Experimental investigation of creep and recovery behaviors of magnetorheological fluids

Creep and recovery behaviors of a magnetorheological (MR) fluid under constant stress shear were investigated. This experiment was accomplished by using a rheometer with parallel-plate geometry. The applied constant stress ranges from a small value to a big one which approaches to the yield stress. The effects of magnetic field strength and the temperature on the creep behavior were addressed. The experimental results indicate that MR fluids behave as linear viscoelastic bodies at small stresses: with increasing constant stresses, nonlinear viscoelastic, viscoplastic, or purely plastic properties will dominate. Hence, MR fluid behavior ranges from predominantly elastic at small stresses to plastic at high stresses. Moreover, the creep and recovery behaviors are explained by a typically thick column structure. (C) 2002 Elsevier Science B.V. All rights reserved.