Determination of parameters of a material obeying Casson’s equation by some rheometers

Article type: Research Article

Authors: Murata, Tadayoshi | Oka, Syoten

Affiliations: Department of Physics, Tokyo Metropolitan University, Setagaya-ku, Tokyo

Abstract: It is shown how to determine parameters of a material obeying Casson’s equation by some rheometers. Casson has proposed an equation for the flow of varnishes relating the shear stress F to the rate of shear D. This relation has the form, (F)=k0+k1(D), k0 and k1 being constants. This equation is generally called Casson’s equation. We have determined the parameters k0 and k1, that is, the viscosity ηc corresponding to k12 and the yield value τf corresponding to k0, by a rotating coaxial cylinder viscometer and a cone and plate viscometer. The determination of the parameters can be made by the following procedure. First, we substitute the flow curve for Casson’s equation into the general relationship between the torque M and the angular velocity Ω for a non-Newtonian fluid. From a plot of Ω vs. M we can get an asymptote. Then we can determine ηc from the slope of the asymptote and τf from the intersection of the asymptote with the abscissa.

DOI: 10.3233/BIR-1968-5201

Journal: Biorheology, vol. 5, no. 2, pp. 95-102, 1968