AnsweredAssumed Answered

Bolt connector preload and factor of safety

Question asked by Chris Fernald on Jun 9, 2011
Latest reply on Jul 25, 2018 by Matthew Zola



Is there a way to ignore bolt preload when SW calculates its Factor Of Safety.  For example, on an M10 bolt I have applied a ~45,000N preload, with a desired FOS of 2.  The applied load on the joint is small (~100N).  When Simulation reports the connector's results, it says its FOS is just above 1.  This is becuase it considers the tension due to preload when calculating the FOS.  In reality, a M10 bolt would have lots of FOS on such a small load.  If the preload is reduced, bending moment in the bolt will increase because the joint would separate.  Is there a way to apply the preload but remove it from the FOS calculation?  The only work around I know of is to multiply the applied force (and friction coefficient if shear is present) by the desired FOS - then make sure the axial force does not exceed the preload.  There must be a better way...