How To Use FreeCAD FEM |JOKO ENGINEERING|
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- Опубликовано: 25 июн 2024
- See AllVisuals4U Table Modeling Tutorial: • How to model a table |...
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jokoengineering
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If there is music in this video, it is legally used.
This is done in FreeCAD Version 0.18
Thanks ! I did my first FEM analysis using your tutorial.
Wow, simply, thank you for your videos - very much appreciated!
Really thanks for this video!
Very useful video. Thanks!
Thank you! This really helped me getting started.
Neat! I have been modeling with RealThunder's mod. FEM doesn't work, but release 0.19 worked fine. Thanks!
It was really helpful,
Thanks Joko Engineeringhelp
Thank you! Excellent.
great video, thank you very much.
thx for video!
Would be great to have a followup video about principle test.
excelent video, you should add one to explain how gmesh an calculix are the base on this and how to fix problems in instalation, Im with Debian and have to configure gmesh by hand
Fantastic. :)
thank you so much
adipoli
When I try to fusion my parts together, it only mirrors the original parts, not the mirrored, so I end up fusing only half my model?
Hey what version of GMSH are you running. My GMSH is not working Warning : Unknown element type for UNV export. The forums seemed to dead end. I am running windows as well.
what if i make a part in sketchup, what would i have to export it as in order to have freecad do the fem on it? thanks
Hi joko. Could you expand a little bit more about frequency analysis please. I tried but its a little hard to interpret the results to be honest. Also, I was wondering if i could import several steps file into freecad ( from catia), assemble them using the A2 plus work bench and then fuse them to finaly run an fem analysis on the union ? Thanks have a nice day.
great video... i wonder if a person would hook up sensors "load, torque, temperature, rpm etc" to a test part to get real results and feed the live info into a freecad spreadsheet, this would be a powerful design tool... Mmmm thanks a lot...:)
Hi Joko. I have been practicing for a few days with this tutorial. I can do a fem analysis for a single body ( like an L shaped bracket for exemple). Now I practice on assy ( convert an assy made of several bodies using A2 into a fusion unsing part work bench), I get this error message when i try to open the ccx_Results file:
FEM: Result node numbers are not equal to FEM Mesh NodeCount.
What is going on? I dont get it it should work i walk exactly in your foot steps but I get this error.
what is the meaning of max stress on the fixed boundary (compare the max stress on structure)in FEM simulation?
Thank you for the tutorial. Why do you always choose such low forces in your FEM related videos? 60N is roughly 9,81m/s² * 6kg. This table looks like it could support a human with ease.
Hi, is it possible to extract a stress-strain curve from a point?
Do you know how to inspect mesh nodes in the result?
hello! could you explain what you mean with the angular distortion and isoparametric distortion? This sounds very interesting
It's a detailed topic, here's a PDF that covers it in depth
web.mit.edu/kjb/www/Publications_Prior_to_1998/Effects_of_Element_Distortions_on_the_Performance_of_Isoparametric_Elements.pdf
Hello and thanks for the tutoriel! Is it possible in FreeCAD to define a rotation speed? I would really appreciate an answer, thank you
Yes it is possible
@@Gspohu thx:) but where is the function/command for rotation speed?
Hi, Do you know How could we specialise the space to exerce the force. I got a big surface but the force is only applied on a little element. Should I creat a new surface from my origin surface ? I did not find a way to create a surface from another one or to split it.
Thanks
A really simple way of getting that is say you want to exert a circular force on a flat surface, extrude cut a circle and then pad the circle to fill the hole. The result gives you a circle on the face to select for the force. This will cause the part to mesh differently
I tried the tutorial but got errors. during the CalcX
*ERROR in e_c3d: nonpositive jacobian
determinant in element 2376
Were you able to solve it?
If so, please let me know. I', stuck there too...
If the Jakobian becomes zero or negative you get a non-positive definite system of equations.
Meaning: you have either 1) rigid body motion (you didn’t apply enough fixing boundary conditions or there are multiple bodies that are meshed but not connected via the nodes) or 2) excessive deformation so an element becomes inside-out. An element becomes inside-out if the angle between two edges are zero degrees or less (or 180 degrees or more).
Tip:
make sure you have no duplicate nodes (I have no idea how you do that in freeCDD/CalculiX, but hopefully there is a “sweep” function(?))
Make sure you have relevant DOF fixed (no rigid body motion)
Check your units. Are they consistent.
Reduce the load (force/“pressure”)
The mesh that was used in this tutorial had some pretty bad angles on the table top. When meshing a thin and wide geometr with tet-elements this is unavoidable (unless you use one million elements 😊)
Great video. As a layman it has accelerated my understanding. I’m stuck on how to do a pressure stress analysis on a closed container without needing a fixed constraint. Any suggestions?
Hi Random Task! That brings up a great point. It's best practice in an analysis to constrain degrees of freedom even if the forces counterbalance, which will prevent what is known as rigid body modes. In this video I use a force, measured in Newtons and acting in a direction. You would want to use a pressure instead of a force, which acts normal to the specified face instead of a single direction and is measured in force per area. I hope that helps!
The pressure button is near the force button in FreeCAD btw, it should be as easy as selecting the geometry, setting your pressure and making sure the pressure is outward instead of inward (the correct direction)
@@JokoEngineeringhelp right, that’s what I did, but it expects a fixed constraint which doesn’t make sense to me if I set all faces to exert pressure. If for example I have a cuboid and select the edge as a fixed constraint, in a stress analysis it acts like that edge is indestructible (sorry if I have butchered the tech speak).
@@RandomTask Very interesting! Is it possible to send me the model?
@@JokoEngineeringhelp thanks a lot, have sent to your email.
Is there any way you can see numerical data on how much force is being applied at the bottom of each able leg?
Check out Michael Hindley. He covers that kind of topic better than I think I can. www.youtube.com/@michaelhindley6311
Could you explain the factor impact on the analysis? the 100 factor is 100% of the force you choose or 100 times the force?
Hi Gabriel; since the material I chose would only deform a few thou, it's difficult to visualize what the deformation would look like. So I used the factor to make the deformation 100 times greater than it would actually be to better visualize the deformation, but the analysis results remain at the same force. Does that make sense?
@@JokoEngineeringhelp thank you so much, since the freecad FEM documentation is not complete, your videos are saving me. Very great job.
Is is possible to add a color legend to the analysis results?
Yes check out my video on pipeline visualization
Can you use this to test the stresses in a machine in motion~?
Yes absolutely.
Joko Engineeringhelp Marvelous~😁😁😁
Can one generate a report with all the values of significant stresses and stains?
There are certain ways to have more reports. Check out the channel of Michael Hindley (May the wonderful man rest in peace)