Numerical analysis on the static–dynamic coupling influences of parallelism flaw in disc-rod rotor ball bearing system

Abstract

The static–dynamic coupling influences of parallelism flaw are investigated in the disc-rod rotor ball bearing system. Three-dimensional finite element method and a contact solving method are combined to analyze the statics of flawed disc-rod rotor. This analysis shows that parallelism flaw causes mass eccentric and rotation-dependent rotor bow. When these dynamic factors are involved, parallelism flaw promotes the nonlinear complexity in high speed and reduces global stability areas for the flawed disc-rod rotor. Unstable motions are more likely to happen when rotating speed exceeds the critical speed when rotor has a parallelism flaw. The spectrums of flawed rotor are composed of rotating frequency, subharmonic frequency, and their linear combinations. Flawed rotor has a larger bow deformation and orbit size than the ideal rotor. Dynamic stress performs the same property with vibration curves which enables rotors to have the first-order bow deformation. Dynamic stress of flawed rotor is much higher than that of ideal rotor. This paper presents a numerical analysis method to study the static-dynamic features of disc-rod rotor ball bearing system with parallelism flaw.