5 Replies Latest reply on Aug 11, 2014 3:34 PM by Jared Conway

    Importing motion loads into simulation

    Knut Fiskergard

      Hello

      I have a motion analysis that runs well. but I am having trouble with FEA.

      FEA within motion return no stresses (legend has zero on all colors)

      When importing into Simulation - only gravity and acceleration loads are transferred.

       

      Anyone have any Idea what I am doing wrong, or are not doing?

       

      SW2011 x64 SP5.0

        • Re: Importing motion loads into simulation
          Jared Conway

          what other loads are you expecting?

           

          what restraint are you using? just inertial relief?

           

          are you getting good data out of motion? zero redundancies?

            • Re: Importing motion loads into simulation
              Knut Fiskergard

              I am expecting the resulting load acting on the part to be transferred also.

              I use body contact between the chain links (section is only graphical, not modeled)

              The motion study behaves as it should, and contact loads makes sence (the jitters I belive are an effect of round-off, and will be reduced when I run with finer resolution).

              Within motion FEA reports no stresses, as you can see.

              I have been a bit triggerhappy and actually stopped thea in Simulation. When I import to Simulation I get a warning about load imbalance, after taking the time to read the whole message, the analysis was completed using inertial relief. Now the stresses are 0,48 MPa, and even over the whole body.

              As I understand it, three loads should be tranferred: ALT-Gravity, ALT-CentriFugal, and ALT-RemoteLoad.

              I only get the two first ones, and that explain my FEA results.

               

              The way I see it there is something wrong with transferring the calculated contact load onto the FEA model.

              I think it might be a geometry challenge and will try something simpler to check if the problem is "consistent"

               

              motion_pic.jpg

                • Re: Importing motion loads into simulation
                  Jared Conway

                  do not believe that contacts get transferred

                  remote loads would come from joint forces which you wouldn't have if you are using contact

                  based on what you want to do, i'd see what you can do to setup a static analysis or nonlinear dynamic to get what you want

                    • Re: Importing motion loads into simulation
                      Knut Fiskergard

                      Seems like you are right regarding not transferring loads on contacts

                      In my simplified test (a pin in a hole), only the 3 first frames where avilable to transfer.

                      Also in cad, I mate aganst sketches to make the asemblying the chain easier - SW simulation/motion is not happy about that either.

                       

                      So I'm starting a nonlinear dynamic analysis. Was hoping not to go there. But while a test run is solving I'm thinking:

                      Since I'm actually only iterrested in the result for one chain link, could I set the other parts to "rigid"?

                      Is it possible to include friction in contact between a rigid and a flexible part?

                       

                      Probably need to narrow down the range of motion as well.

                      Could you suggest some settings that I can use that solves quickly and that are accurate enough to find where (when) the max stresses would be??

                        • Re: Importing motion loads into simulation
                          Jared Conway

                          motion only cares about physical mates. it face to face connections. sketches are almost like virtual so their connections aren't physically translatable. check out the motion training regarding joints.

                           

                          quickly and accurately don't work to well together when it comes to dynamic. the only suggestion i can make there is only save the results you're interested. that will reduce the size of your results file and if you don't need to convert to strain or stress, will reduce the time to complete the results process.

                           

                          if you want to analyze the interaction between components, don't make them rigid. there is no such thing as an infinitely rigid component. it will just skew your results.