3 Replies Latest reply on Jul 27, 2016 8:26 PM by Bert Bourgeois

    Overwritten assembly weight in Drop Test Simlation

    Bert Bourgeois

      Hi,

       

      I am trying to use the drop test module for a design.

       

      I am only interested as to what is happening in a specific corner, so I have simplified my whole assembly to a sensible model of said corner.

       

      Doing so, my simplified model comes up much much lighter than the original, so I have overwritten the weight of my FEA-only assembly to reflect the total weight of the said design.

       

      Will the drop test module successfully assume the updated weight in its calculations? or does it take care only of the mesh volume it sees x density of assigned material in the simulation setup??

        • Re: Overwritten assembly weight in Drop Test Simlation
          Bert Bourgeois

          well I think I have answered my question.

           

          I created a simple assembly, tested two configuration, one with the weight untouched and one with the weight overwritten and factored by 10, and the results are exactly the same.

           

          I guess one way to adapt my problem is to tune the drop height so I get constant potential energy between the real product and the simplified drop test assembly?

            • Re: Overwritten assembly weight in Drop Test Simlation
              Keith Frankie

              Correct, all SW simulation ignores mass properties overrides.

               

              I frequently start all my simulation work with a static 1g study.  I can use this study to apply materials, setup all my contacts and make sure the model will mesh.  I can verify the materials are setup correctly by examining the reaction force and verifying it is the same as that reported by mass properties.  These setup items can then just be dragged/copied over to the study of interest.

               

              If simplification for FEA is minor, like removing the components from a PCB, I'll just create a custom FEA material for that part with a hand-calculated density set to recreate the correct weight.

               

              For the drop test maybe create a super-simple representation of the missing geometry and apply a custom FEA material for just this body so the weight is correct.  Give it a very coarse mesh.  This way the weight and weight distribution are about right, but the calculation time is still vastly simplified.