ELECTRORHEOLOGICAL RELAXATION-TIMES DERIVED FROM PRESSURE RESPONSE EXPERIMENTS IN THE FLOW MODE

We examine the experimental pressure response for a set of electrorheo logical valves operating at several steady flow rates to step function voltage inputs and analyse the factors that may contribute to the com plex forms observed. Using a numerical algorithm incorporating a visco elastic model for the fluid the response of the valve flow profile to changes in theology is found to be relatively fast compared to the exp erimental pressure response and thought not to feature as a significan t contribution to the final shape. The dynamic interaction of the valv e and its associated system of pump and connecting pipes is investigat ed using a multi-element lumped parameter model and reveals a frequenc y spectrum containing resonances comparable to the experimental result s. A simple lumped parameter model is less successful. Using the multi -element model for the system an upper bound can be placed on the basi c response time of the electro-stress itself under realistic engineeri ng conditions.