16 Replies Latest reply on Feb 26, 2015 12:01 PM by Jared Conway

    Help with my FEA simulation?

    Adnan Nweilati

      Hello,

       

      I'm trying to perform a FEA simulation on a telescopic fork. Im trying to find the displacement due to the bending moment when the fork is fully extended. I applied a load of 5000 N and fixed the geometry from bellow. However I am getting this error every time I solve:

      "The Iterative Solver stopped.

      The solver has numerical difficulties.

      Model may not have adequate fixtures

      No results saved."

       

      I read on this form that I'm suppose to add fixtures such as springs, but I have no idea where to apply it.

      Mesh.png

      Any help would be appreciated.

       

      Adnan

        • Re: Help with my FEA simulation?
          James Riddell

          In the lower box on the left of your screen, right click on the top item "Static 1" and select 'Properties'.  Down towards the bottom of the pop-up select 'Soft springs' and try it again.  If this is a non-welded assembly you should probably remove the 'globally bonded' boundary condition and select 'no penetration' for a more realistic response.

            • Re: Help with my FEA simulation?
              Adnan Nweilati

              Hi,

               

              Its giving me very weird results after I solved it. A huge displacement is showing on a part that does not have any load acting on it!


              Any ideas??Results.png

                • Re: Help with my FEA simulation?
                  James Riddell

                  I can't tell your dimensions of the part or the magnitude of the pressure/force and I don't know what the materials are but 1/4" deflection might be because of two things: your restraints aren't complete (the 'internal' parts aren't stopping it from moving in that direction - you may need to add a couple more contact pairs with 'no penetration' and/or restrain movement in the vertical direction, for simplicity) OR the part actually would deflect that much.  I'd suggest a quick calculation of a cantilever beam with uniform loading to give you a feel for what the deflection 'ought' to be.

                  • Re: Help with my FEA simulation?
                    Mikael Martinsson

                    Well, what do you use for contact conditions?

                     

                    If you use "bonded", then you perhaps could get a way with only restraining the bottom part with a "fixed geometry", but then you need to ensure that the contacts are correctly set.

                    If you use the more realistic "no penetration" contacts, then you need to stop the sliders/rollers from moving inte space rigid body motion) with additional fixtures.

                     

                    Don't rely on the default "global bonded" contact. It requires initial contact to work, and sometimes i find that it still misses out on obvious contacts.

                     

                    I also see a lot of small wheels in your picture above. Are these separate parts? In that case you have a lot of parts and contacts to consider. Are these wheels essential for your result? Otherwise you should try and simplify the model and exclude these small parts.

                     

                    Edit:

                    The displacement of the beam is about 5 mm. I thought it said 5e+008 before I scaled the picture :-). Perhaps this is reasonable. Do a simple beam calculation as James suggested.

                • Re: Help with my FEA simulation?
                  Jared Conway

                  this indicates that you are missing contact

                  the soft springs method recommended is good for troubleshooting to find where contact or connections are missing