since in early versions 3D UNV format has been supported, group of element and nodes also. later the implementation in shell element. hopefully line/beam element also interest to supported in the next.
FRD result produced by CalculiX CCX solver are in general format, seems the beam,shell and solid are treated as one as 3D solid for uniformity. PrePomax also capable reading output of beam element if the option 3D are set (nb. output in 2D make some crash). as shown in above pictures, testing an example of B31 element output for stress and deformation.
this workflow could be useful as introduction or preliminary of PrePoMax capabilities to analysis with beam element by importing 1D line and set up trough keyword editor.
group of element and nodes is prepared inside UNV creator (e.g Salome CAE or GMSH), later setting of element and boundary conditions is in Edit keyword features.
as can be seen in above pictures, only few line of definition in keyword could perform an analysis of beam element, displaying group of node and element visually also helping for the user manage easily.
The support for beam elements is very high on the to-do list. But if I implement it, then I would like to implement it as it should be implemented wilt all the support of the GUI. Unfortunately, that requires more time the I have now. Maybe my summer will be less crowded.
Sorry to hear that. Please let us know when it changes. It would be great to have this functionality to create a simplified bolt connections. And this is a must in bolted shell structures.
What type of connections? Could you tell more about it?
I feel I need to explain a bit. Usually when I deal with bolted connections in shell structures I add nodes in centres of the holes, add beam between those 2 nodes and add a rigid connection between hole edge and node of the beam. Then I specify contact between shells. I read forces from bolts and calculate the connection âby handâ. The values around the hole are not real, but this can be also calculated using eurocode. Or adding gap elements plus washers and contact. So this is what I have learned and what I have been doing so far in Salome/Code_Aster.
Calculix (and therefore Prepomax) is a âgeneral purpose FEAâ so it allows you to do a lot of interesting things but is therefore not specialised in beam elements integrated with regulations. The use of beam elements is therefore, in my opinion, âuninterestingâ if not integrated with a verifier. In this case, however, I would personally use other free software (I donât think there are any open source options, given that the verification part is very delicate, time-consuming to implement and constantly being updated).
If the reason is simplified modelling of connections, then it has even less sense because its use would still be limited when using beams.
In this case, it would be much more interesting to implement springs for which it is possible to define a stiffness and apply a preload (simulating the preload of the bolt) and a tool that automates the radial constraint between two holes (thus creating the cylindrical coordinates and avoiding the axial constraint on the hole).
If a specific tool were then implemented for this procedure, we would have a virtually perfect software for this type of calculation (which in practice occurs all the time).
I currently perform this procedure manually, but it is very time-consuming.
NOTE: The check is done âby handâ with the regulations (Eurocode for example)
One is that you can apply preload (pre-tension section) but the beam itself will be deleted then:
For beam elements a linear multiple point constraint is created between the nodes belonging to the beam element. The beam element itself is deleted,i.e. it will not show up in the frd-file. Therefore, no other boundary conditions or loads can be applied to such elements. Their only reason of existence is to create an easy means in which the user can define a pretension.
There are also some bugs related to beam elements in CalculiX. A few have been fixed but you can still find the rest here: GitHub ¡ Where software is built
They may not go well with couplings connecting them to the model either.
And if you search this forum, you will see several attempts to model bolted and riveted connections in different ways with more or less success. Maybe try it on your case (you can define beams and 2-node springs with keyword edits).
Iâm a mechanical engineer and I use general purpose FEA. Iâm not interested in beams like civil engineers are, but, as I mentioned, Iâve been using beams to create bolted connections. Bolted machine frames resemble civil engineering structures. Since there arenât any strict regulations regarding our âmechanical worldâ, itâs good to take advantage of eurocodes.
Could you tell me more how do you use springs in bolt connections? Maybe an example, If youâre so kind? I always used beams and RBE2 for that.
