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Buckling Analysis Questions

Question asked by Chuck Lob on Feb 8, 2010
Latest reply on Feb 13, 2010 by Devi Prasad Samal

See attached jpeg.  I'm trying to do a buckling analysis of an assembly consisting of a rod and identical clevises and cross pins on either end - five parts total.  I've attached a hinged contraint to the middle of the lower pin (I used split lines to define a center of the pin) and have assigned bonded contacts between the pins and their respective clevises and between the clevises and the rod.

My question is in regard to how to apply the load and constraints at the upper end because the analysis, although it runs fine, doesn't produce a symmetrical "bowing" shape with the loading/constraints I'm using.  The upper clevis - where the load is applied - stays relatively in plane.  I don't think this is correct.

I've applied a vertical load to the center section of the upper pin and applied constraints such that the pin can only move vertically, but I don't want to inhibit the clevis from rotating about the pin and I don't think I have, but it appears to be stuck in-plane.  SW Sim only allows bonded and free contact elements in buckling mode so every contact point between the parts is bonded - I have no choice.  Also, there doesn't appear to be any vertical displacement of the upper clevis - it doesn't move down.  I did some really simple models of just a flat plate and the results are similar - no vertical movement of the upper portion.  Any help is greatly appreciated.