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Mitigating vibration of internal combustion engines
Kožuch, Jonáš ; Böhm, Michael (referee) ; Fridrichová, Kateřina (advisor)
This bachelor thesis deals with the problem of vibration damping of internal combustion engines. It gives an overview of the causes of vibration and describes them. The most dangerous phenomenon for the crankshaft is torsional vibration, and it is therefore important to eliminate this phenomenon as much as possible. An overview of current torsional vibration damping solutions is given. Torsional vibration dampers are divided into different groups. The division is mainly based on the type of construction and the way in which the dampers eliminate the vibrations. The final part focuses on the simulation of the crank dynamics in GT-Suite. In the simulations, the parameters of the rubber torsional damper are varied, specifically the moment of inertia and the Maxwell model settings. Then, their effect on torsional vibration is investigated. The output is the ideal damper parameters for a given engine model.
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Modern vibrodiagnostics of machines and evaluation of datasets by neural networks
Koníček, Tomáš ; Holoubek, Tomáš (referee) ; Hammer, Miloš (advisor)
This Master‘s thesis focuses on technical diagnostics with an emphasis on vibrodiagnostics of machines and equipment. The aim is to carry out research on vibration monitoring using modern on-line systems and to investigate the possibilities of processing the acquired data files using neural networks. Vibration monitoring from Siemens SIPLUS CMS is analyzed, including a description of individual hardware and software components. The work also focuses on machine diagnostics using a real model equipped with the SIPLUS CMS system in cooperation with the SIMATIC S7-1200 programmable automaton. The obtained data will be transferred via the FTP protocol for further processing in the Matlab program. Neural network models will be designed and used, which will be trained on the measured data. Convolutional neural network model will be used. The results will be evaluated and a conclusion will be drawn.
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Numerical simulation of gear mesh stiffness
Rackovský, Daniel Milan ; Prokop, Aleš (referee) ; Řehák, Kamil (advisor)
The diploma thesis deals with the simulation of the spur gears mesh stiffness. The introductory part of the thesis presents a detailed review of the knowledge in the field of gear theory, gear error and also NVH of gears. The next part of the thesis describes the basic principles of the function of the parametric FEM model of gear mesh, which was developed for the purpose of this thesis. The last part of the thesis presents the results of FEM simulations in which the effect of manufacturing error of the gears on the STE waveform was investigated. The basis of the simplified production error model was the sine function. The effect of the number of periods of this function and the magnitude of the amplitude on the STE waveform was investigated. The effect of the magnitude of the load torque on the STE of the production-error gear was also verified. The magnitude of the amplitudes of the sine function was determined to match the allowable wheel shape tolerances according to ISO 1328-1. The problem was solved in Ansys Mechanical APDL using a parametric FEM model based on APDL language.
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Crank train of a two-stroke racing motorcycle engine
Šmahel, Matěj ; Tobiáš, Martin (referee) ; Drápal, Lubomír (advisor)
This diploma thesis deals with numerical-construction design of a two-stroke single cylinder internal combustion engine crankshaft. First part of diploma thesis describes main force effects of crank train and describes selected two-stroke engine. The second part of this diploma thesis is dedicated to numerical modelling of crank train in Multi-Body System. The main goal is to determine an effect of balance factor to motorcycle components. Loads of main crankshaft bearing and engine mounts are evaluated. Acceleration in handlebars and attachment points for footrest is also determined. The results are summarised, and further possible process is outlined.
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Reduction of vibration and noise at passenger car interior
Patočka, Pavel ; Prokop, Aleš (referee) ; Řehák, Kamil (advisor)
This thesis addresses the issue of reducing vibrations and noise in the interiors of passenger vehicles, which is commonly tackled today by additional soundproofing using vibration-damping and sound-absorbing materials. In the research part of this thesis, besides methods for measuring vibrations and noise, the properties and application methods of these materials are described in detail. As the name of these materials suggests, their main goal is to dampen vibrations and absorb sound. Their principle, in simple terms, consists of converting mechanical or sound energy into another form of energy (most commonly thermal energy). However, the application of these materials to a structure affects its modal properties, including natural frequencies and mode shapes. To further investigate the influence on natural frequencies and mode shapes after applying vibration-damping material to a structure, both numerical and experimental modal and harmonic analyses of a simple metal sheet sample were conducted. The benefits of vibration-damping and sound-absorbing materials in terms of additional vehicle soundproofing were evaluated based on a road test conducted under real operating conditions.
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Comparison of operational vibrations of selected types of flexible couplings for high-speed applications
Práznovský, Alexander ; Pavlík, Ondřej (referee) ; Pokorný, Jan (advisor)
Focus of the bachelor thesis is the selection from suitable candidate of flexible couplings for high speed applications. Flexible couplings introduce excitation forces into the system that cause vibrations. It was necessary to determine which flexible coupling is the most suitable for the tested assembly. In the research section, the flexible couplings in particular were described, but also all the essential parts of the test assembly and their functionality. Furthermore, the data processing and evaluation procedure is described in the thesis. For the possibility of an overall processing of all measured data, a calculation using the finite element method was performed to determine the applicability of the double-loop flexible coupling. The output of the bachelor thesis was the selection of the best flexible couplings for the test assembly.
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Vibrodiagnostics of electrical machines
Petráček, Samuel ; Cipín, Radoslav (referee) ; Janda, Marcel (advisor)
This bachelor's thesis deals with getting to know vibrations and their description. What types of vibrations occur, what are their parameters, such as deflection or acceleration, and a slightly described frequency analysis for non-harmonic signals. Subsequently, the sources of vibrations in electric rotating machines are described. Types of vibration sources are described here, for example of mechanical origin or on the bearing. The causes of their occurrence are, for example, rotor imbalance, rotor misalignment or mechanical loosening. And their subsequent effect on the machine in axial and radial directions. Furthermore, the Crest Factor measurement method and a summary of other diagnostic methods of vibrodiagnostics such as Envelope Analysis and Kurtosis Factor are described. For what purposes these methods are used and their advantages and disadvantages. In the practical part, 4 asynchronous motors were measured with prerequisites for faults with rotor eccentricity. The effective values of the vibrations and the Crest Factor were calculated here, followed by a frequency analysis using FFT (Fast Fourier Transform). In the end, the resulting data were evaluated.
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Vibration measurement processing for predictive maintenance of mechanical systems
Kuchař, Matěj ; Dobossy, Barnabás (referee) ; Kšica, Filip (advisor)
As technology evolves, so does maintenance. In recent years, predictive maintenance has developed the most and is increasingly used. In the case of vibrations in particular, this type of maintenance brings better results than the types of maintenance previously used. Compared to other types of maintenance, predictive maintenance is more difficult to implement. When implementing it is necessary to follow its procedure: data pre-processing, feature extraction, determination of the health indicator, training of the predictive model, and evaluation.There are many software programs that provide features for predictive maintenance. In this thesis, the Predictive Maintenance Toolbox from the Matlab was used. Subsequently, the knowledge of the implementation of predictive maintenance was applied to the experimental data obtained by measuring bearing vibrations to predict RUL.
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NVH problematics at vehicle testing on chassis dynamometer
Jiříček, Martin ; Prokop, Aleš (referee) ; Řehák, Kamil (advisor)
This bachelor's thesis deals with noise and vibration issues in vehicle testing on a chassis dynamometer. It aims to provide an insight into the field of chassis dynamometers, their design and function, to provide an overview of the possibilities of vibration and noise measurement on vehicles and to explain the possibility of using the chassis dynamometer as a measuring device for a complete noise and vibration analysis, including an evaluation of its advantages and disadvantages based on available studies and literature.
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