4 Replies Latest reply on Oct 13, 2010 1:49 PM by Ryan Werner

    Missing Joints in Weldment Simulation

    Brian Bain

      I am trying to do a load rating for this ramp but when I go to define the joints one is missing.  Is there a way to manually add joints? I have attached the file if somebody has an idea.

        • Re: Missing Joints in Weldment Simulation
          Ryan Werner

          Hi Brian,

           

          There is a way to manually manipulate the joints but not necessarily a good way to add a missing joint.  The best way to do this is to make the tolerance small enough so that all joints are shown even if there are extra ones included.  Once you have done this you can right click on the extra joints and deselect the beams that are highlight, then hit recalculate and that joint will disappear.  That way you can get yourself down to just the joints you want.  It can be a fairly painful process and unfortunately you have to redo it everytime you make a change to the model that changes the joints.  This should work for you but I know from experience it can be very difficult to get all joints showing up no matter how fine you make the tolerance.  Sometimes it takes some tinkering.  I am going to take a look at your file.

           

          Ryan W.

            • Re: Missing Joints in Weldment Simulation
              Ryan Werner

              I have attached your file with all the joints appearing.  I had to redraw the bottom square tubes for some reason so you will see where I deleted them in the feature tree and then re-added them.  You can probably rearrange you features somewhat to make it work better than using a the delete bodies but I did because it was the quickest.  Hope this was what you were looking for.

               

              Ryan W.

                • Re: Missing Joints in Weldment Simulation
                  Brian Bain

                  Tthanks what made you think to delete the bottom square tubes?  That is weird too bad you cant define joints manually.

                    • Re: Missing Joints in Weldment Simulation
                      Ryan Werner

                      This model is a strange one.  The weldment is fairly straight forward and symmetrical so beams should work like a dream on it but they really do not.  Even after I got all of the main joints to show up I tried refining the tolerance again to see if more of the joints showed up properly and when I did that all the joints got completely screwed up again.  I think that because those bottom beams are not intersecting the main, long beams is giving Simulation problems.  I know that with beams surface to surface contact like that can give it troubles if the contact surface area is not large enough.  I would like to know what a VAR said about it becuase I do not think there was or is anything wrong with the modelling.

                       

                      What lead me to believe it was the feature itself was that it was treating all the other beams properly.  Usually when Simulation has trouble with a feature that it is treating fine somewhere else in a model is because it does not like the geometry for some reason or another, ie. interference, gaps etc.  Your model didn't have any of those so I figured I would try redrawing the beam.  I started by replacing just the middle cross beam and that fixed the joints for it but the joints for the other cross beams were then screwed up so I decided to do them all and see what happened.  It worked but again the joints were not what I would call stable because when I changed the tolerance they should not have gone crazy like that.

                       

                      Ryan W.