Finite element method for disc-rotor dynamic characteristics analysis of gas turbine rotor considering contact effects and rod preload

Disc-rotor has the advantages that the common continuous rotor doesn't have, but the specific structure of the disc-rotor makes it complex to compute the natural frequencies and vibration modes. It is mainly reflected in that the discs contact each other, which will bring considerable impact on the dynamic behavior of the disc-rotor. The state of contact between the discs is closely related rod preload. In the present paper the finite element model of a disc rotor is established in ANSYS FE software. Then natural frequencies under different rod preloads are calculated, and dependence of rotor natural frequency on rod preload is analyzed. After that, modes of the rotor under a specific preload are given. By analyzing the modes, some notes of the disc rotor assembly process are obtained.