Nonlinear Dynamic Behavior Analysis of Dual-Rotor-Bearing Systems with Looseness and Rub–Impact Faults

The nonlinear dynamic behaviors of dual-rotor-bearing systems with looseness and rub–impact faults are discussed in this paper. The dual-rotor-bearing system with looseness and rub–impact coupling faults is established by the finite element method. The component mode synthesis (CMS) and proper orthogonal decomposition (POD) methods are introduced. The CMS and POD methods are used to reduce the original rotor system model, and the efficiency of the order reduction method is verified by comparing the dynamic behaviors of the original and reduced systems. The frequency spectrum and amplitude–frequency behaviors of rotor systems are studied. The results can provide qualitative guidance to structural design optimization of large rotating machines and prior information for looseness and rub–impact coupling faults.