5 Replies Latest reply on Nov 10, 2012 4:04 PM by Jerry Steiger

    Springs, Rates, and simulation

    Kris Froehlich

      Hello. So I have designed a coil over shock with 2 springs on it. The springs should compress at different rates in a real life senario. As I manual compress and the assembly only the bottom spring compresses. How can I add spring rates between the components so that when I put this coilover into a suspension system and cycle the suspension; the springs will compress at the proper rates?

       

      Ive attached the Folder. The complete assembly is "Coilover 14 Inch"

      Thanks for any help.

        • Re: Springs, Rates, and simulation
          Kris Froehlich

          Is this even in the right place.  Currently I am not to the point of worrying about actual simulation or animation. I just want the parts to react properly when cycling components in the asssembly.

            • Re: Springs, Rates, and simulation
              Anthony Botting

              Hi Kris:

              Are you using the SW Motion product? If you are only interested in reaction forces (and not stresses, for example) the simulation should work really well in the SolidWorks Motion product (turn-on full Motion simulation so you get reaction forces). You can install two stacked "virtual" springs over the shock, each with different K, but put a separator between them to serve as an attachment point for each spring (such as an annulus, or ring so it will slide over the shock assembly). You can install a virtual shock viscous reaction component between the piston end and the end of the piston cylinder, too.

                • Re: Springs, Rates, and simulation
                  Kris Froehlich

                  This sounds great but I'm newer to this. I can draw parts and build assemblies without too many problems. But I don't know how to add this springs and forces you are talking about? Have you looked at my part yet? I've got the whole coilover Designed except rates and forces.

                  • Re: Springs, Rates, and simulation
                    Kris Froehlich

                    Alright.  I inserted spring rates, gravity, and a force on the top of the shock to simulate weight. I do have a couple questions.  would a spring with 150LB/in spring rate be entered into the simulation as 150lbf/in??  whats the "f" for? Is is the same to simulate a load on that spring? If the rig has a corner weight of 650 pounds; would I enter a force of 650lbf? Last question. I am trying to simulate a bump in the road to see how the shock reacts. I inserted a constant force of 75lbf for .2 seconds and when I press calculate I get an error message as soon as it gets to that point.....  Why is this?

                     

                    So this is all awesome to simulate a shock.  Now if I want to put it in an assembly and drag the axle up and down manually, is there a way for the springs to react properly then? Is that what "full motion" is?  Where is this option at?

                      • Re: Springs, Rates, and simulation
                        Jerry Steiger

                        Kris,

                         

                        The "f" stands for "force", as opposed to "m", which stands for "mass". Remember F=m*a? One pound of mass pushed by one pound of force will will accelerate with 1 gravity acceleration. So, yes, you would put a force of 650 lbf on your coil over shock for the static load.

                         

                        This is not the right place to ask the questions you are asking. There is another forum, Motion Studies under Simulation, to ask about the reaction of a vehicle to a bump in the road. This forum is for asking about what the stresses are in the springs or the other suspension parts.

                         

                        To get your springs to compress properly in your SolidWorks model, you would have to define them in context of the assembly. There are a number of threads that talk about how to do that in the more CAD oriented forums, like General or
                        SolidWorks/Assemblies or SolidWorks/Parts and Features.

                         

                        Jerry S.