Critical speed calculation and modal analysis of rotor for high-speed machine

The critical speed of the rotor can be calculated accurately by the transfer matrix method and the finite element method. Since the mass of the shaft section is neglected by the transfer matrix method, the calculation result is slightly larger. By establishing the 3D finite element model of the rotor system, the critical speed and mode of the rotor are analyzed. The results show that the bearing support stiffness has a great influence on the critical speed of the rotor, and the critical speed can be adjusted by changing the bearing stiffness and the rotor material. In order to avoid the critical speed of the rotor beyond the bending mode, the rotor shaft extension should be controlled within the safe range. The effect of the gyro effect on the natural frequency of the rotor is small, so the rotor gyro effect can be ignored when analyze the rotor dynamics.