Guidelines for Fitting the Material Model
Creo Simulate fits the material model curves to the test data by minimizing the sum of squared error between experimental and fitted stress values using the least square fitting algorithm. By default, Creo Simulate uses normalized stress values. When you set the configuration option, sim_hyperelastic_material_fit to nonnormalized, Creo Simulate uses the nonnormalized stress values for least square fitting algorithm.

If you change the value of configuration option, sim_hyperelastic_material_fit during a session, you must edit the properties of all the hyperelastic materials in the session. To edit properties, you must open the Hyperelastic Material Definition dialog box and click OK on the dialog box. Creo Simulate automatically generates the material model curves for the new type of stress values.

When you set the configuration option, sim_hyperelastic_material_fit to nonnormalized, Creo Simulate calculates the RMS error as follows:
For normalized stress values, Creo Simulate calculates the RMS error as follows:
Here n = total number of test data points.
= i
th test data stress value.
= Stress value from the fitted material model curve in terms of coefficient Cj.
When you select nonnormalized option, you get better fit at higher strain values while the normalized option provides a better fit at lower strain values.