RHEOLOGICAL PROPERTIES OF MR FLUIDS IN THE POST-YIELD REGION UNDER CONSTANT SHEAR INCLUDING THE EFFECTS OF TEMPERATURE

摘要

This paper investigates the theological behaviour of MR suspensions in the post-yield region, including the effect of temperature on their performances. Experimental data show that the behaviour of MR fluids in this post-yield region can be examined effectively using the Herschel-Bulkley fluid model, which is a departure from the popular Bingham model for MR fluids. The Herschel-Bulkley model provided a better fit to the experimental data, and the model parameters provided a convenient means of investigating the effects of various factors such as field density, particle volumetric fraction and temperature on the characteristics of MR fluids. Shear thinning in the fluid was found to increase with magnetic density, but quite independent of the volumetric concentration of the magnetically active particles and temperature. The Herschel-Bulkley consistency index, however, is a function of temperature, and this dependency can be fitted very well to the Arrhenius equation.