Nonlinear Axial Compression (Buckling) of a Cylinder not Converging

[Disla]

@fethio

Hi @Disla , just to understand your model setup, are you applying a preload such that it produces an axial stress of 1 MPa?

Right. You can also consider force applied to the kinematic ref NODE. Your Buckling load will be delivered in terms of Fcr (N)

@fethio

on a node that lies on either one of the edge node sets

That breaks the simmetry of the displacement field. Try with two in oposite sides to get a cleaner solution.

@fethio

does kinematic coupling work on shell edges

In my experience yes as far as it is defined in terms of a SURFACE TYPE=NODE.

*SURFACE,NAME=NSet_KINEMATIC,TYPE=NODE
NSet_KINEMATIC
*COUPLING,REF NODE=XXX,SURFACE=NSet_KINEMATIC,CONSTRAINT NAME=RootCouple
*KINEMATIC
1,3

Don’t forget to run a frequency analisys before Buckling. Kinematic needs a special care to avoid underconstraining the model. Keep this image in your brain when using KInematic.

Prepomax has implement it in it’s last version. Would be a good oportunity to test it althought a saw something strange in the example. I will post there to comment.