10 Replies Latest reply on Dec 4, 2014 7:26 PM by Nathan Foor

    Drop Test Simulation on Packaging with Corrugated Cardboard

    FW Khor

      Hi all,

       

      I would like to know if there is anyone here tried to run a drop test simulation with corrugated cardboard before?

      Anyway to define the materail properties of the corrugated cardboard?

      Is it treated as solid body or surface body with composite?

        • Re: Drop Test Simulation on Packaging with Corrugated Cardboard
          Shaun Densberger

          I've never done a simulation with cardboard, but you might be able to model it with an orthotropic material definition (maybe transversely isotropic depending on how the cardboard in constructed). That being said, I'm sure that an accurate material model is going to be a more complex, especially since you're doing a drop test. Here's a paper I found about modeling cardboard from a FEA standpoint that worth reading.

            • Re: Drop Test Simulation on Packaging with Corrugated Cardboard
              FW Khor

              Hi Shaun,

               

              Thanks for your reply and the suggested paper. I will go through that to see how to model it for my drop test.

              I'm trying to run a simulation with a package protected by sponge/foam inside a corrugated cardboard box. Any advice on that?

                • Re: Drop Test Simulation on Packaging with Corrugated Cardboard
                  Shaun Densberger

                  Depends on what you're after and how much weight you're going to give to the analysis results. Are you looking for trends and which way to head in the design process, or are you trying to valid if a design is acceptable? Are you going to be able to perform physical tests and compare them against the simulation results, or are you going to be validating solely on simulation results? Are you using some sort of standard that defines evaulation criteria for a drop test (i.e. a linear dynamic analysis), or are you using SW Drop Test (i.e. non-linear dynamics)? You're answers will influence how you should approach this, but a general rule of thumb is that the more "realistic" you make your model and the mode weight placed on accurate results, the harder it is to do.

                    • Re: Drop Test Simulation on Packaging with Corrugated Cardboard
                      FW Khor

                      Hi Shaun,

                       

                      I am looking to see if the packaging design is sufficient to absorb the impact and prevent damge to the package. I was thinking in the direction of non-linear dynamics but not sure which model to be use on corrugated box, which I believe, is orthotropic in nature.

                      If running on drop test analysis, it would be much simpler, the results provided would be just the damage and displacement though.

                        • Re: Drop Test Simulation on Packaging with Corrugated Cardboard
                          Shaun Densberger

                          When you say, "prevent damage", how are you quantifying damage? Stress? G load? Displacement? If displacement and acceleration are what you're after, then I think that this is doable. However, if you need accurate stress results, then I'd be hesitant to place significant amount of certainty in the results.

                          • Re: Drop Test Simulation on Packaging with Corrugated Cardboard
                            Jared Conway

                            Before you worry about the box and foam, try running drop test just on the part . See if the solve time and results are reasonable before you deal with the foam and box. Like Shaun and jerry have outlined , there is a lot to consider and setup and runtime will be significant. Simplifying he box structure and using isotopic materials sounds like a good way to handle it but then again, does cardboard follow the behavior of a metal? Not really so regardless, before you go too deep, you would have to test the method.

                        • Re: Drop Test Simulation on Packaging with Corrugated Cardboard
                          Jerry Steiger

                          FW,

                           

                          If you figure out how to model the cardboard, you will also need a good model for the foam. As I recall, the best hyperelastic model for foam is usually Blatz-Ko, but you might want to check on that. You will have to get good stress-strain results in the compressive region for the materials you are planning to look into.

                           

                          Jerry S.

                      • Re: Drop Test Simulation on Packaging with Corrugated Cardboard
                        Nathan Foor

                        Hi FW,

                         

                        Were you able to find a good method to simulate the corrugated box in the package drop test? I'm a packaging engineer with little knowledge of FEA. Often, my company is unable to perform drop tests on electronics mainly due to cost of scrapping a single unit due to damage. Something like this would be of great use to us. Anything you could share would be appreciated.

                         

                        Nathan

                          • Re: Drop Test Simulation on Packaging with Corrugated Cardboard
                            Jared Conway

                            do you want to test the electronics or the box or both?

                             

                            the box is hard considering you need to understand how to model the strength from the construction

                             

                            but then adding the complexity of the electronics could be very difficult. you'd have to simplify that as well.

                              • Re: Drop Test Simulation on Packaging with Corrugated Cardboard
                                Nathan Foor

                                Jared,

                                 

                                Thanks for the reply. I'm interested in testing the entire assembly. For example, a 1U server chassis in a corrugated box with foam cushions.

                                 

                                I agree with you, from what I've read thus far it is very difficult to accurately test (and model) corrugated board. The PDF file that Shaun shared above does provide a lot of good information on simplifying it though.

                                 

                                As far as simplifying the electronics; I'll go back to the 1U server example. Likely I would remove all critical components (motherboard, memory, HDDs, PSU, etc.) and just test the sheet metal chassis. I could then basically add one or two solid block 'fillers' to mock the weight of those components. I'm more concerned about physical damage to the outside of the chassis than to any of the internal server components. From my experience, our basic calculations for cushioning are usually pretty spot on to get the G-levels to an acceptable level, and the typical point of failure is always physical damage (bent rack handles, dents, sagging, etc).

                                 

                                I currently do not have a license of Simulation to try this out, I'm just investigating at this point to see if it would be possible before I make a purchase.

                                 

                                Nathan