SIMULATION STUDIES OF ELECTRORHEOLOGICAL FLUIDS UNDER SHEAR, COMPRESSION, AND ELONGATION LOADING

Mechanical properties of electrorheological fluids under various dynam ical loading conditions have been studied using a computer simulation model. The model assumes electrostatic point-dipole interaction betwee n particles with or without multipolar corrections and the interaction with the base fluid due to viscous laminar flow is described with Sto kes drag. Mechanical loading is introduced as constant rate shear, com pression or elongation to a system of particles set initially to a sin gle chain, a column of body centered tetragonal (BCT) unit cells, a th ick BCT structure or to a structure grown with electric field from ori ginally random configuration. Results show that the single chain struc ture has usually the highest relative strength. Electrorheological sys tems under compressive loading were found to transmit the largest forc e from one plate to another. Under elongation loading a thick BCT stru cture seemed surprisingly weak compared with the system under compress ion or shear. In addition, the response of a BCT structure to sinusoid ally alternating shear or tensile straining has been studied. Under te nsile loading it was found that the ability of the system to transfer force is much more dependent on oscillation frequency than under shear loading. (C) 1998 American Institute of Physics. [S0021-8979(98)05203 -7].