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Modification of coating-substrate interface character of thermally sprayed coatings using electron beam technology
Mareš, Jiří ; Moravčík, Igor (referee) ; Čížek, Jan (advisor)
Tato práce je zaměřena na modifikaci charakteru rozhraní substrát-nástřik NiCrAlY povlaků nanesených pomocí technologie vodou stabilizované plazmy na substráty z oceli S235JRC+C. Přetavení žárové vrstvy elektronovým paprskem bylo zvoleno jako technologie pro modifikaci a dvě různé modifikace byly zkoumány. V práci byl proveden pokus o stanovení vlivu modifikací na adhezní vlastnosti nástřiku. Dále jsou v práci prezentovány analýzy mikrostruktury, fázového a chemického složení a mikrotvrdosti ve stavu před a po modifikaci. Během studie bylo zjištěno, že dochází ke změnám fázového složení jak během depozice, tak během modifikace elektronovým paprskem. Modifikace elektronovým paprskem způsobila roztavení oxidů původní mikrostruktury nástřiku, které následně rekrystalizovaly na povrchu modifikované vrstvy. Dalším získaným poznatkem bylo, že dochází ke snížení mikrotvrdosti po modifikaci, což bylo způsobeno odstraněním oxidů z mikrostruktury a promícháním materiálu substrátu a původního nástřiku. Adheze nástřiků v as sprayed stavu byla kvantifikována. V případě nástřiků modifikovaných elektronovým paprskem přesná kvantifikace nebyla možná, z důvodu předčasného porušení na rozhraní nástřik-adhezivní pojivo během adhezních testů.
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Mechanical response of long-fiber-reinforced polymer composite
Škriniarová, Nina ; Prokeš, Jan (referee) ; Čech, Vladimír (advisor)
This diploma thesis is focused on monitoring of mechanical response of long-fiber reinforced polymer composite. Main part of this thesis was preparation of long-fiber reinforced composite specimens, on which matrix was reinforced by commercially sized glass fibers. For comparison of properties were prepared specimens reinforced by unsized glass fibers. Apart from preparing specimens reinforced by long glass fibers were prepared specimens contains long carbon fibers. For evaluation of mechanical response of the prepared composite specimen were used flexural test and short beam shear test. Mechanical response was evaluated with universal testing machine ZWICK Z010 and data were processed in OriginPro 8 program. Thanks to evaluation of the mechanical response of the prepared specimens was assessed adhesion to fiber-matrix interface. By examining the mechanical response or adhesion can be assessed efficiency of commercial fiber surface treatment and so standardize measurement to compare other options of surface treatments.
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Local-Based and Cloud-Based Systems Management
Nováček, Radek ; Chmelař, Petr (referee) ; Mlích, Jozef (advisor)
The master thesis deals with analysis of existing solutions and architecture design of new solutions for management of unix-like systems. The resulting system is usable for configuration of the local system over the D-Bus and remotely over the network. Usability for cloud computing has been considered during design.
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Server application to process data from a MySQL database and their interpretation
Gardian, Ján ; Zeman, Kryštof (referee) ; Červenák, Rastislav (advisor)
Diploma thesis is about creating server application that process and interprets data from the database. Main aim of such application is able to process a large number of database requests in real-time environment. Provided database contains records of measuring download speed and quality of mobile connection via different radio technology from various providers. Those measured data are sent from users all around the world and amount of data collected is still growing. Therefore created server application can adapt to increasing size of database thanks to aggregation. This method of aggregation and use of index in database tables are further discussed in the theoretical part. Mainly putting indexes in tables produce significant acceleration of processing database requests. Final product of this thesis is an application that consist of three components: a server application running aggregation, website that interprets measured data and back-end interface providing measured data as well. Data at the website are presented in form of graphs for different countries and used radio technologies. Web address and user manual for finished applications are provided in the fourth chapter of diploma thesis. In the last part of thesis are performed various speed tests of programmed application that confirm the effectiveness of selected and described methods to accelerate work with the database.
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Control of multiple-steer vehicle
Krsek, Jiří ; Kopečný, Lukáš (referee) ; Šolc, František (advisor)
The subject matter of the bachelor thesis is a creation of functional model of mobile robot equipped with multiple-steer chassis. The robot will have its own control unit consisting of 32-bit processor and wireless communicatin unit, which enables the contact with superset system. The superset system serves as visualization interface robot - operator and enables to enter the data for requested movement of robot. The calculation of movement of each actuator is ensured by control unit of robot.
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Influence of glass fiber degradation on the mechanical response of a polymer composite
Součková, Lenka ; Knob, Antonín (referee) ; Čech, Vladimír (advisor)
The bachelor thesis studies the effect of fiber degradation with commercial sizing on the flexural properties of polymer composite based on unsaturated polyester resin reinforced with long unidirectionally oriented glass fibers. Fibres of age 23, 61, 67, 112 and 135 months were used to prepare a series of composite samples. The mechanical properties of a composite containing 40.5% % vol of fiber were determined using a three-point bending test defined by ASTM D790-17 standard. From the obtained data, the flexural strength, the flexural modulus and the flexural strain were evaluated. It has been found that the degradation of the fibers and their sizing leads to a reduction in flexural strength. This was due to the reduction of adhesion between the fibers and the matrix, thus also the quality of the interface, which caused insufficient stress transfer from the matrix to the fibre. The resulting difference in strength of composites with fibers aged 23 and 135 months was 0,19 GPa with respect to the origin value of 1,17 GPa. The obtained values were used to assess the correlation between the flexural strength of the composite and the shear strength. Pearson's correlation coefficient set at 0,71 corresponds to a strong correlation. The effect of fiber degradation on the flexural modulus has not been demonstrated.
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Game Interface with Data Projector and Leap Motion
Kendra, Matej ; Beran, Vítězslav (referee) ; Najman, Pavel (advisor)
This thesis describes various game interfaces for human and gradually there are shown more modern and common available interfaces. Work closely describes how you can play games on a regular projector and sensors for gestures detection - Kinect and Leap Motion. This work focus on evaluation of aspects of table-game design with these components and also on display view calibration between projector and Leap Motion. Part of the project is devoted to describing the board game Catan, of which rules are taken to write down specification and options of player. According to this knowledge is then described the design of the play-set and the design of several interfaces of the game. Implementation is briefly described and final chapters covers forms of the testing methods of interfaces and testing evaluation from user perspective.
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Design and implementation of ISA-S88 laboratory model
Husák, Michal ; Pásek, Jan (referee) ; Kaczmarczyk, Václav (advisor)
Bachelor thesis aims to clarify the control of batch processes, by using standard ANSI/ISA-S88. It implements the standard in the school example project, which will become a part of the laboratory practices in the course Process Control (MAUP). The design of assignment contains valuable tips for successfully finishing a laboratory task. The example protocol documents the program solution, which is also a detailed guide for students. The task is realized on the "Balls" laboratory model, which had to have its hardware innovated and wiring documented. Innovation of the model was done during the semester thesis, for the needs of course Programmable Logic Controllers (BPGA).
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Behaviour of the Interface of Low Toughness Materials
Halasová, Martina ; Pabst, Willi (referee) ; Tatarko, Peter (referee) ; Fintová, Stanislava (referee) ; Chlup, Zdeněk (advisor)
The work is focused on evaluation of factors influencing behaviour of interface in low toughness ceramic materials reinforced with fibres. The main aim was to characterise processing effects influencing the quality of fibre-matrix interface, with respect to final behaviour of composites at various loading type. The partial goal was to map the possibility of influencing the composite material by choice of matrix material, eventually by change of its processing, leading to change of interfacial properties without need of modification of reinforcement surface. The materials used in studied composites as a matrix were based on thermal transformation of polymer precursors, thus, the resulting materials were characterised in partially as well as in fully pyrolyzed state. Behaviour of interface in cpomposite materials was first evaluated from the global behaviour (i.e., change of mechanical properties) and in chosen representative composites also from the point of local changes in close surrounding of the interface (i.e., microstructure, chemical processes, fracture-mechanic processes, etc.) due to thermal exposition. In experiment were used particularly composite materials prepared by pyrolysis of polysiloxane resins reinforced by basalt fibres or Nextel™720 fibres. With respect to thermal resistance of the reinforcement, the basalt reinforced composites contained only partially pyrolyzed matrix (i.e., to temperature of 800°C), and in composites with Nextel™720 reinforcement was the matrix in form of fully pyrolyzed polymer into ceramic (SiOC). At partial pyrolysis of polysiloxane resin occurs rapid change of behaviour at temperature of 600°C. It was demonstrated, that around this temperature the formed interface with basalt fibre exhibits optimum adhesion/strength, allowing to reach sufficient level of composite strength at acceptable fracture toughness. Above temperature of 750°C occur significant difusion processes in the area of the interface and formation of new crystalline phases in the fibre, what deteriorates the fibre strength, and on the contrary, strengthen the interface cohesion, what leads to degradation of properties of the whole composite. At composite materials determined for high temperatures, reinforced by Nextel™720 fibres, was detected significant resistivity against oxidation caused especially by fully pyrolyzed matrix. As similarly important factor was observed the formation of mullite interphase in surface area of the fibre. Volume changes caused by formation of the interphase, difusional transport of the matter and thermal exposition led to formation of thermally and stress-induced micro-cracks, weakening interfacial surrounding in matrix as well as in fibre. This mechanism in contrast to amplifying chemical bond between fibre and matrix led to preserving of the composite properties also at high temperatures up to 1500°C. The work also dealed with effects of loading rate, where in contrast to static loading were observed different failure mechanisms. Realized research led to description and explanation of the influence of the fibre-matrix interface by change of matrix material processing parameters, which allow processing of economically advantageous and thermally stable composite.
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Effects of Defects on Composite Structures Load Carrying Capacity: Delaminations at a Bi-Material Interface
Matěják, Vladimír ; Kotoul, Michal (referee) ; Růžička, Milan (referee) ; Juračka, Jaroslav (advisor)
Kompozitní materiály se projevují komplexním způsobem porušování, které může být dále ovlivněno přítomností různých poruch plynoucích z výrobních processů nebo se vyskytujících v průběhu života součásti. Důkladné porozmění procesů porušování a jejich okolností je nezbytné pro navrhování kompozitních konstrukcí, jenž budou bezpečnější, trvanlivější a ekonomičtější. V první části disertační práce jsou popsány způsoby porušování kompozitů a uvedeny současné matematické metody pro analýzu a výpočet únosnosti. Dále jsou zde vyjmenovány hlavní druhy vad a stručně diskutován jejich vliv na vlastnosti kompozitních materiálů. Zvláštní důraz je kladen na delaminace, společně se základními principy lomové mechaniky a jejich uplatnění při výpočtech a zkoušení kompozitů. Druhá část je zaměřena na delaminace na rozhranní dvou různých materialů. Lomová houževnatost byla experimantálně měřena ve třech typech zatížení za účelem stanovení poruchového kritéria založeného na podílu módu I a módu II. Během tohoto experimentu byla vyvinuta nová metoda měření délky trhliny pomocí digitáního zpracování obrazu a rovněž byla navržena nová definice počátku šíření trhliny. Analytické vztahy pro výpočet míry uvolnění deformační energie z naměřených dat byly rozšířeny o vliv rozdílných elastické parametrů materiálů na rozhranní. Podrobnější prozkoumání analytických vztahů a výpočet metodou konečných prvků odhalil, že podíl módu I a módu II je závislý na vzdálenosti od čela trhliny a poruchové kritérium založené na podílu smíšenosti tak nemůže být použito.
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