Rotational and sliding surface rheometers are widely used for measuring shear properties of melts. In the case of viscoplastic material models with vanishing viscosity, the qualitative behavior of solutions in the vicinity of rigid walls is affected by the asymptotic behavior of the yield stress as the viscosity approaches zero (i.e., the shear strain rate approaches infinity). This feature of the solutions should be taken into account for the adequate interpretation of experimental data. In the present paper, a new theory for several types of rotational and sliding surfaces rheometers is developed. The theory accounts for the qualitative behavior of solutions near rigid walls and demonstrates the effect of this behavior on the interpretation of measurements made using such rheometers.

Sergei Alexandrov is a Visiting Professor at Beihang University (China) under the program “Recruitment Program for Global Experts”, a Research Professor of the Institute for Problems in Mechanics of the Russian Academy of Sciences (Russia) and an adjunct faculty member of Ton Duc Thang University (Vietnam). He received his Ph.D. in Physics and Mathematics in 1990 and D.Sc. in Physics and Mathematics in 1994. He is a member of the Russian National Committee on Theoretical and Applied Mechanics and on the editorial board of several international journals. His research areas are plasticity theory and fracture mechanics.