3 Replies Latest reply on Dec 9, 2011 4:26 PM by Jerry Steiger

    find forces on supports

    Pascal M

      hello,

       

      i have a shaft supported in 3 points, the middle point has 1mm play and there is 2800lb applie between heach support so 2x2800lbs.  i would like to see the forces applied to each support. 

       

      i tried running the simulation then doind stactic force and selecting the 3 supports but i always get the same result.  and the shaft always stays straight when i do this...  i would have expected the middle supprt to get less and less weight on it as i made the gap between the shaft and the support bigger.

       

      am i doing something wrong?

       

      thanks

        • Re: find forces on supports
          Bill McEachern

          well if the shaft is sufficiently rigid that it will not deflect anywhere near a 1 mm then the middle support will see no load. this is essentially a beam with a distrubuted load with a gap at teh middle support that is 1 mm below the shaft. The restraints on the other ends need to reflect the bearing types and stiffnesses. It should be pretty straight forward. The two end support will be reactions and hte middle one is a contact force. They should add up to whatever the load is.

            • Re: find forces on supports
              Pascal M

              no matter  how low i put my middle support, it always show same mass on every suppport when i do reaction force then select my 3 supports...

               

              i run simulation then result advisory, then list result force then select the 3 supports :S

               

              if i simulate with 2 support, it says 4mm deflection. i put the middle support to 12mm : the shaft shouldnt touche the middle support, the shaft still shows a form suggesting it is touching the support and it still says there is force on the support.

               

              i tried this on a computer that has SW2011 premium

                • Re: find forces on supports
                  Jerry Steiger

                  Pascal,

                   

                  It sounds like you have your contacts set up wrong, that the beam is bonded to all three supports. You need to have a no penetration contact set for the middle support and that needs to be its only form of contact.

                   

                  I'm not very familiar with the way SW Simulation handles contacts, but I seem to recall that you can set up a "universal" contact, which applies to all parts/bodies. If you set that up as bonded, then that would explain your results.

                   

                  Jerry Steiger