2 Replies Latest reply on Dec 9, 2011 10:54 PM by Aaron Moncur

    Correct Loading for Symmetry Constraint?

    Aaron Moncur

      I have a stepping stool that is symmetric between left/right sides.  I have split it down the middle (on the symmetry plane) and applied a symmetry constraint on it.  If I expect the max load on the stool to be 300 pounds, should I use this full load when the stool has been cut in half (and the symmetry constraint has been applied)?  Or should I only be using half of the load since I am only using half of the stool.  My thought is that I should be using the full load, not just half, since, even though the reaction of both sides of the stool is accounted for by use of the symmetry constraint, it does not account for the other half of the load.  Am I thinking about this correctly?

       

      Even if I use the full load, I don't think I can simulate one half of the load on the left side and the other half on the right side (as would be the case if someone were standing in the middle of the stool).  Or should I be using a remote load for the half that would be applied to the side of the stool that has been removed?

        • Re: Correct Loading for Symmetry Constraint?
          Jerry Steiger

          Aaron,

           

          I'm not that familiar with SW Simulation, but from my experience with ANSYS, I would apply half the load. You are analyzing just half of the stool and the symmetry condition takes care of the influence of the other half.

           

          A very simple way to check is to apply half of the load and then check the reactions at the feet. If I am right, they will add up to half of the load. The feet on the "other" half would be bearing the rest of the load.

           

          Having said that, I would also model the full stool, because real loads are not necessarily going to be applied on the center line. As a person climbs up or down, they will put their full weight on one foot at a time.

           

          Jerry Steiger