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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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Friction and lubrication of fascia
Chmelík, Jiří ; Daniel, Matej (referee) ; Vrbka, Martin (advisor)
The diploma thesis was part of the project "Regeneration and lubrication of fascia with hyaluronan" of the company Contipro a.s., whose main goal is the development of an injectable medicinal product. The number of patients suffering from so-called myofascial lower back pain is increasing. The cause of the pain is increased hyaluronic acid, which is produced between the layers of the fascia. If the viscosity is low, the fascia layers are not affected and the coefficient of friction is low. The purpose of the product is to improve the sliding movement of the fascia and relieve patients of pain. The main component of the medicine is hyaluronic acid. The project included rheological and tribological analysis of hyaluronic acid samples. A tribological model of fascia in a pin-on-plate configuration was created for the analysis of the coefficient of friction. Based on the fascia models used, the dependence between the coefficient of friction and viscosity of native hyaluronic acid solutions was found. For models and real fascias, the native solution (Bonharen) was found to have better friction properties than hyaluronic acid derivatives. These analyzes have contributed not only to the development of the drug, but also to the emergence of other studies that would like to address the biotribology of fascia.
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Analysis of contaminants in wheel and rail contact
Straka, Tomáš ; Galas, Radovan (referee) ; Kvarda, Daniel (advisor)
Wheel/rail contact is significantly influenced by so called third body – contaminants. Aim of this bachelor’s thesis is to analyse those contaminants in the contact and to create a brief overview. Short introduction into problem of wheel/rail contact is included, followed by description of main contaminants occurring in the contact. This thesis may be used as introduction into contamination of wheel/rail contact problem.
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Biotribology of artificial tears for the treatment of dry eye syndrome
Černohlávek, Mikuláš ; Daniel, Matej (referee) ; Vrbka, Martin (advisor)
This master thesis is a part of the project TAČR TREND, which aim is the development of new ingredient for treatment of dry eye syndrome. Developed ingredient is derivative of hyaluronic acid, which is in this thesis compared with native hyaluronic acids and commercial eye drops. Aim of this thesis is to describe rheological and tribological properties of measured samples in terms of viscosity, mucoadhesivity and coefficient of friction. Coefficient of friction was measured on created tribological model of the eye in pin-on-plate configuration which represents physiologically relevant sliding speeds of blinking. Comparison with native hyaluronic acids and commercial products of eye drops showed, that derivative reaches higher values of viscosity, has mucoahesive properties and has low values of coefficient of friction. Those key parameters show that modification of hyaluronic acid is promising way for drug development for dry eye disease.
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Animation of force relations on power screw
Jonáš, Tom ; Klapka, Milan (referee) ; Hartl, Martin (advisor)
The bachelor thesis deals with creating animations in program Cinema 4D. The animations show what forces are generated during nut movements along the moving bolt, also show self-locking conditions and geometry between forces. These animations will be used for educational purposes for students, for a better understanding of the issue, and for a better idea of spatial distribution of forces. The thesis describes the software environment and the process of creating particular animations.
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Software for Determination of Aerodynamic Losses
Ondrák, Adam ; Skála, Zdeněk (referee) ; Lisý, Martin (advisor)
This work deals with the creation of a program for calculating the tensile losses of an in-dustrial boiler. The work is divided into four parts. The first part of the thesis deals with a theoretical introduction to the issue of pressure losses. The second part deals with all equations and procedures by which the program was created, as well as the limitations and conditions of using a given type of equation. The third part consists of a sample calculation of pressure loss-es of a real boiler. Furthermore, in the third part, the correctness of the program function is checked, where the measured losses on the real device were compared with the losses calcu-lated by the program. The fourth part deals with the influence of the boiler's parameters on its pressure losses, where the individual losses were graphically represented and compared to determine the sensitivity analysis. The output of this work is a functional program that has been optimized for ease of use and requires almost no knowledge of the user.
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Skid resistance of asphalt layers with recycled materials
Bambulová, Lucie ; Nekulová, Pavla (referee) ; Hýzl, Petr (advisor)
The diploma thesis deals with the problems of pavement surface skid resistence of wearing course of asphalt mixtures with R-material. Specifically, it is a mixture of type ACO 11 (asphalt concrete for wearing layers). In the theoretical part of the thesis there are dismantled the problems of Antiskid properties of the road surface and recycling of R-material. The practical part is dedicated to the design and laboratory production of the asphalt mixture ACO 11 without admixture of R-material and with content of 38 % R-material. In addition, the results of the measurement of friction coefficient after smoothed for these bitumen mixtures are shown in the work. The aim of the thesis was to determine the influence of the increased content of R-material on the anti-skid properties of the road surface as it is planned to update the standard ČSN EN 13108-1, which will allow the use of up to 40 % R-material into the mixtures of type ACO 11.
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An experimental investigation of friction coefficient in hip joint replacements
Tkadlec, Tadeáš ; Urban, Filip (referee) ; Nečas, David (advisor)
This bachelor thesis deals with an experimental analysis of friction coefficient within hip joint replacements. The measurements were realized on Mini Traction Machine device in ball-on-disc configuration. The main goal was to determine the effect of implant material, kinematic conditions and model synovial fluid composition on the development of coefficient of friction as a function of time. For this purpose, three different materials (metal, ceramic, polymer), two mean speeds (5.7 mm/s; 22m/s), three different slide-to-roll ratios (SRR = 0 %, SRR = -150 %; SRR = 150 %) and six various model fluids containing albumin and -globulin in a various ratios and concentrations were employed. The results are evaluated in the form of graphs showing the dependence of friction coefficient on time and are confronted with previously published studies.
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Conceptual design of a polymeric gear tester in vacuum
Ptáček, Matyáš ; Šperka, Petr (referee) ; Černohlávek, Mikuláš (advisor)
The bachelor thesis deals with the conceptual design of a polymeric gear tester in vacuum. Using a test device, it is possible to test the coefficient of friction in gears. At the beginning of the work is described the issue of operating conditions of satellites in low orbit together with the effects that affect them. Subsequently, suitable polymeric materials are selected, and current publicly available test rigs are described. Based on the research, two conceptual designs are made, one of them is selected and described in detail at the end of the work.
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Wear analysis of the sliding surface material of large-scale hydrostatic bearings
Daněk, Lukáš ; Robenek, Dětřich (referee) ; Svoboda, Petr (advisor)
This thesis focuses on the experimental investigation of the wear behavior of sliding surface materials in large-scale hydrostatic bearings during oil supply failure. The aim is to clarify the influence of materials and surface treatments on friction and wear. For this purpose, a testing methodology was designed and implemented in laboratory conditions. An experimental module was developed for the tribometer to simulate a critical state and a new procedures were established for evaluating the behavior of the contact. Wear results were observed using a profilometer, precise scales, and a microscope. A set of suitable materials for pad sliding surfaces was created, which were tested under critical conditions. The selected materials were representatives of construction steel and anticorrosion treatments (galvanization), soft and hard (aluminium) bronzes, composite bearing linings (Babbitt), polymers (UHMWPE), and composite materials (PTFE). The experimental results show the dependence of friction on sliding velocity, wear rate, and other phenomena repeatedly measured on a statistical sample of selected materials. The final result is a list of characteristics, limitations, and recommendations for the tested sliding materials, which can be used for more effective design and operation of large-scale hydrostatic bearings.
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