10 Replies Latest reply on Apr 18, 2013 11:25 AM by Agustin Morales

    Bearing simulation in an assembly

    Teodor Penchev

      Dear SolidWorks users,

       

      I would like to ask here for your help. I am modeling a steel structure that will hold some photovoltaic panels/modules and one degree of rotation is realized with bearings. Please, have a look at the pictures below to see it clearly. I will be very grateful for your help. I generaly understand the basics of SolidWorks Simulation but here I have some problems. I do not know how to include my bearing with housing in the FEA Simulation or how to model it. It is a model that is readily available on the online 3D databases and I downloaded one model and imported in SolidWorks. The problem is that the bearing is just simply modeled and it does not depict the its real structure. I am not sure If I have to design and model my own bearing so that the meshing is properly generated. I really do not want to do this since I already have the models. The question is how to include these bearings in my FEA simulation and combine them with the support profile, support arms and bolts. I would like to be able to apply some load on the PV modules (for example pressure due to wind and also own weight due to gravity) and see how the structure will react and how the stress will be distributed. I want to see how my supporting arms will react and thus size (optimize) them properly. I also want to see the load on the 25 mm bolts that go through the bearing and also through the supporting arms. I know that I can apply the load directly to the bolts, but I wanted to ask you if it is possible to still somehow include the bearings in the FEA simulation so that I would not have to make many local/separate FEA simulations.

       

      I could imagine that a possible solution would be to model the bearing down to the smallest detail including the proper materials and sizes and then mesh it. But it would be very difficult for me to do this. Would a bearing fixture or bearing load help somehow? Could you please give some guidelines?

       

      On the pictures below you can clearly recognize the support profile to which the bearing is bolted using two M13 bolts, the support arms that hold the bearing (currently 1 cm thick) with a bolt (M25) and the bearings (SNR/NTN UCP205) themselves.

       

      I would be very grateful for any general comments on how to proceed with this simulation. A bearing is a very common machine element and I hope to receive some help on how to simulate the entire assembly that you see on the pictures. I could not find any help on the forum that is related to my question. If you have any links to such tutorials or discussions I will be grateful to receive it!

       

      Thank you in advance for your help!

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        • Re: Bearing simulation in an assembly
          Jerry Steiger

          Teodor,

           

          I'm not familiar with how SolidWorks Simulation handles bearing stiffness and I don't work with assemblies like this, but I believe the bearing manufacturer can give you numbers that show how the bearing itself reacts to loads, so that the bearing can be modeled as a set of springs or flexures. I think you can probably input these numbers into some kind of bearing stiffness model in SolidWorks Simulation so that you can get the answers you are looking for.

           

          I looked up "bearing stiffness" in SolidWorks Help and it pointed me to "Connector-Bearing". That allows you to input a radial and/or an axial stiffness.

           

          With any luck one of the experts here will chime in to help.

           

          Jerry S.

          • Re: Bearing simulation in an assembly
            Jared Conway

            Not sure what happened to my post. What you describe is a bearing connector. Leave the shaft and housing, place a split line on the shaft and apply the connector. The hard part is getting the properties for the flexibility but like Jerry said, some mfgs have that data. Or you could setup and run the full bearing to get that data. It won't be easy but it is possible.

            • Re: Bearing simulation in an assembly
              Salim Benyoucef

              Teodor,

               

              You should view the training course in the help SolidWorks Simulation tutorials.

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              I hope that this tutorial will help you.

                • Re: Bearing simulation in an assembly
                  Jared Conway

                  That's a good start, but the bearing load is meant to replace the loading created by a shaft in a bearing. So for example, analyzing the housing.

                    • Re: Bearing simulation in an assembly
                      Teodor Penchev

                      Thank you all for your quick and valuable responses. Actually, I expected this answer: it would be very difficult to perform FEA simulation using a bearing unit consisting of the steel/molded housing and the bearing itself. I think, I will perform multiple separate simulations so that I can at least see the distribution of the forces in the support profiles.

                       

                      This week I went to the famous trade fair in Hannover, Germany and I had the chance to speak with some of the biggest bearings manufacturers: SKF, Schäfler (FAG, INA), TIMKEN, NKE and others. Just for your information, the responsible technical staff from all these companies confirmed that with the readily available CAD models online no FEA simulations can be performed. Of course, these companies are in possesion of much better and more precise CAD models but those are not publicly available. They could perform some simulations for me, but as they told me, I was not a "BIG PLAYER", just a poor student, so it would be mission impossible.

                       

                      Anyway, thank you all for your answers.

                        • Re: Bearing simulation in an assembly
                          Jared Conway

                          what kind of simulation would you want them to do for you? or are you saying to get the stiffness properties? did they mention whether that exists internally for people to use in an FEA? (axial and radial stiffness for something like a bearing connector/fixture) I've seen people with it, but I have never been able to find it myself.

                            • Re: Bearing simulation in an assembly
                              Teodor Penchev

                              Well, I asked them if they could perform complete FEA simulation for me and they told me that they have CAD models and software that could do this or at least they could provide some interface between the components with some factors. They did not tell me more. But what I know for sure is that normal people like me would not be able to get these models, nor the software. If I were a producer of some equipment, that would be a different story. They also told me that I could use some publicly available software, called BEARINX, which can at least tell me if the bearing is going to support the load in radial and axial directions. The user just has to enter the load in kN and choose the bearing and the software performs some calculations and comes up with some safety factor that can, as I already mentioned, give you a clue if the bearing is the right one.

                                • Re: Bearing simulation in an assembly
                                  Chris Fernald

                                  Are you interested in stresses internal to the bearing (such as contact stress on the rolling elements)?  If so, it seems like a difficult simulation. 

                                   

                                  However, if I understand your problem correctly you are trying to analyze your existing assembly, but the complex bearing geometry is causing analysis problems.  Rather than create an entire new simulation assembly, could you just add a "simplified" configuration to your bearing model.  This configuration could just be a solid mass version of the existing bearing outside geometry.  This simple config should transmit the loads applied to the PV cells to the supporting bolts and brackets.  Not sure what your bearing model looks like, but a simple extrude/combine operation should merge all the bearing internals without too much difficulty.

                                    • Re: Bearing simulation in an assembly
                                      Teodor Penchev

                                      Thank you for your suggestion, Chris Fernald. I will do this, I will apply a material and then do the meshing. This is a very good possibilty to see how the forces distribute to the bolt and other components. But I think that in this way the bearing will be more robust than in reality, but anyway it is a good suggestion.

                                       

                                      I am using this model for the bearing. You can download it and open it. I think I just have to apply some material to the proper parts of the model.