Modelling the response of a beam past its buckling load using Karamba

I am trying to model the response of a single panel under a vertical force past its buckling capacity.

For my first attempt I created a beam with a slight eccentricity and provided a force to the top of the beam. This model works, however it does not give the correct real life response, as the force is applied it initially does not displace much but as the force increases the displacement increases by larger amounts. This suggests that the material has yeilded.

Instead I would expect my beam to get more and more curved (a C like shape), and as it gets more curved the larger the force required to maintain the curve.

My second try involved trying to model a straight panel and produce a buckling curve, however I have not been able to make this successful.

Is there any better way to model the forces involved in producing a C-shaped curve from a straight panel in order to achieve an accurate representation of the forces and displacement in the panel?

Many thanks in advance.

Attachments:

TRY 2- - REPLICA OF EXPERIMENT_without cable.gh, 38 KB
REPLICA OF EXPERIMENT_without cable.gh, 38 KB

Replies to This Discussion

Permalink Reply by Yike Qin on March 19, 2019 at 7:29pm

I am not sure when you said that the response is not “real life response”. As I understand, the initial small deformation is the elastic deformation of the panel until it reaching the buckling load when the sudden large displacement occurs. This should be the type of behavior expected from buckling.

What you described in the next paragraph sounds more like a elastic deformation behavior that follows hook’s law.

Correct me if I understand your situation wrong.

Permalink Reply by Becky Miller on March 20, 2019 at 6:09am

Thank you for your reply.

Oh yes, you are correct that my first model with a slight eccentricity should behave the way it does. I did not think about that.

But for my second attempt if you view the attached picture, I am trying to model a panel which has just buckled and I would like to obtain the forces required to keep it in certain curvatures (C-shapes). This sort of behaviour should be elastic deformation, however, intuitively if you try to make the straight panel more and more curved it should require a larger force (this is after the buckling has occurred).

I am expecting a graph similar to the second attached image.

Attachments: