Abstract: Aiming to the vibration problem of the bolted rotor system caused by the assembly process of the aero-engine, the effect of bolts assembly sequence on time-varying bending stiffness of connected structure and the initial deformation of rotor shaft caused by unbalanced preload were analyzed by the ANSYS. The dynamic model of bolted rotor system was established based on finite element method, and the bolted connection structure was simulated by two joint elements. The effect of assembly sequence on the critical speed and its corresponding amplitude was studied by the Newmark-β method, The validity of the theoretical analysis results is verified by experiments on a bolted rotor test rig. Results show that the bending stiffness exhibits piecewise linear characteristics when bolts are tightened in sequential and cross tightening, and the residual preload of cross-tightening is larger and more symmetrical than sequential tightening, so the cross-tightening shows the smaller initial deformation of rotor shaft and the larger first stage bending stiffness of corresponding connection structure, which lead the first-order critical speed of rotor system is higher than sequential tightening. The initial deformation of the rotor shaft will affect the time domain amplitude of the rotor system. The bolted assembly technology is researched to further understand the effect of bolted connection structure on the response characteristics of rotor system.

Key words: bolted joint, rotor system, assembly sequence, imbalance preload force, vibration characteristic