Vibration Characteristics of Rotor System with Loose Disc Caused by the Insufficient Interference Force

The loose of mechanical parts is one of the common failures in rotating machinery. The current researches of loose fault mainly focus on non-rotating components. However, the loose of disc, which is the main work part in the rotor system, is less paid attention, and the mechanism and dynamics characteristics of the loose fault are also almost ignored. In this paper, a dynamic contact model of the rotor system with loose disc is established considering the microscopic surface topography. Through the numerical simulation, the vibration characteristics of the disc-shaft rotor system are analyzed and discussed. The simulation results are further verified by experiments. The results show that the rotation state of the disc is affected by the rotation speed of the shaft, contact stiffness, a gap between the disc and shaft, damping of the disc, and the rotational damping. When the speed difference between the disc and shaft is zero or large, the collision frequency is mainly composed of one frequency component. When the rotational speed of the disc approaches the shaft, the beating vibration phenomenon of the disc occurs in the horizontal direction. As the decreases of relative speed between the disc and shaft, the disc trajectory changes from ‘circular’ to ‘double ring’ and then ‘circular’. The research results on nonlinear dynamics characteristics of the loose disc has important theoretical value and practical application value, and makes up for its shortcomings in the rotor system with loose disc.