FEM MESH HAS NO VOLUME ELEMENTS

About the development of the FEM module/workbench.

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thschrader
Posts: 1384
Joined: Sat May 20, 2017 12:06 pm
Location: Germany

Re: FEM MESH HAS NO VOLUME ELEMENTS

Postby thschrader » Mon Feb 11, 2019 2:24 pm

Hi cti2019,
I had a look at your model. Running a 3D-FEM analysis is
an overkill of work and not necessary. It is much easier to use
a frame program for such a problem
http://members.ziggo.nl/wolsink/
https://www.ftool.com.br/Ftool/

Your load case uses only vertical loading near by the knots of the structure.
The (static relevant) bending-moment in the beams is nearly zero, the load directly
runs into the columns. The complete structure will tilt, you must use anchors
at the floor (or more selfweight).

You can divide the 3D-structure into several 2D-subproblems (the yellow frame
for instance). Critical loading is horizontal / diagonal.
regards Thomas
tilt.JPG
tilt.JPG (71.84 KiB) Viewed 113 times
2D_frame.JPG
2D_frame.JPG (49.87 KiB) Viewed 113 times
thschrader
Posts: 1384
Joined: Sat May 20, 2017 12:06 pm
Location: Germany

Re: FEM MESH HAS NO VOLUME ELEMENTS

Postby thschrader » Mon Feb 11, 2019 2:30 pm

or the good old fashioned way "by hand"...
https://structx.com/frames.html
cti2019
Posts: 12
Joined: Fri Feb 08, 2019 4:14 pm

Re: FEM MESH HAS NO VOLUME ELEMENTS

Postby cti2019 » Mon Feb 11, 2019 2:38 pm

The problem is that the structure always yields in the 3 points indicated in green.
And I do not know if increasing the thickness of the tubular I can solve the problem.
Attachments
tilt.JPG
tilt.JPG (114.66 KiB) Viewed 106 times
thschrader
Posts: 1384
Joined: Sat May 20, 2017 12:06 pm
Location: Germany

Re: FEM MESH HAS NO VOLUME ELEMENTS

Postby thschrader » Mon Feb 11, 2019 2:51 pm

ah, ok.
But that means, that only a part of the whole structure is of interest.
Is there horizontal loading at the plate (especially perpendicular to plate)?
Before meshing: eliminate the bolts and some holes...
Use mesh refinement at the cracking zones.
remaining_problem.JPG
remaining_problem.JPG (28.08 KiB) Viewed 102 times
refinement.JPG
refinement.JPG (21.71 KiB) Viewed 102 times
cti2019
Posts: 12
Joined: Fri Feb 08, 2019 4:14 pm

Re: FEM MESH HAS NO VOLUME ELEMENTS

Postby cti2019 » Mon Feb 11, 2019 3:21 pm

thschrader wrote:
Mon Feb 11, 2019 2:51 pm
Use mesh refinement at the cracking zones.
how can I do?
thschrader
Posts: 1384
Joined: Sat May 20, 2017 12:06 pm
Location: Germany

Re: FEM MESH HAS NO VOLUME ELEMENTS

Postby thschrader » Mon Feb 11, 2019 3:38 pm

I unrefined your model, maybe this helps...
prova1_part.FCStd
(38 KiB) Downloaded 5 times
mesh-refinement:
mesh body
click on mesh in tree, select mesh refinement,
then select the lines you want to refine.
FEM_part.JPG
FEM_part.JPG (55.79 KiB) Viewed 96 times