3 Replies Latest reply on Nov 11, 2011 5:49 PM by Jerry Steiger

    Drop Test Analysis of Electronic Unit and Box within a Box

    David Maxham
    David Maxham Nov 2, 2011 12:02 PM

      We use Solidworks Simulation for random vibration of our designs, but the idea came up of using the software for drop test analysis.  We have all the add-on simulation packages, including Solidworks Simulation Professional that can do drop test analysis of the unit, we've designed,  but what we're looking to do is model the unit within its shipping container.  The container is actually a cardboard box within another cardboard box, and there are two layers of dense foam - one layer in the first box that surrounds the electronic unit and then another layer that is between the internal box and the exterior box.  Each foam layer is about 2 inches thick.

       

      Any ideas on how this could be modeled with Solidworks Simulation?  Has it been done before and if so, is there any reference material, etc that I could get?

       

      Thanks,  Dave

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        • Re: Drop Test Analysis of Electronic Unit and Box within a Box
          Jerry Steiger
          Jerry Steiger Nov 7, 2011 5:14 PM (in response to David Maxham)

          Dave,

           

          I think this will take quite a bit of work to do right. You've got two materials that are going to behave in a very non-linear fashion. It is probably going to be difficult to get material properties for either. The cardboard has an interesting structure that causes it to behave non-isotropically. The foam is probably isotropic, but not the least bit linear, possibly hyperelastic. With luck, SW Simulation will have material models for foams, but you will probably have to do a bunch of testing to get data on its performance and see which model to choose. I think you will probably end up approximating the cardboard as a solid material with peculiar properties in different directions that you also establish by testing.

           

          Someone may have already done the development of programs to solve container drops, but they might not be selling the program or the knowledge.

           

          Good luck!

           

          Jerry Steiger

            • Re: Drop Test Analysis of Electronic Unit and Box within a Box
              David Maxham
              David Maxham Nov 11, 2011 9:12 AM (in response to Jerry Steiger)

              Thanks Jerry.  We just passed the drop test, so looks like I don't need to do any analysis just yet.  I appreciate your advice and plan on making a simple model of a box within in a box.  I'm hoping that Solidworks Simulation Premium, etc, can handle the large-scale deflection of the foam material, which was and is my main concern.

               

              Dave

                • Re: Drop Test Analysis of Electronic Unit and Box within a Box
                  Jerry Steiger
                  Jerry Steiger Nov 11, 2011 5:49 PM (in response to David Maxham)

                  David,

                   

                  I'm pretty sure that Solidworks Simulation Premium has material models that can handle the non-linear deflection of the foam, but you will need to come up with the data to get the property values needed. Look for an Ogden hyperelastic foam model. You might also be able to use a Blatz-Ko foam model, although ANSYS says that model is not as good for large deflections.

                   

                  I think you will find that the cardboard is not a simple model either, but maybe you can ignore some of the peculiar behavior as the layers collapse.

                   

                  Jerry Steiger