Large amplitude oscillatory shear flow of viscoelastic materials

Abstract

Recently, a number of rate-dependent viscoelastic models have been proposed which are quite successful in predicting the stress growth behaviour on start up of steady simple shear flow. None of these models has been evaluated for any different time-dependent nonlinear flow, other than stress relaxation on cessation of steady simple shear flow. Here, one of these models, theCarreau-B model, is solved numerically to determine its predictive ability for large amplitude oscillatory shear flow. The model predictions are compared with experimental data and with the predictions of theBird-Carreau model, a model which is known to do poorly in predicting stress growth behaviour. TheCarreau-B model predictions are quantitatively and qualitatively incorrect for large amplitude oscillatory shear and are significantly worse than those of theBird-Carreau model. Some conclusions ofGross andMaxwell and ofGordon andSchowalter concerning rate-dependent models are discussed. Possible reasons for the poor performance of theCarreau-B model are given.