Vibration characteristics of a rub-impact rotor system with a parallel misalignment under the unsteady oil-film forces

The dynamic model of the rub-impact rotor system with an parallel misalignment was set up. By the displacement constraint between rotors, the dynamic equations was developed on the Lagrange method. Simulations show that the rotor system´s low frequencies with large amplitude are 1/2, 1 and 3/2 octave spetrums. If the parallel misalignment is small, the displacement is small as the parallel becomes large. The results provide important theoretical references for fault diagnosis, shaft alignment and the safety operation.