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by fandaL
Sat May 23, 2020 10:15 am
Forum: FEM
Topic: FreeCad_FEM CalculiX is he calculating right or wrong?
Replies: 7
Views: 282

Re: FreeCad_FEM CalculiX is he calculating right or wrong?

When boundary condition is on vertical (z) displacement (in the model Z2a.FCStd), it acts on more nodes next to each other due to small circular area. This effectively constrains also rotations around in-plane axes. In fact, reaction forces are not uniform on the constrained surface, so that there a...
by fandaL
Sun May 10, 2020 10:13 pm
Forum: FEM
Topic: beam analysis with beams in z-direction
Replies: 117
Views: 8522

Re: beam analysis with beams in z-direction

I had a trouble with beam orientation formatting in inp file - see this post https://forum.freecadweb.org/viewtopic.php?f=18&p=397293#p396715 It is written here: https://github.com/FreeCAD/FreeCAD/blob/master/src/Mod/Fem/femsolver/calculix/writer.py#L1736 and again for other cross sections few lines...
by fandaL
Sun May 10, 2020 9:44 pm
Forum: FEM
Topic: Help with CalculiX *MASS card for my FEM models
Replies: 8
Views: 353

Re: Help with CalculiX *MASS card for my FEM models

My understanding is that mass element with *MASS property card is a mass concentrated at node, which I guess is what you need for the simple wing and engine model, supposing that beam or shell elements will simulate structural stiffness, and mass elements will simulate (structural) mass. For frequen...
by fandaL
Fri May 08, 2020 10:02 pm
Forum: FEM
Topic: Help with CalculiX *MASS card for my FEM models
Replies: 8
Views: 353

Re: Help with CalculiX *MASS card for my FEM models

Hello everyone, I've been trying to create a clamped-free beam model with lumped mass at the free end in CalculiX but i got many errors. Then i tried to create spring-mass system to understand how i can create mass model at node, again i got error as: "*WARNING in calinput: no elastic constants wer...
by fandaL
Fri May 08, 2020 7:51 pm
Forum: FEM
Topic: Help with CalculiX *MASS card for my FEM models
Replies: 8
Views: 353

Re: Help with CalculiX *MASS card for my FEM models

I suppose that you are doing frequency analysis of the model in your picture. See the attached analysis in FreeCAD where are few beam elements and manually added mass element to *.inp file above *STEP card: ** manually added mass element with id 33 at node number 22 *ELEMENT, TYPE=MASS , ELSET=EM 33...
by fandaL
Fri May 01, 2020 10:58 am
Forum: FEM
Topic: [Solved]CalculiX FEM Freq Analysis: No nodes found in Frd file.
Replies: 17
Views: 330

Re: CalculiX FEM Freq Analysis: No nodes found in Frd file.

Frequency is just above requested range, so no output is made by ccx. In *.inp file you can delete the range. Instead of *STEP *FREQUENCY 10,0.0,10000.0 (which limits frequency search to 0-10000 Hz) Use only *STEP *FREQUENCY 10 which will search for 10 lowest frequencies up to "infinity". (Isn't thi...
by fandaL
Mon Apr 20, 2020 8:21 pm
Forum: FEM
Topic: FEM: mesh: interested in STL volume mesh???
Replies: 3
Views: 185

Re: FEM: mesh: interested in STL volume mesh???

It could be useful in some cases. Currently one needs to make solid from Mesh first (in Mesh wb) which is with many faces cumbersome to work with. Complication is that to prescribe boundary conditions and loads you need to select manually all faces, since FreeCAD FEM wb applies them to geometry. The...
by fandaL
Mon Apr 13, 2020 1:08 pm
Forum: Open discussion
Topic: Start page Contribute card
Replies: 0
Views: 421

Start page Contribute card

Hi all, Free sw often contain button or link to donations on the introduction screen. I don’t see anything like that in FreeCAD. We offer help in Help menu and on the Start page, but we don’t ask for help :-o I would suggest to add link to Help menu to https://wiki.freecadweb.org/Help_FreeCAD and cr...
by fandaL
Sat Feb 29, 2020 11:25 pm
Forum: Python scripting and macros
Topic: STL (Mesh) voxelization to Array
Replies: 6
Views: 363

Re: STL (Mesh) voxelization to Array

Maybe a way would be a regular 3d grid of points an then doing a "point cloud merge" (calcuate the signed distance field of the points to the stl mesh, and afterwards filter the negative or positive pts away) with the stl mesh in cloudcompare which should result in a point cloud which lies within t...
by fandaL
Wed Feb 19, 2020 8:56 am
Forum: FEM
Topic: [SOLVED] Issue with CalculiX
Replies: 2
Views: 157

Re: Issue with CalculiX

Hi, Try to open it with the latest cgx. I have downloaded Launcher CL34-win64 from https://sourceforge.net/projects/calculixforwin/ and when opening I can chose different cgx versions: 2.5 fails, 2.10 even brakes frd file, 2.16 works well. I suppose that this is due to binary format used in the frd ...

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