A few remarks on rheological constitutive equations of the network-rupture type

Abstract

Material functions of rheological constitutive equations of the network-rupture type were investigated for steady simple shear flow at high shear rates. It was found that a systematic deviation occurs in the normal stresses predicted by these models compared with experimental data, whereas the viscosity function is well approximated. This is due to an unrealistic dependence of the critical shear on the shear rate. A modification of the known constitutive equations is presented which results in an better description of the behaviour at high shear rates.