4 Replies Latest reply on Jul 7, 2017 10:22 AM by Swme Eng

    Moment on a part

    Kody Spaberg

      I'm trying to design a rather simple L bracket that will hold a flag. The flag is roughly 5 feet long and 2 lbs (in total weight) and will be whipping back and forth as the car accelerates and brakes. I want to simulate this so I can decide how thick/hole placement/etc. of the bracket so it has no chance of failing. How can I do a simple simulation applying a moment along a bar that is mounted in a hole? Am I going to have to use another resource or even run hand calcs?

        • Re: Moment on a part
          Swme Eng

          Do you have an upper bound for the acceleration that the car could see? If so you can apply a static acceleration on the part and see the resulting stress state. Depending on material, you probably also want to run a fatigue analysis.

            • Re: Moment on a part
              Kody Spaberg

              How would I go about applying a static acceleration? I'm not very versed on running SimulationXpress and only have experience doing very simple fixture & and force/pressure analysis on parts. And having a part where a moment will be applied (I figured I'd just calculate the maximum moment possible from the flag and apply that force to the hole) still seems a little confusing with my knowledge of SimulationXpress.

                • Re: Moment on a part
                  Swme Eng

                  Kody, in a case like this, the moment is caused by inertia, so the force acts on the center of mass of the part. By using an acceleration rather than a force, you skip the step of having to calculate a moment and pick a location to apply the force. I don't have a ton of experience with SimulationXpress, but I'll give it a quick look and get back to you.

                    • Re: Moment on a part
                      Swme Eng

                      Looks like SimulationXpress can only do force and pressure. You are going to have to do a hand calc of F=MA with the max expected acceleration. Just remember that the inertial force always acts on the center of mass. Depending on how close to yield strength you are, a fatigue analysis may be in order as well.