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Published: 2004

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Rolling element bearings are a class of mechanism used to support and locate rotating shafts. Their construction and geometry is relatively complex. Even though they allow free rotation between the inner and outer raceways, translational vibration can still transmit through the bearings forming one of the major structure-borne paths in rotating machineries. Previous bearing load-deflection analysis is based on the Hertzian theory that describes the idealized contact between two bodies. The Hertzian contact theory also assumes one body as rigid and other mating pair as elastic. In the case of bearing analysis, the rolling elements are assumed elastic while the raceways are considered rigid, which tends to over-simplified the problem. In this thesis research, a more realistic contact model is introduced to improve the vibration response of rolling element-bearing systems as described below. The primary objective of this research is to apply an elastic contact theory to formulate a new bearing stiffness matrix for use in predicting the vibration response of rotating systems and analyzing the vibration transmission through rolling element bearings. This proposed theory also accounts for the time-varying stiffness characteristics of the bearing due to orbital rotation of the rolling elements. Using the proposed bearing model, numerous parametric studies are performed to improve the understanding of the role of bearings in vibration transmission. The model is also employed to demonstrate the salient features. Obtrusive discrepancies are observed amongst the two theories for force preloading cases. Lumped parameter dynamic models based on the new contact-elastic theory are developed to study vibration transmission characteristics through single stage rotor and geared rotor systems. Also, the centrifugal force, which is shown to have significant effect on the rotating system natural frequencies, is included in the new formulation. This effect is found more acute in angular contact ball bearings compared to other conventional designs.

Download or read book An Elastic Contact Theory for Modeling Vibration Transmissibility Through Rolling Element Bearings written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Rolling element bearings are a class of mechanism used to support and locate rotating shafts. Their construction and geometry is relatively complex. Even though they allow free rotation between the inner and outer raceways, translational vibration can still transmit through the bearings forming one of the major structure-borne paths in rotating machineries. Previous bearing load-deflection analysis is based on the Hertzian theory that describes the idealized contact between two bodies. The Hertzian contact theory also assumes one body as rigid and other mating pair as elastic. In the case of bearing analysis, the rolling elements are assumed elastic while the raceways are considered rigid, which tends to over-simplified the problem. In this thesis research, a more realistic contact model is introduced to improve the vibration response of rolling element-bearing systems as described below. The primary objective of this research is to apply an elastic contact theory to formulate a new bearing stiffness matrix for use in predicting the vibration response of rotating systems and analyzing the vibration transmission through rolling element bearings. This proposed theory also accounts for the time-varying stiffness characteristics of the bearing due to orbital rotation of the rolling elements. Using the proposed bearing model, numerous parametric studies are performed to improve the understanding of the role of bearings in vibration transmission. The model is also employed to demonstrate the salient features. Obtrusive discrepancies are observed amongst the two theories for force preloading cases. Lumped parameter dynamic models based on the new contact-elastic theory are developed to study vibration transmission characteristics through single stage rotor and geared rotor systems. Also, the centrifugal force, which is shown to have significant effect on the rotating system natural frequencies, is included in the new formulation. This effect is found more acute in angular contact ball bearings compared to other conventional designs.