How could I missed this disscusion. I have't time at all today but I can't help it writing a few hints. I do not know pybar. I even do not speak french at all
But it seams really interesting. Is there any english docoumentation available?
yorik wrote: ... We could add to structural elements something like the sketch grid ... Some visual widget that you can turn on/off, that would show the structural nodes and lines of an object. ...
Would be just brilliant even for walls and floors.
Mainly you guy are disscussing how to transform a geometrical model in an analytical model.
This kind of work is every day buissness for me at work but mostly for building shell which contains shapes and plate. Trusses I have been converting only a few. (http://www.youtube.com/watch?v=Vwmrb7X8UZ8
) But videos are not up to date.
To give you guys hope. Even the best structural calculation software packages still have big problems with the task of converting geometrical modells to analytical modells. The engineer has to to the rest depending on how good the software transfered the model. This mainly excactly for the reason disscussed here. The geometrical model consists of solids (volumes) and the analytical model only uses axes (trusses) or planes (slabs and plates). Ideally the axes of trusses meet in a point and the planes of plates and slabs meet in a line. But in reallity this mostly does not happen at all.
Most mechanics do not have the axis problem because they directly use volume elements to do structural calculations. This is what the FEM Modul of Jürgen is going to do in the future. See the videos in this thread (viewtopic.php?f=18&t=4190#p33193
For trusses mostly the following 2 solutions are used (I need to think if there are more which makes sense):
1 The method shown in the video. Between the end points of the elements an kontact element is added which connects the trusses together. Big problem here is, if a few trusses connect at one point it could cause nummerical problems depending on the length of the kontakt element (could be only 0.0001 cm or 10 cm). And if one would set recessed and relaxed nodes it is difficault because there are a lot nodes in the zone where the trusses are connect to each other.
2 A parameter is given. For example 10 cm, and during the transformation of the geometrical modell to the analytical model all trusses endpoints which are inside a zone of 10 cm are just connected together at one point. Means for the video. If the space between the elements are less than 10 cm the element end points are automatically moved together. For the analytical model this is the way one would go if he had to put in the analytical model by hand. But if the software does it automatically sometimes happens funny things
with your model.
It is quite difficult to write such stuff in an foreign language. Bernd