Creo Simulate > Modeling Structure and Thermal Problems > Structural Constraints > Guidelines for Structure Constraints
  
Guidelines for Structure Constraints
Creo Simulate assumes that any part of your model that you do not constrain is free to move in all degrees of freedom available for that model type. For analysis to succeed, all degrees of freedom should be constrained somewhere in your model.
Before you add constraints to your model, be sure you have the geometry and references you need already in place. Pay particular attention to the following items:
Geometry
Coordinate Systems
Datum Points
Regions
Points—If you attempt to delete a point associated with a load or constraint, the software informs you of the association by displaying a message with the information that the geometry you want to delete is referenced by a simulation feature. You can delete the point, but Creo Simulate also deletes the associated load or constraint.
Surfaces—If you apply a displacement constraint to a surface by selecting the surface with Box Select or Part Boundary, and Creo Simulate later creates a new surface due to a parameter change, the software does not automatically apply the existing constraint to the new surface.
Shell Models—If you plan to constrain a shell model surface, edge, region, curve, or point that Creo Simulate may compress during analysis, see Model Entities and Idealizations to learn about how the software processes constraints placed on these geometry types.
Cyclic Symmetry Models—If you plan on assigning a cyclic symmetry constraint to a portion of a symmetric model, you must first create the model section in Creo Parametric, using the Cut feature on the original model.
Mirror Symmetry Models—If you apply a mirror symmetry constraint to a surface that is collapsed to a curve due to midsurface compression during analysis, the software ignores the mirror symmetry constraint.