Dynamic modeling and bifurcation analysis of blade-disk rotor system supported by rolling bearing

Abstract

The dynamic modeling and bifurcation analysis are carried out for a blade-disk rotor system supported by rolling bearing in this paper. Considering the nonlinearity of rolling bearings and the flexible coupling between multi-stage blades and disk, the coupled dynamics model of the blade-disk rotor system is established by using the finite element method. Subsequently, with numerical simulations the steady-state responses of the nonlinear system are obtained. Using the bifurcation diagrams, the time histories, whirling orbits, Poincaré maps and power spectrums, the parametric studies are conducted in detail to investigate the system's bifurcation characteristics. The results indicate that considering the blade mass and stiffness will create a new resonance peak near the first-order resonance of the rotor system with linearized rolling bearing stiffness. For the rotor system with nonlinear rolling bearing forces, with the increase of the blade length, the system motion pattern becomes complex, slender blades will lead to chaotic motion at high speed, and blade stiffness and mass will obviously increase the rotational speed region of quasi-periodic motion. Moreover, the Young's modulus of the blade significantly affects the bifurcation characteristics of the system, i.e., small Young's modulus values make the motion form complex, which leads the range of quasi-periodic motion and chaotic motion increased obviously. The results of this research would be helpful to deepen comprehensive understanding of the nonlinear dynamic characteristics of blade-disk rotor system supported by rolling bearing.