Random vibration analysis of rotating machines under seismic excitations

For rotating machines subjected to six component earthquake ground motions, the equations of motion involve random inhomogeneous as well as parametric excitations. Both inhomogeneous and parametric excitations are correlated and nonstationary. The method of Monte Carlo simulation using the fast Fourier transform (FFT) technique is used to obtain the statistics of the rotor-bearing system response. It is found that the rotational components of earthquake ground motions have a significant effect on the rotational type response of the rotor-bearing system, whereas their effect on the translational type response is not quite significant.