Nonlinear Dynamic Analysis of Rub-Impact Rod-Fastening Combined Rotor Systems with Internal Damping

The objective of this study is to examine the nonlinear dynamic behavior of the rod-fastening combined rotor-bearing (RFCR) system with rub-impact, with a specific focus on the influence of internal damping. A dynamic model for the RFCR system is formulated using the finite element method based on the Lagrange equation. This model takes into account the system’s nonlinear characteristics, including rub-impact forces and oil-film forces. Through the analysis of bifurcation diagrams, Poincaré maps, time-domain plots, and frequency spectra, the effects of internal damping and stator stiffness on the system’s instability and nonlinear response are investigated. The findings reveal that both internal damping and stator stiffness have a significant impact on the vibration and instability of the RFCR system at varying speeds. Particularly, systems with rubbing faults exhibit pronounced nonlinearity and instability in high-speed regions. Furthermore, the presence of internal damping disrupts the stability of the P3 motion in the system, and the effect of divergence becomes more pronounced as the friction coefficient increases. In conclusion, considering internal damping is crucial when undertaking dynamic modeling and analysis of such complex rotors, as it plays a vital role in fault diagnosis and vibration control for practical RFCR systems.