Simultaneous estimation of the residual unbalance and bearing dynamic parameters from the experimental data in a rotor-bearing system

Two separate identification algorithms, for the simultaneous estimation of the residual unbalance and bearing dynamic parameters in a rigid rotor-bearing system, have been described and demonstrated both by numerical simulations and experimental measurements. The first method uses the impulse response measurements of the journal from bearing housings in the horizontal and vertical directions, for two independent impulses on the rotor in these directions. Time-domain signals of impulse forces and displacement responses are transformed to the frequency domain, and are used for the estimation of the residual unbalance and bearing dynamic parameters. The second method employs the unbalance responses from three different unbalance configurations for the estimation of these parameters. Unbalance response measurements are taken for both the clockwise and counter-clockwise rotations of the rotor. To test the developed identification algorithms, numerical simulations have been performed and algorithms are found to be excellent even in the noising measurement environment. Then experimental measurement responses have been fed to identify the residual unbalance and bearing dynamic parameters by both the methods. To check the suitability of the identified parameters, they are substituted in a numerical model of the test rig to generate the simulated responses. The simulated responses are in fairly good agreement with experimental responses in terms of mimicking predominant resonances. The identified unbalance masses match quite well with the residual masses taken in the dynamically balanced rotor-bearing test rig. (C) 2008 Elsevier Ltd. All rights reserved.