1 Reply Latest reply on Sep 6, 2013 6:32 PM by Jared Conway

    Hydraulic Cylinder Buckling

    Dennis Pietrantoni



      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?  

        • Re: Hydraulic Cylinder Buckling
          Jared Conway

          bonded global contacts only apply to faces that are touching at the beginning of the analysis, otherwise you need to add contact sets. in your case where the bearing is, you'd need no penetration contact it sounds like because they slide with respect to each other and aren't glued together?


          the other thing i'd be concerned about here is symmetry. that may overrestrain your model from a buckling perspective.


          nonlinear buckling is ideal for all buckling problems. it is a truely nonlinear phenomena. you might want to double check how it is executed in simulation (linear buckling) and really outline what you want to learn in this analysis and what you expect before moving too much further.