Stiffening effect of the rotor during the rotor-to-stator rub in a rotating machine

Rotor-to-stator rub is one of the common malfunctions in rotating machinery. When rub–impact occurs, the transient dynamic change of the natural frequencies of the system will appear. This change actually reflects the stiffening effect of the rotor during the rotor-to-stator rub. In this paper, the dynamic model of the rubbing rotor system is established and the dynamics of the rubbing rotor is investigated. The parameter identification is used to process the vibration data obtained by numerical simulation and experimental test. The change in the transient stiffness of the rotor is analyzed and the stiffening effect of the rotor is investigated quantitatively. It is found that the change of the transient stiffness can effectively reflect the severity of the rub–impact.