RESEARCH ON COUPLED BENDING AND TORSION VIBRATION OF BLADE-ROTOR-BEARING SYSTEM WITH NONLINEAR OIL-FILM FORCE

A coupled bending and torsion model of blade-rotor-bearing with nonlinear oil-film force was presented. To analyze the impact of blade-bending, the blade was assumed to be a cantilever beam and then discretized using the assumed modes method. The motion equation was established by the Lagrange approach and numerically calculated by Runge-Kutta method. The bifurcation diagrams, waterfall plot, phase spectrum map and poincarésection were obtained to analyze dynamic characteristics of the system. The results reveal multiform complex nonlinear dynamic behavior of the blade-rotor-bearing system. Thorough a comparison with the system whose blades were not considered, it is shown that the blade-bending vibration advances the unstable region of the system and arises the chaotic motion of the system in some rotational speeds.