FEM and PartDesingNext

About the development of the FEM module/workbench.

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ickby
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Re: FEM and PartDesingNext

Post by ickby »

bernd wrote:For connected multibody meshes we need to pass CompSolids to the mesher. BooleanFragments can be used to make CompSolids out of Part objects, but it does not work on PartDesignNext bodies. FreeCAD raises exeptions. The question is just: How to make a CompSolid out of PartDesignNext bodies? Anybody any idea?
A PArtDesign body is just a Part::feature like any other FreeCAD Part Object and should hence work exactly like a box or cone or whatever. There should be no difference. What does the exception say?
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bernd
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Re: FEM and PartDesingNext

Post by bernd »

Just tested again, and it works like a charm. Attached the file.

- Select tow PartDesingNext Bodies
- Make Part --> BooleanFragment out of it
- change BooleanFragment mode to CompSolid
- To be sure extract the CompSolid out of the Compound (all booleans return Compounds)

Attached the file and screen
PartDesingNext--CompSolid.FCStd
(16.29 KiB) Downloaded 20 times
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OS: Windows 7
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.17.8939 (Git)
Build type: Release
Branch: master
Hash: cb16eda2165d1af34ebbd73628f82aa00037f667
Python version: 2.7.8
Qt version: 4.8.7
Coin version: 4.0.0a
OCC version: 7.0.0
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bernd
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Re: FEM and PartDesingNext

Post by bernd »

Just played with different element size again. The algorithm for GMSH are done. The problem is how to define the different mesh size for the element in gui and python.

cube 1 and 10 -- > 4 mm
3 and 8 --> 1 mm
cube 5 and 6 --> 8 mm
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HoWil
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Re: FEM and PartDesingNext

Post by HoWil »

I hope I do get your question right?

Isn't it the same GUI as we have it now? I think we simply need this GUI (called 'Tet parameter' or 'FEM Mesh by GMSH') for at least the overall mesh and for each domains/bodies which were set separately.

As an example how I am used to set mesh parameters for multiple domains see the COMSOL example here https://www.youtube.com/watch?v=58GHDdR1HUg starting from 1:40.
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bernd
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Re: FEM and PartDesingNext

Post by bernd »

HoWil wrote:I hope I do get your question right?

Isn't it the same GUI as we have it now? I think we simply need this GUI (called 'Tet parameter' or 'FEM Mesh by GMSH') for at least the overall mesh and for each domains/bodies which were set separately.

As an example how I am used to set mesh parameters for multiple domains see the COMSOL example here https://www.youtube.com/watch?v=58GHDdR1HUg starting from 1:40.
Thanks for the link. Exactly. We need to be able to set the mesh parameter for each body or better for each shape the user would like to have different mesh size. this could be solids, faces and edges of the shape to mesh. I do not know what is best to archive this.


Different element size works for faces of solids too. :D
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HoWil
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Re: FEM and PartDesingNext

Post by HoWil »

The pics do look very promising!!

Now I think I know what you meant about the GUI.
Until now there was only one overall mesh element in the analysis tree and one associated interface.

This gets a little bit more complicated since there should be several mesh-definitions for several bodies/faces/edges.

To avoid an messed up analysis tree I would suggest to keep one single, fold-out main mesh element/symbol (equivalent to the one shown in the COMSOL example) for the overall Part-element.
This is created by clicking the main Part or Body and then one of the mesh symbols.

From now on one has to differentiate between the selection of Parts and Bodies on the one hand and Faces and Edges on the other Side.
Until now was selecting a face evaluated as selecting the body associated with this face. Now it could also mean that you want to select and mesh only this face and not the complete body. How is than a single body/domain selected for meshing?

A separate button for meshing the overall mesh after defining all setting is also necessary. Until now pressing the Apply button initiates the meshing what is contra-productive if you want to set up further sub-mesh parameter.
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Re: FEM and PartDesingNext

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