6 Replies Latest reply on Sep 28, 2017 2:33 PM by Conrad Cormier

    using pivots in strength test simulation

    Conrad Cormier

      Looking to simulate a strength test. As you can see in the picture, the idea is to use some round supports and apply a force to the center pipe. I have the bottom supports set as bearing supports, thinking that would allow them to pivot. But it`s not working. The sides of the part should be in line with the red lines. So my pivots are not working. I`ve been trying to find a way around it, but nothing works. How can this be done? I have a contact set between the pipes and the test piece.

       

        • Re: using pivots in strength test simulation
          Mats Lindqvist

          I sort of a beginner at Solidworks simulation but I do have a bit of experience with Creo Simulate.

           

          First of all, this looks like a non-linear problem with contact, large deformation and material plasticity(?).

           

          With those non-linerarities, it is a good practice to utilize symmetry, assuming your problem is symmetric: geometry, constraints, loading and deformation are all symmetric about the same symmetry plane.

           

          With a symmetry model, the symmetry constraint will take care of horizontal (in your picture) displacements.

           

          I'm not sure how these "bearing supports" behave, but if you model the problem using contacts, you will be fine. Contacts (as with all non-linearity) are more computationally expensive though, so it is important to reduce the element count, use symmetry etc.Moreover, I would try to not use contact for the loading, instead apply the load directly on the surface. The fewer contacts the better.

            • Re: using pivots in strength test simulation
              Conrad Cormier

              I can how using symmetry will cut down on the required run time, but how would it solve my issue? The test piece is not fully symmetrical, but the changes are on the ends and will not effect the results.

               

              As for "bearing supports", they where just used on the bottom pipes, instead of using a "fix" constrain, in the hopes that this exact problem would not happen and the part would rotate around the pipes as it gets bent.

               

              I`m not following when you say I should just use "contacts" I do have some "contact set" constrains between the pipes and the test piece.

                • Re: using pivots in strength test simulation
                  Keith Frankie

                  You say you have contact set, but it looks like bonded contact instead of no-penetration contact.

                   

                  Symmetry does look like a good idea.  Depending on the beam profile you might be able to do symmetry in two directions.

                   

                  You can probably just fix the round supports.  The default for no-penetration is to have 0 friction, which means they'll act like rollers.  I'd imagine you're more concerned with results related to the beam bending, and you're not worried about contact stresses with the rollers.

                  • Re: using pivots in strength test simulation
                    Mats Lindqvist

                    Here is an example I made some years ago using Creo Simulate. I think it resembles what you're trying to do. It includes large deformations, contact and plasticity. This is in fact a 2D problem, but at the time, all of these nonlinear options could not be combined, I think it was Creo 1.0. So in this case, I made it 1 solid element thick. It's in Swedish, but at least you can watch the animation.

                     

                    Econotips #10 - YouTube

                • Re: using pivots in strength test simulation
                  Bill McEachern

                  if you put split lines where you want the supports you can just "fix"  as lines. There are no rotational degrees of freedom on the solid elements so it will behave as "pinned". Probably a decent first level approximation that avoid the contact iterations. Probably as good as a contact analysis for small displacements, all things considered.

                  • Re: using pivots in strength test simulation
                    Conrad Cormier

                    Hi Guys

                     

                    Thanks for the help. I`ve try the no penetration constraints on the roller, runs for a while then just crashes without explanation. The only way I could get it to work was with a fix constrain on the split lines. Not ideal, but it works.