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Realization of educational problem based on experimental apparatus with cam mechanism
Tomeček, Vojtěch ; Vrbka, Martin (referee) ; Vaverka, Michal (advisor)
Bachelor's thesis is focused on solving educational problem based on experimental apparatus with cam mechanism. The task of the educational problem is to teach students to analyse kinematic quantities of cam followers. The thesis contains general discourse on the topic of cam mechanisms and basic terms definition. This is followed by putting the device into service, eliminating its particular imperfections, analysis of kinematic quantities of various combinations of available cams and followers and definition of methodics of the educational problem. The educational problem itself follows the presentation and commentary of gained results. At last some recommendations for the future modifications of the experimental apparatus are given followed by foreshadow of its eventual future usage.
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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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Design of parts of tribometer with reciprocating motion
Dražka, Ondřej ; Vrbka, Martin (referee) ; Čípek, Pavel (advisor)
The bachelor thesis deals with design of parts of tribometer with reciprocating motion. Several conceptual solutions are made on base of existing studies from which the best solution for given application is selected. The tribometer will be used for experimental measuring on real cartilage which should lead to better understanding of friction and lubrication processes in synovial joint. The outcome of this thesis are component parts along with the manufacturing drawings.
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Construction of gears with plastic teeth
Selzer, Tomáš ; Vrbka, Martin (referee) ; Křupka, Jiří (advisor)
The thesis discusses the matter of construction of gear trains using plastic parts in both lubricated and non-lubricated environment, trying to give an overview of an up-to-date information in the process. Nowadays, thanks to several years of development, polymer-based gear systems can be used in many cases as a replacement for metal-based ones. The undeniable advantage of such replacement is mostly the lower production cost and its lower weight, which, together with favorable friction properties of polymer materials, makes a number of technological applications much more effective. The first part is dedicated to listing and defining the typical characteristics of polymer materials, which are essential in the process of designing the gear. The next part focuses on evaluation of the available types of solutions for plastic gear trains construction. The last topic is centered around possible defects and the wear as well as the operation conditions and a real-life application of such plastic gear system. The most notable findings are summed up and commented on in the form a discussion. Thanks to the chosen topic, the bachelor’s thesis adds to a closer understanding of the construction and operation of the plastic gear systems.
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Design of a bath on the device for testing human joints
Svoboda, Tomáš ; Vrbka, Martin (referee) ; Čípek, Pavel (advisor)
The bachelor thesis deals with the design of the bathtub of an experimental device for testing human joints. Tribometer is used for experimental measurement of friction and visualization of real cartilage film in flooded synovial fluid. The result of this work is the design of air releasing, heating and sealing the bathtub in which the synovial fluid is located. By removing air bubbles and heating the liquid to the temperature of the human body, more accurate shear coefficient values and improved contact visualization are achieved. This should lead to a better understanding of the friction and lubrication processes in the synovial joint. The result of this work is chosen optimal design variant and production drawing documentation.
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Research and development of bearings for traction motors
Prášilová, Alena ; Čermák, Jan (referee) ; Vrbka, Martin (advisor)
This master’s thesis deals with construction design of cylindrical roller bearing for traction motor and design of life test tool for designed bearing. At the thesis beginning there is an overview of new trends in design of cylindrical roller bearing, according to new trends is designed a new construction design of cylindrical roller bearing. Other part of thesis is strain stress analysis, which assesses an optimal inclination of collar faces and optimal raceway modification of hybrid bearing rings. At the end life test will be analyzed.
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Effect of toothpaste abrasiveness on friction and wear of dental fillings
Formánková, Pavla ; Čípek, Pavel (referee) ; Vrbka, Martin (advisor)
This bachelor thesis dealt with research, that links dental hygiene issues with tribology. The aim of the thesis was to analyze the effect of abrasive particles of toothpastes on friction and wear of dental fillings. The friction coefficient was evaluated in a tooth brushing simulation on an UMT TriboLab tribometer that lasted 260 minutes. The tribological system consisted of a toothbrush, a sample of composite material and a solution of artificial saliva with a selected toothpaste. Each paste was defined by an RDA value from 0 to 250, expressing the degree of abrasiveness therefore the ability of the toothpastes to wear the material. Wear was analysed on a Bruker Contour GT-X optical profilometer. From the measured values it was found that the influence of abrasive particles is significant in terms of wear of dental fillings. For both the friction coefficient and the material loss when measured only in the presence of artificial saliva, the resulting values were generally lower. However, the material loss in the toothpastes measurments did not increase linearly with the RDA value as expected. Literature studies and measurements have shown that this may be due to other factors affecting wear. Future research on these factors could lead to the selection of more gentle toothpastes in dentistry and thus prevent the increase in wear of dental fillings
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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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Design of frame of recumbent bicycle
Gayer, Tomáš ; Maňas, Pavel (referee) ; Vrbka, Martin (advisor)
The aim of this diploma thesis is evolution of the new model of tricycle. This thesis describes process of engineering from design of several parts and whole frame in CAD system Autodesk Inventor, to creating complete drawing documentation. Next part of this thesis is focused on basic static-structural analysis using finite element method in software ANSYS Workbench and determining boundary conditions for this analysis. The final part is about visualization of the new tricycle.
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