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Evaluation of machine elements surface topography by optical profilometer
Vrána, Jakub ; Křupka, Ivan (referee) ; Šperka, Petr (advisor)
This thesis deals with the issue of surface texture topography of engineering parts. Research provides general view of surface texture topography evaluation and puts the aforementioned into the context of international standards. In the practical part of this thesis, an experiment is implemented. With help of optical interferometer, parameters are measured and their robustness is evaluated. In the conclusion part of this thesis, acquired information are evaluated and resumed.
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Lubrication of plastic gears
Hartl, Petr ; Čermák, Jan (referee) ; Křupka, Jiří (advisor)
The work deals with the process of lubrication of gears from a combination of materials that have significantly different material properties. The experimental measurement is performed on a tribometer in simulated gear contact with a ball-disk configuration. The Chromatic Optical Interferometry method is used to measure the formation of a lubricating film in contact. The purpose of this work is to clarify the process of film thickness formation and compare experimental measurements with predictions, which are valid in Soft EHL regime.
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Design of impact microviscometer
Nepovím, Radovan ; Svoboda, Petr (referee) ; Hartl, Martin (advisor)
The bachelor thesis deals with engineering design of mechanical parts of impact microviscometer. Impact microviscometer is intended for educational tool for the study of rheological properties of lubricants in the laboratory in VUT Brno. The bachelor contains a brief summary has designed equipment and measuring methods used, restrictions of engineered apparatus, designs of constructional variation and description of constructional parts of the apparatus.
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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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Design of Artificial Hip Joint Test Rig
Dočkal, Kryštof ; Košťál, David (referee) ; Vrbka, Martin (advisor)
In this thesis, is described one of possible approachs to the design of the hip joint simulation rig, primarily designed for analysis of the lubricant film thickness at the contact of two conformally curved surfaces (femoral head and acetabulum). In relative motion of those two components of artificial hip joints is necessary to observe the behavior of lubrication film between them. The observation is also related to choice of appropriate observational method. In the design of the artificial hip joint is today primarily used wear simulations on smulations rig with very accurate simulation of kinematics of biological hip joints. For description of the behavior of the lubricants between conformall surfaces is used a simplified kinematics along with optical interferometry. The simulation rig will be able to study behavior of lubricant layer using optical inteferometry,
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Lubrication of plastic gears
Poledník, Radim ; Vimmr, Jan (referee) ; Šperka, Petr (advisor)
The purpose of this diploma thesis is to describe the influence of input parameters (rolling speed, load, temperature, dynamic viscosity and pressure coefficient of the lubricant) on film thickness in point and elliptical contacts using optical interferometry. Regression based film thickness formula has been obtained using universal form of non-dimensional parameters of entrainment speed U, load W and material G. Equations were also complemented by the function of ellipticity k. New regression formulas for central and minimum film thickness have been compared with existing EHL thickness equations. These film thickness measurement and new regression formulas have applicability to our understanding of the performance and more effective design of lubricated gears from polymeric materials.
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Design of hip joint simulator
Žonda, Peter ; Čížek, Petr (referee) ; Vrbka, Martin (advisor)
The master's thesis is concerned with design and execution of an experimental acetabulofemoral joint simulator. Its primary use is the study of lubrication film thickness in hip implants. The work first describes available hip joint simulators, which simulate particular joint positions. Next, the thesis proposes author’s own designs and solutions. The result is a produced device allowing for dynamic change of load in simulation of hip joint flexion and extension as set by ISO standard. Contact is recorded by an optical apparatus composed of a high-speed camera and a microscope. The work also includes the initial testing experiment and the complete design documentation of the device including electrical wiring diagrams.
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Cam-follower contact
Urban, Filip ; Zimmerman, Martin (referee) ; Šperka, Petr (advisor)
This bachelor thesis deals with construction design of a cam-follower contact simulator. At the beginning of the thesis there is a brief overview of cams, forces acting in valve train system and types of cam-follower contact wear. There is also review of other apparatuses developed for cam-follower contact research. Main part is devoted to construction design, variants of design and calculations.
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Study of lubricant film formation in textured conformal contacts
Plachý, Ladislav ; Dzimko, Marián (referee) ; Omasta, Milan (advisor)
The aim of this diploma thesis is to describe mechanisms involved in a lubricant film formation in textured conformal contacts. For exploring of the lubricant film formation, the method of optical interferometry is implemented on a pin-on-disc tribometer. That allows to study an influence of a texture on lubricant film thickness and coefficient of friction of textured samples. These samples have different parameters of a texture. On the basis of these effects and the visual image of the contact, the flow of lubricant in the contact area is described. Shallow dimples lead to larger film thickness in elasto-hydrodynamic lubrication regime. They act like a lubricant reservoir. Deep dimples positively affect film thickness in hydrodynamic lubrication regime, where the effect of shallow dimples descend. During experiments, the formation of a cavitation is observed. The cavitation causes a starvation of dimples in many cases. This leads to reducing of the lubricant film thickness. This effect can be eliminated by appropriate parameters of texture in operational conditions of elements.
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Sliding Bearing Apparatus
Sabo, Karol ; Šperka, Petr (referee) ; Hartl, Martin (advisor)
The bachelor’s thesis concerns with a design of experimental apparatus for a film geometry detection in hydrodynamic lubrication thrust bearing using optical interferometry. The thesis includes the current state of knowledge about experimental apparatus using optical interferometry, engineering design and drawings of design apparatus
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