Problem with tied constraints in FEA BCs


I think I’ve encountered a bug dealing with the definition of tied constraints. The tied constraints are easy enough to define using two coincident sidesets. (Note: Exporting the mesh to an Abaqus .inp file produces an error in Abaqus because the produced .inp file does not define a name for each constraint which is a necessary parameter in Abaqus. The fix for this is easy – simply type NAME=“your_constraint_name” after each constraint definition in the .inp file). The Abaqus export works well (except for the small mistake I mentioned above), but if I save the model as a .cub file, upon trying to reopen it, trelis does not recognize the constraints any longer and it prints this error:
Unknown constraint type encountered in constraint 1.

Any help with this would be much appreciated as it would be very laborious to go through and redefine any tied constraints every time I would like to reopen the .cub file using trelis to edit the model.



This appears to be a bug. It can be reproduced and the issue has been submitted for a fix.

brick x 1
mesh vol 1
sideset 1 surface 1
vol 1 copy move z 1
sideset 2 surf 8
create constraint tie master sideset 1 slave sideset 2
save as ‘junk.cub’ over
open ‘junk.cub’

When opening the cub file, you get this:
ERROR: Unknown constraint type encountered in constraint 1.