3 Replies Latest reply on Jan 4, 2013 2:21 PM by Shaun Densberger

    Fully Defined Assembly is Unstable?

    Jeremy Notestine
    Jeremy Notestine Nov 24, 2012 11:03 PM

      I have made a static 2-D Simplification study of a model consisting of a cylindrical cone made of 5 bonded (contact set) and mated parts. Each part is concentric and mated together. The front planes are also mated, making the model fully defined. In the 2D study, I added a fixture to the bottom and a 500N load on the top. The mesh seems fine but when running it I get, "Model is unstable. Restraints may not be adequate."

      When soft springs or inplane is enabled, I get the same error.

       

      Also, is there somewhere (Run error file etc.) where I can find more information on where an error occurred?

       

      Thank you for your time.

      Jeremy

        • Re: Fully Defined Assembly is Unstable?
          Dave Laban
          Dave Laban Nov 26, 2012 3:38 AM (in response to Jeremy Notestine)

          What I often find helpful in these situations to to apply a Fixed restraint where any restraints are normally applied, then re-run the model replacing each Fixed restraint with its proper one, one at a time.  This then normally identifies the part / parts at fault.  This has been particularly useful with 2D Simplifications, which seems remarkably unstable given that they can only move in two directions! 

           

          I have also found applying a Fixed restraint to a single node beneficial - the model is free to move due to loadings, but is still fixed in space and hence more stable.

           

          Are you able to post any pictures of the set up?