General Mechanical

General Mechanical

Pipe constraints, deformation and DOF

    • ammorey
      Subscriber


       


       


      evening to all of you , hope that all are fine 


      what Im doing here is an analysis for a pipe which contain surface crack. The pipe here under internal pressure,  I fixed the both ends so  it will not move in any direction and applied the internal pressure, but after doing the simulation the pipe deformed in the way as showed in the picture above which is not supposed to deform like that ! as you see above the pipe got something like swelling which can be noticed with the lite color.. I googled this problem but what I got this deformation occurred due wrong constraint or the model has more degree of DOFs, could you just guide me how to model or what is the suitable constraints required for this model.  I'm using ansys workbench 19.0.


      I tried also to decrease the value of the internal pressure and the results (for the pipe deformation ) are same .


       Thanks in advance 

    • Aniket
      Ansys Employee

      ammorey,



      ANSYS employees cannot download attachments in the post, can you please add some inline images? What do you mean by it is not supposed to deform this way? 


      Are you following any tutorial?

    • ammorey
      Subscriber

      hello Aniket 


      thanks for your reply , I attached the photo again . for the second part of your reply about what I mean I think it will be clear with the photo . 


      thanks again 

    • Keyur Kanade
      Ansys Employee

      Please insert images. 


      Moving this thread to sturctural mechanics category for better response. 

    • Aniket
      Ansys Employee

      Hi ammorey,


      Sorry, your question is still not clear to me as I am unable to understand the issue from the image that you have posted. Please provide additional details to help you better with this question.

    • ammorey
      Subscriber


       


      hi Aniket , 


      thanks for your reply .. what Im doing here is analysis for pipe which contain surface crack. The pipe here under internal pressure,  I fixed the both ends so  it will not move in any direction and applied the internal pressure, but after doing the simulation the pipe deformed in the way as showed in the picture above which is not supposed to deform like that ! as you see above the pipe got something like swelling which can be noticed with the lite color . So what Im expecting now is the problem with constraint that I applied or there is something else. I wish that everything has been clarified. 


      Thank you so much 

    • Aniket
      Ansys Employee

      What is the result is scoped to? How is the crack modeled?


      What is the total deformation of the entire pipe? What is result display scale? Can you insert image of entire Mechanical window?

      You have fixed the ends, and applied internal pressure, why do think that the pipe won't swell in this condition?

    • ammorey
      Subscriber

      Hi Aniket and thanks for your reply; 



      What is the result is scoped to?



      linear Elastic if I did not misunderstand you .. 



      How is the crack modeled?



      I used semi- elliptical crack from fracture icon 




      What is the total deformation of the entire pipe?



      Iam looking for the value of the stress intensity factor at the crack front 



      What is result display scale?



      I don't know exactly what it is; because Im not that much familiar with Ansys workbench  may be this one ( 1.1e+003 (Auto Scale)) 



      Can you insert image of entire Mechanical window?




       



      You have fixed the ends, and applied internal pressure, why do think that the pipe won't swell in this condition?



      Yes , normally any pipe with any internal pressure should not deform like that , the pipe deform even with very low pressure .. 


       


      I think the problem with model which has degree of freedom higher than what my problem should have .. what I did is draw to circles then I extruded it to the desired length . Is it wrong ?


      Thanks Again  

    • Aniket
      Ansys Employee

      ammorey,


      I believe this is due to the fact that the result scale is auto and it is a very high number. Please change it to true scale and see if that looks the way you would expect.


       

    • ammorey
      Subscriber


       


      thanks Aniket , 


      its now good ., previous results was magnified with that scale factor so the deformation of the pipe was so close ? the problem was like that if Im not mistaken 

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