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Design of a rubber coupling for railway applications
Blach, Jiří ; Prokop, Aleš (referee) ; Řehák, Kamil (advisor)
The diploma thesis deals with the design and stress-strain analysis of a flexible coupling composed of individual rubber-textile segments. This concept allows the manufacturer to simplify and unify the production thanks to the ability to use a single segment design for multiple coupling configurations and thus leads to a reduction in costs on the part of the manufacturer. From the consumer side this allows only mechanically or chemically damaged segments to be replaced instead of the entire coupling and saves costs for the potential user. The coupling assembly is primarily designed according to the parameters of intercity electric units and locomotives, however, the individual flexible segments are not limited by this use. When designing a coupling assembly, it is necessary to place requirements primarily on the high safety of all components. The operating mode, in which the relative displacement of the input and output shafts can occur, indicates a relatively wide range of transmitted loads which, if any assembly part is improperly designed, can cause problems leading to temporary putting the entire machine/vehicle out of order. The most critical areas of the assembly include the flexible segments, the bolt connections, the strength of the hubs and the spline joint for torque transfer. Last but not least, the requirements for the non-complex production of components must be taken into account, together with the assembly and maintenance without collision of the components and the necessary tools. In order to verify the above-mentioned requirements, stress-strain analyses are performed simulating the variation of operating load conditions. Due to the reduction of hardware requirements and computational time, together with the absence of experimentally measured data of rubber and PES codes, the flexible segments were modelled at a lower level with a reduced material model favouring the tensile properties of PES cords. However, this reduction provides a more conservative approach, as this use causes higher stresses on the steel components of the assembly. Subsequently, a stress analysis of the splined joint is performed. Due to the absence of specific shaft geometry models of commercial motors and gearboxes, a parallel splines were chosen for this purpose and designed according to the specified maximum torque. The last part of the thesis is focused on verifying the tensile properties of an individual flexible segment.
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NVH of electric vehicles
Dufek, Martin ; Prokop, Aleš (referee) ; Řehák, Kamil (advisor)
There is no internal combustion engine in electric cars and although this is a positive shift in development, it presents new challenges in terms of NVH sources. In these days electric cars seem to be the future of the automotive industry so it is necessary to pay attention to it. In the first part the work is focused on the distribution and description of NVH sources, comparison of their importance in the electric car compared to a car with an internal combustion engine and proposing a possible solution for their damping. The second part of the work is then focused on the importance and implementation of numerical simulations and technical experiments for individual parts of EV used in their development nowadays.
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Design of the Tractor's Cabin Suspension
Rekem, Jakub ; Řehák, Kamil (referee) ; Prokop, Aleš (advisor)
Diploma thesis is devoted to tractor cabin's suspension. First part of the work consists of the overview of used suspension designs and their various modifications. Next, law requirements for roll-over protective structure are described. Subsequently, the suspension design for small-sized tractor is explored. Law compliance is revised via ROPS procedure simulation using finite element method. In the last part of the work, virtual prototype of agricultural tractor in Multi-body environment is built and it is used for studying the dynamic characteristics of proposed cabin suspension design.
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Design of Unconventional Suspension of Tractor's Cabin
Kuric, Michal ; Řehák, Kamil (referee) ; Prokop, Aleš (advisor)
The Master’s thesis deals with the design of unconventional tractor cab suspension. It contains overview of current conceptions, mensions description of single components, takes closer look at torsion bar calculations and strength analysis. Subsequently, there is dynamic analysis of suspension in the thesis, performed with use of Adams View software aimed at ride over bump. Last section describes strength analysis of whole construction according to OECD methodics with use of numerical simulations in ANSYS Workbench software. Part of the thesis is also complete drawing documentation.
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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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