Liebes Forum,
ich arbeite derzeit mit der RFEM 6 API in Verbindung mit Grasshopper, um eine automatische Modellanpassung in Abhängigkeit von Verformungen umzusetzen.
Ich möchte das Modell iterativ anpassen, indem bei Erreichen bestimmter Verformungskriterien automatisch zusätzliche Strukturelemente (z. B. Zugstäbe) eingefügt werden.
Ein einfaches Beispiel:
Ich habe einen Kragarm. Wenn die Durchbiegung am freien Ende > 1 m beträgt, soll bei der nächsten Laststufe automatisch ein Zugseil hinzugeschaltet werden.
Dazu plane ich, mehrere Lastfälle zu definieren (diese berücksichtigen die jeweils vorhergehende Lastfälle) und nach jeder Berechnung den Verformungszustand zu überprüfen, insb. die Verschiebung des Endknotens relativ zur Ausgangsposition.
Frage 1: Laststufen einzeln berechnen:
In der API habe ich bisher nur die Funktion calculate_all gefunden, wodurch alle Lastfälle auf einmal berechnet werden.
Gibt es eine Möglichkeit, gezielt nur einen bestimmten Lastfall oder eine einzelne Lastfälle zu berechnen (um daraufhin dynamisch das Modell anzupassen unter Berücksichtigung des vorhergehenden Lastfalls )
Frage 2: Resultate bei Solids vs. Surfaces:
Mir ist aufgefallen, dass bei Solids in den Ergebnissen verschiedene Spannungen (stresses) ausgegeben werden, während bei Surfaces nur interne Kräfte (internal forces) zur Verfügung stehen.
Darf ich nach der Begründung dafür fragen?
Vielen Dank im Voraus für Rückmeldung!
Hi MariliesFrei,
I have good news for you: the method you requested to calculate only one or selected load cases or load combinations is already in development and will be available shortly 
. The method will probably be called RFEM_app.calculate_specific(), but the best way to find out will be through the documentation and the release notes once it is ready.
If you have specific application examples or further questions, we are very happy to support you!
Best regards
Robert Milrath
1 Like
Hello robert.milrath!
Thank you very much for the good news!
May I ask more specifically once again:
Will it be possible with RFEM_app.calculate_specific() to perform structural modifications via script between load cases? Or would previous results be deleted in such a case?
Thank you very much!
Marilies Frei
Hello MariliesFrei,
with structural modifications, the results are deleted. If you want to keep the old results, you have to temporarily store them somewhere in your code. Of course, you can also save the entire model right away and create a copy, for example, with the index of the iteration step. You just have to be careful not to generate a huge amount of data.
Best regards
Robert Milrath
Thank you very much for the response!
I have a follow-up question:
So far, I have not found a way to directly access the individual FE nodes via the API.
While it is possible to read the results at the nodes – that works – it is not clear to me which method I should use to specifically transfer or reuse these intermediate results (e.g., displacements) in the next calculation step.
Is there an example or a recommended procedure for passing intermediate results in a multi-stage load approach via the API?
Thank you in advance!
Marilies Frei
Hello MariliesFrei,
I believe there has been a misunderstanding. You cannot transfer intermediate results from the first calculation to the second calculation after the structural modification. However, you can temporarily save these in your script and then compare them with later calculations and results within your script.
Regarding your second question (Solid vs. Surfaces), I kindly ask you to create a new topic. One question per topic in the Dlubal community helps keep discussions clear and focused, facilitates findability, and improves problem-solving.
Thank you very much.
Best regards,
Robert Milrath
Exactly – that’s what I suspected… Thank you nonetheless for the explanation!
Best regards,
Marilies Frei
Hello MariliesFrei,
it's not over yet
In RFEM 6, the Add-On Construction Stage Analysis (CSA) is available to you. It may be possible to use this Add-On in the API (gRPC) for your application at a later time.
The best approach is to first test directly in the RFEM application with a simple example whether the functions offered there meet your requirements.
If that is the case, I will gladly register you as an interested party for the implementation of this Add-On in the API (gRPC).
Currently, the Add-On is unfortunately not yet available via the API – but development is steadily progressing 
Feel free to let me know if you have any further questions!
Best regards
Robert Milrath
Hello robert.milrath!
Thank you very much for the preview!
Funny - we also tried it with construction states!
The strategy didn't work out because we would have to link the addition and deactivation of elements to conditions (e.g., "if the distance between node 1 and node 2 is < x mm", etc.) - which, to my knowledge, is not possible even with parameter input, right? (This feature would be very helpful - so please feel free to include me as an interested party!)
Best regards,
Marilies Frei