Rheological behavior of a magnetorheological shear-thickening fluid (MRSTF) and dynamic characteristics of an MRSTF damper

Abstract In this study, a magnetorheological shear-thickening fluid (MRSTF) containing nano-grade fumed silica and polyethylene glycol mixed with different iron powder mass fractions was first evaluated, and the rheological behavior of the MRSTF was analyzed. The viscosity amplitude of thickening with the MRSTF decreased with increasing magnetic field strength. When the magnetic field strength of the MRSTF reached 197 mT, the thickening effect was eventually eliminated. An increasing content of carbonyl iron powder effectively increased the viscosity of the fluid under a weak magnetic field environment. And then magnetorheological shear-thickening damper (MRSTD) was designed and its dynamic characteristics were studied using an MTS809 fatigue testing machine. The results indicated that the damping force of the MRSTD changed with the vibration frequency, amplitude, and magnetic field strength. Finally, according to the mechanical characteristics of the MRSTD, linear and nonlinear damping models were established based on the energy storage stiffness and energy dissipation stiffness, respectively. And the results of the two fitting functions were compared with those of the experiments. The nonlinear damping model was found to better replicate the nonlinear stiffness, nonlinear damping, and shear rate-related characteristics of the MRSTD. The results of this study provide guidance for future theoretical and applied research into MRSTDs.