Electrorheological Device

Fluids capable of rapid, dramatic and repetitive changes in their rheological properties in the presence of an electric field are known as electrorheological (ER) fluids. In the absence of an electric field, ER fluids are usually in a liquid-like state. As soon as an electric field is applied, the fluid generally becomes solid-like, or at least becomes highly viscous.

1 Introduction

Electrorheological fluids have been successfully used in state-of-the-art automobiles, in damping systems and clutches (Corvette Anniversary Edition 2003).

ER fluids usually consist of particles held in suspension by a non-conducting liquid. The suspending liquid is typically a low-viscosity hydrocarbon or silicone oil. The particles are commonly metal oxides, organic–inorganic aluminosilicates or polymers. Sedimentation of the particles is a well-known problem in electrorheology. In order to stabilize the dispersion and avoid sedimentation, the suspended particles should have a lower density than the surrounding liquid. Thus, the behavior of an ER fluid in an electric field depends strongly on its composition.

The Electro Rheological Device (ERD) (images above: left conventional ERD, right ERD for the convectional temperature device CTD) is a special accessory for the MCR rheometer series from Anton Paar. The ERD can provide voltage from 0 V to 12000 V, and can be set to constant or ramping voltages.

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