|
|
Tractor cabin skelet optimization
Saňák, Stanislav ; Prokop, Aleš (referee) ; Řehák, Kamil (advisor)
This thesis addresses the issue associated with the design of the tractor cabin frame. Agricultural machinery, including tractors, is utilized for work in highly challenging conditions such as fields or forest terrains, characterized by uneven, hilly, and often unpaved surfaces. Working in such extremely hazardous environments poses a significant challenge, especially for the operators of these machines. It is very common for drivers to lose control of the vehicle while navigating such terrain, resulting in the tractor tipping over on its side or roof, and in worse cases, experiencing repeated rollovers due to inertia. In such situations, the presence of a protective frame around the tractor cabin is the only possible means of crew rescue. However, the rollover of such a vehicle imposes extreme stress on the cabin frame due to the weight of the tractor and often its cargo. Historically, rollovers have been the leading cause of accidents resulting in fatalities of tractor crews, which prompted the establishment of standards aimed at reducing this type of accident. Tractors are tested against these critical situations to ensure the maximum possible crew safety. Nowadays, every manufactured tractor must comply with these tests. Since these tests are of a destructive nature, it is more cost-effective and time-efficient to first conduct tests using numerical simulations, within which the tractor cabin is optimized to successfully pass the given tests. The actual test is then performed on the final, already optimized cabin frame. In this study, a numerical simulation using the finite element method was conducted on the tractor cabin skeleton for the ROPS (Roll-Over Protective Structure) test, which simulates the tractor overturning. Based on the simulation results, optimizations were made to the cabin that were necessary to pass this test, which consists of several load cases. The optimized cabin frame was subsequently subjected to a basic dynamic analysis (modal analysis). This analysis identified the natural frequencies of the cabin that could be excited in the event of typical excitations acting on this structure (road surface irregularities, vibrations from the engine unit, and so on). Finally, based on real values obtained from experimental measurements, a harmonic analysis was performed. This analysis monitored the response of the frame to excitations corresponding to actual excitations from the engine unit.
|
|
|
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.
|
|
|
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.
|
|
|
Methodology for Identification of Turbocharger Noise and Vibration Sources
Valenta, Otakar ; Kocman, František (referee) ; Novotný, Pavel (advisor)
Malfunctions of machines and machine components are usually accompanied by an increase in vibration and noise. By analysing these vibrations and noises, it is possible to assess their overall condition, diagnose problems and detect possible anomalies and malfunctions. For a successful and practical analysis of turbocharger sounds and vibrations, it is necessary to distinguish turbocharger sounds and vibrations from ambient noise and obtain their characteristics in real time. In the thesis there is performed detailed analysis of the turbocharger noises and vibrations, the sources and reasons for the occurrence of individual vibrations and noises are described, their dependencies on the characteristics of the turbocharger and their allocation to the frequency band. In Matlab Simulink environment, a mobile phone software is developed to provide real-time analysis of the turbocharger sound and to display the probable cause of the turbocharger noises and failure in a graphical interface. The software was tested using sound recordings of Garrett GTD2056 and PBST TCR16 turbocharger sounds. The software is developed using a student version of Matlab and may serve as a foundation for the development of commercial software applications.
|
|
|
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.
|
|
|
Design of an experiment to investigate the influence of the frequency of mechanical vibrations on the structure of a solder joint
Podolák, Šimon ; Košelová, Zuzana (referee) ; Otáhal, Alexandr (advisor)
The main goal of this bachelor's thesis is to study the influence of vibrations on the structure of solder joints, specifically SAC305 solder paste droplets. The thesis consists of three parts: theoretical, practical, and evaluation of results. The theoretical part focuses primarily on solder joints and the phenomena surrounding them, such as diffusion, voids, crystal morphology, and others. It also describes vibrations and everything related to them, including ultrasound and its use in the field of soldering. The practical part deals with designing workstations for creating individual samples, specifically without vibrations, with 5 kHz vibrations, and with ultrasonic vibrations. This is followed by the process of preparing the samples and modifying them to a state suitable for microscopic examination. The final part involves evaluating the results obtained and comparing the samples with each other.
|
|
|
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.
|
|
|
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.
|
|
|
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.
|
|
|
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.
|
guest ::
