Dynamics analysis of rod fastening rotor bearing system with pedestal looseness and rub-impact faults

ZHENG Mei-ru1,2, HEI Di1,2
(1.Department of Mechanical and Electrical Engineering, Shanxi Railway Institute, Weinan 714000, China;
2.Sada Traffic Energy Saving Technology Co., Ltd, Sanmenxia 472000, China)

Abstract: Aiming at the problem of nonlinear dynamics of the rod fastening rotor with both pedestal looseness and rub-impact faults, the model of the rotor with pull rod and its motion differential equations were established. The analysis of nonlinear dynamic responses of the faulty rotor were implemented with the changing of the speed, looseness stiffness and rod stiffness. For hydrodynamic sliding bearing taken as supporting part of the rotor, an approximate analytical solution of nonlinear oil film force of finite length hydrodynamic slide bearing was presented by combining the separation of variables method, variation principle and the infinite length bearing model based on boundary condition of the oil film. Finally, Newmark method was adopted to calculate the dynamic responses of the rotor system, and the comparison of dynamic behaviors was performed between the faulty rotor and the rotor without faulty. The results indicate that the dynamic behaviors of the faulty rod fastening rotor are very rich and complex. Comparing with the healthy rotor system, the bifurcation point of the faulty rod fastening rotor bearing system moves backward, and the dynamic characteristics can be analyzed in a wider speed range. It is also found that the pedestal looseness fault has more influence on the movement of the pull rod rotor bearing system.

Key words: rotor bearing system; finite slide bearing; pedestal looseness; rub-impact faults; dynamic characteristics