3d mesh and thickness variation.

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Message 1 of 9
teopado89
776 Views, 8 Replies

3d mesh and thickness variation.

Good morning i have some questions:

1) i have a dual domain mesh and i change some triangle's thickness. If i change to 3d mesh, will 3d mesh keep this thickness variation i insert before?

2) how can i change thickness of some areas on my model using a 3d mesh in moldflow?

 

EDIT: i need it because i haven't a good model of a lens, so i repaired aspect ratio to 30 and i create a 3D mesh. But i need to facilitate flux in some regions to control weld line position (gate position is imposed).

Thanks

8 REPLIES 8
Message 2 of 9
xusho
in reply to: teopado89

3D mesher does not use thickness data defined on particular triangles. 

If you need to change thickness, you need to move corresponding nodes to intended positions.

 

Shoudong Xu

Moldflow Meshing Team

Shoudong Xu
Autodesk Moldflow Meshing
Shoudong.Xu@autodesk.com
Message 3 of 9
Alex.Bakharev
in reply to: teopado89

Hi,

 

1. The answer is No, 3D mesher ignores all the thickness information stored  in the surface mesh and just meshes the water-tight volume inside the surface mesh.

 

2. Any parametric CAD packages should be able to help quickly change thickness of a 3D body. Autodesk Moldflow Insight usually bundles with a free copy of Autodesk Inventor Fusion that should be able to do the job. Alternatively you could write an API script that would e.g. multiply all the z-coordinates of the nodes to a factor, for simple geometical manipulations it should do the the job.

Message 4 of 9
teopado89
in reply to: Alex.Bakharev

is it normal if i have a dual domain mesh with maximum aspect ratio 30, and then i switch to 3d mesh, aspect ratio maximum becomes 150?
Message 5 of 9
Alex.Bakharev
in reply to: teopado89

Yes, it is common when the surface mesh is coarse and the size of a typical surface element is much larger than the thickness. The recommended maximum aspect ratio value is 50; the absolute maximum value is 500. Thus, 150 is sort of acceptable but high. If the results looks suspicious I would first remeshed the surface mesh finer and then recreate the 3d mesh.

Message 6 of 9
teopado89
in reply to: Alex.Bakharev

To avoid remesh again from dual domain (i delete the file, and i had 600 triangles over 30 aspect ratio to modify again) can i take my 3d mesh, change to a dual domain, and recreate a 3d changing some options?

 

Following what xusho said, i moved nodes of external tetras layer, moving to internal by 0.5mm so i can obtain a thickness reduction.

The problem is that when i start a filling analysis it gives me an error of 25000 non oriented tetras...

Message 7 of 9
Alex.Bakharev
in reply to: teopado89

Yes, just change the mesh type to the dual domain (and if neccarily remesh it)

Message 8 of 9
teopado89
in reply to: Alex.Bakharev

oh no...

changing to a dd mesh from 3d now i have 18000 triangles with aspect ratio > 30...

do you know a good way to orientate tetras so i can start an analysis with the preceding 3d mesh?

Thanks

Message 9 of 9
teopado89
in reply to: teopado89

OK, starting from another analysis i turned to dd mesh, i resolved aspect ratio higher than 30. I moved triangles to obtain a thickness variation and i change back to 3d mesh.
Question:
in dd mesh (with thickness variation of 0.5mm using triangle properties) i have 75 MPa pressure at switchover.
In 3d mesh (both in 3d coming from original dd mesh thickness, and in the other coming from dd mesh with moved triangles) pressure at switchober is about 45 MPa.
Which one is more correct?
dd mesh has aspect ratio 30, 3d has 150.
Thanks for help and advices

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