4 Replies Latest reply on May 27, 2018 8:43 PM by Cl So

    [FEA error] The iterative solver stopped.

    Cl So

      Hi! I just finished a simple internal flow simulation with my pipe.

      And I would like to do a pipe stress analysis due to the flow, therefore I exported the flow simulation result into the FEA study.

      However, I have encountered a lot of problems, e.g. meshing problem (interference problem...), and I have tried very hard to solve it with meshing control.

      But after the meshing is ready, when I run the FEA study, it shows this message when it is about 50%.


      " The iterative Solver stopped.

      Numerical difficulties. (Preconditioning failed)

      Please check model boundary conditions.

      No results saved."


      I have tried to check my boundary conditions in flow simulation, but I couldn't find anything I can do.

      Please help if there are any ways I can solve this FEA study for my pipe stress analysis.



      Iterative solver 01.png

        • Re: [FEA error] The iterative solver stopped.
          Cl So

          Please download all 3 files.


          01. Parts Asemble.zip               (include all the parts and assemble)

          02. Flow Sim Result.zip              (include the internal flow simulation, "1.fld" is used to the flow effect in FEA)

          03. FEA.zip                                 (include the mesh i guess?)

          • Re: [FEA error] The iterative solver stopped.
            Ryan Dark

            Hi Cl,

            This is a common question that comes up a lot on this forum.  The model is definitely unstable but tracking down how it is unstable is the real problem.  I went through a quick stability diagnosis in a duplicate of your study like this:


            1. Go into the study 'Properties'

                      Turn on 'Use soft springs to stabilize model'

                      Turn off 'Compute free body forces'

                      Turn off 'Large displacement mode'

            2. Suppress all loads and apply only 'Gravity'

            3. Mesh/Run the study

            4. When the solver stops (if it stops) due to large displacements and prompts to put the study into 'Large Displacement mode' declined this offer.  The solver will dump what results it has so far

            5. Inspect the displacement plot in the results to find the unrestrained body



            For any body that is unconstrained you would need to create explicit 'Contact Sets' in order to bond these unrestrained bodies to the rest of your structure.


            This video (GoEngineer - Simulation: Common Errors in Simulation Webinar) and this document (GoEngineer - Simulation: Diagnose Unstable Studies) give more detail study instability.