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A study of a rotor system with ball bearing induced non-linearities; and the development of transfer matrix techniques suitable for analysing such systems

This thesis is concerned with enhancing analysis tools for evaluating the non-linear dynamics of rotor bearing systems and in particular those where non-linearity is likely to result in aperiodic or chaotic behaviour, such as rolling element bearing systems. The tool to be enhanced was the transfer matrix approach which has been extensively used in the past for analysing linear rotor bearing systems. However, its use for evaluating non-linear behaviour has been virtually non-existent. Hence, the major aim of the thesis is to extend transfer matrix capabilities to handle non-linear systems. To this end a harmonic balance transfer matrix technique capable of analysing non-linear systems with multiple pedestal supported bearings was first developed. However, this approach is restricted to periodic response. To enable the analysis of non-linear systems with non-periodic response and provide a stability check for the harmonic balance technique, a transient transfer matrix has also been developed. The softwares for both of these newly developed transfer matrix techniques have been successfully verified for various non-linear rotor bearing systems using an established system matrix based transient rotordynamics software as the yardstick. These developments have been published in refereed journals. To investigate systems with rolling element bearings, appropriate bearing modelling which incorporates angular contact and rolling element inertia needed to be developed and incorporated into transient analysis softwares. Theoretical results from this were compared to data obtained from an experimental test rig which was designed to represent the salient features of an F/A-18 aircraft mounted accessory drive. The rig allowed for variation of bearing preload, unbalance loading and bearing support stiffness and could be run up to 17,000rpm. Full details of the design and commissioning are presented. Results showed better agreement than linear analyses but significant differences were encountered. Errors were largely due to estimated bearing parameters, in particular bearing damping, which was found to be a sensitive variable, so that agreement between theory and experiment was mainly qualitative. Other sources of error were those associated with experimental measurement and limitations of the bearing modelling. Further improvement of the bearing model is needed if better quantitative agreement is to be obtained between the predictions and experiment.
Date January 2003
CreatorsLiew, Andrew, Mechanical & Manufacturing Engineering, Faculty of Engineering, UNSW
PublisherAwarded by:University of New South Wales. School of Mechanical and Manufacturing Engineering
Source SetsAustraliasian Digital Theses Program
Detected LanguageEnglish
RightsCopyright Andrew Liew,

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