As “smart” are characterized materials which have properties that can be changed in real time by a way of an external control action. Electrorheological (ER-) fluids are such materials since their apparent viscosity can be altered substantially under a controllable electric field. ER-fluids consist of a dispersion of fine dielectric powder, usually strongly hydrophile, into a fluid lubricant.

An ER-fluid is used to fill the gap between two parallel sets of circular, concentric plates assembling the “smart” vibration dynamic absorber as part of a rotor system. One set of plates is resiliently connected to a rotor but the other is rigidly attached to it. The effect of the ER-fluid activation by an external electric field on the relative motion of the plates results in a controllable damping force of viscous and friction type.

Numerical simulations of the rotor vibrations are carried out for a range of speeds including resonance and for several electric field levels. Increasing the electric field in the absorber yields in rotor amplitude reduction up to a threshold electric field which sticks the plates. Substantial improvement in the absorber efficacy is obtained by active control of the electric field using a feedback control scheme which optimizes the electric field input for maximum energy dissipation.

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