3 Replies Latest reply on Jan 5, 2012 8:53 AM by sandeep pawar

    Need help with Threaded Rod static simulation

    Andrew Gerges

      Hi,

       

      I am trying to simulate an assembly with a threaded rod that screws into a block and is secured with a nut, then the other end of the threaded rod goes through a plate and is secured to the plate using two nuts, one from the bottom and one from the top.  The reason behind this is to allow the distance between the plate on top and the block on the bottom to be adjustible from the two nuts at the top plate. (see attached)

       

      Now the question is how do i define the connections as bolted connections when trying to run a static simulation? 

       

      Also a side question should the bolts/threaded rod be simulated as smooth surfaces or would it be best (more accurate) to cut the threads?  If the latter how does one mate it to the threaded nuts/block without having interference issues?

       

      Thanks for your help!!!!

      Andrew

        • Re: Need help with Threaded Rod static simulation
          sandeep pawar

          Andrew,

           

          Is the objective to find out if the threaded rod will will take the load? If I were doing this, I would do a simple static analysis without the threaded rod, extract reaction forces and estimate the stresses (axial, shear, bending) on the threaded rod using bolted joint analysis theory.

           

          Or you can use bolt connection. The only problem I see in that is how do you define two nuts. If you do want to include the threaded rod, imo, you will have to inlude the threads because that's what gives you the joint. But it will have to to be multi-step process. You will have to first induce compressive forces in the rod with a fictitous thermal load corresponding to your preload.

          You will use No Penetration contact between the nut and the rod.

           

          It would be interesting to see how others would go about this problem. Thanks.

            • Re: Need help with Threaded Rod static simulation
              Andrew Gerges

              Sandeep,

               

              First off thank you for taking the time to respond and try to help me out !

               

              I already calculated the stresses on the threaded rod and designed it for infinite life working the numbers by hand (as well as the other components).  I wanted to somewhat double check my numbers/assumptions using solidworks, plus i wanted to see where the reactions occur at the top connection.  I know that by tighenting things down there would be some compressive stress in the members(bottom block and top plate) and I wanted to know if those stresses would affect infinite life.

               

              I guess I just wanted to put my forces and define all my connections/fixed geometry and see how the part holds up in static and fatigue loading.

               

              Is there an option in solidworks to have a threaded rod tightened to a part?

               

              Thanks again for your help!!!

                • Re: Need help with Threaded Rod static simulation
                  sandeep pawar

                  Andrew,

                   

                  From what I know there is no option to define a threaded part tightened to other part. Bonded contact will not be accurate to use.

                  In your model, you will have to include the preload generated by the torque. There are various ways to do that. Please search on this forum for bolted joint. Else, google it.

                   

                  If it is possible, can you attach one more picture showing your boundary and loading conditions?

                   

                  Thanks,

                  Sandeep