Modelling and experimental verification of an asymmetric Jeffcott rotor with radial clearance Joseph Páez Chávez a,b , Vahid Vaziri Hamaneh a , Marian Wiercigroch a,n a Centre for Applied Dynamics Research, School of Engineering, University of Aberdeen, Aberdeen AB24 3UE, UK b Facultad de Ciencias Naturales y Matemáticas, Escuela Superior Politécnica del Litoral, P.O. Box 09-01-5863, Guayaquil, Ecuador article info Article history: Accepted 26 May 2014 Handling Editor: A.V. Metrikine abstract This paper presents a new mathematical model of a Jeffcott rotor within a snubber ring with anisotropic support. The derivation and validation of the model are based on an experimental rig designed and developed in Aberdeen University. Special attention is given to the estimation of the physical parameters of the snubber ring support, which reveals the presence of damping effects that are incorporated in the mathematical model. Furthermore, the numerical implementation of the model is described and mathemati- cally justified in detail. The experimental investigation shows a sequence of different dynamical scenarios obtained under variation of the rotational speed, which in turn is satisfactorily reproduced by the theoretical model. The experimental and numerical results demonstrate the predictive capabilities of the model around the onset of impacts between the rotor and the snubber ring, which is one of the most common unwanted phenomena encountered in industrial applications of rotating machinery. & 2014 Elsevier Ltd. All rights reserved. 1. Introduction Dynamics of rotating machinery has been extensively studied in the past by many researchers, mainly due to the numerous applications in industry, such as power generation, large-scale manufacturing, automobile engines, aerospace propulsion and home appliances, among others. In all these applications, one of the most common concerns of designers and troubleshooters is the long-term exposure of the rotating machines to vibration, which eventually can lead to catastrophic failures or accidents. This can be the case when e.g. the undesired vibration becomes close to one of the natural frequencies of the machine structure (resonance) or due to dangerous vibration-induced impacts between rotating and stationary components. Such unwanted vibrations are often caused by mass imbalance, which occurs when there is a mismatch between the principal axis of the moment of inertia of the rotating element and its axis of rotation. From a practical point of view, this phenomenon can be produced by blade-loss conditions, looseness of parts, misalignment, thermal deformation, factory residual imbalance, etc., which makes the presence of lateral vibrations unavoidable. This undesired effects can have quite negative consequences in terms of durability, reliability and safe operation of rotating machines. Our main concern in the present work is the study, both experimental and theoretical, of the vibration-induced impacts between a planar rotor subject to mass imbalance and an outer snubber ring, which falls into the field of rotor–stator Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/jsvi Journal of Sound and Vibration http://dx.doi.org/10.1016/j.jsv.2014.05.049 0022-460X/& 2014 Elsevier Ltd. All rights reserved. n Corresponding author. E-mail addresses: jpaez@espol.edu.ec (J. Páez Chávez), vahid.vaziri@abdn.ac.uk (V. Vaziri Hamaneh), m.wiercigroch@abdn.ac.uk (M. Wiercigroch). Journal of Sound and Vibration 334 (2015) 86–97