Simulation studies of electrorheological fluids under shear, compression, and elongation loading

Abstract

Mechanical properties of electrorheological fluids under various dynamical loading conditions have been studied using a computer simulation model. The model assumes electrostatic point–dipole interaction between particles with or without multipolar corrections and the interaction with the base fluid due to viscous laminar flow is described with Stokes drag. Mechanical loading is introduced as constant rate shear, compression or elongation to a system of particles set initially to a single chain, a column of body centered tetragonal (BCT) unit cells, a thick BCT structure or to a structure grown with electric field from originally random configuration. Results show that the single chain structure has usually the highest relative strength. Electrorheological systems under compressive loading were found to transmit the largest force from one plate to another. Under elongation loading a thick BCT structure seemed surprisingly weak compared with the system under compression or shear. In addition, the response of a BCT structure to sinusoidally alternating shear or tensile straining has been studied. Under tensile loading it was found that the ability of the system to transfer force is much more dependent on oscillation frequency than under shear loading.

Apparent stress–strain relationships in experimental equipment where magnetorheological fluids operate under compression mode

“…According to Lukkarinen and Kaski (1998), thicker structures may occur in a system with a small gap size between the two plates. Thus, at the beginning of compression, the gap is considered to have a large size and this occurs during the first and second regions.…”

Effect of friction between particles in the dynamic response of model magnetic structures

“…The mutual polarization of the particles is considered self-consistently, and is found to increase with the enhancement of the particle concentration and the permittivity ratio between the solvent and the particles. Lukkarinen and Kaski [14] studied the mechanical properties of electrorheological fluids under various dynamical loading conditions (shear, compression and elongation loading) using a computer simulation model. Compressive loading was found to transfer the largest force from one plate to another.…”

Transient response of compressed electrorheological fluid

“…For low mechanical output of ER fluids working in shearing mode, to achieve higher mechanical performance, recently, compression and elongation of ER fluids have been experimentally and theoretically carried out [23][24][25][26][27][28][29][30][31][32]. These investigations indeed show that compression and elongation of ER fluids could bring much higher mechanical outputs than that working in shearing mode.…”