step file from solidworks crashes elmer

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fbartra
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step file from solidworks crashes elmer

Post by fbartra »

I created a simple step file with solidworks
when I open the file from elmer,
It does show the proper geometry on the preview.
Then it starts the mesh generator and then it just crashes, closes elmer, no error message

Attached is the step file from solidworks

any suggestions please will be appreciated

thank you

Fausto Bartra
Attachments
2D.STEP
(43.46 KiB) Downloaded 78 times
kevinarden
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Re: step file from solidworks crashes elmer

Post by kevinarden »

There are three surfaces in the step file but they do not know about each other. This is not the intent in FEA. Generally there would be a boolean operation to partition the bigger surface with the two smaller blocks. Or cut the bigger surface with the two smaller blocks with the bigger surface so that they have a common boundary.

ElmerGUI is running netgen in the background and netgen is crashing, I also thin ElmerGUI is asking netgen to generate solid elements.

This picture is the step file meshed in gmsh, the elements do not line up at the boundaries.
mesh1.png
mesh1.png (47.46 KiB) Viewed 1218 times
This picture is the mesh generated after the boolean operations, which is the desired outcome in FEA.
mesh2.png
mesh2.png (25.93 KiB) Viewed 1218 times
This is the step file used for the second one.
new2d.step
(20.38 KiB) Downloaded 81 times
ElmerGUI is not a very robust meshing tool. It is better to use gmsh or salome for meshing. gmsh is very straightforward to learn, it can import a step file, mesh it, and save a mesh file that ElmerGUI will open.
fbartra
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Re: step file from solidworks crashes elmer

Post by fbartra »

kevinarden:

many thanks for taking to time to reply

please if you know of a good tutorial or video showing how to use GMSH please email me the link

Thank you again

Fausto Bartra
fbartra
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Re: step file from solidworks crashes elmer

Post by fbartra »

kevinarden:

I am sorry to bother you again
but I still can not get the boolean function to work

I have look a few tutorials and videos.
I followed the steps the best I could

can you please email me the steps of how to "boolean difference" the surfaces?

thank you again

Fausto Bartra
kevinarden
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Re: step file from solidworks crashes elmer

Post by kevinarden »

I imported the solidworks step file in gmsh, but apparently you can not edit, boolean, or delete surfaces from a step file. Typically you would do this manipulation is in solidworks and only use gmsh to mesh.

You can easily create this geometry in gmsh without the import. You create all of the points first, then create the outer surface by selecting the boundaries. It will ask you to select hole boundaries, so you select the inner surfaces. You now have a surface with holes in it.

You then create the internal surfaces by selecting the internal boundaries.

You now have individual surfaces that shares boundaries.
fjimenez
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Re: step file from solidworks crashes elmer

Post by fjimenez »

Hi Fausto,

In my humble opinion, SALOME is an easier beast to tame than gmsh. I use FreeCAD to create step files for both 2D and 3D simulations but if the geometry is easy I just do everything in SALOME. I am attaching a script that you can use for meshing the geometry you uploaded. Just download SALOME, load script and voila, you have your mesh. Just make sure that you have the step file you uploaded in the same directory where you have the script. The bear instruments channel in youtube has a great example for a simple electromagnet https://www.youtube.com/watch?v=J83n0goGz8o. These are the steps in SALOME:

1. Import Step file
2. Explode in edges
3. Create faces (they can be overlapping)
4. Create partition
5. Explode new partition in faces
6. Name faces
7. Create groups of edges for boundary conditions
8. Mesh partition
9. Export mesh

You can control the mesh size for individual faces very easily, just look at the file I am attaching to see how easy it is. Now, when you export the mesh as unv you actually have the name of body and boundaries already there so you can refer to them by name in the sif file. For 3D the process is exactly the same.

Cheers,

step2unv.tgz
(1.71 KiB) Downloaded 86 times
kevinarden
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Re: step file from solidworks crashes elmer

Post by kevinarden »

The getting started elmer doucument is very usefull, chapter 9 covers using salome and gmsh

https://www.nic.funet.fi/pub/sci/physic ... dElmer.pdf
fjimenez
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Re: step file from solidworks crashes elmer

Post by fjimenez »

Hi Kevin,

I am not sure why I hadn't checked in more detailed the getting started guide, chapter 9 is very much what I just said explained in a much better, detailed way. Probably the title kept me away from it since I don't really use windows.

Cheers,

Francisco
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