Earthquake-Induced Instability of a Rotor Supported by Oil Film Bearings

Abstract

The effect of seismic waves on the stability of a Jeffcott rotor supported by oil film bearings is investigated by calculating loci of the centers of the journal and the disk using the Runge-Kutta-Gill method. It will be shown that a linearly stable rotor can become unstable under a strong artificial shock and a real seismic wave, if it is running at speeds above twice the first critical speed, which is close to the natural frequency of the rotor. Thus, it will be pointed out that the linear analysis is insufficient to examine the stability of a rotor-bearing system if the rotor is operated above twice the critical speed and a strong shock such as due to an earthquake is expected.