• Dimensioning Conflicts—When a design variable changes, it can create dimensioning conflicts that prevent Creo Parametric from regenerating the model. In this case, the software displays a warning indicating that it cannot regenerate the model.

• Topology Changes—As a design variable changes, it can alter your model's topology. Topology is the association and connectivity between the model's geometric entities. Topological changes can create new surfaces and curves or delete existing surfaces and curves. Keep in mind the following when determining whether to accept a design variable that changes topology:

◦ If your model undergoes a topology change, the optimizer may encounter discontinuities that cause it to stop prematurely due to a stress peak when new geometry appears or old geometry disappears.

◦ If the design variable change deletes a surface, curve, point, or region associated with a load, constraint, or measure, Creo Simulate cannot update the model.

◦ If the design variable change causes surface regions to intersect, Creo Simulate retains the first region as is but removes the section of the second region where the overlap occurred. The software redistributes any loads applied to the second region over what remains of that region. Consequently, your model may experience stress concentrations as the second region becomes smaller.

• Dependent Dimensions—If you are applying a design variable to a dimension, you can only work with independent dimensions. If you create a design variable and add a Creo Parametric relation that makes the design variable's dimension dependent, Creo Simulate does not recognize that design variable.