General Mechanical

General Mechanical

Solver Pivot Warning in Beam Element Model

    • JoshuaValdivia
      Subscriber

      Hello, 


      I am currently having issues when solving my car chassis beam element model. I uploaded the drawing from Solidworks. There are bent elements so I have made those pipes, and added pipe idealization while also switching element order to quadratic in mesh details. 


      I have fixed supports at vertices in the rear of the car and a load acting on a vertice in the front of the chassis. I then receive three solver pivot warnings. When I go to object and suppress it, another body just gives the same warning.

    • peteroznewman
      Subscriber

      The solver pivot warnings could be caused by bodies that are not connected.  How do you know all the beam ends are connected to each other?


      If you drop a Modal analysis on top of the Model cell of the analysis you are doing, and solve the Modal system, if you get any zero frequency modes, that tells you there are unconnected bodies. They will be the ones floating around in the Deformation plot of the Modal solution.

    • JoshuaValdivia
      Subscriber

      Thank you for replying. I have tried that and attached a picture to this post. I don't understand why less complicated structures are working.


      This triangle/arc structure works fine, and I am 99% sure i set up everything the same way. 



      I also have solved a section of the chassis, but I do not understand why the arcs are connecting in the front. I am beginning to assume the reason the frame isn't solving is due not of the arcs connecting throughout the model



      Is there any way you could explain to me what's going on?


      Again, I appreciate the help. Thank you


       

    • peteroznewman
      Subscriber

      If you have used bonded contact to connect one vertex to another, there is the Contact Tool to check that contacts are closed, and you can adjust the pinball radius to make them change status from open to closed.


      How were you trying to connect these end points?

    • JoshuaValdivia
      Subscriber

      I did not use any function to connect vertices. I imported the sketch from Solidworks, grouped them all into one part enable share topography.


    • sathya
      Subscriber
      Hi Eventhough you share topology ,make sure the gap between any two line body is less than cad tolerance.or you can zoom in and check distance between those vertices.if high you have to close the gap manually.
    • JoshuaValdivia
      Subscriber

      I figured it out. Thanks for the help. The lines were only connected at nodes, not when one line met in the middle of another line. I added bonded contacts whenever this occurred.

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