Quads shaped elements composed of 4 triangles

[abdiel]

Dear all, good day:

I would like to mesh my geometry with 4 diagonally intersecting triangles inside a quad. This I want to do it
for the sake of reducing volumetric locking.

4t.png (4 KiB) Viewed 3966 times

I Have looked in GiD for some time now, and I have not been able to find a suitable function to perform that. Is there a way
to achieve this in GiD? Sorry for the time if this issue was already discussed in the forum.

Thanks in advance,
Abdiel

[escolano]

You must set that do you want your four-sided surface to be meshed structured,
Mesh->Structured->Surfaces->Assign number of cells
and select the surfaces and specify the nxm divisions on each direction.

and set also that do you want triangles or quadrilaterals (in your case triangles)
Mesh->Element type->Triangle
and select the surfaces

and depending on a preference variable each quadrilateral will be splitted in two, or four triangles (creating a new node in the center)
Utilities->Preferences...

preferences_structured_triangles.png (14.79 KiB) Viewed 3964 times

The symmetrical option create 4 triangles.

[abdiel]

Good day,
thanks again for the prompt reply.

I have followed the procedure as suggested, nevertheless I still have the issue of not been able
to keep the mesh symmetry (4 triangles diagonally crossed in a center node) once the simulation is running.

For example, the first picture is the original mesh I create following the procedure and the second one is the same mesh once It is set to run (the mesh looks more or less random). Even without the application of any load or whatsoever, I keep getting this problem.

mesh.jpg (491.08 KiB) Viewed 3955 times

mesh1.jpg (584.18 KiB) Viewed 3955 times

Would you have any idea on why this might happen? I am using GiD 12 and GiD 10 in case that would have any effect.

Thanks a lot for the help

[escolano]

I think that you are confusing GiD features and solver features.

I think that the first mesh has been created by GiD and the second mesh seems a mesh modified by the solver itself, based on the initial mesh.
What is the solver (problemtype) that you are using?
Probably it is doing some kind of re-mesh during the calculation and writing for postprocess a modified mesh (a .post.msh file)
Then your question must be asked to the problemtype developers.