THE EFFECT OF SOLID FRACTION CONCENTRATION ON THE TIME-DOMAIN PERFORMANCE OF AN ER FLUID IN THE SHEAR MODE

Some aspects of electro-stress and electro-hydraulic time delay in an electro-rheological fluid are examined for their dependence on the vol ume fraction of solid in the mixture. Early results show that the dens ity matching of the solid and liquid phases of an ERF brings little im provement in the serviceability of a suspension. Subsequent testing is based on non density matched mixtures which are examined over a range of 0 less than or equal to sheer rate less than or equal to 19000s(-1 ), 15 less than or equal to temperature degrees C less than or equal t o 50 and 20 less than or equal to % volume fraction of solid less than or equal to 40. The effect of prolonged operation on the durability o f the fluid is also reported. The results are used to provide pointers towards fluid selection, a control strategy and to help in the determ ination of operating parameters in order to optimise clutch performanc e. Testing took place on a concentric clutch (Couette) type apparatus which had an electrode separation of 0.5 mm.