Dynamic excellence in magnetorheological shear thickening fluid: Fabrication and formulation of a constitutive model

Abstract

Improving the dynamic rheological properties of magnetorheological shear thickening fluid is beneficial to its improved application in dampers. In this work, we mixed silicon dioxide (SiO2), carbonyl iron powder (CIP), and sepiolite (Sep) into polyethylene glycol to prepare a novel sepiolite magnetorheological shear thickening fluid (MR-Sep/STF). The dynamic rheological properties of the MR-Sep/STF and stress attenuation were studied through orthogonal array testing. Specifically, we mean that using this experimental design to evaluate the effects of varying proportions of SiO2, CIP, and Sep on the damping factor, dynamic yield stress, and shear thickening effect. The excellent performance of the MR-Sep/STF was achieved at an optimal ratio of 55% SiO2, 10% CIP, and 2% Sep. In addition, stress attenuation tests indicated that when the shear rate was within the range of 30–40 s−1, the stress attenuation is roughly between 42.85% and 59.78%. Once the shear rate exceeded 40 s−1, the stress decreased by more than 300%. Furthermore, we proposed a structural kinetics constitutive model that offers profound insight into the dynamic response mechanisms of the MR-Sep/STF: at the maximum shear rate, the structure generation rate a has a maximum value. Once maximum shear rate is exceeded, the structure decomposition rate b is greater than the generation rate a, and the viscosity and stress decrease macroscopically.