Coupled lateral-torsonal vibration analysis of a geared shaft rotor system using a complex rotor variable approach

Abstract

Though there have been numerous studies on both rotor dynamics and gear dynamics, the studies on geared rotor dynamics have been rather recent. The study of the dynamic behavior of geared rotor systems usually requires that torsional and lateral vibration modes be coupled in the model, a problem not present for studies of rotors without gears. For rotor dynamics studies, the finite-element method seems to be a highly efficient modeling method. In the present work, a finite-element model of a geared rotor system on flexible shaft bearings has been developed. The whirling motion and critical speed of the system has to be found by considering all the rotors in the system as well as interactions between them. It is shown that the lateral vibrations have considerable effect when the natural frequencies of the lateral vibration and torsional vibration are close to each other, which is well expected. By studying the responses of the system with strong lateral-torsional coupling, the nature of the coupling effect is discussed.