In this example, the automatic method will be used to perform fitting for a non-isothermal differential viscoelastic model with experimental data curves of shear viscosity vs. shear rate at three different temperatures, plus data curves for the storage and loss moduli.

The Giesekus model has been chosen according to fitting guidelines for a 2D extrusion simulation where shear thinning is desired (see Recommended Models and Parameters). Three relaxation times are used to fit the experimental curves properly, since multiple relaxation times are computationally affordable for 2D extrusion. The relaxation times are set automatically by Ansys Polymat to cover the whole range of experimental data. The large relaxation time that Ansys Polymat computes is useful only for low-shear-rate flows (up to 0.1 s ) with a long residence time (10 to 100 s). The viscosity ratio is set to zero for all relaxation modes, except for the first mode where it will be computed automatically by Ansys Polymat.

For temperature dependence, the standard Arrhenius law has been chosen. is automatically set to 220° C, which is one of the temperatures at which experimental data were measured, close to the average of those temperatures. Since the experimental data are based on degrees Celsius, is set to , as required for proper scaling.