PARAMETER ESTIMATION IN IMBALANCED NON-LINEAR ROTOR-BEARING SYSTEMS FROM RANDOM RESPONSE

✍ Scribed by R. Tiwari; N.S. Vyas

• Publisher: Elsevier Science
• Year: 1997
• Tongue: English
• Weight: 334 KB
• Volume: 208
• Category: Article
• ISSN: 0022-460X
• DOI: 10.1006/jsvi.1997.1083

✦ Synopsis

This study attempts to explore the possibility of estimation of linear and non-linear stiffness parameters of rolling element bearings in rotor systems experiencing harmonic excitation from unknown imbalance as well as random excitation from a variety of sources, primarily the progressive random deterioration of the bearing surfaces and subsurfaces. The random forces inflicted on the system are comparable to the harmonic imbalance forces, if the imbalance is not very significant. In earlier studies, the authors addressed the inverse problem of parameter estimation in non-linear rotor-bearing systems experiencing only random excitations, under the assumption that the rotor is perfectly balanced. The problem of parameter estimation, in a non-linear rotor-bearing system experiencing small residual imbalance forces along with random forces, is transformed into one of slowly varying parameters through the stochastic averaging procedure. The resulting equations are modelled as an approximate Markovian process and a Fokker-Planck equation is derived to describe it. The Fokker-Planck equation is solved and processed further, to obtain the bearing stiffness parameters. The procedure has the advantage that it does not require an estimate of the excitation forces (harmonic and random) and works directly on the measured response signals of the system. The algorithm is illustrated for a laboratory rotor rig and the results are compared with those obtained through an existing analytical model. Estimates of the unknown imbalance of the rotor, its angular location and the damping ratio are also obtained, as by-products of the procedure developed.