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Dhondtguido / CalculiX

This repository contains the source files of CalculiX, a three-dimensional Finite Element Program (www.calculix.de).
GNU General Public License v2.0
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Truss and beam elements disconnected #14

Open victorkemp opened 1 year ago

victorkemp commented 1 year ago

They should both deflect at their common node but the truss behaves like it isn't connected to the beam.

*NODE
1,0,0,0
2,0,0.625,0
3,0,0.875,0
4,0,0.5,0
5,0,0.125,0
6,0,0.75,0
7,0,0.375,0
8,0,1,0
9,0,1.125,0
10,0,0.25,0
11,-0.5,0.5,0
*ELEMENT,TYPE=B31,ELSET=1
1,5,1
2,10,5
3,9,8
4,8,3
5,3,6
6,6,2
8,7,10
9,2,4
10,4,7
*ELEMENT,TYPE=T3D2,ELSET=2
7,11,4
*MATERIAL,NAME=Material
*ELASTIC,TYPE=ISOTROPIC
200000000000,0
*BEAM SECTION,ELSET=1,MATERIAL=Material,SECTION=RECT
0.05,0.05
1,0,0
*SOLID SECTION,ELSET=2,MATERIAL=Material
0.0025
*BOUNDARY
1,1,3,0
9,1,3,0
11,1,3,0
*STEP
*STATIC
*CLOAD
2,3,1000
*NODE FILE
U
*END STEP

Untitled

FEA-eng commented 1 year ago

It seems that this issue is fixed in CalculiX 2.21.

victorkemp commented 8 months ago

It's not really fixed. In 2.21, they're not disconnected anymore but instead are connected too hard. The beams don't deflect as far as without the truss, which should have no impact on the solution. I think it's just a coincidence and it still needs a proper fix which is moving beam=.false. outside the loop in gen3dnor.f starting around line 455.