5 Replies Latest reply on Aug 4, 2018 11:28 PM by Mehdi Rezaei

    connection option in analysis

    Suhail P.

      Hi,

      i have one doubt regarding the connections option in analysis. while making an assembly if we are using required mate options (like concentric and coincide mate to represent the bond between two plates held by a bolt) then do we need to specify any other connections(like the bolt option comes under the connection option ) while doing the analysis other than the default global contact option ?

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        • Re: connection option in analysis
          Mehdi Rezaei

          Hello Suhail,

           

          The mates do not carry over to the simulation settings. The connectors such as bolts and pins need to be specified in simulation environment.

          The global contacts such as bonded or no penetration work when you have a face of one component contacting a face of another component. If you want to treat them as welded or glued together, you select bonded. If they are not glued together and maybe due to a force added to a component, it moves and hits the other component or pushes away, you need to use no penetration contact set.

          Hope this helps.

            • Re: connection option in analysis
              Suhail P.

              Hello Mehdi,

              Thank you for your response, I need some more clarification about the topic. I am attaching some portion of my design here

              Capture.JPG2.JPG

               

              3.JPG

              here I want to attach the part with blue color to the grey color part by a screw. while making the assembly I just used the concentric mate option between the holes and coincide mate option between the two plane faces (figure 3), so it will serve the purpose of the screw in the assembly. then I inserted the screw to just show that the screw is there. So for the analysis purpose, I have removed the screw(part)to reduce computation time and under <connection> options there was the default global contact(bonded) option. so to serve the purpose of this screw what kind of connection other than the bonded contact should I use. or since the two coincide surfaces are acting like glued (if tighten by a screw) bonded contact is enough?

                • Re: connection option in analysis
                  James Riddell

                  The answer is ... it depends.

                  What are you looking for?  Will it be sufficient to treat the entire structure as one piece (result of bonded contact) or do you need to see how this connection would react?  If the former - you have too much detail - but keep on keeping on.  If the latter, you may still have too much detail but you'll need to use some non penetration and bolt connections - or at the very least split surfaces to mimic the bolt/screw clamp area (my personal favourite to get useful answers quickly).

                    • Re: connection option in analysis
                      Suhail P.

                      4.JPG

                      i have a structure like this. i need to do static stress analysis, modal analysis etc of the structure after applying some loads. so the aim is to know the response of the structure after the application of loads.

                      so from your explanation, i think i have to do two simulations

                      1) consider the whole as one piece to know its behavior (by considering only the bonded contacts)

                      2)insert bolt connectors to know the stability of the joints only

                        • Re: connection option in analysis
                          Mehdi Rezaei

                          Sorry Suhail, I was away for some time. I guess you are on the right track. From the pictures you provided it seems that you have bolt connections on two directions for each joint. That seems fairly sufficient to assume bonded connection at least for early analyses. Considering the fact that you have too many bolt connections and to make sure other settings of the simulation are correct, go for bonded first. Troubleshoot all other issues, then as your final assessment go with bolt connectors. If I were you, I would add bolt connectors to some holes, run simulation and if everything was OK, I would go ahead and add more bolts. This way you can improve your experience working with software and also prevent getting too many error messages that you don't even see where they are coming from. Also note:

                           

                          - For Modal analysis you don't add any loads. Just Fixtures.

                          - When you add bolt connectors, you need to add no penetration contact set to the components you adding bolts to. Otherwise, they will still use the global bonded connections.

                          - The amount and orientation of added loads, defines how careful you should be with defining connectors or bonded. For instance, if you have only one load vertically downward (e.g. a weight on top of structure), it really doesn't matter what type of connector you apply.

                          - Make sure you aim for a big factor of safety. If with bonded connection, factor of safety is close to 1, then, bolt connector will probably fail structure. 

                          - Use above procedure for all of your simulation cases in SW. Simplify the model first. Run and debug your settings, and then go with engineering understanding with details settings.

                           

                          Hope this helps.:)