How to select bottom surface of the midsurface body to provide supports?

- January 31, 2019 at 10:16 am
  
  naveen28
  Subscriber
  
  Hi,
  
  I have extracted midsurface for a sheet metal part. Now I need to provide two supports to the midsurface body. One support is on the top surface of the body and another one is on the bottom surface of the body. After midsurface extraction, I only able to select the top surface for support conditions. If I try to select bottom surface, only corresponding top surface is being selected again.
  
  Please guide me on this.
  
  Thanks,
  
  Naveen
- January 31, 2019 at 10:36 am
  
  jj77
  Subscriber
  
  Well I think you can only apply BC on the face/surface, there is no top and bottom in the geometry (it is just a surface, not a 3D body).
  
  One can still apply say a compression only support (say soil), and then apply a pressure, that should be fine.
  
  If your structure is very thick thus cannot be approximated as a thin shell (and you need to define BC on the different faces), then model it as 3D body and mesh with 3D elements.
- January 31, 2019 at 10:51 am
  
  naveen28
  Subscriber
  
  Thanks for your response.
  
  But in contacts, we have option to choose the shell surface as top or bottom. Likewise, don't we have for support conditions?
  
  Also attached the cross section of the geometry for your reference.
  
  Surfaces highlighted in yellow needs to be given as frictionless supports. Here, two surfaces are top surface of the shell and one is bottom surface of the shell.
  
  Thickness of the geometry is 1.5mm.
- January 31, 2019 at 11:05 am
  
  jj77
  Subscriber
  
  This is just when we visualise the mesh (showing element thickness), it is still a surface (not a 3D part).
  
  As I said it does not exist as far as I can see.
  
  What type of boundary condition do you put in the yellow marked area? If it is really important then model the other part and put in a contact there where you can account for that.
- January 31, 2019 at 11:16 am
  
  naveen28
  Subscriber
  
  Surfaces highlighted in yellow needs to be given as frictionless supports.
  
  I have got this query because in contacts, we have option to choose the shell surface as top or bottom. I thought similar option would be there for support conditions also.
  
  Fine, if it is not available in workbench, then as you mentioned I need to create a additional body to provide support for one of the surfaces.
  
  Thanks for your quick response!
- January 31, 2019 at 11:23 am
  
  jj77
  Subscriber
  
  Or model it in 3D if this is important (have in mind that frictionless support is available for shell ele.). No worries. Glad to help.