Insight on uncertainty of geometrically nonlinear rotor with rub-impact under maneuvering motion

Abstract

Maneuvering motion inevitably leads to parametric excitations and inertial forces, which greatly aggravates the whirling motion of rotor system and then induces rub-impact fault between rotor and stator. Under this circumstance, rotor dynamic analysis under maneuvering conditions is of considerable importance for safe and efficient functioning of rotating machinery. Furthermore, the uncertainties are inherently present in mechanical systems due to wear, properties variations and working condition evolutions. The main objective of this paper is to investigate the nonlinear characteristics and interval responses of deterministic and uncertain rotor systems under maneuvering motion. Due to whirling motion with large amplitude, the geometrical nonlinearity of shaft and rub-impact nonlinearity are considered in the rotor system. Then the equations of motion of deterministic rotor system with rub-impact under maneuvering motion are theoretically derived according to the Lagrange's equation. On this basis, the parametric uncertainties of disk eccentricity and flight maneuvers involved in the rotor system are described by the Chebyshev interval algorithm. After that the nonlinear dynamic characteristics of deterministic rotor system under maneuvering motion are numerically solved and analyzed in terms of bifurcation diagram, time histories, whirling orbit, Poincaré map and frequency spectrum. Additionally, the interval responses of vibration displacement and impact force at different rotational speeds are further examined.