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Analysis of lubricated compliant contact
Dočkal, Kryštof ; Dzimko, Marián (referee) ; Nečas, David (advisor)
This diploma thesis deals with the proposal of methodology for film thickness eva- luation within compliant contacts. With respect to characteristics of such contact pairs, like variable film thickness, high surface roughness, or poor conductivity and reflectivity, the usage of conventional experimental methods is particularly complicated. In present study, an optical method based on the principle of fluo- rescent microscopy was employed in present thesis. An evaluation algorithm in- volving background normalization and calibration of fluorescent intensity to film thickness was created in a form of experimental software. The proposed algori- thm was validated by using elastohydrodynamic contact formed between ceramic ball and glass disc. The measured film thickness was compared with theoretical prediction, while very good agreement of obtained data was observed. Further, a series of experiments with compliant samples was conducted, while the central film thickness was evaluated as a function of mean speed, applied lubricant, ap- plied load and slide-to-roll ratio. The last part of the thesis is focused on results analysis and discussion considering the previously published literature.
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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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Stress strain analysis of the femur based on the CT data collection
Nečas, David ; Marcián, Petr (referee) ; Vosynek, Petr (advisor)
The area of clinical biomechanics is a rapidly growing engineering discipline in the world of today. This master's thesis is concerned with the stress-strain analysis of human femoral neck. In the first place it emphasizes the creation of computational model, especially the model of bone material, because of its high level of inhomogeneity. The creation of the computational model has been tested using several software packages, which are often mentioned in connection with the biomechanical tasks. The latter part of the thesis contains finite element method analysis for several material models, which are based on extensive analysis of relations used to transfer the information from computed tomography data to material model properties. Subsequently, the realization of experimental measurement is described. The final part of the thesis contains evaluated results obtained from the FEM analysis, which are also compared with the experiment.
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Lubricants created by nature
Drobilič, Ivo ; Urban, Filip (referee) ; Nečas, David (advisor)
This bachelor thesis provides an overview of substances which can be considered as the lubricants in its natural environment. The first part of the thesis of focused on lubricants in human body. The substances such as water, blood or synovial fluid are analysed in a detail. The following chapter deals with lubricants in everyday life. As the example, decrease of tyre adhesion in case of rain or longer breaking distance of trains as a consequence of presence of leafs on rails, can be mentioned. The last part, in addition, summarizes the lubricants which are based on natural products.
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Methodological guide and digitization of gear pump
Ševčík, Ondřej ; Nevrlý, Josef (referee) ; Nečas, David (advisor)
The aim of this bachelor thesis is to provide a methodological quide of U10 type gear pump. In the first part of the thesis, analysis of individual pump components including its main parameters is presented. The next part is focused on the identification of the defect suggesting the instructions for the reparation. All the operations such as dismantling, inspection, reparation, and assembly are described in a detail in a form of the technological processes. After the reparation, an operating test was conducted to verify the functionality of the pump. In addition, all the components of the pump were digitized by using SolidWorks CAD system. The last chapter provides FEM analysis of the cogwheels contact. For this purpose, computational system ANSYS Workbench was used.
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Design of the loading mechanism for low load
Polnický, Vojtěch ; Galas, Radovan (referee) ; Nečas, David (advisor)
The aim of the bachelor’s thesis is to provide a design and full drawing documentation of instrument for applying low loads. In case of realization, the mechanism will be implemented into a ball-on-disc laboratory tribometer, which is used in the laboratory of IMID FME BUT in Brno. The first part of the thesis deals with research study of tribometers considering the configuration of test samples and loading mechanism systems. According to information analysis, four different variants are introduced. The final design is described in detail, including the information about the advantages and disadvantages. This design is developed into technical drawings and electronic models.
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Design of adaptive wiper of liquids
Novotný, Antonín ; Nečas, David (referee) ; Košťál, David (advisor)
This thesis deals with the structural design of the adaptive fluid wiper, which is the complement of laboratory equipment. Laboratory equipment is used to study the thickness of the lubricating layer and the frictional force at contact. The purpose of the adaptive wiper is to remove the maximum amount of liquid from a moving planar disc or to make a uniform film in a rolling path around the periphery of the disc. Among the most controllable features, there are the wiper geometry, the evenly pressing and the follow the disc throwing. The thesis includes the design report, drawings and 3D model.
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Thermal analysis of plastic part using finite element method
Zemanová, Lucie ; Nečas, David (referee) ; Zatočilová, Aneta (advisor)
The bachelor thesis deals with the thermal deformation of a plastic component after thermal loading and ways of processing digital data for a thermal analysis. There is optical digitizing outlined, since input data were obtained this way, and methods of subsequent processing for the thermal analysis. The analysis is carried out by the finite element method using ANSYS Workbench software. The finite element method is described. The work builds on measuring performed by photogrammetry, the aim is to compare applicability finite element method and photogrammetry for measuring deformation.
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Design of Device for Regrinding of Specimens
Matečka, Martin ; Nečas, David (referee) ; Smejkal, David (advisor)
This bachelor thesis is focused on design of device for regrinding of specimens. In the first part is described grinding technology, cutting conditions for grinding of outer cylindrical surfaces and kinematic and dynamic phenomena arising in these conditions. There are also analyzed the grinding tools and their using. In the next points are described the designs of the grinder’s basic components. The last in this chapter is described the testing device on which the specimens are tested. The next chapter is focused on description of the objectives and analyzing the problems. There are described the variants of design solutions. After assessment of advantages and disadvantages of all variants is selected optimum design solution which is detailed described in the last section.
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Summary of unconventional aircraft concepts
Nečas, David ; Šošovička, Róbert (referee) ; Lajza, Ondřej (advisor)
This bachelor´s thesis deals with civil aircrafts of unconventional conceptions, which got into serial production. The thesis will be divided according to categories of aircrafts, whereas in every category with the exception of large transport aircrafts one conventional and two unconventional aircrafts will be specified for comparing various properties. Military aircraft will be mentioned only marginally because of the representative of significant unconventional conception.
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