Seismic effect on the stability of a rotor supported by oil film bearings.

The effect of seismic waves on the stability of a rotor supported by oil film bearings is investigated by calculating the loci of centers of the rotor and the journal using the time-marching method. It will be shown that the rotor-bearing system, operated at a speed above twice the critical, becomes unstable when a sufficiently strong shock is given to the system, in spite of the fact that the rotational speed of the rotor is lower than the linear stability limit. At first, the effect of an artificial sinusoidal shock is considered, and then that of a real seismic wave (Taft in California, USA, 1952) is examined.