Creo Simulate > Modeling Structure and Thermal Problems > Verifying Models > Structure Errors > Missing Constraints
  
Missing Constraints
Creo Simulate makes sure that there are constraints in your model. Note that a point-to-ground spring is a constraint.
You cannot define an analysis for a model with no constraints, unless you select one of the following:
For a modal or prestress modal analysis select Unconstrained on the dialog boxes for modal analyses.
For a dynamic time, dynamic frequency, or dynamic random analysis select Use modes from previous design study on the Previous Analysis tabs of the dialog boxes for dynamic analyses.
Return to Structure Errors.