Quad Mesh Topology

[Md%20Motiur%20Rahman]

Hello,
I want to 4 noded quad element for the following model. I tried with quad/hexa topology option for both structured and unstructured algorithm. But I found some of the elements are triangles. How can I solve this problem?

[akanon]

Dear Md%20Motiur%20Rahman,

In order to have a four-node quadrilateral mesh, you should ensure that all the sub-geometries in the face are four noded. This can be done by drawing guiding lines on the main geometry. Please see the attached figure to see an example that would be suitable for your case.

So following the figure, you can

1) draw the red lines, always ensuring 4 node sub geometries

2) then finally merge all by selecting everything and clicking on the merge button under the geometry tab

After doing these, you can pick the quad/hexa topology option and generate a structured or unstructured mesh without any problem.

Have a nice day,

[GiorgioAltin]

Hi,

I've got the same problem with my model and I can't solve it. I tried with the suggestion you gave above, but the issue still exist. I need to mesh with quadrilateral elements but when I run the model I only get triangolar elements. I'll attached the file, so maybe you can help me.

[ValentinaSB]

Hi GiorgioAltin,
You are using mesh control and it is correct, just select solids instead of faces there. Don't forget to select the geometry before pressing the assign button.

Screenshot 2023-04-17 184250.jpg (228.76 KiB) Viewed 648 times

Another thing that I saw you have many geometries that you probably don't need, I think that it is only a sweep that you are really want to use.

Screenshot 2023-04-17 183922.jpg (52.11 KiB) Viewed 648 times

Also, you are using a very fine mesh that your model is quite heavy, you can use a parallel analysis and partitions if you really need such a fine mesh.

Screenshot 2023-04-17 184322.jpg (79.03 KiB) Viewed 648 times

Best,
Valentina

[GiorgioAltin]

Thank a lot now I can define the mesh as I wish but the analysis stops immediatley reporting the error "cannot find initial permutation". I've seen on the forum that I probably have to regolarize the mesh. It means substantianlly to build a new model. Is it right?
Thank you
GA

[STKO Team]

Could you share your file?

[GiorgioAltin]

Attached the model.
Thank you

[STKO Team]

Ok, this happens because in the XY plane, your elements are distorted. The Automatic version of the absorbing boundary only accepts non-distorted (or slightly distorted) elements.
If you cannot make the mesh non-distorted, you can manually extrude the boundaries and use the non-Auto version of the absorbing boundary. But it will be a little longer to set-up.

Another option is to create an outer-part of your soil mesh with a regular mesh. Since this new part will not have a compatible mesh with the inner part, you can connect them using the ASDEmbeededNodeElement.
If you choose this option let us know