Guidelines for Using Relations
When using relations with Creo Simulate, bear the following factors in mind:
• You cannot use dependent dimensions as design variables. Dependent dimensions are dimensions that appear on the left side of a relation. If your model contains dependent dimensions, Creo Simulate does not display them during design variable definition.
• You can use Tools > Relations to add relations.
• You can use nested relations in design variables. If you do so, be aware that Creo Parametric maintains all relations in a chronological list. When it refers to the list, Creo Parametric tries to satisfy the relations sequentially, starting with the first relation.
Therefore, for nested relations, be sure to define the highest level relation first and work downward from there. If you do not work downward through the nest, the order in which you assigned the relations may prevent Creo Parametric from satisfying all the relations.
• If you want to change the thickness of a shell model using a design variable, you need to make sure both surfaces that make up the shell pair move an equal distance in opposite directions. This type of movement maintains the correct positioning of the midsurface during the thickness change.
If you dimensioned the paired surfaces in relation to a datum plane or an entity in the part, the easiest way to create this effect is by setting up a relation between the two paired surfaces.
In this case, you could create a datum plane at the midsurface and write the relation in terms of that plane. As an alternative, you could treat the distance from the midsurface to the dimensioning entity as an absolute value and write the relation in terms of that value.