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by josegegas
Wed Sep 11, 2019 12:45 pm
Forum: FEM
Topic: FreeCAD as pre-post processor for MBDyn
Replies: 134
Views: 15667

Re: FreeCAD as pre-post procesor for MBDyn

mfasano wrote:
Wed Sep 11, 2019 12:36 pm
MBDyn needs to be run from a terminal. Is there a way to run a shell script from python?
Yep. I've don this. So that MBDyn can be executed from FreeCAD with a click...
by josegegas
Wed Sep 11, 2019 12:40 pm
Forum: FEM
Topic: FreeCAD as pre-post processor for MBDyn
Replies: 134
Views: 15667

Re: FreeCAD as pre-post procesor for MBDyn

in the regard of a new solver ... Before a new solver runs with FreeCAD FEM the new solver needs to be implemented in FreeCAD FEM. As an example have a look at the implementation of oofem solver in FreeCAD FEM. https://github.com/berndhahnebach/FreeCAD_bhb/commits/femoofem mainly what FreeCAD FEM d...
by josegegas
Wed Sep 11, 2019 11:48 am
Forum: FEM
Topic: FreeCAD as pre-post processor for MBDyn
Replies: 134
Views: 15667

Re: FreeCAD as pre-post procesor for MBDyn

Previously only the "revolute pin" joint was included. A bit of progress made today: added the "revolute hinge" joint, which allows linking two solid bodies. Made the classic double pendulum simulation. See the reaction forces on the revolute pin joint :) https://www.youtube.com/watch?v=Nv5qaQjPRME&...
by josegegas
Tue Sep 10, 2019 5:33 am
Forum: FEM
Topic: FreeCAD as pre-post processor for MBDyn
Replies: 134
Views: 15667

Re: FreeCAD as pre-post procesor for MBDyn

I see. So to include the object's mass or density I'll have to use the OCCT classes. The easiest solution I could think about (to avoid this) is to multiply (or whatever operation is needed) the given Ixx Iyy and Izz by the mass. I could do this if I knew what units these values have. Yes moving the...
by josegegas
Tue Sep 10, 2019 4:04 am
Forum: FEM
Topic: FreeCAD as pre-post processor for MBDyn
Replies: 134
Views: 15667

Re: FreeCAD as pre-post procesor for MBDyn

I've been using MBDyn to do simulations of engines and other mechanisms. It is a free and open source multi body dynamics software. It is very powerful but it lacks pre and post processing graphic interface. I've been using FreeCAD as pre and post processing tool for MBDyn and all works very well. ...
by josegegas
Tue Sep 10, 2019 3:38 am
Forum: FEM
Topic: FreeCAD as pre-post processor for MBDyn
Replies: 134
Views: 15667

Re: FreeCAD as pre-post procesor for MBDyn

MBDyn license is GPL so it would have to be installed separately, ok, but it seems like default installation packages are only for linux? I've never used MBDyn on Windows. Not sure if there are installation packages... I don't care much about this :P MBDyn is such a nice software and if we could in...
by josegegas
Tue Sep 10, 2019 3:14 am
Forum: FEM
Topic: FreeCAD as pre-post processor for MBDyn
Replies: 134
Views: 15667

Re: FreeCAD as pre-post procesor for MBDyn

One issue with using FreeCAD for multibody dynamics is there is no routine to calculate moment of inertia for arbitrary shapes(part design); that would need to be written. Yes, I found this to be a problem. By now I am using my own code to calculate inertia moments, only for basic shapes (spheres, ...
by josegegas
Tue Sep 10, 2019 3:05 am
Forum: FEM
Topic: FreeCAD as pre-post processor for MBDyn
Replies: 134
Views: 15667

Re: FreeCAD as pre-post procesor for MBDyn

I would not need a constraint solver because MBDyn would notify if there was a problem. I also thought it would be difficult to translate constraints from assembly 3 or A2+ into MBDyn joints. I thought exactly the same. There is no need for constraint solver because MBDyn already does this. My idea...
by josegegas
Tue Sep 10, 2019 2:59 am
Forum: FEM
Topic: FreeCAD as pre-post processor for MBDyn
Replies: 134
Views: 15667

Re: FreeCAD as pre-post procesor for MBDyn

I was going to use assembly 4 as a base. Why would you need assembly 4? I mean, MBDyn already takes care of the mechanism assembly. It will yield an error if the assembly was not consistent. My approach to animate the simulation results is just to use a timer (imported from Qt) to update each part'...
by josegegas
Tue Sep 10, 2019 2:53 am
Forum: FEM
Topic: FreeCAD as pre-post processor for MBDyn
Replies: 134
Views: 15667

Re: FreeCAD as pre-post procesor for MBDyn

I have just started a work bench as a pre and post processor for MBDyn. Sounds great that you had the same idea! Would you mind sharing some details? My approach has been to create customized objects in FreeCAD that contain the properties of each object required by MBDyn. Thus, I create a "Gravity"...

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