3 Replies Latest reply on Jun 4, 2015 7:06 AM by James Riddell

    Restraint Help

    Robert Smith

      Hi all,

       

      Looking for some assistance in regards to restraints in simulation. up until now i have only done basic simulation on single solid pieces and am currently working on an assembly that i am really struggling to understand where and how you apply restraints to give a real life simulation.

       

      I have attached a screenshot of what i'm working on. It's a hose saddle for allowing hoses to bend over the edge of vessels that's being worked from. There are 2 main profiles that are connected by 6 pieces of angle. There are then 2 sizes of tubing inserted in between the 2 main plates. These tubes act as spacers with 1 size having rollers on them. There is then the main top hanging channel that is connected to the main arrangement via 4 connecting legs. Apart from the 6 pieces of angle being welded to the main side profiles, the rest is a bolted assembly.

       

      I have set non penetrations to all the tubes and connecting legs. i have fixed on the 4 off faces on the base and applied a load to top hanging channel profile. The aim of this was to simulate a pull test. I have tried to apply restraints and ran the simulation but parts keep disappearing onto the other side of the work space and when they don't i can't see any loads paths on the final result as if nothing has happened.

       

      I'm just struggling to realize which restraint is best used in which circumstance and My question is how do i restrain this properly to give the best real life simulation results?

       

      Thanks in advance for any assistance, much appreciated for any help.

        • Re: Restraint Help
          James Riddell

          If you are holding that by the hole at the top then that should be the only restraint.  All those pins you have restrained and then applied a force to will not move.  You have way to many restraints on this in any case.  I'd recommend STARTING with the entire assy with it globally bonded and only use contact sets (NP) if you NEED to have a part able to move.  And then only restrain minimally, i.e. sliding restraint on one end of a pin only.  As Jared Conway would say, start small and build up to the real-world case.  You'll need to use the advanced restraints for some of these but look at how it is supposed to react and remember that if you fix something in 3DoF then it isn't moving and will not transmit force.

            • Re: Restraint Help
              Robert Smith

              hi James, thanks for your response. i had ran it as a global bond only before but i was unsure if this gives a good indication to what would happen so i tried complicating things, which didn't help.

               

              i am only a novice at this so the help is much appreciated.

               

              Just as a general question, in simulation do i only really need to apply advanced fixtures to parts that move, i.e slider, and not the likes of my spacers in this model, where they can move(as in be removed) but once assembled, cannot move.

               

              Below was the result of changing it back to a global contact - bonded , only.