JOURNAL OF SOUND AND VIBRATION www.elsevier.com/locate/jsvi Journal of Sound and Vibration 276 (2004) 361–379 Non-linear dynamic interactions of a Jeffcott rotor with preloaded snubber ring E.E. Pavlovskaia*, E.V. Karpenko, M. Wiercigroch Centre for Applied Dynamics Research, School of Engineering and Physical Sciences, King’s College, University of Aberdeen, Aberdeen AB24 3UE, UK Received 3 February 2003; accepted 22 July 2003 Abstract A two-degrees-of-freedom model of a Jeffcott rotor with a preloaded snubber ring subjected to out-of- balance excitation has been developed. The purely impact interactions have been investigated. The rotor makes intermittent contacts with the preloaded snubber ring and as a consequence it can be in one of five different contact regimes, which boundaries have been found analytically. The current location of the snubber ring has been determined using the principle of the minimum elastic energy in the snubber ring. Consequently a non-linear piecewise smooth dynamical system has been obtained and studied numerically. The results in form of bifurcation diagrams, phase portraits and Poincar ! e maps show significant differences for the cases with and without preloading. r 2003 Elsevier Ltd. All rights reserved. 1. Introduction Complex rotor systems have wide industrial applications, such as aero engines, steam and gas turbines, turbogenerators, etc. Forced vibrations in these systems are usually caused by centrifugal forces due to rotor mass imbalance, and various transmission forces. Even if the rotor is well balanced, the balance may deteriorate with use. To prevent the housing from deterioration caused by the excessive amplitude vibrations the preloading of the stator is often introduced. The level of the preloading together with imbalance, stiffness and damping crucially effect the dynamic system behaviour. A full understanding of dynamics of real rotor systems (like gas turbines) is difficult and sometimes impossible without first considering the behaviour of simple models. To study the ARTICLE IN PRESS *Corresponding author. Fax: +44-1224-272-497. E-mail address: e.pavlovskaia@eng.abdn.ac.uk (E.E. Pavlovskaia). 0022-460X/$ - see front matter r 2003 Elsevier Ltd. All rights reserved. doi:10.1016/j.jsv.2003.07.033