Investigation of a flexible rotor system with squeeze film dampers by a combined numerical procedure

Abstract

Dynamical behavior of a flexible rotor system with supporting nonlinearities are investigated by using a hybrid numerical procedure. Finite element method is used to model the linear dynamics of the rotor structure and the discrete element method to model the supporting parts at two ends, which contain ball bearings and squeeze film damper. The discrete bearing part consists of four elements, inner and outer races of the ball bearing and the squeeze film damper respectively, and each element has three degrees-of-freedom. The two parts are coupled together such that the motion of the flexible rotor is transmitted to the inner race of ball bearing with corresponding reaction force from bearing applied to the rotor. A hybrid numerical method is proposed to investigate the dynamical characteristic of the rotor/bearing system. Numerical results show that the responses of the complicated rotor model are different from that of simple rotor model under same working conditions. New phenomena are presented using motion orbits, spectrum and bifurcation diagram. It is found that the proposed combined model and hybrid numerical method are efficient and the responses can more coincide with the practical ones than simple rotor model.