3 Replies Latest reply on Sep 3, 2013 10:48 AM by Marc Lauzon

    Model Not Stable

    Marc Lauzon
    Marc Lauzon Aug 22, 2013 4:40 PM

      Good evening,

       

      I have a problem with a simulation I'm trying to do. The model isn't stable and I don't know why. The structure is 11.5m x 1.23m and the force applied is in N/m. No rotation is blocked. Y translations are blocked on each of the four extremities of the structure, X translations are blocked on the extremities of one side of the structure and Z translations are blocked for one extremity.

       

      I have done a similar simulation with a different structure, and Solidwork was able to compute it no problem. Any clue?

       

      Thank you

        • Re: Model Not Stable
          Jared Conway
          Jared Conway Aug 22, 2013 6:20 PM (in response to Marc Lauzon)

          Use soft springs or extra fixes restraints to figure out where you're missing contact or connectors.

           

          We recommend in out training to start small. Add one part at a time with a gravity load till you have the whole structure. If you run into an issue, you'll know where it happened.

          • Re: Model Not Stable
            Robin Boudreault
            Robin Boudreault Aug 30, 2013 3:59 PM (in response to Marc Lauzon)

            I had lots of cases where it was just a bug related to the mesher. It happened only with quadratic element and was ok with draft elements.

             

            Try solid elements instead of beam element to do a quick test. You can also look at it by changing the force by an imposed displacement. Doing so, parts won't go at an infinite position and throw an error message. Soft spring can help in some case too.

              • Re: Model Not Stable
                Marc Lauzon
                Marc Lauzon Sep 3, 2013 10:48 AM (in response to Robin Boudreault)

                Found it! The transversals at each ends were at fault. I removed them and remodeled them using a different sketch and it works. No need for soft springs either. I still don't know why that happened thou, since all the other transversals worked, but not those two...