How to apply damping and elastic foundation stiffness to mimic an external elastic support on wall?

- October 1, 2018 at 2:49 pm
  
  yk2359
  Subscriber
  
  Hello,
  
  I am learning to simulate a transient analysis of an arterial wall (pipe like structure). I realized that to provide an external tissue support, stiffness and damping coefficients are to be applied. Something like these,
  
  "Transverse shear factor of the arterial wall k = 5/6 and coefficients related to the stiffness, k = 0:01 Pa/mm and damping, c = 0:15 Pa.s/mm, of the external tissue support."
  
  Now in Ansys Mechanical (Workbench), elastic support on the outer wall seems like the right way to go about the analysis set-up. But how to calculate Elastic Foundation Stiffness (EFS)? Or is there any other way for defining above mentioned coefficients?
  
  Please help.
  
  Thank you.
- October 1, 2018 at 5:10 pm
  
  Sandeep Medikonda
  Ansys Employee
  
  Hi,
  
  Can you please see if you find this discussion helpful?
  
  Regards,
  Sandeep
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- October 1, 2018 at 5:39 pm
  
  yk2359
  Subscriber
  
  Thank you for the response, Sandeep. The link you shared definitely helped me in applying stiffness coeff on wall in my model. I didn't need the command snippet to couple support directions as it's a simple elastic support acting normal to the wall.
  
  But I am yet to find a way in defining damping onto the wall. Please let me know your thoughts.
  
  Thank you.
  
  Yogesh
- October 1, 2018 at 6:42 pm
  
  Sandeep Medikonda
  Ansys Employee
  
  Hi Yogesh,
  
  I don't think this is currently possible from what we have in mechanical. Probably through APDL scripting, what I would recommend is see what element type mechanical is writing out for the elastic foundation by default (in your input deck). Go back to the manual, check and see if that element supports damping and if it does you can use a command snippet similar to the link to try and edit it?
  
  Regards,
  Sandeep
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- October 2, 2018 at 1:33 pm
  
  yk2359
  Subscriber
  
  Alright that sounds doable. Thanks for the info, Sandeep.
  
  If you don't mind, I have another question to ask. Solution might be simple or maybe I am missing some key piece in the set-up process.
  
  Problem is to apply FSI condition on inner wall and elastic support on outer wall in a pipe-like structure. This was possible with solid brick elements but how to select inner and outer for respective conditions in a thin-walled shell structure? As you can see the attached images irrespective of the surface body offset (top, bottom & middle) I select, the load & support are applying onto native thin-wall. Please review and help me fix this.
  
  Thank you.
  
  Yogesh