Transient Response of a Support Structure Excited by an Accelerating Unbalanced Rotor

Abstract

The transient vibration of a beam supporting an unbalanced rotor is investigated using finite element discretization techniques. The rotor speed is time dependent to simulate transients at startup. The beam is low-tuned relative to the rotor operating speed. A rigid rotor shaft mounted in an oil-film bearing is considered. The “short-bearing” approximation and nonlinear performance of the journal bearing are assumed. The method of solution for transient response is based on direct integration of the system equations of motion using finite element in time formulation. The results of numerical anlaysis are presented in graphical form and discussed. One notes significant effects of the journal bearing on the system response.