According to the characteristics of the rotor system of a turbo-fan engine

a simplified rotor dynamic model with structural damping and squeezed film damping was constructed.Stability of the rotor system was analyzed by the Routh-Hurwitz criterion and the tracing method of the steady-state.The results show that the structural damping may cause the rotor system to be out of stability within a range of speed over the system's critical speed and may reduce the threshold speed for dynamic instability caused by the squeezed film damping.