Nonlinear Dynamic Analysis of Rotor-Bearing System with Coupled Fault of Parallel Misalignment, Unbalance and Impact Rubbing

Abstract

Misalignment and rubbing faults between the rotor and stator of rotor-bearing system are the most common faults of rotating machines. In this paper, the nonlinear dynamic behavior of rotor-bearing system with coupled fault of parallel misalignment, unbalance and rubbing is investigated. The equations of motion of the rotor system are derived by Lagrange’s equations, and many techniques such as bifurcation diagram, Poincare diagram, axial orbit, time domain waveform and amplitude spectrum diagram are employed to study the dynamic behavior of rotor system with rubbing, mass unbalance and parallel misalignment faults. The effect of variation of the parallel misalignment on various nonlinear phenomena such as periodic, three-periodic and quasi-periodic motions is investigated. Finally, some significant results for the safe operation and accurate identification of faults in rotating machinery are provided.