I am trying to perform a buckling analysis of a hydraulic cylinder. I setup the model of the entire cylinder and tried running it but kept getting a bunch of errors. Simplifying it really didn't help and it was difficult to figure out exactly the problem. So I started from the opposite end, with the simplest possible model and progressively made it more complicated to see at what point the analysis is getting fouled. I got to the point with one end of the cylinder fixed and a load applied to the other end. The model is split in half with a planar symmetry constraint. The only other constraint is a fixed constraint at the rear of the cylinder. Looking at the deflection plot (.pdf attached), the rod clearly deflects into the front bearing of the cylinder. All the contacts are set to "bonded". I tried every conceivable combination of contacts to get the shaft and the bearing to move together, but keep getting the same result. I saw another thread with something similar to this and the answer was that you need to do a non linear buckling analysis. Can anyone offer any insight?