Would you like to knw to which PART a element belongs to, or would youl like to know to which Solid of a Part an element belongs to?
That’s indeed what meant. The main issue was that initially I could not achieve a jump in displacement boundary condition as shown in the above example. The reason is that in a compound, nodes are duplicated across solids. Only mesh volume elements have unique nodes. So I wanted to test for every “ConstraintDisplacement” node what elements it is attached to and then see what solid those elements belong to. This is an indirect way of testing if the node is really part of the target face.
Harry,HarryvL wrote: ↑Fri Feb 15, 2019 11:47 pmHi Thomas,
General/motivation; there are quite a few practical and interesting engineering problems that are hard to do or even impossible with the current FreeCAD/Calculix combination and I don’t think adding more external solvers or waiting for their developer(s) is the answer. For example: mixed meshes (sandwich panels, soil/structure interaction, pre-stressed concrete, bridges), analysis beyond limit points (plastic collapse of frames, plates and soil bodies, non-linear buckling of structures, etc.)
Specific: I built a macro that takes FC mesh and material data and performs the basic tasks of a finite element program. Now I am adding functionality that allows me to do the analyses that were previously out of reach. Zero-thickness elasto-plastic interface elements were high on the list for me as they are a simple and robust alternative for (small deformation) contact problems and can be used in mixed meshes to model the interaction (e.g. cohesive or frictional slip) between 1D/2D structural elements and the surrounding 3D matrix (eg concrete reinforcement, soil anchors, tunnel linings, foundation plates, piles).
Status: basic linear elastic solver framework and curved 2D interface elements work, although I am still running into trouble with more complex contact geometries. This is work in progress.
Next steps: 1) calculate and export stress results (note: interface elements are really handy to visualize contact stresses); 2) extend the solver framework to handle plasticity and collapse (simplest example being the slip and pull-out of structural elements along elasto-plastic interfaces); 3) include simple, traditional, beams and shell elements; 4) include general material and geometric non-linearity for 1D, 2D and 3D elements; 5) Add essential QT5 GUI functionality to provide specific input; 6) Make available for testing.