4 Replies Latest reply on Dec 5, 2016 4:53 AM by Alex Clarke

    large displacement not converging

    Robert Sarkissian

      Assembly contact analysis

      456000 elements

      using standard mesh draft format

      stops at Large displacement 1 with message, not converging do you want to stop the process?

        • Re: large displacement not converging
          James Riddell

          That's only ~1.5M DOF - not really that many.

          Pics? Upload model? Solver?  What are you trying to accomplish?  Have you tried refining the mesh?

            • Re: large displacement not converging
              Robert Sarkissian

              Initial run was with using curved draft mesh, this solved ok up to 10% then message came up

              force step is less than 0.01% of load, then stopped!    with Large displacement iterations reaching 181, after 5 days, frustrating

              Reduced elements from 1,5 million to 460,000 to get it to solve using standard mesh

              Its a thin stack of multiple layers shaped like an glass lens frame with a flexible inner membrane, includes thermal shrink and forced deformation.

              Iterative solver with Large Displacement Fails to solve

              Sparse Solve with Large Displacement working, but  very slow

            • Re: large displacement not converging
              Alex Clarke

              Usually I find that Large Displacement warning only comes up if I have contact errors or gaps which I didn't spot.


              One trick is to use "Use soft springs to stabilise model" which stops the model from displacing too much. This is usually enough for the solver to finish, and then you can see which parts have moved in an unexpected way and fix the contacts/geometry errors.

              The FFE solver is usually quickest but doesn't work with large displacement. Uncheck lager displacement, check use soft springs, use FFE solver, and try again.


              Hope that helps