beam analysis with beams in z-direction

About the development of the FEM module/workbench.

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FemUser
Posts: 133
Joined: Wed Aug 23, 2017 6:45 pm

Re: beam analysis with beams in z-direction

Postby FemUser » Fri Oct 13, 2017 2:35 pm

I am trying to change the .inp file adding the normal's on each beam however I keep getting a
*ERROR reading *BEAM SECTION: *BEAM SECTION can only be used for beam elements. Element 0 is not a beam element.
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FemUser
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Re: beam analysis with beams in z-direction

Postby FemUser » Fri Oct 13, 2017 2:56 pm

The calculated normals are bellow. In attached is the project with added beam bodies. I get an error on the entries that start with 0.

Code: Select all

*ELSET,ELSET=Mat0Beam0
4,
1,1,0
*ELSET,ELSET=Mat0Beam1
12,
0,1,1
*ELSET,ELSET=Mat0Beam2
11,
1,1,0
*ELSET,ELSET=Mat0Beam3
3,
1,1,0
*ELSET,ELSET=Mat0Beam4
5,
0,1,1
*ELSET,ELSET=Mat0Beam5
10,
-1,1,1
*ELSET,ELSET=Mat0Beam6
9,
1,1,0
*ELSET,ELSET=Mat0Beam7
6,
0,1,1
*ELSET,ELSET=Mat0Beam8
1,
1,1,0
*ELSET,ELSET=Mat0Beam9
7,
1,0,1
*ELSET,ELSET=Mat0Beam10
8,
1,0,1
*ELSET,ELSET=Mat0Beam11
2,
1,0,1
Attachments
cubeBeamTest_R1.FCStd
(17.74 KiB) Downloaded 20 times
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FemUser
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Re: beam analysis with beams in z-direction

Postby FemUser » Fri Oct 13, 2017 3:40 pm

Was placing in the wrong zone! All is well...

Code: Select all

** Sections
** written by write_femelementsets function
*BEAM SECTION, ELSET=Mat0Beam0, MATERIAL=SolidMaterial, SECTION=RECT
2 , 1 
1,1,0
*BEAM SECTION, ELSET=Mat0Beam1, MATERIAL=SolidMaterial, SECTION=RECT
2 , 1 
0,1,1
*BEAM SECTION, ELSET=Mat0Beam2, MATERIAL=SolidMaterial, SECTION=RECT
2 , 1 
1,1,0
*BEAM SECTION, ELSET=Mat0Beam3, MATERIAL=SolidMaterial, SECTION=RECT
2 , 1 
1,1,0
*BEAM SECTION, ELSET=Mat0Beam4, MATERIAL=SolidMaterial, SECTION=RECT
2 , 1 
0,1,1
*BEAM SECTION, ELSET=Mat0Beam5, MATERIAL=SolidMaterial, SECTION=RECT
2 , 1 
-1,1,1
*BEAM SECTION, ELSET=Mat0Beam6, MATERIAL=SolidMaterial, SECTION=RECT
2 , 1 
1,1,0
*BEAM SECTION, ELSET=Mat0Beam7, MATERIAL=SolidMaterial, SECTION=RECT
2 , 1 
0,1,1
*BEAM SECTION, ELSET=Mat0Beam8, MATERIAL=SolidMaterial, SECTION=RECT
2 , 1 
1,1,0
*BEAM SECTION, ELSET=Mat0Beam9, MATERIAL=SolidMaterial, SECTION=RECT
2 , 1 
1,0,1
*BEAM SECTION, ELSET=Mat0Beam10, MATERIAL=SolidMaterial, SECTION=RECT
2 , 1 
1,0,1
*BEAM SECTION, ELSET=Mat0Beam11, MATERIAL=SolidMaterial, SECTION=RECT
2 , 1 
1,0,1
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FemUser
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Re: beam analysis with beams in z-direction

Postby FemUser » Fri Oct 13, 2017 5:01 pm

From the beam element we need to take the two nodes that make it then calculate the normal.

The only problem I am seeing is that if the truss problem has 100 components we need to manually create 100 components through da GUI. That doesn't seem like good. :( just to create the example ones was a pain. Any one got a workaround for this?
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bernd
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Re: beam analysis with beams in z-direction

Postby bernd » Fri Oct 13, 2017 5:33 pm

my idea is to define a standard direction. If nothing is defined by the user the standard direction is used.
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FemUser
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Re: beam analysis with beams in z-direction

Postby FemUser » Fri Oct 13, 2017 8:18 pm

The problem is that if we define a standard direction there is a chance that one beam is aligned with that definition. Why can't we generate automatically the beam elements for each bar in the .inp? When we generate a 1 beam body without specifying the beams it would generate individually all beam entries as if we made them manually. Don't know if this approach would make the inp too heavy but it feals more problem prof.
What do you think?
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bernd
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Re: beam analysis with beams in z-direction

Postby bernd » Fri Oct 13, 2017 8:35 pm

bernd wrote:
Fri Oct 13, 2017 5:33 pm
my idea is to define a standard direction. If nothing is defined by the user the standard direction is used.
I mean a standard local definition. This is translated than into the right location into the inp file. Only if the user would like to change this he needs to input something.
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FemUser
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Re: beam analysis with beams in z-direction

Postby FemUser » Fri Oct 13, 2017 9:00 pm

Nice. So what are the next steps? :)
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FemUser
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Re: beam analysis with beams in z-direction

Postby FemUser » Sat Oct 14, 2017 7:18 am

After applying the transformation all works well.
Result.jpeg
Result.jpeg (85.43 KiB) Viewed 533 times
I attached the project.
Attachments
cubeBeamTest_R1.FCStd.zip
(13.41 KiB) Downloaded 20 times
calculated_normal.rtf
(1.47 KiB) Downloaded 28 times
generated.inp.rtf
(4.7 KiB) Downloaded 17 times
fandaL
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Re: beam analysis with beams in z-direction

Postby fandaL » Sat Oct 14, 2017 7:36 am

imho: If you rotate rectangular cross section you get globally different quadratic moments so that (on detailed level) it is different model and that's why I think that orientations of beams are quite important and "responsible" user :geek: should take care about them.
On the other hand I understand that for preliminary analysis FemUser :-) or "efficient" user :ugeek: don't want to loose time with defining orientations (e.g. for a pipe cross section). In that case and in case that I make a mistake in the orientation input, FreeCAD could warn me during writing inp file that highlighted elements might have wrong orientations and asks if I want to correct them manually or FreeCAD would use automatically alternative orientation or if I want to proceed (probably getting error in ccx).
FemUser wrote:
Fri Oct 13, 2017 9:00 pm
Nice. So what are the next steps? :)
Write a function to highlight elements which might have wrong orientations.?

btw: when we will add orientation input field we can add also offset1 and offset2 inputs.

btw of btw: offset can be defined also for shell elements.

In the future It would be cool to display cross sections in the model with orientations and offsets.