Correction of instrumental inertia effects in controlled stress rheometry

¹ Laboratoire d'Énergétique et de Mécanique Théorique et Appliquée, Institut National Polytechnique de Lorraine (CNRS–UMR 7563), 2 avenue de la forêt de Haye, BP 160, 54504 Vandœuvre-lès-Nancy, France
² Laboratoire de Biorhéologie et d'Hydrodynamique Physico-Chimique, Université Paris 7, Denis Diderot (CNRS–URA 343), 2 place Jussieu, 75005 Paris, France

Received: 24 October 1997
Accepted: 2 March 1998
Published online: 15 May 1998

Abstract

An analysis of inertia effects in controlled stress rheometry is presented. For Newtonian fluids, this study takes exact account of both the instrumental inertia and the discontinuous stress change in this type of rheometer. In fact, supposedly smooth stress ramps are always approximated by a series of stress steps. The significance of this limitation, which is sometimes critical, is pointed out for the first time. The error induced by assuming that the stress ramps are smooth in Krieger's method for inertia correction [1], is quantitatively evaluated. An improved calculation for non-Newtonian, inelastic fluids is described.