Abstract: Based on a Jeffcott rotor model, dynamic characteristics of rotor’s radial rub-impact with the consideration of turborotor’s nonlinear fluid-structure interaction forces are studied in six degrees of freedom of the rotor. Dynamic behaviors of the system are analyzed with bifurcation diagrams, waveforms, frequency spectrums, orbits, Poincaré maps and waterfalls. It is concluded that the stable range of the system responses is largely reduced, the rotating speed threshold of rub-impacting is decreased, and the complicated motion patterns appear at the early stage of rub-impact, compared with the case without considering turborotor’s nonlinear fluid-structure interaction forces; thick superharmonics and subharmonics emerge in the axial and torsional vibration spectrums respectively, and these components characterizing chaotic motion are the main motion patterns of the system; in the full range of rotating speed, lateral vibrations almost take on pure synchronous component, the axial vibration demonstrates rich superharmonics, which mainly scatter in three thick superharmonic bands that approach to three fixed frequencies with their amplitudes growing up as rotating speed increases, the torsional vibration displays rich subharmonics near 1/2 time frequency component, the amplitudes of which increase with rotating speed. These conclusions are of great significance to the rotordynamic design and fault diagnostics of turborotor systems.

Key words: Dynamic analysis, Full degrees of freedom, Nonlinear fluid-structure interaction, Radial rub-impact, Rotordynamics, Turborotor