Master's Thesis: Spring Stiffness of a Leaf Spring

Within the work, a BoF model is to be created. That is, an embedded beam with which the embedding behavior of the connector in the wooden component can be simulated.

I want to model the spring stiffness, i.e., the behavior of the wood, via the diagram input. However, in the input area, there is a field for axial stiffness next to the diagram. If I enter 0 there, since I want to determine my stiffness via the diagram, the program treats the springs as if no stiffness is present. What do I need to do so that the program calculates using the diagram values?

Furthermore, I wonder if the stiffness ux of the spring is defined by the bar direction?

Best regards
Felix

Hi FelixZ,

thanks for your message!

To analyse the problem more precisely, the model file would be very helpful:

:right_arrow: Click on FileSave as and choose the following settings to reduce the file size:

:right_arrow: Then upload the file here (e.g. *.rf6, *.rs9) – this way, the community can also contribute to the solution.

:owl: Prefer not to share the file publicly? No problem – send it to me via direct message: click on my profile picture or user nameMessage.

Best regards
Bastian Kuhn

Hello @bastian.kuhn,

Thank you very much for the feedback. Here is the file and specifically the section it concerns.
I was under the assumption that the force-displacement relationship I defined in the diagram overrides the axial stiffness in the base window, or that RFEM 6 also uses these values for the axial stiffness when selecting the diagram. However, this does not seem to be the case. My question in this regard is: how do I proceed correctly here so that my stiffness is correctly represented according to the diagram?

Best regards
Felix

BoF-Modell.rf6 (1.2 MB)
Screenshot 2026-02-19 162716
Screenshot 2026-02-19 162710

Hello FelixZ,

Thank you very much for the file and the images. Currently, you have to enter the unit value 1 for the axial stiffness there. Then you will get the desired deformation.

image

However, we want to improve this. This process is listed under the internal ID [605360] with us.

Best regards

Bastian Kuhn