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Research on the load-carrying capacity of lubricating film in rolling bearings
Šmíd, David ; Čermák, Jan (referee) ; Omasta, Milan (advisor)
This diploma thesis deals with the problem of sudden contamination of the elastohydrodynamic contact by solid particles and their influence on parameters affecting the lubricating film, such as surface texture and real film thickness, especially for line contact. The contact is operated under conditions corresponding to the operation of the main wind turbine bearings, with measurable parameters supported by optical observations. The main effort of this work is to relate the influence of the flow of solid particles in the lubricant to the parameters determining the lubrication regime. For the experiments, a taper-on-disc device was constructed to simulate linear contact. Using this device, the effects of different solid particles on the damage of a sample (roughness parameters Ra and Rq) with linear contact and the influence of this altered structure on the lubricating film thickness (hmin) are experimentally described. These remarks are partially compared with the effect of particles on point contact. The result of this paper is a better understanding of the solid particle flow in the Hertzian contact region and clarification of the influence of this flow on the surface structure and associated lubricating film thickness, especially for linear contact.
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Experimental rig for study of lubricant film in compliant contact of oil seal using fluorescence technique
Michalec, Michal ; Nečas, David (referee) ; Dočkal, Kryštof (advisor)
The thesis deals with design of the device that is used for observation of lubricant film thickness in line, compliant contact of rotary lip seal. The problem is, that with use of components made from standard materials, it is not possible to look inside their contact. Therefore, it is necessary to replace one body by optical transparent material, that will allow the insight into the contact using existing equipment, which is fluorescence microscope. In theoretical part are described issues of lubrication and observing method of fluorescence. Based on findings, there was designed a device allowing observation of lubricant behaviour. The last part of thesis describes modified design of existing equipment and individual components in detail. Functionality of designed experimental rig was verified by experiments using of R834/80 mineral oil.
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FEM simulation of elastohydrodynamic contact
Brhlík, Rostislav ; Hartl, Martin (referee) ; Nečas, David (advisor)
This diploma thesis deals with an application of the finite element method on elastohydrodynamic (EHD) lubrication simulations. Commercially available software COMSOL is used for the computation, while two different modules for modeling EHD lubrication are described in a detail. Firstly, a new approach using the module Thin-Film Flow is developed, considering and describing some limitations of this approach. This is the very first published work dealing complex with EHD simulation in Thin-Film Flow module. In the second part of the thesis, there was created a model of line contact using the module for the introduction of partial differential equations (PDE). The model is partially verified with available works for different values of the input parameters. Subsequently, the velocity effect of the contact surfaces on the pressure and the lubricant thickness in contact is analyzed. Finally, the last part is examines the influence of the values of some parameters on the final value of the contact pressure and the lubricant thickness, as well as on numerical stability of the entire model.
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Experimental rig for study of lubricant film in compliant contact of oil seal using fluorescence technique
Michalec, Michal ; Nečas, David (referee) ; Dočkal, Kryštof (advisor)
The thesis deals with design of the device that is used for observation of lubricant film thickness in line, compliant contact of rotary lip seal. The problem is, that with use of components made from standard materials, it is not possible to look inside their contact. Therefore, it is necessary to replace one body by optical transparent material, that will allow the insight into the contact using existing equipment, which is fluorescence microscope. In theoretical part are described issues of lubrication and observing method of fluorescence. Based on findings, there was designed a device allowing observation of lubricant behaviour. The last part of thesis describes modified design of existing equipment and individual components in detail. Functionality of designed experimental rig was verified by experiments using of R834/80 mineral oil.
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FEM simulation of elastohydrodynamic contact
Brhlík, Rostislav ; Hartl, Martin (referee) ; Nečas, David (advisor)
This diploma thesis deals with an application of the finite element method on elastohydrodynamic (EHD) lubrication simulations. Commercially available software COMSOL is used for the computation, while two different modules for modeling EHD lubrication are described in a detail. Firstly, a new approach using the module Thin-Film Flow is developed, considering and describing some limitations of this approach. This is the very first published work dealing complex with EHD simulation in Thin-Film Flow module. In the second part of the thesis, there was created a model of line contact using the module for the introduction of partial differential equations (PDE). The model is partially verified with available works for different values of the input parameters. Subsequently, the velocity effect of the contact surfaces on the pressure and the lubricant thickness in contact is analyzed. Finally, the last part is examines the influence of the values of some parameters on the final value of the contact pressure and the lubricant thickness, as well as on numerical stability of the entire model.
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