There are many pieces, or frameworks, or calculations systems already. Some actually pretty good. But so far nothing with a...

Commenting post 121: There are many pieces, or frameworks, or calculations systems already. Some actually pretty good. But so far nothing with a complete interface, or easy to use. Those I know of are these:

https://sourceforge.net/projects/frame3dd/ http://www.calculix.de/ http://pybar.fr/

But have also a look at the FEM workbench of FreeCAD too ( http://forum.freecadweb.org/viewforum.php?f=18 ), things are evolving fast and well there...