Import of external mesh file (.msh etc.)

[SilberVogel]

Good day for all, is there possibility to import and use external mesh file for this code?

[epsi1on]

Hi.
It could added if the mesh file is a well known format.
Any document or standard etc.?

[SilberVogel]

Thx for answer. Standard formats for ANSYS export (.msh, .prj), maybe .stl or text formats...

And how to do it?

[epsi1on]

It would not be hard.
To start we must know the syntax of .msh file etc so we need some document or reference etc.

[SilberVogel]

Some of shell mesh.

If needed different format, I will send it

[epsi1on]

Thanks for the file. I think we also need the .msh file (assuming we want to add support for .msh file input)

[SilberVogel]

.msh is not necessary at all. I just want understand how to add external mesh in already supporting formats for this soft. Can you list this formats and show example how?

[epsi1on]

It is simple. Just create a class named "MshFileImport", put a method "Import()" and write the import code inside...
Then there is need for minor documentation and done...

[SilberVogel]

Thanks for explain! If you have any example of project in Viual Studio formats (like .sln) with "Import", please, send it for more understanding.

[SilberVogel]

If your code need specific mesh (shell or solid) in specific formats (.db; .inp; .dat; .inc; .uns; .k; .key; .bdf; .nas; .msh; .cas), for make example of "Import" code, tell me, I`ll make it.

[epsi1on]

Any of these would be good I think. Can you please suggest one? simple and widely used one. :)

[SilberVogel]

Many thanks, .msh format

And last question, does it support shell meshes or only solids?

[epsi1on]

good. Do you know any white sheet or definition or standard something that do describe this .msh format?

[epsi1on]

These are present elements:
1D: BarElement (2node)
2D: Triangle (3node) and Quadrilateral (4node)
3D: Tetrahedral (4node) and Hexahedral (brick element, 8 node)
I think both shell and solids. Not sure exactly what you mean.

[SilberVogel]

.msh proprietary file format. Some of I can find about it Im place in archive. In .pdf see Appendix B.

If any problems with this format, please, tell me.

And what is the next step to start calculations with my own mesh? Please, show me on the example of a Visual Studio project.

[epsi1on]

Thanks for the link. its a large file i need to see on PC which will do today or tommorrow. I just found a link from google, is it right format?

http://www.manpagez.com/info/gmsh/gmsh-2.2.6/gmsh_63.php

Next step is to make a class and implement the code. I just created the empty class:
https://github.com/BriefFiniteElementNet/BriefFiniteElement.Net/blob/master/Sources/BriefFiniteElementNet/Utils/MeshImport.cs

[SilberVogel]

Yes, think its right, .msh has ASCII encoding.

I saw your changes "Sources/BriefFiniteElementNet/Utils/MeshImport.cs". Wait for your code, and try to do it too.

[epsi1on]

ok, so I made an issue for this item (#141)
just need an example .msh file to go. @SilberVogel can you please put an example .msh file? thanks

[SilberVogel]

Not too big?

[epsi1on]

right size but seems wrong format. (have some non ascii characters in the content)

Are you sure it is exactly the version that you mean?
Thanks

[SilberVogel]

I think its Binary option of export problem, make new files in .msh, .dat and .inp Maybe if you can’t open it, then you should try later with a different file or format...
Mech.zip

I decided to create a code with my simple (Cartesian mesh with 5 elements) model (a console with one fixed wall and a load applied to the other edge) according to the coordinates of the nodes.

But I found that I can't add more than two nodes to the model for the BarElement class. I understand that a large (100000+) number of nodes is possible only for the TetrahedronElement class? Tell me please, how can I implement the code for my model (I can make Tetrahedron mesh for it). My code:
BfeTestApplication.zip
Many thanks!

[epsi1on]

each finite element is related to one bfe element. for above image there should be 5 distinct elements, but you only define one bar element.
There is some documentation for available elements:
https://bfenet.readthedocs.io/en/latest/elements/finiteElements/index.html
on the left panel of this you can see documentation for different elements

bar
triangle
tetrahedron

[SilberVogel]

Im trying Tetra mesh, but VS show me errors when Im add TetrahedronElement class... Where Im wrong?

Also send .sln project

Tetra.zip

[epsi1on]

you can do like this:

var e1=new TetraHedronElement();
e1.Nodes[0]=n1;e1.Nodes[1]=n25;e1.Nodes[2]=n12;e1.Nodes[3]=n7;

[SilberVogel]

Question is about code. What I'm missing, especially in material properties (Young and Shear modulus). And do I need calc moments of inertia and set it? It's the same model/mesh:

Tetra.zip

[epsi1on]

Hi
Does the compiler show you any error? pretty much like red lines in your visual studio screenshot?
I think the way you define material is not right. can you please send and screenshot like your last screenshot?
thanks

[SilberVogel]

Sure)

[epsi1on]

thanks as you can see the error message, it says the TetrahedronElement do not have properties of E and G. This is how you should define the material:

var e = 210e9;//210 gpa
var nu = 0.3;

var steelMat = UniformIsotropicMaterial.CreateFromYoungPoisson(e, nu);

e1.Material = e2.Material = steelMat;

[SilberVogel]

How to chek Internal Forces in each element for Tetrahedron class? Didnt find it in TetrahedronElement.cs

[epsi1on]

Yes you are right. it is not implemented yet. Added and issue for it #142 .
Hopefully will be added this week...

[SilberVogel]

If I can help with it, tell me

[epsi1on]

Wonderful.
Is it identical model with exact node location and element-node connection?
If yes then it should report exactly same nodal displacement with current case_3 but i did not see the nodal displacements in order to check it.
By the way i'll use it for validation.

Thanks again

[epsi1on]

If you mind, can you please create a pull request and put these output files into Case_3 folder?
This way your username will be listed in project history, and make it simpler to track the creator of file in future.
If you have any issue with creating the pull request, then please let me know, I'll add them myself ...

Thanks.

[SilberVogel]

Sorry, Im newbie at GH... Better you put them.

I`ll chek displacements.

[SilberVogel]

Wonderful. Is it identical model with exact node location and element-node connection? If yes then it should report exactly same nodal displacement with current case_3 but i did not see the nodal displacements in order to check it. By the way i'll use it for validation.

Thanks again

Yes, for this case were used Job-10.inp file from .../BriefFiniteElement.Net/Validation/Case_03/

Case 3 Deformation for Brief.zip

[epsi1on]

As you know the strain and stress in constant through a tetrahedron element, But as long as i see, in your output, the stress is not constant through tethrahedrons. Just thinking about the reason... Do you have any idea?

Can we please continue discussion about tetra hedron internal force here: #142 (for future reference)
Thanks

[epsi1on]

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