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Friction measuring of human joints
Šnejdar, Radim ; Ranuša, Matúš (referee) ; Čípek, Pavel (advisor)
This bachelor thesis concerns about the tribology of real joints. The aim of this work is an elucidation of the influence of chosen operating conditions on shear force coefficient. It deals especially about speed, strain and rehydration. The experimental tasks will be realized on tribometer, which is available in laboratories of ÚK. In this work, current state of knowledge in the area of discussed issues are described. Also the device and measured methods which help to measure and evaluate data files. In the last section of this work, the results are evaluated and the following conclusions are established.
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Increasing the range of a vehicle with alternative propulsion
Dryml, Tomáš ; Ranuša, Matúš (referee) ; Navrátil, Václav (advisor)
The bachelor's thesis deals with increasing the range of a vehicle with an alternative drive, which is compressed air. First, an analysis of the pneumatic circuit is performed, from which the areas to be modified result. To improve, it is chosen to find a suitable working pressure and the correct filling, which is calculated on the basis of constant pressure filling and subsequent adiabatic gas expansion. From the theoretical calculation, the runs per cylinder stroke at different pressures are determined and the selected pressures are subsequently experimentally verified. The results show that the most suitable setting increased the range from 331 meters using the original setting, to 616 meters with the new setting.
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Pumps of artificial kidney
Březina, Marek ; Ranuša, Matúš (referee) ; Nevrlý, Josef (advisor)
This bachelor thesis deals with issue of pumps of artificial kidney, especially with blood pumps of artificial kidney. It compares available technical, economic and hemolysing properties from different manufacturers. It concisely informs about the history of pumps of artificial kidney.
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Tribology of hydrogels for articular cartilage replacement
Křížová, Michaela ; Ranuša, Matúš (referee) ; Vrbka, Martin (advisor)
The bachelor's thesis deals with the description of the tribological properties of focal joint implants in the place of a cartilage defect. The application of focal implants is aimed at a group of younger patients who have to undergo surgery to repair damaged cartilage, but a total replacement is not suitable for them due to its lifetime. The contact of the focal implant and the opposite cartilage was simulated using metal samples and hydrogel, which has very similar properties to natural cartilage. For a possible comparison of values, a tribological measurement of the cartilage samples against the hydrogel was carried out. This pair serves as a model for defining friction in a healthy joint. The main task of this thesis was to determine the coefficient of friction of Ti6Al4V, Ti6Al4V+DLC, CoCrMo and cartilage against the hydrogel. The experiments were carried out using a tribometer in a pin-on-plate configuration. The Ti6Al4V alloy without coating and with DLC coating came out with the lowest coefficient of friction for both variants, almost identically 0.0526. Higher friction was measured for CoCrMo, but it differed from the titanium alloy to one-hundredth. On the contrary, the highest coefficient of friction was unexpectedly manifested in the cartilage samples, where the lowest friction was assumed. The error was due to poor selection of cartilage samples. The thesis simply describes the tribological behaviour of focal implants and the result is a material with the lowest coefficient of friction. The measurements performed could help further research into the issue of focal implants.
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Impact of joint implant surface structure on friction behaviour
Kučera, Ondřej ; Nečas, David (referee) ; Ranuša, Matúš (advisor)
In osteoarthritis of small joints, the use of total endoprosthesis is currently being developed to ensure physiological movement, but it provides only a limited-service life. The use of microstructures on the implant surface may improve tribological properties, but this issue is not described enough. Thus, this work addresses the impact of microstructures on friction coefficient, lubricant thickness in the contact area, wear, as well as surface topography and geometry of the structures. Furthermore, the influence of DLyte electrochemical machining on the change of microstructures geometry and tribological properties is investigated. Measurements were performed using a reciprocal tribometer, interferometry and optical profilometry. The textured samples achieved an increase in both friction coefficient and lubricant thickness in the contact area. Furthermore, a correlation between the height of the texture edges and the measured lubricant thickness was demonstrated. DLyte significantly reduces these edges, also reducing wear, however, it degrades the surface of the CoCrMo samples. Implant texturing can lead to reduced wear, prolonged life, and thus improved quality of life for many patients. Texturing of Ti6Al4V alloy in combination with DLyte shows great potential.
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Design of a steel pipe dril
Montag, Jakub ; Dočkal, Kryštof (referee) ; Ranuša, Matúš (advisor)
The goal of this work is to create a drill that can drill into steel pipes. Part of the work is designing the drill in a way, that drilling into the pipes is as easy as possible. The output is a drawing documentation that can be used to make a prototype. The designed drill will enable faster, more accurate and safer drilling into steel pipes for mass production.
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Influence of viscosupplementation on cartilage lubrication
Ondra, Martin ; Horák, Zdeněk (referee) ; Ranuša, Matúš (advisor)
This work deal with the determination of the effect of viscosupplementation on the lubrication of articular cartilage in the beginning phase of osteoarthritis. This effect was evaluated based on the development of CoF measured by a tribometer in configuration pin-on-plate. The tribological model of incipient osteoarthritis was simulated by using two articular cartilages lubricated with osteoarthritic synovial fluid to which viscosupplementation agents were added. These preparations differed mainly in cross-linking and molecular weight of hyaluronic acid (HA). Measurements have shown that viscosupplementation may be effective in the beginning phase of osteoarthritis. The efficacy of viscosupplementation preparations with cross-linking HA was significantly higher compared to the efficacy of viscosupplementation preparations without cross-linking. These results support the use of viscosupplementation to delay the advanced stage of osteoarthritis.
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Influence of surface microstructure on implant lubrication processes in contact
Matovič, Martin ; Odehnal, Lukáš (referee) ; Ranuša, Matúš (advisor)
This bachelor thesis deals with the lubrication of microstructured prostheses of the first metatarsophalangeal joint. The aim of the research is the service life of joint replacements by creating a microstructure on the surface of the material. The work focuses on the influence of microstructures on lubrication processes in contact and coefficient of friction. Fluorescence microscopy in combination with a reciprocating tribometer with the possibility of recording frictional and loaded forces was used to observe the contact area. The number and average particle size of albumin, which plays an important role in contact lubrication, were then examined to record the camera. The testing was performed on two material combinations, namely CoCrMo - Glass B270 (hard pair) and CoCrMo - PMMA (soft pair), which were only four different microstructures. Elsewhere, the influence of microstructures on lubrication processes in contact for hard and soft pairs is indicated, which can be used to design further measurements.
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Design of a Rotation Module for a Knee Simulator
Pauliuchenka, Aliaksandr ; Polnický, Vojtěch (referee) ; Ranuša, Matúš (advisor)
The bachelor thesis is focused on the design and construction of a rotational knee joint simulator module. The purpose of the rotational module is to approximate the simulations to the actual movements during the gait cycle. The module will be used for programmed tibial rotation of the spacer. After the boundary conditions were determined conceptual designs of possible solutions were developed and then the selected option was developed. The resulting design allows the implementation of conditions compliant with ISO 14 243-3. The work includes complete drawings and digital data.
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Development of the coefficient of friction and lubrication film in a total knee replacement during a gait cycle
Odehnal, Lukáš ; Horák, Zdeněk (referee) ; Ranuša, Matúš (advisor)
This master´s thesis deals with the experimental analysis of the coefficient of friction and lubrication film in total knee replacement. The experiments are performed on a knee joint simulator, with an implemented module for measuring friction. To observe film formation, fluorescent microscopy is used. The experiments are mainly focused on a detailed description of the influence of parameters occurring during the gait cycle. This approach should significantly help in describing the tribological processes that occur in the total knee replacement. The results confirm previous investigations in terms of axial load, where the coefficient of friction decreases with the increasing load. In the case of lubrication film, no significant changes are observed. On the contrary, while investigating the influence of SRR, noticeable changes in film formation are observed while the coefficient of friction being unaffected. While describing the whole gait cycle, precise results are obtained only in the first half of the cycle as the second half is accompanied by the occurrence of large deviations from a rapid decrease of load. This work provides a better understanding of the field of lubrication film in total knee replacements. Moreover, thanks to the simultaneous measurement of the coefficient of friction and the observation of the contact area, it is possible to draw better conclusions than if the experiments had been carried out separately.
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