In Creo Simulate, you can use design variables to define the design space you want to explore during sensitivity and optimization studies. When you define design variables, identify aspects of the model that you can vary within manufacturing constraints and tolerances. Define individual design variables, that you can vary from 0% to 100%, for those aspects. If you want to vary more than one aspect at a time—in other words, as a unit—you can build a relation that moves the aspects together and use that relation as the design variable.

In a global sensitivity study, use the Shape animate the model button in the Design Study Options dialog box of the global sensitivity study to make sure that the model geometry and mesh remain valid throughout the design space that you plan to use for a particular study.

You may find that you need to change some of the design variable limits or add additional design variables to achieve the desired modification. Use the following strategies for reviewing the effect of your design variable on the model:

Before running a global sensitivity study, use Shape animate the model and set the values for each parameter to the range that you plan to use for the study. Then review an animation of the model's changes across each of those ranges.

For example, if setting the radius of a curve to 100% of its range while setting the translation of that curve to 0% of its range could cause the geometry to significantly change its shape, review the shape using that combination.

You can also use the results of local and global sensitivity studies to predict how the engine might change a particular design variable to achieve your goal. Use this information to set the design variable ranges for your optimization study.