General Mechanical

General Mechanical

Distortion – Bolt Pretension

    • Fabricio.Urquhart
      Subscriber

      Hello


       


      I think that there is problem with my bolts. Because when I take the stress results, with a 2x scale, I have the pictures below:




      I think that it occures because I applied the bolt pretension in the face of the thread. Is it correct?The shared topology is being used.


      Thank you!!I saw it, because I need to show the deformation of the bolt in the end of pretension load, and to see something I have to multiply the scale.

    • Sandeep Medikonda
      Ansys Employee

      Fabricio,


      What does the edge that you highlighted refer to? Is it the thread or do you think this is a discrepancy in the graphics?


      It's not clear how many parts you have? Is it 2? The bolt and the nut?


      I am not sure if I understand what the problem is? Can you explain a little?



      Regards,
      Sandeep
      Best Practices to post on the Student Community

    • Fabricio.Urquhart
      Subscriber

      Sandeep,


      I think that it is a discrepancy in the graphics. It is in the thread, but I did not model the grooves of the thread, because it is not necessary.


      I have 5 parts in the bolt, as you can see in the picture below.



      I am expecting a bolt deformation like the picture below:



       


      But the results show the thread going out from the head of the bolt. Do you know why?


       


       

    • peteroznewman
      Subscriber

      Fabrico,


      I took your model above and solved it in ANSYS 19.0 and got a very reasonable looking bolt stress displayed at a Result Scale of 2.0



      If I increase the Result Scale to 20, it starts to reveal some of the shape you were looking for.



      I have no idea how you got what you were displaying in the first post.


      Regards,


      Peter

    • Fabricio.Urquhart
      Subscriber

      Hello Peter.


      The deformation in the first post I took at the end of pretension load. If you see in your second picture, I am not looking for this distorion in the middle of the thread, do you understand?


      I was looking for a continuous stress, but with deformed bolt.

    • peteroznewman
      Subscriber

      Hello Fabricio,


      Here is the deformation at the end of Step 1, with a Results Scale of 2.



      None of my plots look like your first post. Do you want to see a more exaggerated Result Scale?


      Regards,


      Peter

    • Fabricio.Urquhart
      Subscriber
      Peter
      I would like to see the deformation along the bolts withiut distortion.

      If I exaggerate in the result scale, the distortion appear.

      Did you try larger scale?
      In your pictures is not possible to see the thread’s deformation, do you agree with me?
    • peteroznewman
      Subscriber

      It is not possible to see the thread (shaft) deformation at a True Size of 1.0 Result Scale, because the deformation is so small. That is why you have the ability to type in large numbers to exaggerate the deformation.


      Sometimes, you want no deformation to appear on the geometry, and you can type a 0 for the Result Scale, or Undeformed. Then you can color the geometry with any result you want, such as Y displacement. Is that what you want to see?


      Below is the Undeformed Geometry (Result Scale 0), with the contour plot of the Y displacement at time step 1.



      Is this what you are looking for?


      Regards,


      Peter

    • Ashish Khemka
      Ansys Employee

      I agree with Peter above that you will see distortion - just a scaling effect but will give you an understanding how the load is acting.


       


      Regards,


      Ashish Khemka

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