Non-stationary analysis of rotor/casing systems with rubs

A flexible Jeffcott rotor supported at the ends by identical squeeze film dampers is considered in this paper, to study the non-stationary vibration due to rubbing with casings during passage through the critical speed. The rotational speed of the rotor is supposed increasing at a constant angular acceleration. The contact force theory is used to calculate the impacting forces and friction forces. The aim of this paper is mainly at revealing the effects of rotational acceleration on the occurrence of diverging backward whirl, from which one can determine whether the rotor can pass through the critical speed or not. The influence of some system parameters on the critical acceleration are also discussed.