fem analisys on carbon tube specs?

About the development of the FEM module/workbench.

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josheeg
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Re: fem analisys on carbon tube specs?

Postby josheeg » Sun Jul 29, 2018 4:37 am

Mine did not convert but I have 17 you may have 18 and yours has the fields displayed differently.
I would like to know how and why other people added other materials and how they saved it in here.
mat.png
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josheeg
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Re: fem analisys on carbon tube specs?

Postby josheeg » Sun Jul 29, 2018 4:50 am

If I have to make the shape out of cubes I will but has anyone used cilanders in freecad fem?
Also has anyone gotten the shell part of fem to work to see how my tube frame would be effected by forces.
thschrader
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Re: fem analisys on carbon tube specs?

Postby thschrader » Sun Jul 29, 2018 9:38 am

josheeg wrote:
Sun Jul 29, 2018 4:50 am
If I have to make the shape out of cubes I will but has anyone used cilanders in freecad fem?
Also has anyone gotten the shell part of fem to work to see how my tube frame would be effected by forces.
Here is a 2D-Cylinder example (based on your model)
tube_2D.FCStd
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josheeg
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Re: fem analisys on carbon tube specs?

Postby josheeg » Wed Aug 01, 2018 4:58 am

That is very interesting!
I got it to make the solution mesh and colored it with abs displacement and displacement checkbox and slider.

So it seems to have a shell
is made of some material it says aluminum looking at its features we might be able to do it with calculix steel.
The fem constraint displacement is different from me trying the lock shaped.

I tried fixing the end face of your cylander and it seems like it is hollow?

I looked at the components it was modeled with. It doen't look like draw a circle and extrude to tube?
josheeg
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Re: fem analisys on carbon tube specs?

Postby josheeg » Wed Aug 01, 2018 5:06 am

I tired making a circle and extruding it setting its material and forces I get a error ..
shell.png
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schupin
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Re: fem analisys on carbon tube specs?

Postby schupin » Wed Aug 01, 2018 5:35 am

Apparently, you're trying to use shell elements. Shell elements are used on surfaces, not volumes (the idea is to tell the solver that the faces have a "thickness" to represent a volume).
If you want to do a simulation on your cylinder, you must not use shells but real 3D elements (like the cantilever 3D example).
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bernd
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Re: fem analisys on carbon tube specs?

Postby bernd » Wed Aug 01, 2018 10:15 am

exactly! Check 3D FEM example and 2D FEM example for the difference!
josheeg
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Re: fem analisys on carbon tube specs?

Postby josheeg » Wed Aug 01, 2018 2:18 pm

Well If I start with a circle give it a radius pad it.
  • set the diameter
    set the pad
    run fem on it as a 3d object I get a error
.0: We are going to start ...
0.1: Start Gmsh ...
2.7: Gmsh had warnings ...
2.7: Error : Self intersecting surface mesh, computing intersections (this could take a while) Error : Could not open file 'intersect.pos' Warning : Volume 1 consists of no elements Warning : OCC Project Point on Surface FAIL Warning : OCC Project Point on Surface FAIL Warning : OCC Project Point on Surface FAIL Warning : OCC Project Point on Surface FAIL Warning : OCC Project Point on Surface FAIL Warning : OCC Project Point on Surface FAIL Warning : OCC Project Point on Surface FAIL Warning : OCC Project Point on Surface FAIL Warning : OCC Project Point on Surface FAIL Warning : OCC Project Point on Surface FAIL Warning : OCC Project Point on Surface FAIL Warning : OCC Project Point on Surface FAIL Warning : OCC Project Point on Surface FAIL Warning : OCC Project Point on Surface FAIL Warning : Surface mesh: worst distortion = -0.735409 (avg = 0.776081, 18 elements with jac.
2.7: Gmsh done!
gmeshtube.png
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bernd
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Re: fem analisys on carbon tube specs?

Postby bernd » Wed Aug 01, 2018 6:50 pm

would you post the FrerCAD file? From your sceen I would assume you should use a finer mesh for your geometry. Set max elementsize in GMSH mesh object.
josheeg
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Re: fem analisys on carbon tube specs?

Postby josheeg » Thu Aug 02, 2018 4:37 am

I am running windows 10 and freecad 0.17 and the max and min element sizes are 0.0 both of them that equals auto. But maby selecting the circle part and putting a force on it. does not mesh in gmesh ok because it is not closed manafold correctly. The outside identified or something?

Here is the file.

0.5" circle extruded by 24" in
Attachments
gmeshtube.FCStd
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