Dynamic Study of Nonlinear Rotor-System Under Imbalance-Rub-Pedestal Looseness

Abstract

In order to achieve the purpose of perfect design of the rotating structure, analysing the dynamic performance associated with geometric nonlinearity emanating from the combination of loose rotating part and rotor-stator rub is of paramount significance. This work presents a theoretical study of the dynamics of geometrically nonlinear rotor shaft under various loose components, such as loose disc and loose pedestal. The novelty of this work lies in integrating the loose rotating parts in the equation of motion of nonlinear rotor model. The research offers validation modules for the loose rotating disc and nonlinear rub imbalance pedestal looseness models separately. The numerical simulation is applied to obtain the both linear and nonlinear vibration response of the rotor system at different rotational speeds. Runga-Kutta (R-K) method is employed for accurate and efficient solutions aimed at valuable insights into the dynamic behavior of the rotor system. A comparative study of frequency and time response behaviour between the linear and nonlinear rotor is presented here to identify various resonant conditions. It is evident from the results that the responses remain stable across the observable frequency range, while the jump phenomenon occurs within specific frequency ranges, which is the distinctive hallmark of the nonlinear rotor system.