Symmetry Region vs. Frictionless Support

- July 30, 2018 at 10:30 am
  jonsys
  Subscriber
  In a symmetric structure, what is the difference between using:
  - "Insert Symmetry Region" in Model
  - applying "Frictionless support - Static structural" at the face where the model is cut due to symmetry?
- July 30, 2018 at 10:44 am
  
  Rohith Patchigolla
  Ansys Employee
  
  Hi Jonsys,
  
  If the face (where the model is cut) is geometrically flat, then, Frictionless Support is equivalent to applying a Symmetric Region.
  
  Best regards,
  
  -Rohith
- July 30, 2018 at 11:00 am
  
  jonsys
  Subscriber
  
  Hi Rohith,
  
  thank you for the answer.
  
  What if it is not flat, which one should be used? (even though I can't think of any cutting that is not flat)
- July 30, 2018 at 1:02 pm
  
  Rohith Patchigolla
  Ansys Employee
  
  Hi Jonsys,
  
  When the cut surface is not flat, Symmetry is not applicable.
  
  In such cases, if a Frictionless Support is applied, this results in a constraint in the surface normal direction. For example, if the frictionless support is applied on a cylindrical surface, the nodes are constrained in the radial direction (similar to a Cylindrical Support in Mechanical, with radial fixed, but, Axial and Tangential directions free).
  
  Best regards,
  
  Rohith
- July 30, 2018 at 1:28 pm
  
  jonsys
  Subscriber
  
  Hi Rohith,
  
  thank you for the explanation of the frictionless support.
  
  So, since the surface is always flat (for the symmetry to be applicable), this means that "Symmetry Region" and "Frictionless support" will always be the same?
  
  Regards,
- July 30, 2018 at 1:41 pm
  
  peteroznewman
  Subscriber
  
  Hi Jon,
  
  You are only thinking of flat surfaces. A good example where Frictionless Support is used is on the cylindrical surface of a hole to represent that hole being mounted to a rigid shaft, which is not in the model, and gives the body with the hole rotational and axial freedom about the hole axis. I don't think you can do that with Symmetry Region.
  
  Regards,
  
  Peter
- July 30, 2018 at 3:01 pm
  
  Rohith Patchigolla
  Ansys Employee
  
  Hi Jonsys,
  
  "So, since the surface is always flat (for the symmetry to be applicable), this means that "Symmetry Region" and "Frictionless support" will always be the same?"
  
  -Yes, that is correct.
  
  Best regards,
  
  Rohith
- July 30, 2018 at 3:04 pm
  
  Sandeep Medikonda
  Ansys Employee
  
  Just to add to the discussion, here's a relevant thread from an older XANSYS forum.
- August 1, 2018 at 10:00 am
  
  jonsys
  Subscriber
  
  Peter, Rohith, Sandeep,
  
  thank you very much
  
  Regards,
  Jon