Sensitivity Analysis for Unbalance Identification of Rotor Systems

Various types of rotor faults may appear in rotating machines over time. Unbalance is the most commonly occurring fault in rotating machines. This work proposes sensitivity analysis for unbalance identification in rotating machines using a model-based approach. The sensitivity for unbalance response has been computed as response per unit rotating unbalance force using the finite element method. The rotor system has been considered under various end supporting conditions, e.g. isotropic undamped, damped bearing and anisotropic bearing cases. Viscous form of damping has been considered to model bearing damping. The effect of gyroscopic forces has been included in the model. In the analysis, the response of the rotor system is recorded at various locations on the shaft when a unit unbalance is applied on any of the rotor disc/plane. The process has been repeated to find out the unbalance response sensitivity of the rotor system to unit rotating unbalance force at other disc/plane locations. The idea of the work involves applying the sensitivity analysis in proper selection of measurement points of unbalance responses in rotating machines in the process of unbalance identification.