Thanks I will try when I have access to my computer.
Yes the higher eigen-modes (that go with high frequencies) can look funny, but the first one should be a simple symmetric sway pattern perpendicular to the plane of the structure.
FEM object types
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Re: FEM object types
The rectangular beam section indeed works. However, the result is very sensitive to mesh refinement (U_max = 16.1 mm, 202 mm, 281 mm for the three meshes below) and plain wrong for the coarsest mesh 
That should certainly not be the case for the simple beam element. I first want to find out what causes this before I move forward with the more complicated mixed-mesh example. I will report back on that in a separate post.
EDIT: Hmmmmmm - I suspect it is has to do with the loads !! How are uniform loads distributed over the element nodes? This needs to be done in a manner consistent with the element shape function, not just equally spread out. That would explain why in the coarsest mesh the mid-node moves up !!
That should certainly not be the case for the simple beam element. I first want to find out what causes this before I move forward with the more complicated mixed-mesh example. I will report back on that in a separate post. EDIT: Hmmmmmm - I suspect it is has to do with the loads !! How are uniform loads distributed over the element nodes? This needs to be done in a manner consistent with the element shape function, not just equally spread out. That would explain why in the coarsest mesh the mid-node moves up !!
- PB_Static_Disp_Mesh1.png (215.65 KiB) Viewed 2909 times
- PB_Static_Disp_Mesh2.png (216.02 KiB) Viewed 2909 times
- PB_Static_Displ_Mesh3.png (218.12 KiB) Viewed 2909 times
Re: FEM object types
load are consistent with shape functions! At least rhey should, see input file.
But beams in ccx les than 2.13 have some problems, see https://forum.freecadweb.org/viewtopic.php?f=18&t=16044
But beams in ccx les than 2.13 have some problems, see https://forum.freecadweb.org/viewtopic.php?f=18&t=16044
Re: FEM object types
Some further views on the CCX three-noded beam element behaviour: https://forum.freecadweb.org/viewtopic. ... 38#p226038
Re: FEM object types
Happy to report a pleasing result mixing Plates and Beams. Pedestrian bridge loaded with 1 kN/m2 on central span only.
However this raises quite a few questions that I will post separately to prevent polluting this post on mixed meshes.
- PB_2_Def_1.png (261.47 KiB) Viewed 2852 times
- PB_2_Def_Detail_1.png (298.02 KiB) Viewed 2852 times
- PB_2_Def_Detail_2.png (313.78 KiB) Viewed 2852 times
However this raises quite a few questions that I will post separately to prevent polluting this post on mixed meshes.
Re: FEM object types
Bernd, I never quite managed to resolve this and it is quite frustrating to have to move between FC-Daily and local version all the time. I managed to download and compile a new OCCT 7.2 but dont know how to link this to FC. Is there a path in a FC make file that needs to be set?bernd wrote: ↑Sun Apr 01, 2018 6:50 am because your ubuntu has an older version of occt. What you could do is compile occt yourself. It is on 7.2 allready. There are various topics araound to occt. If you are able to compile FreeCAD it is simple to compile occt too.
If you use ppa newer version of occt was use to compile.
Ahh probably ready packages are available too, there have been disscusdions around. You may ask in instatallation part of the forum.
Ahh you may use ppa to create geometry and just do the FEM part with my branch.
A few possibilities ...
Re: FEM object types
@bernd had a nice script before... but don't know it that is still valid.
Re: FEM object types
https://gist.github.com/berndhahnebach and https://forum.freecadweb.org/viewtopic.php?f=4&t=18967
I have updated it on my local machine to occt 7.2 on Debian Stretch. But did not have the time to update the ubuntu ones. But in the regard of cmake and occt I did not had to change anything. Means you should find what you are looking for harry.
bernd
I have updated it on my local machine to occt 7.2 on Debian Stretch. But did not have the time to update the ubuntu ones. But in the regard of cmake and occt I did not had to change anything. Means you should find what you are looking for harry.
bernd
Re: FEM object types
Wooooow. That worked really well. Thanks Bernd.
Everything works now. My new concrete stuff + Boolean Fragments + Netgen (which I never had on Ubuntu).
I see from the script that when it runs it starts from scratch (deletes the whole directory). Can I now do a simple pull request and compile/make to incorporate changes from my repository? Will it know to find OCCT and NETGEN?
Everything works now. My new concrete stuff + Boolean Fragments + Netgen (which I never had on Ubuntu).
I see from the script that when it runs it starts from scratch (deletes the whole directory). Can I now do a simple pull request and compile/make to incorporate changes from my repository? Will it know to find OCCT and NETGEN?