The dynamic response characteristics of the internal rotor⁃bearing system are directly related to the pros and cons performance of the turbine.In this paper, the finite element method is used to model the rotor⁃bearing system, considering the effect of bearing stiffness on the critical speed of the system, the unbalanced response characteristics at the same speed and different speeds,the unbalanced response characteristics are discussed in detail, the sensitive position of the system is determined, which provides the basis for the optimization design of the steam turbine.

Taking the rotor-bearing system of a steam turbine as the research object, considering the influence of the shaft gyro moment and moment of inertia, the finite element model of rotor-bearing system dynamics is established . The dynamic response characteristics of the rotor-bearing system under earthquake excitation are studied by inputting different ground motion peak acceleration and changing phase angle in X direction and X-Y direction. The equivalent stress and displacement trends of key nodes in rotor-bearing system are analyzed, and the safety of turbine rotor-bearing operation under seismic load is discussed. The aim is to provide a theoretical reference for the seismic design of rotor-bearing system.