Modeling, measurements and validation of magnetic field dependent flow behavior of magnetorheological fluids; static and dynamic yield stress

Abstract

The issue which is always debated in the magnetorheological (MR) fluid is the dynamic and static yield stress values obtained from a flow curve. To evaluate these, a suitable constitutive equations are required. The aim of this article is to provide suitable rheological models for the prediction of static and dynamic yield stress from a single flow curve under wide shear rate and magnetic field ranges. The proposed model is well suited for isotropic and anisotropic particle-based MR fluids. The parameters, like yield stress, critical shear rate and viscosity at high shear rate obtained from the fit show systematic variation with applied magnetic field strength. These variations in the parameters can be related to the mesostructure formation and its influence on the MR suspension rheological properties. To further confirm the value of the static yield stress derived from the proposed model, the small-strain oscillatory shear flow experiment is carried out and the static yield stress values are obtained. These values agree well with that obtained from the proposed model. Similarly, to evaluate the dynamic yield stress from the flow curve, modified three parameter model applied to soft glassy materials is used. Here, the critical shear rate parameter obtained from the proposed model is used to deduce dynamic yield stress. It is identified that the values obtained are lower than the static yield stress. Furthermore, at low magnetic field, the static and dynamic yield stress follows the relationship defined by the square dependence of the magnetic field strength. The difference between the static and dynamic yield stress values at high field is greater for anisotropic particle based MR fluid than isotropic particle based MR fluid. This reflects the contribution of particle-particle and particle-carrier interaction in the value of the yield stress in anisotropic particle based MR fluid. Thus, the present model provides a clear idea of the dissipation process that occurs in a shear MR fluid.

Deformation Properties of Hydrogel Compositesof Α-Lipoic Acid With Colloid Silica

“…The yield stress (τ0) determined by model fitting is dynamic yield stress, which is the minimum stress to maintain the material's flow or terminate it after the stress is removed [31,32]. It is related to the structure of the material destroyed by shear forces and characterizes the level of structure of the material restored after removal of the shear stress (for example, after extrusion from the syringe, tube).…”

Magnetorheological fluids: A concise review of composition, physicochemical properties, and models

“…In turn, in Lee and Chang (2020) the devices for MRFs shear force measurement, which enables a determination of the relationship between yield stress and magnetic flux density, were proposed. Modeling and experimental validation of the fluid flow subjected to a magnetic field under consideration of static and dynamic yield strength was presented in Upadhyay and Choi (2021).…”

A novel adjustable magnetorheological fluid gradient material of low frequency vibration isolation: a theoretical and experimental study

“…The interaction between the particle chains changes the parameters of the MRF itself [3]. The interaction between the particle chains also changes when the magnetic field strength changes, making the parameters of the MRF modifiable by the external magnetic field [4,5]. Based on the magneto-controlled properties possessed by MRF, they can be combined with different magnetic fields to have different properties.…”