10 Replies Latest reply on Feb 24, 2017 2:59 PM by Ryan Dark

    Electric Bike's frame static analysis

    Hani Rousta

      Hello,

      I am trying to run a static analysis on electric bikes frame but I am not sure if all the loads and fixture that I applied are enough to get the correct result .

      I do have the results but still not sure if this is correct.

      I would appreciate an expert advise .

      I look forward to hearing from you.

      Thank you

        • Re: Electric Bike's frame static analysis
          Keith Frankie

          So far these results are gibberish.

           

          Your connections aren't setup completely.  Parts aren't fully constrained, so they're flying off into the ether (note the high values in the displacement plot).  You shouldn't need "soft springs" enabled to solve this study.  If you have SW 2016 you can use the new "find unconstrained bodies" command to help hunt down these issues.

           

          Some of your parts are sheet metal, so they're getting a shell mesh.  I doubt this is your intention.

          • Re: Electric Bike's frame static analysis
            James Riddell

            As Keith says: 1) it looks as if your handlebar post is not connected to the frame; 2) it looks like one side of the rear frame is not connected to the area where the seat post mount is located.

            I can't see where your restraint(s) is/are.  It 'appears' as if you have someone 'standing' on the crank bearing mount (not sitting on the seat) and torquing over the handle bars (very unevenly) to one side.  If you ARE doing that, why wouldn't you also have the front forks shown and restrain the front and rear axle bearing mounts?

            • Re: Electric Bike's frame static analysis
              Ryan Dark

              Hi Hani,

              Taking a look at the latest build of your model and the study you made there is really only one thing that stands out as an issue.  One of the brackets attaching to the rear tire is set to use solid elements and the other is set to use shell elements.  You would want them both to be the same as this asymmetry will lead to issues in your results.  In this case I would set all bodies in your analysis to be solid (there are two set to shell right now) as these are not really good candidates for shell elements.

               

              You would probably wish to apply a mesh control to the head tube and the three brackets attaching it to the rest of the frame as this is where the model is experiencing the highest stress.

               

              The rest seems fine.

                • Re: Electric Bike's frame static analysis
                  Hani Rousta

                  Hi Ryan,

                  Thank you for your response,

                  I made the the brackets in sheet metal because of the bending in the part .

                  After reading your comment I set them to treat as solid part and something very weird happen .EV Frame 23022017 true scale.JPG

                  The above photo is in true scale and below is automatic scale .

                  You can also see the very high value in displacement plot.

                  I also create a bonded contact between all touch and none touching faces .

                  EV Frame 23022017.JPG

                   

                  Have you seen the Solidwork parts ?

                  I will try to upload them on the main discussion too.

                  I look forward to your response .

                  Thank you

                    • Re: Electric Bike's frame static analysis
                      Ryan Dark

                      Hani,

                      From the image you posted it is apparent that the head tube on the front of the bike is not attached to the rest of the structure.  Your study would not be stable without it attaching.  You would probably want to just delete and remake the bonded contacts attaching that tube to the 3 brackets.

                        • Re: Electric Bike's frame static analysis
                          Hani Rousta

                          Hi Ryan,

                          Thank you for your comment,

                          I fixed the issue with the Model and its stable now .

                          I am still not sure if all the loads and fixture that I applied are correct to get the realistic result .

                          May I drive this bike ?

                          May I consider vibration of electric motor ?

                          Is there any other analysis that I  need to consider ?

                           

                           

                          EV Frame 24022017 Displacement.JPG

                           

                           

                            • Re: Electric Bike's frame static analysis
                              Ryan Dark

                              Simulation is only a precuroser to building prototypes and testing.  It would not act as a complete replacement of the step but just ensure that you are not making prototypes that could have been predicted to fail.  Keep this in mind as you are running analysis.  It seems like you are holding the bike at the rear hub, standing on the peddles, and twisting the handle bars.

                               

                              This study would confirm that you could stand on the bike at stand still and twist the handle bars.  From here you would want to conduct a frequency analysis to see what the natural frequency of the structure is so you can make sure a motor you mount is not running at that frequency.  You may also wish to run dynamic studies to see how the frame would behave as it hits pot holes and road debris.