Predicting Performance of an Electro-Rheological Fluid Clutch for Power Transmission

A clutch has the duty of interrupting power transmission without shutting off the source. As expected from any friction dependent operation, a traditional clutch suffers from wear and dynamic instability. What is proposed in this paper is to employ a liquid with a controllable apparent viscosity to avoid the inherent problems of friction. Electro-Rheological (ER) fluids can reversibly change between the liquid phase and a solid-like gel phase in response to electric potential fields in the order of a few kV/mm. Therefore, it is possible to use ER fluids as power transmission agents. If the level of power transmission is the result of the phase change of an ER fluid, then such a design has no moving components, smooth operation, low power consumption and a fast reaction time. This paper details experiments to quantify the variation of the shear strength of an ER fluid as a function of its important parameters. Then, these values are used to predict the amount of power transmission. Although ER fluids have attracted significant attention in the literature, published works deal with investigations either in the molecular level or in pure application. To the best of the authors’ knowledge, this paper reports the necessary information to predict performance in a practical format for the first time.