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Noise associated with the rail wheel
Mareš, Adam ; Řehák, Kamil (referee) ; Rec, Matouš (advisor)
The issue of noise associated with rail transport, focusing primarily on noise from the wheel – rail contact, is examined mainly in connection with rail transport, but also concerns tram transport in cities and, to a lesser extent, funicular railways. The noise of rail transport is one of the reasons why it is perceived negatively by the public, even though it offers many advantages over other modes of transport, such as environmental friendliness, travel comfort, travel speed and more. This is one of the reasons why it is necessary to focus on noise in rail transport and to understand, research and further develop and improve the whole issue as well, both in the area of passive and active noise control measures. For this reason, the aim of this work is to provide a comprehensive overview of the issue. The work therefore deals with the issue of noise in a comprehensive way, from the theoretical definition of noise, through noise sources and their distribution to noise measurement and the use of numerical methods for its evaluation and determination of appropriate preventive and anti-noise measures.
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NVH Analysis of the Powertrain
Mrózek, Jan ; Řehák, Kamil (referee) ; Prokop, Aleš (advisor)
This master thesis is focused on the diagnostics of vibrations and noise of an internal combustion engine. The work also includes a summary of the current state of knowledge in which the quantities used, transmission paths, measuring devices and the possibilities of performing frequency analysis are analysed. As part of the technical experiment on which this work is based, vibrations and noise on the tractor engine are measured. The obtained data are then further processed using the BK Connect program. Subsequently, a frequency analysis is performed, specifically an order analysis. The conclusion of the analysis consists of an evaluation of individual orders that cause excitation that occur in the investigated motor.
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Optimisation of electric vehicles gearbox housing with focus on emitted noise
Fürich, Adam ; Prokop, Aleš (referee) ; Řehák, Kamil (advisor)
This thesis deals with the vibration and noise of the gearbox for an electric vehicle. The gearbox itself acts as an emitter of unwanted noise caused by vibration excitation of the internal components of the gearbox. It is therefore necessary to deal with a complex unit such as the gearbox at system level as soon as it is being designed. This can be achieved using analytical tools and software. In this thesis, in order to evaluate the validity of the designed gearbox, a procedure is developed using both technical experiment and numerical simulations. The effect of the bolt preload is not overlooked for the following computational modelling dealing with the radiated noise of the gearbox. The results obtained from the performed technical experiments were then evaluated and compared with the results of the computational models. In this way, it is possible to compare the different approaches, their limitations and weaknesses. Furthermore, the thesis deals with design modifications that are analyzed using computational modeling. The thesis is concluded with a brief description of the application of each approach and an evaluation of the gearbox design modifications.
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Determination of Acoustic Properties of Sound-Absorbing Materials
Ďurica, Matej ; Řehák, Kamil (referee) ; Prokop, Aleš (advisor)
This diploma thesis is focused on experimental determination of acoustic absorption of four different material samples. The aims of the work include: research on the given issue, determination of the procedure for the performance of a technical experiment and modification of the measuring device for the determination of acoustic absorption. The performed experiments were evaluated and the results of the sound absorption coefficient were compared with the values given by the manufacturer. Sensitivity analyzes of the experiments were performed.
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Stress strain analysis of membrane coupling
Sýkora, Tomáš ; Prokop, Aleš (referee) ; Řehák, Kamil (advisor)
This master’s thesis deals with the strain stress analysis of a membrane coupling with different membrane shapes and under different operating conditions. Thanks to their flexible membrane, these couplings are able to transmit torque even in the moment of misalignment of the connected shafts. However, too much misalignment is one of their most common causes of failure. For this reason, it is necessary to define the critical areas of the coupling during the design and to reduce these areas with the right optimization. For this purpose, a geometric and subsequently a numerical model of the membrane coupling for simulations using FEM software Ansys Workbench is created. At the beginning, the initial shape of the membrane is determined and according to the results of individual simulations, the shape is gradually optimized. At the end of the thesis, based on the distribution of equivalent stress in the membrane, the results of individual optimizations are compared and evaluated.
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Planetary Gearbox Design for the Formula Student
Viktořík, Marek ; Řehák, Kamil (referee) ; Prokop, Aleš (advisor)
The purpose of the bachelor thesis is to design a reduction gearbox for a Formula Student Electric car. Firstly, the theoretical part summarizes the distribution of used transfers in the competition. Secondly, the research part analyses the proposals of reduction gears for monoposts of this competition in more detail. Thirdly, the description of reduction gears for passenger cars is provided. Finally, the result is the design of gears itself and their components transmitting torque. Furthermore, the FEM analysis of all critical parts of the transmission system is performed.
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Flat Plates Noise
Zlámal, Josef ; Řehák, Kamil (referee) ; Prokop, Aleš (advisor)
The master thesis summaries the findings results of a study focused on the spread of noise vibrating flat plates. Part of this thesis is measurements of flat plate noise in the anechoic chamber and finally their processing and evaluation. The next part of the thesis is focused on FEM acoustic simulation and comparing results with measurements.
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Vibroacoustic Analysis of the Combustion Engine
Špačková, Jana ; Řehák, Kamil (referee) ; Prokop, Aleš (advisor)
This thesis is focused on vibration and noise diagnostics of a combustion engine. In the range of the current knowledge there is an analysis of measuring devices, units of measure, possibilities of frequency analysis and a combustion engine from the point of view of vibrations and noise. Part of this work is creating a technical experiment where there were measured both vibrations and noise of two combustion engines. From the data it was done a frequency analysis. Conclusion of the analysis is an evaluation of frequencies which occurred on given engines.
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Determination of sound power level of transmission
Švanigová, Lenka ; Prokop, Aleš (referee) ; Řehák, Kamil (advisor)
The field of vibrations and associated noises is a very current topic. Noise can be measured with different equipment and the gained data might be compared using different methods, which are in accordance with defined norms. This bachelor thesis deals with the CSN EN ISO 9614 norm, especially its first part which focuses on the method of measuring in points. To apply this method to measure the transmission, basic terminology and formulas used to determine the individual indicators were described in detail. The whole procedure was applied to two industrial transmission units with different parameters and transmitted power. The total sound power on these sources was determined as well as the sound power levels for the individual measured sides, even without using the A-filter, which is the most commonly used filter in transmissions. Lastly, acoustic maps were created. These maps make it possible to discover locations which dominantly contribute to the total sound power level.
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Train transport
Netolický, Jan ; Prokop, Aleš (referee) ; Řehák, Kamil (advisor)
This bachelor thesis deals with train transport. Train transport has been with us for many years and is constantly evolving. Many years have passed since the early days when rail vehicles were only used for transporting materials in mines, and today's rail vehicles serve as one of the main means of transport all over the world. The congestion of road transport is contributing to the use and development of train transport and thus to the increased speed and comfort that the carriers are trying to offer us. For this reason, the trains have been divided according to different criteria and the distance of their journey. Freight trains have also been included. Because of the constant increase in speed, more space has been given to high-speed trains, which have been divided into individual high-speed families. This overview of the trains gives us an indication of the direction of future development. As the Czech Republic has an extensive rail network, the paper includes an assessment of future developments in terms of speed increases, electrification and freight transport. As a result of the thesis, a breakdown and overview of current trainsets is presented, from which trends in this sector have been drawn. The thesis also concludes with a critical assessment of future developments in the Czech Republic.
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