Non-Linear Stability Analysis results

Hello,

I am doing a non-linear stability analysis, in principle to define the capacity of a system that is prone to buckling failure. If I run the incremental method (non-linear) I can define the load increments and get a result for every load increment. However, how should I define failure? I know I can have the calculation stop at a certain deflection, but assuming I don't know what that might be, how do I define the increment to failure? Does the software simply give me the internal forces/stresses for all increments or should I expect an message pointing at loss of stability after a certain number of increments?

Thank you

Hi _lobo,

thank you for your inquiry.

When performing a nonlinear stability analysis, failure criteria are defined in the model itself, e.g. by using

  • nonlinear material models (requires add-on Nonlinear Material Behaviour)
  • nonlinear member/line hinges
  • nonlinear supports (e.g. failure under tension)
  • nonlinear stiffness types for main objects (e.g. tension member, membrane surface)

Next week there's be a webinar that will tackle this topic:

If you have any further questions, just ask. I'm happy to help

Best regards
Clemens Gutmann

Hi @clemens.gutmann,

Thank you for your reply. Yes, I will definitely watch the webinar, as it looks interesting, I have already registered.

However, the topic could be also good for a general discussion. I usually use a geometry and material non-linear model and run a non linear stability analysis with the incremental method where the load increases until failure in principle. My understanding is that the capacity of the system is the last converging step. So, at some point, the model does not converge anymore and that is the point of failure, theoretically. Is this approach correct? Is this tool meant to be used like this?

Theoretically, yes. But practically, it depends on the standard you base your design on. For example, this webinar shows what criteria are used for a design according to the Eurocode 3:
https://www.dlubal.com/en/support-and-learning/learning/webinars/003472