Computing Critical Speeds for Rotating Machines with Speed-Dependent Bearing Properties

MI Friswell (University of Wales Swansea), SD Garvey, JET Penny (Aston University) & MG Smart (University of Wales Swansea)

Journal of Sound and Vibration, Vol. 213, No. 1, May 1998, pp. 139-158

Abstract

This paper examines available methods for computing critical speeds for rotating machines whose bearings have speed dependent properties and proposes a modification which can be incorporated into almost all of the established techniques. The established methods for the calculation of critical speeds are adequately efficient when only a single configuration is analysed. The trend towards incorporating critical speed calculations into the design optimisation process and model based fault diagnosis systems requires the more efficient calculation of critical speeds. The proposed modification involves replacing the sets of speed dependent bearing characteristics by fictitious multi-degree of freedom systems whose characteristics emulate those of the bearings themselves. The method by which these fictitious systems can be found is explained and the advantages of using this method for computing critical speeds are demonstrated in conjunction with the finite element approach to evaluating critical speeds. The proposed technique is also well suited to efficiently computing the machine response to unbalance using a truncated modal decomposition.

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This material has been published in the Journal of Sound and Vibration, Vol. 213, No. 1, May 1998, pp. 139-158, the only definitive repository of the content that has been certified and accepted after peer review. Copyright and all rights therein are retained by Academic Press. This material may not be copied or reposted without explicit permission.

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Link to paper using doi:10.1006/jsvi.1998.1503

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