HIGH-SPEED JOURNAL BEARINGS LUBRICATED WITH ELECTRORHEOLOGICAL FLUIDS- AN EXPERIMENTAL INVESTIGATION

It is well known that the imposition of an electric field on an Electr o-Rheological (ER) fluid alters the viscosity and as a consequence the flow properties of the fluid If such a fluid is used to lubricate a j ournal bearing system, it is expected that the imposition of an electr ic field between the rotor and the stator will cause the alteration of the dynamic properties of the journal bearing. For the present, it ha s been proved that this is valid only for low speeds and high radial c learances of Couette type viscometers. In this paper an experiment in a high speeds (16000 to 65000 s(-1)) journal bearing with small radial clearance is presented The experiment performed has showed the phenom enon and has proved that the ER FLUID at high shear rates under consta nt temperature, follows the Bingham model in realistic bearings. Prope rties such as wall shear stress, dynamic yield stress relative viscosi ty are experimentally determined as functions of the electric field, f or different particle concentrations and the shear strain rate under c onstant or free to vary temperature (due to operating conditions, angu lar velocity, friction). Concluding the ER fluids can be used to creat e ''smart'' journal bearings. Vibration controllers can be constructed to control the stability of the ER fluid lubricated bearings.