Model verification and vibration analysis of the four-disk hollow flexible shaft rotor system

Abstract

Rotor unbalances failure due to various factors such as manufacturing defects, mounting errors, and material inhomogeneity is inevitable, and will be aggravated by bearing pulse displacement excitation caused by maneuvering flight. Therefore, the purpose of this paper is to study the vibration of the rotor system under disk unbalance forces and bearing pulse displacement excitation. Firstly, the differential equation of motion for four-disk flexible hollow shaft rotor system modeling with a simple finite element model(SFEM) is established by the Lagrangian method in non-inertial systems, and the shaft is modeled using Timoshenko beam theory. Then, the dynamic characteristics of the four-disk flexible hollow shaft rotor are analyzed and compared with the 3D finite element model(3D FEM) to verify the accuracy of the model. To analyze the effects of different disk unbalanced positions and pulse displacement excitation on the vibration characteristics of the rotor, the characteristic vector method and the Runge–Kutta method are used to obtain the steady-state solution and the transient solution, respectively. In addition, the simulation results show that suitable in-shaft damping has a stable effect on the rotor during the start-up. Disk2 and Disk3 are more sensitive to synchronous harmonic excitation and pulse displacement excitation than Disk1 and Disk4. The research of this paper provides an important basis for vibration monitoring and control, and vibration transmission analysis of aero-engine rotor system.