National Repository of Grey Literature 57 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Diagnostics of rotating parts mounting systems in a wind turbine nacelle
Krontorád, Jakub ; Vlašic, František (referee) ; Mazal, Pavel (advisor)
The core aspect of thesis is management of work and diagnostics of wind turbines. It contains an overview of wind energy in Czech Republic and collects a relevant information from international papers and studies regarding the topic of diagnostics and maintenance of main mechanical components located in nacelle of wind turbine. It contains a recommendation for improvement of working conditions of wind turbines and their maintenance, which would lead to decrease of failure rates of the wind turbines main mechanical systems due to the utilization of acoustic emission and high frequency vibrations monitoring. Experimental part of the thesis contains analysis of acoustic emission signal from anonymous wind turbine with maximum energy output of 2000kW in Czech Republic to illustrate the sensitivity of acoustic emission and introduce its principles.
Design of a milling table for machining wooden boards
Uhlíř, Radim ; Mazal, Pavel (referee) ; Čípek, Pavel (advisor)
The bachelor's thesis deals with the design and implementation of a milling table for machining wooden boards. In the research part, an analysis of the solutions available on the market was performed together with an analysis of workpiece fixtures, hand milling fixtures and linear guides. Based on the research, two conceptual solutions and several variants of structural nodes were proposed. The most suitable constructional solution was selected from the conceptual solutions, calculations of critical nodes were performed and drawing documentation was made. Subsequently, a prototype of the table was made and its functionality was tested. The table can clamp and machine a wooden board with maximum dimensions of 1000 x 800 x 100 mm.
Modernization of R-mat test stations
Papaj, Lukáš ; Dočkal, Aleš (referee) ; Mazal, Pavel (advisor)
The aim of the thesis is to reconstruct obsolete R-mat test stations, which are used for rolling contact fatigue tests of material, which are still of interest from industry. It was necessary to replace the original control electronics with a new industrial computer to allow use modern sensors and automate the entire test process. At the same time, the measurement was supplemented by an acoustic emission method, which can also record the development of damage. Design modifications have been made that allow the installation of all new sensors. The main method for evaluating the tests is vibrodiagnostics, which is supplemented by the acoustic emission method. With the help of several experiments, the shortcomings of the new control system were identified, some parameters were designed, and the main functionality of the modernized R-mat station was verified. According to the proposed parameters and the identified shortcomings, the control system was modified, and a script was created, which is used to evaluate the test. It is still possible to perform rolling contact fatigue tests of the material on the modernized equipment, and thanks to the modernization of the electronics, it is possible to test completely new methods of test evaluation.
Methods for solving the tolerance chains
Fiala, Lukáš ; Mazal, Pavel (referee) ; Svoboda, Petr (advisor)
This bachelor’s thesis deals with methods of solving dimensional chains. At the beginning, basic terms related to dimensional chains are explained. The next section describes worst case, statistical, group interchangeability and compensation methods. For better explanation, an example is solved for each method. Attention is also paid to systems in which the calculation of tolerance analysis can be performed. In conclusion, statistical and compensatory methods are used at the same assembly for comparison, and then, results are compared and evaluated. The thesis should provide the reader, in which cases it is appropriate to use a certain method.
Design of the feeding mechanism for L profiles
Witos, Anton ; Vlašic, František (referee) ; Mazal, Pavel (advisor)
In this bachelor thesis was designed machine for feeding L profiles and end effector of service robot. Machine uses pneumatic piston to create frictional force between profile and feeding wheels. For movement of profile is used chain transmission which drive feeding wheels. End effector uses for work special type of electromagnet which uses electric voltage only for disabling. Thesis includes review of suggested solutions and choice of optimal solutions.
Optimization of ultrasonic leak detector of pneumatic system
Macků, Ondřej ; Mazal, Pavel (referee) ; Vlašic, František (advisor)
The thesis deals with design and optimization of exchangeable modules for localization of air distributable ultrasound in concept of ultrasound probe design. Several series of these modules were manufactured using the technology of rapid prototyping and tested on artificially created source of air leak. Based on these verification experiments two types covering wide use for identification of pneumatic systems leaks were selected and modified. These two types are long range module for more accurate and expended reach of the leak detection and focusing attachment for narrowing the received range of scanning module and elimination of surrounding ultrasound. Part of the thesis is also analysis of the acoustic signal processed by modern acoustic emission analysers which allow besides standard parameters recording also continuous sampling up to 10 MHz and design solution for attachment of add-on modules to the detector. The thesis is beneficial for raising awareness of leak measurements, prototype manufacturing by using the 3D printing and designing and manufacturing of modules.
Influence of dynamic loading on the contact fatigue characteristics of bearing material
Hložek, Jiří ; Hutař, Pavel (referee) ; Mazal, Pavel (advisor)
This thesis deals with the study of sudden step changes observed in model testing of standard bearing steel 100Cr6. Methodology of experiments with step change of load is proposed and applied in measurements. Three complete series of experiments were conducted, and rating life was determined for each loading trend. Based on the experiments carried out, it was found that the selected steel is able to withstand the sudden step of load changes, despite the fact that it is not material of choise for this type of load. Part of this work was to verify functionality of the innovated test stations AXMAT with modern diagnostics and a new control system, and also of the hydraulic variant of AXMAT, which allows to remotely derive dynamic loading of the test sample.
Design of clamping device for machining of manifold part
Foltýn, Jan ; Mazal, Pavel (referee) ; Svoboda, Petr (advisor)
This thesis deals with clamping fixtures. It aims to design an effective clamping solution for machining parts on a milling machine. The clamping solution was designed and then verified by a series of calculations. The main goal and partial objectives were fulfilled. The output is the design of fixture, which can clamp given part. Subsequently, based on the calculations it was decided to use four of these fixtures on one machining table. When calculating the appropriate variation of the fixture layout, an estimate of the time required for the operations performed by the machine operator was made. The thesis offers an overview of the materials used in the automotive industry. Furthermore, the study of clamps and clamping systems. It also touches the problem of optimizing manufacturing process and demand for ways to speed up the manufacturing process.
Diagnosis of Pneumatic Cylinders Using Acoustic Emission Methods
Mahmoud, Houssam ; Baran,, Ireneusz (referee) ; Santos, Serge Dos (referee) ; Mazal, Pavel (advisor)
Tato práce se zabývá vývojem nového efektivního diagnostického postupu pro kontrolu funkce pneumatických válců pomocí metody akustické emise. Cílem práce bylo navrhnout a určit diagnostická kritéria pro hodnocení kvality vybraných typů pneumatických válců. Prvním krokem bylo nalezení typického akustického emisního signálu, který je spojen s určitým typem poškození ve válci využitím frekvenčního spektra signálu. Později byl tento parametr nahrazen parametrem RMS během sledování změn v průběhu testů. Na konkrétních válcích byl sledován vztah mezi akustickou emisí a různými typy defektů a byl představen nový přístup k určování těchto typů vad a jejich odlišením v signálu akustické emise. Druhý krok studie že neporušené a poškozené válce byly porovnávány tak, aby se zjistily výrazné rozdíly, které určují, zda je válec poškozen nebo nepoškozen. Několik nepoškozených válců bylo testováno akustickou emisí a následně v nich byly vytvořeny umělé vady. Signály z vysouvání a zasouvání pístu byly zaznamenány a analyzovány pomocí řady parametrů. Na základě časového zpoždění a normalizace RMS byly rozpoznány odezvy mezi poškozenými a nepoškozenými pneumatickými válci. Rozdíly byly zjištěny porovnáním maximální hodnoty RMS ze snímače upevněného na předním víku válce a snímače upevněného na zadním víku válce pro jeden cyklus. Poškozené a nepoškozené válce byly rozlišeny pomocí rozdílů energetických hodnot přítomných v signálech z obou snímačů v závislosti na zdvihu pístu. Konečné vyhodnocení válce bylo určeno výpočtem celkové hodnoty RMS. Ve třetím kroku experimentu byly válce postupně zatěžovány různými závažími ve svislém směru. Signály akustické emise byly zaznamenány z vysouvání a zasouvání pístu a poté analyzovány. Časové zpoždění se vypočítává z digitálního vstupu a začátku pohybu pístu. Energie signálu a RMS akustické emise porovnávají různé reakce v poškozených a nepoškozených pneumatických válcích s a bez zatížení. Výsledky testu ukázaly lineární vztah mezi křivkou RMS a zatížením. Defekty ovlivňují vztah mezi aplikovaným zatížením a zaznamenaným signálem snímačů.
Suspended bicycle carrier for buses
Svoboda, Pavel ; Vlašic, František (referee) ; Mazal, Pavel (advisor)
This bachelor´s thesis describes the construction of universal the rack for bicycles to different types of buses. The aim was to produce a simple, lightweight, safe, affordable, accessible design of the rack for bicycles with easy the suspension, but also with the access to the engine compartment of the bus.

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