12 Replies Latest reply on Jul 15, 2014 8:11 PM by Jared Conway

    I need to be able to stress test this assembly

    Tyson Hueppelsheuser

      I have this assembly built up and now i need to stress test it, I am unable to as it tells me not enough fixed geometry or something along those lines (try it for yourself and youll see the message.). Anyway i would like you to correct my assembing pocedures so that i know what the best way to create simular assemblies in the future. So, please fix it so it is able to stress test and let me know what you did.

       

       

      Thanks so much: Tyson

        • Re: I need to be able to stress test this assembly
          Shaun Densberger

          Your zip file is just the assembly; it doesn't include the parts used in it. Use the Pack and Go function in SW to save your assembly as a zip with all of the associated parts.

           

          Most likely you have components that are not properly connected to one another, resulting in rigid body motion.

              • Re: I need to be able to stress test this assembly
                Shaun Densberger

                So what exactly are you trying to simulate here? What are the boundary conditions? What results are you after? How do you want to use the results?

                 

                This is most likely something that can be simulated, you'll have just to do some simplifications and connect to components together in the appropriate way. If you have no experience doing FEA, then I suggest to start doing some of the tutorials.

                  • Re: I need to be able to stress test this assembly
                    Tyson Hueppelsheuser

                    Im looking more so just to have them put together to allow a simple side impact on the lower foot simulation, parameters of force etc dont matter. Do you have any tutorials you suggest because I havent found any at the moment that really pretain to what im trying to do. i need one for large assembly stress testing.

                      • Re: I need to be able to stress test this assembly
                        Shaun Densberger

                        How models are built depend highly on the scenario being simulated and the results (and their accuracy) that need to be captured. Certain scenarios are harder to simulate that others because of the complexity of the physics involved. There is no one tutorial that I can point you to, partly because I don't understand what exactly you want to simulate, and partly because there is a wide range of topics that need to be covered to properly simulate assemblies.

                         

                        SW has tutorials built into them (with SW simulation open, go to Help -> SolidWorks Simulation -> Tutorials).

                          • Re: I need to be able to stress test this assembly
                            Tyson Hueppelsheuser

                            Well i wanted to simulate an impact from any side of the bottom part of the dolly leg. But ill figure it out, thanks for your help. I'll begin the long and exstensive learning process haha.

                             

                            Thanks: Tyson

                              • Re: I need to be able to stress test this assembly
                                Shaun Densberger

                                I can tell you this: impacts will involve linear (and potentially non-linear) dynamics, which can be very difficult to simulate correctly.

                                  • Re: I need to be able to stress test this assembly
                                    Tyson Hueppelsheuser

                                    Well i got thrown into this situation at work and im not even done highschool but the goal is for me to learn how to do all these complex simulations as I need to create  many parts for Highway propane vessles and simulate roll overs and all other kinds of impacts. So my goal is to be able to do just that but there isnt a large amount of people in my area, well non that i know of actually that do simular to what im doing.

                                     

                                    So I'm learning alot and this is something that I need to learn how to do so we can save the shop thousands of dollars in engeneering fees, etc.

                                      • Re: I need to be able to stress test this assembly
                                        Shaun Densberger

                                        the goal is for me to learn how to do all these complex simulations as I need to create  many parts for Highway propane vessles and simulate roll overs and all other kinds of impacts.

                                         

                                        Could the failure of a design result in someone being hurt/killed?

                                          • Re: I need to be able to stress test this assembly
                                            Tyson Hueppelsheuser

                                            Well this dolly leg im building is an attachment to a vessel obiously. ( I'll attach it as a refrence.) Now we need to design every part of this unit and stress test it all and to ensure it passes all standards set by ABSA which is the baisically the governing body for all highway propane vessels in my area. they say wether a vessel is road worthy or not. Now we want to modify the plumbing to this vessel and according to ABSA any modifications to the vessel require fully tested engeneer approved drawings. Thats where I come in, I draw the tank and do the stress testing, then send all my results to an engineer and they put their stamp of approvial on it and send it back. then we submit it to ABSA and the approve it or decline it. This plumbing we want to modify needs to be surounded by this (or something very simular to) drawing of a support system I will attach also. I need to have all parts able to stress test as one large model or it wont be accepted, (trust me if i could do the individual parts I wouldnt be on here haha). so I mean if ABSA didnt approve it and we sent it out on the highway anyways and then it got in a roll over or something there would a major possibility for exsplosion but as it stands no, no one is directly in danger from this design. (exept for the pocket book if we have to call in an engineer to do all of it haha.)

                                             

                                            So I need to learn how to do all of it basically

                                              • Re: I need to be able to stress test this assembly
                                                Shaun Densberger

                                                So the design and results are going to be reviewed by a senior engineer prior to sending them to ABSA? I don't know the exact laws in Canada, but I'd be shocked if an engineer licensed in Canada would go along with this process.

                                                 

                                                FEA is an incredibly deep and technical field. Many software companies like to market their software as this tool that allows you to digitally 'validate' your design, but in practice that is incredibly hard to do, even with an experienced analyst using a robust FEA code (which I wouldn't categorize SW Simulation as). There are a plethora of technical details both on the finite element analysis side and on the engineering side that go into making an accurate simulation, and it's insanely easy for someone without the appropriate background to make a number of very serious mistakes without realizing it.

                                                 

                                                If you've been tasked with this as a learning experience and to help you decide if you want to study engineering when you go to university, but there is a senior (licensed) engineer that will be ensuring that everything is in order, then I think this is great and that you should learn as much as you can (although it'll be very challenging).

                                                 

                                                If you've been tasked with this because someone thinks, "hey, SW has FEA so we can have Tyson learn to use it so that we can save a bunch of money on engineering consulting fees", then back away from this. FEA is an incredibly powerful tool (some are more powerful that others though!), but only if it's used correctly (which requires a great deal of knowledge). If used incorrectly, FEA can end up doing significantly more damage than good. There are two saying to keep in mind:

                                                 

                                                1. Garbage In = Garbage Out
                                                2. FEA makes a good engineer great, and a bad engineer dangerous.
                                                • Re: I need to be able to stress test this assembly
                                                  Jared Conway

                                                  hi tyson, i work for Hawk Ridge Systems your SolidWorks reseller

                                                  if you're looking for some help getting started on this analysis and talking about the approach, please contact me at jared@hawkridgesys.com

                                                  as Shaun says, there are a lot of things to consider here, from the type of analysis, to how to set it up to how to have it validated to make sure it is safe