Electrorheological devices with annular electrodes
Strong electric fields (kV/mm) induce yield stresses (kPa) in electrorheological (ER) materials. The attraction of ER materials for control applications lies in their fast response to the field (1 ms) and low power requirements. Furthermore, actuation via the ER effect involves no moving parts. A dimensionless analytical solution for ER flow through rectangular ducts is valid for annular geometries, provided certain assumptions regarding the yield stress - electric field relationship are not violated. An approximation to the solution of the flow equations for annular geometries is useful for design with more general ER materials. ER devices with annular electrode gaps use space more efficiently than devices with rectangular electrode gaps.