Abstract
The ER activity of a number of ER fluids incorporating liquid crystalline (LC) and non-LC materials have been measured using a laminar-flow shear cell. The results from this static study are presented and clearly show that the unique self-organising and anisotropic physical properties of the LC materials contribute greatly to the ER activity of LC based ER fluids. A more in-depth evaluation was then carried out on a LC based ER fluid which involved measurements of the steady state behaviour, under various operational conditions, and the results compared with those from two conventional silicone based fluids. From this dynamic study it was found that within the shear rates tested, for an electric field strength above 1 kV mmn' there existed a linear relationship, culminating in a shear stress of 12 kPa at an electric field strength of 4 kV mmi'. The unique property of the shear stress increasing with increase in the shear rate makes LC based ER fluids an exciting area for further research and this could be of considerable importance in their use in a variety of control systems.
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