Vibration control of a rotor supported by journal bearings and an asymmetric high-static low-dynamic stiffness suspension

Abstract

In this paper, the optimum design of an asymmetric model of a high-static low-dynamic stiffness (HSLDS) suspension for the vibration control of a rotating machine is studied. The rotating system consists of a flexible rotor supported by short journal bearings and HSLDS suspensions and is excited by an unbalance force. The equations of motion are solved numerically using the Runge–Kutta method. The bifurcation diagrams, phase portraits, Poincare maps and power spectra show the existence of various response regimes, such as periodic, period-two and quasi-periodic, in the dynamic response of the system. The design procedure is formulated as a multi-objective optimization problem which minimizes objectives including the rotor and bearing vibration, the bearing force transmission and the compliance of the HSLDS suspension under static loading, to obtain the appropriate force–displacement relation for the asymmetric HSLDS suspension. The multi-objective genetic algorithm is applied to identify the best set of the design parameters. The advantages of using an optimum HSLDS suspension to fulfill the design requirements in an operating speed range are demonstrated. It is also shown that the optimum suspension with low-dynamic stiffness can suppress the non-periodic behavior of the rotating machine in the considered operating speed range.