A Non-Linear Model for Dynamic Response of Electro-Rheological Fluid in Flow Mode

In this paper a model is presented for the electrical and mechanical properties of ER fluid in flow mode and it is concluded that a similar model must also govern the properties of ER fluid in shear mode of operation. A settling time constant is defined for the fluid which determines the speed of response. The model has been derived from several years of experience gained working with ER fluid and has not been verified experimentally. The proposed model is based on the theory that the electrical properties of ER fluid such as resistance and capacitance are functions of the applied voltage and time. This function is characterised by a time constant (TR) for a simple model and may be characterised by a natural frequency and a damping ratio for more complex model. The numerical solution of these functions when compared with the experimental results obtained from large step input confirm the viability of the proposed model. Further work, however, is required to identify the coefficients numerically from data obtained on a special test rig.