General Mechanical

General Mechanical

Unrealistic deformation when frictional contacts are used between flange and bol

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    • ziahussain252
      Subscriber

      Hi

      I am doing analysis on gasketed flange joint with 8 bolts as shown in the model. I want to tight the bolts in cross tightening order (1,5,3,7,2,6,4,8) using bolt pretension.

      When I tight the bolt 1 , 5 then there comes a gap between other bolts means contact status changes. After this as I tight the other bolts then the head of the bolt elongates unrealistically towards the nuts side as shown. I am using frictional contact between the flange surface and the bolts head because it is one of my objectives. Kindly help me in this regard as I have tried my best to solve this but unable to get the realistic results.

      Thanks

    • peteroznewman
      Subscriber

      I will try and help if you create a Project Archive .wbpz file.  Use File, Archive.  Take the .wbpz file and put it on a file sharing site such as Dropbox, Google Drive or Jumpshare, which is what I use, then post the link to the file in your reply. If using Googe Drive, make sure to set the permissions so anyone with the link can download it.

      Say what version of ANSYS you are using in your reply.

    • ziahussain252
      Subscriber

      Thank you Peteroznewman. Here is the link
      https://drive.google.com/file/d/1Gj7jdkrPxLt1KwzRqnD3Pdo2h6vADl7F/view?usp=sharing
      Also, I am using ANSYS 18.1. 

    • peteroznewman
      Subscriber

      I don't have ANSYS 18.1 to use to send you back an archive. I can look at your model and try to figure out what you need to change to make it work.

    • ziahussain252
      Subscriber

      Thank u so much

      Moreover as I guess that this issue is related to contacts because as I use bonded contact then I get the realistic result but I want to use either frictional or frictionless.

      In addition to it,  u may send m archive in ansys 2020 R1 or 2021 R1 I have acces to it. 

    • Florian.CHANCEL
      Subscriber

      Hello,
      I tried some configurations, and I found one working.

      I think the problem comes from setting of your bolt pretension.

      I didn't load 1N and locked.
      I just let "load to 0" during the time of pretension of other screw.
      Pretension  screw 1 :

      Pretention screw 2

      Pretention screw 3

      And results are : No distortion or peak stress apprears

      Can you try ?

       

      Regards

      Florian C.

    • peteroznewman
      Subscriber

      Hello Florian,

      You have a valid solution to the problem.  Sorry I did not have time to look at this till the weekend.

      Regards,

      Peter

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