Experimental and theoretical investigations of the lateral vibrations of an unbalanced Jeffcott rotor

Ali Alsaleh, Hamid M. Sedighi, Hassen M. Ouakad*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)


The current work experimentally explores and then theoretically examines the lateral vibrations of an unbalanced Jeffcott rotor-system working at several unbalance conditions. To this end, three conditions of eccentric masses are considered by using a Bently Nevada RK-4 rotor kit. Measurements of the steady-state as well as the startup data at rigid and flexible rotor states are captured by conducting a setup that mimics the vibration monitoring industrial practices. The linear governing equation of the considered rotor is extracted by adopting the Lagrange method on the basis of rigid rotor assumptions to theoretically predict the lateral vibrations. The dynamic features of the rotor system such as the linearized bearing induced stiffness are exclusively acquired from startup data. It is demonstrated that, with an error of less than 5%, the proposed two-degrees-of-freedom model can predict the flexural vibrations at rigid condition. While at flexible condition, it fails to accurately predict the dynamic response. In contrast to the other works where nonlinear mathematical models with some complexities are proposed to mathematically model the real systems, the present study illustrates the applicability of employing simple models to predict the dynamic response of a real rotor-system with an acceptable accuracy.

Original languageEnglish
Pages (from-to)1024-1032
Number of pages9
JournalFrontiers of Structural and Civil Engineering
Issue number4
Publication statusPublished - Aug 1 2020
Externally publishedYes


  • Jeffcott rotor
  • Lagrange method
  • lateral vibrations
  • oil film induced stiffness
  • rotor-dynamics
  • sleeve bearings
  • system-equivalent stiffness

ASJC Scopus subject areas

  • Civil and Structural Engineering
  • Architecture


Dive into the research topics of 'Experimental and theoretical investigations of the lateral vibrations of an unbalanced Jeffcott rotor'. Together they form a unique fingerprint.

Cite this