Something important when doing FEA is the size of the mesh elements. If the mesh elements are too big, the FEA results cannot be trusted, If the mesh elements are too small, the time to solve the simulation will be too long. So in order to trust or have some confidence that a real part will behave and deform as in the simulation, you have first to so a "convergence annalysis", in which you will find out the propper size for the mesh elements. The shape of the mesh elements is also important. Also, since you mention you used this for PLA parts, I assume you are 3D printing them. The phisiscal properties of 3D printed parts are very different from those of the material itself, so some times is hard to trust FEA for 3D printed parts. 3D printed parts are very un-isotropic, meaning that their mechanical properties change with space. When I did FEA for PLA 3D printed parts I selected a safety factor of 10 and a yield strenght 75% of that of pure PLA. This was te only way to get results consistent with the lab experiments... Hope this helps...
I saw his mesh, and I died a bit inside. There should be a mesh inflation region near the rib so there's less artificial diffusion around it. Currently it shows that there are no stress concentration regions around the rib, which is physically incorrect.
I know this comment is really old. Sorry I almost killed you :), I was really just trying to show how to get A result, I know nothing about FEM or FEA, should've made that clearer. Glad there are folks here smarter and more experienced than me.
Great video! If you want to see the displacement more exaggerated (for smaller objects) you can increase the max value below the displacement slider (eg. from 100 to 1000).
Cool! I started exploring the FEM WB a couple weeks ago while designing laser cut flextures. I didn't get to the point of getting anything truly useful but was nice to get a feel for the WB. Hopefully will revisit if/when I have laser cutter access again. *sigh*
I couldn't see anyone commenting on this so hopefully, someone hasn't already given a solution. I suspect the reason the deformation/displacement not showing on the finished solver is that the force in the ConstriantForce parameter was only set to 1N and this isn't enough to show any deformation, even at a factor of 100.
wonderful, wonderful "lawrence welk".. gee, does the freecad folks make training videos they really should? also, what about freecad-19 is it ready? thanks for all your work ...:)
The last 3 minutes of the video are a repeat of an earlier part... feels like a video editing mistake (or mispate). Thanks fir the explanations though, it makes it easy and understandable.
*it might be easier if you're a fem person* I was confused thinking about that for a good minute before i realized you mean finite element method not fem as in feminine person xD
Hey do you know how to refine the mesh around certain features/edges at all? For example I want to model a beam with a hole and find the stress right at the edge of the hole, how can I have more, smaller elements right near the hole without needing to make all of the cells smaller? Cheers
I dont think I showed changing the forces value. But if you click on the ForceConstraint in the history tree, there is a parameter for the amount of force.
6:00 by the way, you need other things installed that weren't mentioned AND don't come standard in freecad AND have difficult windows install AND remains completely unaddressed. thumbs down, wasted 7 minutes
Only 7 minutes? I probably used up 7 hours trying to figure this thing out. I thought I linked the two additional libraries needed. But, yes I didn't want the video to be overly long/complex. I run :Linux so I can only really talk to that. Those two libaries "Calculix" and "gmsh" install with two commands. I feel your pain tho' I am sure windows is not anywhere near that simple.
On windows nothing needs to be installed. All is included. On Linux one needs to install gmsh and calculix. Takes less than a minute on Debian based distributions. My recomendation is. If you not succeed just ask on FreeCAD FEM forum for help. cheers bernd
Something important when doing FEA is the size of the mesh elements. If the mesh elements are too big, the FEA results cannot be trusted, If the mesh elements are too small, the time to solve the simulation will be too long. So in order to trust or have some confidence that a real part will behave and deform as in the simulation, you have first to so a "convergence annalysis", in which you will find out the propper size for the mesh elements. The shape of the mesh elements is also important. Also, since you mention you used this for PLA parts, I assume you are 3D printing them. The phisiscal properties of 3D printed parts are very different from those of the material itself, so some times is hard to trust FEA for 3D printed parts. 3D printed parts are very un-isotropic, meaning that their mechanical properties change with space. When I did FEA for PLA 3D printed parts I selected a safety factor of 10 and a yield strenght 75% of that of pure PLA. This was te only way to get results consistent with the lab experiments... Hope this helps...
I saw his mesh, and I died a bit inside. There should be a mesh inflation region near the rib so there's less artificial diffusion around it. Currently it shows that there are no stress concentration regions around the rib, which is physically incorrect.
You have to make mesh size sequence to study the influence of the mesh, but that mesh seems very good to me for the kind physics studied.
assuming the 3d printed shape is solid and not filled with air, isn't there something like annealing?
I know this comment is really old. Sorry I almost killed you :), I was really just trying to show how to get A result, I know nothing about FEM or FEA, should've made that clearer. Glad there are folks here smarter and more experienced than me.
Very interesting write up. Helpful to know you ran experiments to validate the meshing choices. Thanks for the help!
Thanks for sharing that, I also have tried to get FEM results but gave up long before you did.
Great video! If you want to see the displacement more exaggerated (for smaller objects) you can increase the max value below the displacement slider (eg. from 100 to 1000).
great job！this example help me understand the routine of simulation using FreeCAD. Thank you very much.
Appreciated the explanation - kind thanks!
Very nice, looks useful for basic analysis. Note also you have a rerun starting at 10:17.
thanks for the video!
Thanks for video.
Cool! I started exploring the FEM WB a couple weeks ago while designing laser cut flextures. I didn't get to the point of getting anything truly useful but was nice to get a feel for the WB. Hopefully will revisit if/when I have laser cutter access again. *sigh*
I'll cross my fingers for ya.
I couldn't see anyone commenting on this so hopefully, someone hasn't already given a solution. I suspect the reason the deformation/displacement not showing on the finished solver is that the force in the ConstriantForce parameter was only set to 1N and this isn't enough to show any deformation, even at a factor of 100.
gmesh and calculix are now included in freecad by default i think
That's awesome if true, they where a bit fiddly to install.
You helped me a lot!!
Hello, very usefull video
Question: can one clean up CAD in Freecad?
Thx
wonderful, wonderful "lawrence welk".. gee, does the freecad folks make training videos they really should? also, what about freecad-19 is it ready? thanks for all your work ...:)
Thank you for the video. Can you please make a video in FEM analysis for assembly?
I wish there was a software that did proper analysis for 3d printed objects on the Z axis
Thanks for this. FYI: at the end, your video repeats again. If you can get the part deflection visualization to work that would be great.
Thanks. So embarrassing. Recoded after error :(, I am planning another on the deflection.
what is the meaning of max stress on the fixed boundary (compare the max stress on structure)in FEM simulation?
Do you know how to get results off of multipart meshes?
Great video. Thanks. How do you apply an elastic constraint?
The last 3 minutes of the video are a repeat of an earlier part... feels like a video editing mistake (or mispate). Thanks fir the explanations though, it makes it easy and understandable.
It was a mistake. I thought I mentioned it in the description. Sorry bout that.
*it might be easier if you're a fem person*
I was confused thinking about that for a good minute before i realized you mean finite element method not fem as in feminine person xD
Hehe :)
Hey do you know how to refine the mesh around certain features/edges at all? For example I want to model a beam with a hole and find the stress right at the edge of the hole, how can I have more, smaller elements right near the hole without needing to make all of the cells smaller?
Cheers
I'm missing how you get the actual result values at locations around the model. There's not even a legend that shows up next to the contour plot.
Hello and thanks for the tutoriel! Is it possible in FreeCAD to define a rotation speed? I would really appreciate an answer, thank you
You can use the View Turntable in the Tools menu
Do you mean a centrifugal force? Yes this is possible. There is even an example analysis included in FreeCAD FEM. cheers bernd from FreeCAD FEM
Didnt get how to change forces value?
I dont think I showed changing the forces value. But if you click on the ForceConstraint in the history tree, there is a parameter for the amount of force.
@@mathcodeprint OK, gotcha
Firs comments :) super cool :D
You rock!
@@mathcodeprint
You rock too.
dump
6:00 by the way, you need other things installed that weren't mentioned AND don't come standard in freecad AND have difficult windows install AND remains completely unaddressed. thumbs down, wasted 7 minutes
Only 7 minutes? I probably used up 7 hours trying to figure this thing out. I thought I linked the two additional libraries needed. But, yes I didn't want the video to be overly long/complex. I run :Linux so I can only really talk to that. Those two libaries "Calculix" and "gmsh" install with two commands. I feel your pain tho' I am sure windows is not anywhere near that simple.
Worked just fine in my version on Windows - I did build it myself from the source, maybe that helped.
On windows nothing needs to be installed. All is included. On Linux one needs to install gmsh and calculix. Takes less than a minute on Debian based distributions. My recomendation is. If you not succeed just ask on FreeCAD FEM forum for help. cheers bernd