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Effect of synovial fluid composition and surface topography modification on lubrication of joint replacements
Hekrle, Pavel ; Vampola, Tomáš (referee) ; Vrbka, Martin (advisor)
The main objective of this diploma thesis is to determine the influence of synovial fluid compodition and the influence of surface microtextures on lubrication of hip join replacements. For all experiments, hip joint simulator based on the pendulum principle was utilized. Metal heads (CoCrMo) manufactured by B Braun company and and tailor made acetabular cups from optical glass were used as contact couples. Acetabulum dimensions were fabricated according to dimensions of real implants. Experiments with surface microtextures simulated walking cycle for 210 s and development of lubrication film over time was observed.Results have shown that all types of tested structures improved lubrication of contact area, where the best results were obtained for square and triangle shapes respectively. Second set of experiments was based on the fact, that the composition of synovial fluid of healthy people differs from the composition of patients with various stages of osteoarthritis. Therefore, experiments with different model fluids were compared, which in their composition correspond to different groups of patients. For the model fluid that corresponds to the largest number of cases, experiments with individual components and combinations thereof were subsequently performed to provide a more detailed description of how these components affect the film-forming mechanism. The results show, that a change in fluid composition of patients with osteoarthritis can have a major negative effect on fluid formation process within the pair.
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Optimization of EDM process control parameters
Prokeš, Tomáš ; Beneš, Libor (referee) ; Bednář, Josef (referee) ; Matoušek, Radomil (advisor)
The dissertation thesis is focused on the optimization of control parameters of an EDM machine; the subject of optimization is cutting speed and surface topography. The first part of the thesis contains a research study on the technology of electrical discharge machining with the attention paid to the optimization methods use for control parameters of this process. The second part of the thesis is focused on real application of knowledge gained from studied sources. Here, a design of experiment aim at optimizing the parameters of the EDM machine is designed and carried on to maximize the cutting speed with the highest possible surface quallity. The result of the work is to build adequate regression models and find the optimal setting of machine control parameters.
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Advanced methods of surface topography evaluation
Hroděj, Daniel ; Osička, Karel (referee) ; Píška, Miroslav (advisor)
This paper deals with the analysis of data obtained from the surface of aluminum alloy 7475-T7351 after face milling with a tool inclination of 1°. The theoretical part explains the basic principles of measuring the topography of the surface and instruments that are able to provide relevant data directly from the scanned part. The following part contains the methods of evaluating the information, especially using various types of parameters acquired from ČSN EN ISO standards. The practical part focuses on the data obtained from the sample surface using the Alicona IF-G5. This information determines the character of the surface texture with the tool inclination and the difference between the profile and surface parameters. There is also described surface texture in the tool path and on the edge of the tool path. In the final economic evaluation, the connection between the feed per tooth and the machining price is found.
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Analysis of solar cell surface features
Lipr, Tomáš ; Macků, Robert (referee) ; Škarvada, Pavel (advisor)
This thesis is focused on the study of electrical and optical properties of solar cell samples using the near field optical microscope. Process of the image formation is described. Artefacts which are presented on some of topography images are described, too. There are some timing problems with measuring of the sample local electric response. If the measuring and scanning devices are not in the time synchronization there will be some difficulties with measured data representation and 2D image offline formation. Created electronic for SNOM and measuring devices synchronization is presented.
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Influence of the surface texturing of non-conformal surfaces at the friction coefficient
Pišťáček, Karel ; Náhlík, Luboš (referee) ; Koutný, Daniel (advisor)
This diploma thesis deals with the influence of the surface texturing of non-conformal surfaces at the friction coefficient. In the work were made adjustment of experimental apparatus for measuring friction in the contact between ball and flat disk. Friction coefficient was calculated by the size of the torque on the ball, which was measured by the torque sensor. For recording and processing signal from the sensor was designed software that makes it possible to measure the coefficient of friction for selected conditions (loading of contact, speed of rubbing surfaces and rolling-sliding conditions). Experiments were carried out with smooth and textured ball, glass, and steel disc at different speeds and rolling-sliding conditions. To determine the effect of the influence of the surface texturing at the friction coefficient the size of the coefficient of friction of smooth and textured ball was compared. It was found that the microtexture of the friction coefficient has little effect.
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Optimization of EDM process control parameters
Prokeš, Tomáš ; Beneš, Libor (referee) ; Bednář, Josef (referee) ; Matoušek, Radomil (advisor)
The dissertation thesis is focused on the optimization of control parameters of an EDM machine; the subject of optimization is cutting speed and surface topography. The first part of the thesis contains a research study on the technology of electrical discharge machining with the attention paid to the optimization methods use for control parameters of this process. The second part of the thesis is focused on real application of knowledge gained from studied sources. Here, a design of experiment aim at optimizing the parameters of the EDM machine is designed and carried on to maximize the cutting speed with the highest possible surface quallity. The result of the work is to build adequate regression models and find the optimal setting of machine control parameters.
|
|
|
Advanced methods of surface topography evaluation
Hroděj, Daniel ; Osička, Karel (referee) ; Píška, Miroslav (advisor)
This paper deals with the analysis of data obtained from the surface of aluminum alloy 7475-T7351 after face milling with a tool inclination of 1°. The theoretical part explains the basic principles of measuring the topography of the surface and instruments that are able to provide relevant data directly from the scanned part. The following part contains the methods of evaluating the information, especially using various types of parameters acquired from ČSN EN ISO standards. The practical part focuses on the data obtained from the sample surface using the Alicona IF-G5. This information determines the character of the surface texture with the tool inclination and the difference between the profile and surface parameters. There is also described surface texture in the tool path and on the edge of the tool path. In the final economic evaluation, the connection between the feed per tooth and the machining price is found.
|
|
|
Effect of synovial fluid composition and surface topography modification on lubrication of joint replacements
Hekrle, Pavel ; Vampola, Tomáš (referee) ; Vrbka, Martin (advisor)
The main objective of this diploma thesis is to determine the influence of synovial fluid compodition and the influence of surface microtextures on lubrication of hip join replacements. For all experiments, hip joint simulator based on the pendulum principle was utilized. Metal heads (CoCrMo) manufactured by B Braun company and and tailor made acetabular cups from optical glass were used as contact couples. Acetabulum dimensions were fabricated according to dimensions of real implants. Experiments with surface microtextures simulated walking cycle for 210 s and development of lubrication film over time was observed.Results have shown that all types of tested structures improved lubrication of contact area, where the best results were obtained for square and triangle shapes respectively. Second set of experiments was based on the fact, that the composition of synovial fluid of healthy people differs from the composition of patients with various stages of osteoarthritis. Therefore, experiments with different model fluids were compared, which in their composition correspond to different groups of patients. For the model fluid that corresponds to the largest number of cases, experiments with individual components and combinations thereof were subsequently performed to provide a more detailed description of how these components affect the film-forming mechanism. The results show, that a change in fluid composition of patients with osteoarthritis can have a major negative effect on fluid formation process within the pair.
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On the milling technology of thin-walled parts for aerospace industry
Ohnišťová, Petra ; Polzer, Aleš (referee) ; Píška, Miroslav (advisor)
This thesis is focused on the analysis and on the design of the milling technology of the components for the aerospace industry which are characterised by a high aspect ratio, reduced stiffness and all covered by a high demand on the fatigue performance. This work includes the experimental verification of the proposed technology using CNC machining center, evaluation of surface structure using optical high-resolution 3D surface measurement system ALICONA, analysis of the force loading using KISTLER device, fatigue testing and fatigue fracture analysis.
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Influence of the surface texturing of non-conformal surfaces at the friction coefficient
Pišťáček, Karel ; Náhlík, Luboš (referee) ; Koutný, Daniel (advisor)
This diploma thesis deals with the influence of the surface texturing of non-conformal surfaces at the friction coefficient. In the work were made adjustment of experimental apparatus for measuring friction in the contact between ball and flat disk. Friction coefficient was calculated by the size of the torque on the ball, which was measured by the torque sensor. For recording and processing signal from the sensor was designed software that makes it possible to measure the coefficient of friction for selected conditions (loading of contact, speed of rubbing surfaces and rolling-sliding conditions). Experiments were carried out with smooth and textured ball, glass, and steel disc at different speeds and rolling-sliding conditions. To determine the effect of the influence of the surface texturing at the friction coefficient the size of the coefficient of friction of smooth and textured ball was compared. It was found that the microtexture of the friction coefficient has little effect.
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