What could be a practical application for rheology?
On the one hand, rheology studies the constitutive equations (or constitutive models) to mathematically describe the relation between force and deformation of the material.
On the other hand, rheological measurements register the material behaviour.
The measurements are used to fit the parameters of the constitutive equations.
Once a constitutive equation with its parameters is determined to describe the material behaviour in a rheological sense, this model can be applied to simulate more complex processes, such as for example injection moulding processes. In such a way, information about the complex process can be obtained.