4 Replies Latest reply on Aug 23, 2012 1:37 PM by Sean Gaulter

    Mesh Density and Bolt Connectors

    Sean Gaulter

      I have a question regarding the relationship between the density of a mesh on an assembly and the output data for the bolt connector tool. I'm working a fairly large assembly that I've successfully meshed with various mesh parameters. The problem I'm running into is that the model/assembly is so large that my solver has ran for five days and is only incrementally making progress towards a solution. What I'm wanting to do is increase the mesh density (make the elements larger) to reduce the overall number of elements to decrease the solve time. The concern I have is that this could have a negative impact on how representative the stresses are in the bolts (which is the main reason for the simulation). Any help or guidance is appreciated.

       

      Sean

        • Re: Mesh Density and Bolt Connectors
          Nate Sieger

          Sean,

           

          If your simulation has been running for 5 days, then I think you're right in that the mesh density needs to be changed up. If the focus of your analysis is the bolt loads, then I agree that you should probably split some faces and refine the mesh region near the bolted connectors. I have found that increasing the mesh within the bolted connector ring does increase the solution accuracy, so that will be important. As for the rest of the assembly, if you're not interested in stress accuracy, then a course mesh should suffice to transfer the loads to your bolted connectors.

           

          I hope this helps.

            • Re: Mesh Density and Bolt Connectors
              Sean Gaulter

              Nate, thanks for the reply. I think I understand what you're saying but just want to clarify. The bolt stress is dependent on the mesh density in the area of the bolt connectors, i.e. the faces where the bolt head and nut contact, and therefore you recommend splitting those faces to increase the mesh density. The question I still have is whether the mesh density in those areas impacts the evaluated bending and tensile stresses given as an output from the bolt connector feature?

                • Re: Mesh Density and Bolt Connectors
                  Nate Sieger

                  The program is going to solve for the reaction forces on the bolt (shear, axial and bending) combine them and provide you a safety factor based on the parameters you defined. I know that reaction forces aren't very mesh sensitive, but when I was using the bolted connector, I did find that refining the element size within the connector region produced better results. I'm not totally clear why, but I imagine it has to do with there being more links spanning from the hole region and connecting to the bolt beam element, providing a more accurate solution. To answer your question, based on my results (which I just reviewed), yes, refining the mesh in that region -to an extent- will impact your results.

                   

                  I would say just try out a sub model real quick and see the impact that refining the mesh has on your results.