General Mechanical

General Mechanical

Gear Static Structural

    • evogel
      Subscriber

      Hello,


      I have been working at trying to get a useful output from from static structural of these two gears under torque. Ansys has been unable to converge on a solution, even when I change the contact of the gears from frictional to rough or add in weak springs. What can I do to solve these issues or where else can I go to find a fix to this problem?


      Thanks

    • Wenlong
      Ansys Employee

      Hi Evogel,


       


      Would you please post more information about the settings? Like did in this post: https://studentcommunity.ansys.com/thread/modal-analysis-73/


      Only then can I provide more useful comments.


       


      Regards,


      Wenlong

    • evogel
      Subscriber

      Hi Wenlong,


      Here's some screenshots of what I have set up.


      I have two gears I made in Solidworks and converted into a STEP file.Gears 


       


       There is a frictional contact between the two gears and both have revolute joints.


      Frictional Contact


      Frictional Coefficient set to 0.1


      Frictional Settings


      72 Support


      40 Support


       


      I did not adjust anything with the mesh. 


      Mesh


      Loads


      Large Deflections is turned on and weak springs set to program controlled


      Static Structural Settings


      These are the errors that when the program ran


      Errors


       


      I hope this is useful and thanks in advance,


      evogel

    • Wenlong
      Ansys Employee

      Hi Evogel,


      Thanks for your reply. Here is the first thing I would recommend to do: Change the "Auto Time Stepping" in "Step Controls" to "Manual", and set the maximum sub-step number to a large value, say 1000, and the min=20, initial = 10. The program-controlled time-stepping may result in a time step not small enough, and as a result, the force applied in that substep may be too large to cause element distortion. 


      Let's see how it works.


      Regards,


      Wenlong

    • peteroznewman
      Subscriber
    • Wenlong
      Ansys Employee

      Hi Peter,


      Wow, that's a very comprehensive thread about gear modeling. Thanks for pointing it out. 


      Regards,


      Wenlong

    • evogel
      Subscriber

      Hi Peter,


      Thanks for linking those threads! First off I do not have involute gear teeth, I made them rather crudely on solidworks. Also, I have adjusted my parts so that they do contact and also taken included the suggestions from Wenlong on adding substeps. However it still is having the same issues.


      Thanks,


      evogel

    • peteroznewman
      Subscriber

      The mesh looks way too coarse with only one element across a tooth. Insert a Sphere of Influence Body Size mesh control and for the few teeth in contact, make sure there are at least 8 linear or 4 quadratic elements across the width of the tooth and along the tooth face in both directions.

    • evogel
      Subscriber

      Peter,


      I was able to set use the sphere of influence however it still did not work. 

    • peteroznewman
      Subscriber

      What is the error?  What does it suggest you do to correct it?

    • evogel
      Subscriber

      The error I received at the end stated: "An unknown error occurred during solution.  Check the Solver Output on the Solution Information object for possible causes." I still was got an warning stating "Matrix coefficient ratio exceeds 1.0e8, check results carefully." and "One or more bodies may be underconstrained and experiencing rigid body motion. Weak springs have been added to attain a solution.  Refer to Troubleshooting in the Help System for more details." Whoever I did not receive any other errors or warnings that I have been previously getting. 

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