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The beginnings of the application of finite element method in biomechanics
Hájek, Petr ; Řehák, Kamil (referee) ; Florian, Zdeněk (advisor)
Bachelor’s thesis is aimed to beginnings of the application of finite element method in biome-chanics. We can define the period of beginnings by the ages 1972, when Brekelmans et al. introduces the method in biomechanics, and 1983, when the method was well established in this field. The main part of the thesis is research study describing this period, presents author (or author’s group), model used, a focus of their work. The works of some authors are discussed in detail; other works are mentioned more marginally. Beside the research study, there is a strain-stress analysis of femur in the thesis, which summarizes basic findings from research study. This is a practical application of the finite element method.
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Strain Stress Study of Burch-Schneider Split
Řehák, Kamil ; Horyl, Petr (referee) ; Janíček, Přemysl (referee) ; Florian, Zdeněk (advisor)
This thesis deals with problems of the hip endoprosthetics area, namely total endoprosthesis (TEP) with Burch-Schneider (BS) split, in which there are many problems in clinical practice. The hip joint load depends on the patient weight and the performed activity. Sedentary job, little exercise, a lot of stress or poor eating habits and overweight associated with it affect negatively hip joint. Increasing hip joint wear and its pain in movement is necessary in several cases to be solved by a surgical procedure in which TEP is applied. When selecting and subsequently applying individual TEP, it is important to pay attention to creating conditions which will allow good fixation. In case of worse mechanical properties of bone tissue, it is very problematic to ensure stability of the implant. Based on several classifications which assess the degree of hip joint damage, it is possible to select a suitable TEP. The BS split, on which this work is focused, is dominantly used in cases of large defects in the acetabulum area. The use of this cage allows to bridgelarge defects and create a new centre of rotation of the hip. Knowledge of the mechanical properties of hip bone tissue can significantly affect the prediction of BS split damage. For this purpose, it was necessary to perform a biomechanical study, which is focused on the influence of worse mechanical properties of bone tissue on BS split failure. The computational modelling using finite element method implemented in the ANSY S software was used for the solution, which enables to solve the mechanical interaction between bone tissue and TEP with BS split. Due to the absence of bone tissue data before application of TEP with BS split, the variants before application of TEP and after application of resurfacing and standard TEP were solved. All variants were solved with the material properties of bone tissue that were determined based on CT images. In addition, all variants were solved for the case of degraded mechanical properties. Based on the numerical simulations results and the Mechanostat hypothesis, a bone tissue analysis of the hip joint was performed before and after application of TEP and TEP with BS split. The results show the influence of the computational model level, which considers the distribution of bone tissue through the inhomogeneous model of the material. Therefore, the degraded mechanical properties have a major impact on the stability and strain of the BS split, particularly in the cranial part of the acetabulum.
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Design of Reversing Gearbox for Historic Railway Draisine
Rekem, Jakub ; Řehák, Kamil (referee) ; Prokop, Aleš (advisor)
Bachelor's thesis deals with the design of the reversing gearbox for the historic railway draisine. First part of the work is devoted to the overview of power units of railway draisines and technical solutions used in their design. The next part contains the description of the original reversing gearbox. The rest of the work explores the design of the gearbox itself.
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Design of a Unified Mechanism of Shifting and Activation of the Parking Brake
Hagara, Adam ; Řehák, Kamil (referee) ; Prokop, Aleš (advisor)
This bachelor thesis deals with the design of a unified mechanism of shifting and activation of the parking lock. The theoretical part is devoted to a more detailed description of the current shifting mechanisms, synchrosystems and parking lock mechanisms. The practical part starts with the analysis of the movements and positions of the individual mechanisms, followed by conceptual designs and the selection of the most suitable one. This is followed by the final design elaboration, which includes the development of a force analysis and torque calculations. The functionality of the geometry of the designed mechanism is verified by dynamic analysis, while the other components of the mechanism are detailed. Finally, an FEM analysis of the components of the unified mechanism is performed to confirm the functionality of the selected design. The thesis also includes a drawing documentation attached in the annex.
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Methods for the wear determination of a railway wheel
Čížek, Petr ; Prokop, Aleš (referee) ; Řehák, Kamil (advisor)
This bachelor thesis deals with the problem of measuring the wear of railway wheels. Railway wheels are subject to high loads and therefore their profile also suffers from high wear. Early exposure of a damaged wheel can prevent fatal train accidents, and hence there is a need to measure wear not only periodically in laboratory but also in during train operation. Wear measurement methods are currently divided into 3 types, the most developed of which are the on-track and laboratory measurement methods. On-train measurement methods are in most cases only at the study stage due to the difficulty of their application to the train set.
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Design of the Differential Test Rig for Testing in Anechoic Chamber
Ivanič, Michal ; Řehák, Kamil (referee) ; Prokop, Aleš (advisor)
The diploma thesis describes the design of a test stand for experimental determination of vibroacoustic parameters of a part of the powertrain system. Thesis contains a research part, describing the problems of the drive system, vibroacoustics, measuring devices and also the division and the description of test stands. At the same time, the reasons for choosing a closed loop test stand are explained. Thesis also includes the results of analytical calculations and numerical results of FEM methods performed using ANSYS software, as well as drawing documentation of individual parts.
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Development of turbochargers
Zogata, Filip ; Prokop, Aleš (referee) ; Řehák, Kamil (advisor)
This bachelor thesis deals with the development cycle of a turbocharger. When we are developing complex components, which completely include the turbocharger, it is necessary to use a number of technical experiments, both testing on a physical model and using computer programs. The aim of this work is to create a basic overview of the requirements for the development of turbochargers, then to approach the use of numerical simulations and testing at gas stations. This work also mentions current trends in this industry based on published studies from recent years. In the final part, the calculation of the modal analysis of the turbocharger is performed using two approaches.
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Design of direct shift gearbox
Kliš, Vojtěch ; Prokop, Aleš (referee) ; Řehák, Kamil (advisor)
This thesis deals with the conceptual design of a double clutch gearbox and the inspection of selected designed parts of this gearbox. The first part of the thesis is focused on the theory of automotive transmissions and analysis of already available double clutch gearboxes. The following is the conceptual design itself, which is based on the selected vehicle on which the transmission will be located and on driving resistances. Based on these default values, the gear graduation is selected, which affects the vehicle’s driving dynamics. With regard to the installation space, a conceptual arrangement of the gearbox is proposed. Furthermore, the thesis is focused on the basic design and calculations of individual functional components of the gearbox. The last part of the thesis is involved to the control of selected structural nodes using the finite element method in the ansys workbench software. The whole thesis describes the individual steps for the design of the basic concept of a double clutch gearbox and the design of their basic components.
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Computational Modeling of Gear Mesh Engagement Dynamics by MBS Approach
Pykal, Vojtěch ; Řehák, Kamil (referee) ; Prokop, Aleš (advisor)
This master’s thesis is focused on the compilation of a computational modelling of gear mesh engagement dynamics of a spur gear by MBS approach. The user input is the specific geometry of gears, the operating speed, and the load torque. The output are the forces in the gear engagement and the reaction of the forces in the wheel bearings depending on the change in the stiffness of the gear due to the changing number of teeth in the engagement and the change in the axial distance. This model is characterized by a fast and relatively accurate calculation in the time domain. This means that it can react to changes in parameters during simulation such as axial distance, speed, and torque.
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