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froztbear November 9, 2011 04:41

Problem making structural mesh on a surface
5 Attachment(s)
Hey guys

I experience big problems while trying to create a structural mesh on a surface. I would like to be able to block it, maybe its easiest with hexa blocking.

I have almost no idea when it comes to blocking with hexa. I don't know wether to use 3d or 2d blocking, because it is a surface, but a surface that can be described with coordinates in three dimensions.

All geometry is imported a .model format from CATIA v5. My version of Ansys ICEM is 11.0.1.

Can someone help me with the blocking?
I have tried to create some lines to make the blocking part easier but I have not succeded. I think the fail of mesh creation that you can see in the picture (a hole in the surface) is due to the bad geometry that is created of me inside ICEM. (whole geometry from CATIA but all help lines and help points is created inside ICEM)

I don't need a good quality mesh, just to be able to fully control the mesh (the number of nodes/elements) because this mesh will only be used form interpolate another mesh from a shrinked geometry. (The mesh in picture 5 is good for me)
I guess curve mesh with defined number of points is mandatory for me if I want to control the number of nodes.

In all simulations, I use folllowing settings:
global mesh:
size = 8-16
global surface mesh:
all quad, patch dep, patch dep
mesh calculation (surface mesh)
all quad
autoblock OR patch dependent

Explanations of the pictures:
I use autoblock in the first one. All nodes seems to be quite good but two surfaces where failed. As you can see in picture number 3, my blocking is not made in hexa, but with curves made from points created in ICEM and splitting surfaces with those curves. I think this way of creating m blocking is not very stable.

Picture 2 is my geometry from the start which I would like to have a structural mesh on.

Picture 4 is as the first one but with patch dependent in mesh calculation options

Pictuer 5 is a mesh with patch dependent in mesh calculation options. I can easily control the number of elements/nodes if the mesh look like that!

I really hope you have some good ideas and have time to help me. Its really a big problem and I have struggled for almost 2 weeks now and I start to run out of ideas.

Thank you in advance!

PSYMN November 10, 2011 08:52

You would start with a 3D hexa blocking... Then at the end you can convert 3D to 2D blocks (it is under Create blocking => 3D to 2D) and delete the 2D blocks that you don't need.

As for the projection issues... You should probably fix your geometry... But under "Blocking => Associate => Face to Surface" there is an option for "interpolate". This will turn off the face association to the surface (that isn't there) and instead just interpolate across that surface based on the perimeter and surrounding mesh.

If you think you are breaking your model during the chopping up, then don't do that. The Hexa blocking edges will associate to curves just fine. You do not need to chop up the original geometry. Of course, we could probably look into what you are doing wrong in the chopping or how to fix those bad surfaces, but since you are new, it is probably easier to say "dont do that.":eek:

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