Because a material model represents a mathematical relationship between response and load, it requires input parameters so that the model matches the material behavior.

In some cases, the parameters can be a function of physical field quantities such as temperature, frequency or time or interaction quantities such as normal pressure, relative distance, or relative velocity.

Matching the model to the actual behavior can be challenging; therefore, some built-in curve-fitting methods are available that use minimization to select a set of parameters that give a close fit to measured material behavior. The curve-fitting methods help you to select material parameters for creep, hyperelastic, viscoelastic, and some plastic models.