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 poincare section 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.