Comparison of Rotating Speed and Unbalance Influence on Journal Whirling Center

The dynamic equations of rotor-bearing system are built up by combining d'Alemdert principle with Rize way,and the nonlinear oil film forces based on steady short bearing model are coupled to system.Such nonlinear equations are numerically solved by Newmark integration method.The nonlinear response and the journal trajectory of the rotor-bearing system are numerically and experimentally investigated.It is found that the journal whirling center relates not only to the rotating speed and static load but also to the vibration amplitude,and the influence degree of the rotating speed and the unbalance on journal the whirling center is equivalent.Hence the nonlinear oil film force cannot be well expressed by the Tarloy series.When unbalance of the nonlinear rotor system is identified by adopting such oil film force the error will be lager.