Stochastic dynamic characteristics of a flexible rotor with rubbing fault

The occurrence of rubbing faults in rotor systems generally possesses significant uncertainty due to manufacturing or installation tolerances. This paper presents a stochastic finite element model for a rub-impact rotor system subjected to probabilistic uncertainties of parameters. The combination of the Harmonic Balance Method (HBM) and general Polynomial Chaos Expansion (PCE) are employed to evaluate the stochastic dynamic responses of the system, which enables the expedient quantification of uncertainties of the periodic solution branches. Parametric studies are carried out to investigate effects of variability involved in the contact stiffness, gap and unbalance on the global nonlinear amplitude frequency response. Moreover, the effectiveness of the proposed model is verified by the classical Monte Carlo simulation (MCS). Numerical results reveal that the occurrence of uncertainties may bring about variations of dynamical behaviors in rubbing rotors, emphasizing the necessity to consider uncertainties in the robust analysis of rub-impact faults. The understanding of the uncertain dynamic behaviors of rubbing rotors is of guiding meaning in diagnosis and prevention of rubbing faults in gas turbine.