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

    Fully Defined Assembly is Unstable?

    Jeremy Notestine

      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.


        • Re: Fully Defined Assembly is Unstable?
          Dave Laban

          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?