17 Replies Latest reply on Feb 20, 2014 9:23 AM by Wayne Matus

    stimulation problem

    Feizc Zc

      I stimulated a section of roller chain under the stress of 100N. The resolver sorted the length of its stretch is 0.00246mm. And then I created another very similar analysis. Set the roller chain is stretched to 0.00246mm. However, the calculation result shows it only need 74Newton pull force to stretch 0.00246mm.

        • Re: stimulation problem
          Jared Conway

          post the details of your analysis setup

          maybe a picture of your model

          and your hand calculations

           

          this sounds like a classic example of setup doesn't match calculations

            • Re: stimulation problem
              Feizc Zc

              The model of roller chain comes from the tutorial book CD.

               

              The steps of my operation lists as following:

               

              Phase-1

              open the roller chain.asm

              THE FULL SECTION OF ROLLER CHAIN.jpg

              1. creat a new static study

              2. set all parts material AISI 304  (steel)

              3. set the connections: 16 sets was seleted and set as no penetration all the rest set as default (global contact bonded)

              4. give a boundary condition: soft spring to

              boundary condition.jpg

              • Re: stimulation problem
                Feizc Zc

                5. set the exteral loads and fixture: from this step I tried two settings for comparing. The frist one is both sides of the model was conducted a 2(faces)x400N force. The second one is one side 2(faces)x400N force, the other side was set as a slider fixture both sides force.jpgfixture and force.jpg

                6. creat mesh: curvature based mesh

                mesh setting.jpg

                7. Until now the final results is not very different from the tutorial.

                • Re: stimulation problem
                  Feizc Zc

                  Phase-2 (symmetry model)

                  because the model is symmetrical, it was cut into one eighth for time saving before calculation.

                   

                  1. cut the model into eighth. as the following pictures display

                  eighth model.jpgeighth model-2.jpg

                  2. give the same meterial and same connection settings

                  3. fixtures:  advanced fixture and select all the symmetrical face (shows in the following picture)

                  • Re: stimulation problem
                    Feizc Zc

                    symmetry faces.jpg

                     

                    4. then give a 100N pull force on the side of model

                    100N force.jpg

                    • Re: stimulation problem
                      Feizc Zc

                      and then I created another study for trying to use the displacement to calculate the pulling force.

                       

                      1.  I suppressed the extermal loading (the 100N pulling force).

                      2.  And then through the fixture setting I designated a 0.00246mm displacement on the face was set a 100N pulling force. 

                       

                      0.00246.jpg

                       

                       

                      Then according to the tutorial, we can get the pulling force by: list result force

                      list result force.jpg

                      but the result force is only 74N it is very different from the tutorial result 117.08N

                      result force.jpg

                      That is my problem. I don`t know why did it happen? It is because my misoperation or its the solidworks` error?

                       

                      thanks for your help!

                        • Re: stimulation problem
                          Shaun Densberger

                          Can you post your model? Assuming everything was set up correctly, it sounds like an issue with SolidWorks. The tutorial's result of ~117 N makes since (in that it is higher than the 100 N applied load from the previous analysis) because you're forcing the entire surface to displace 0.00246 mm.

                            • Re: stimulation problem
                              Feizc Zc

                              And thanks for your reply. It remind me that the deformations are different between two studies. That could be the foremost reason for the difference of the results.

                              But I still feel confused that the stimulation of 0.00246mm displacement studies unexpectedly achieved by only 74N pulling force according to the calculation result by my operation. The tutorial shows its result is 117N. I mean even my result is smaller than 100N, it should be bigger than 100N.

                               

                               

                              Do you mean to put the model files on here? I`ve tried to, but it seems there is no option for uploading files.

                                • Re: stimulation problem
                                  Shaun Densberger

                                  Feizc Zc wrote:


                                  But I still feel confused that the stimulation of 0.00246mm displacement studies unexpectedly achieved by only 74N pulling force according to the calculation result by my operation. The tutorial shows its result is 117N. I mean even my result is smaller than 100N, it should be bigger than 100N.

                                   

                                  I agree; it seems to me that calculated reaction load should be higher than 100 N if everything between the two analyses is the same. Speaking of which, you can attached using the following process:

                                  Attach.PNG

                          • Re: stimulation problem
                            Feizc Zc

                            5. mesh: default mesh settings (curvature based)

                            6. the result shows the displacement is 0.00246mm

                            displacement.jpg

                            • Re: stimulation problem
                              Mike Pogue

                              Have you refined the mesh a few times (in both studies) to show that the stress is convergent? You have 1mm elements to resolve .001mm strain. It's easy to imagine that introducing the amount of error you are seeing.

                               

                              Its possible everything may be correct, but you just haven't gotten to the answer yet. The force will follow right from the stress, and it is an unfortunate fact that stress (and temp) converge from the bottom.

                               

                              Just a thought.