Analysis of fully coupled torsional and lateral vibrations of unbalanced rotors subject to axial loads

Sukkar R., Yigit A. S.

Kuwait Journal of Science and Engineering, vol.35, no.2, pp.143-170, 2008 (Journal Indexed in SCI Expanded) identifier

  • Publication Type: Article / Article
  • Volume: 35 Issue: 2
  • Publication Date: 2008
  • Title of Journal : Kuwait Journal of Science and Engineering
  • Page Numbers: pp.143-170
  • Keywords: Axial loading, Coupled dynamics, Torsional and lateral vibrations, Unbalanced rotors


Vibration problems can be serious cause for concern in rotating machinery. An accurate diagnosis and treatment of these problems requires a thorough understanding of all the dynamic phenomena involved. In this study, a fully coupled model, which includes lateral, and torsional vibrations and the effect of axial forces is developed. A lumped parameter model is obtained by a Lagrangian procedure. The equations are numerically solved to obtain response for typical excitations. Simulation results presented show the importance of including the shaft rotation as a separate degree of freedom. It appears that most nonlinear phenomena are not evident in the case of a constant shaft speed, since most of the nonlinearities involve shaft speed and acceleration. On the other hand, when the shaft speed is considered as a separate degree of freedom, several nonlinear phenomena including chaotic behavior can be observed. The simulations also show that axial forces may affect the response significantly. It is anticipated that the results will be of use in developing effective condition monitoring strategies.