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The Influence of the Isothermal Transformation Dwell on the Structure and Mechanical Properties of ADI
Falta, Petr ; Kohout, Jan (referee) ; Věchet, Stanislav (advisor)
The thesis ,,The Influence of Transformation dwell on the Structure and Mechanical Properties of ADI´´ deals with problems of optimal properties of the unalloyed nodular cast iron, which are obtained by the heat treatment. The heat treatment consists of austenitization and then rapidly quenching to the transformation temperature, isothermal transformation and water cooling in the end. The aim of the thesis is focused on estimating the influence of isothermal transformation on the content of stabilized austenite, static mechanical properties and on the fatigue properties in high-cycle fatigue region for selected samples. The theoretical part of this work analyses the production of the nodular cast iron and its possibilities of the heat treatment, final technological and mechanical properties. Furthermore, it examines the conditions of austempering (temperature and time of isothermal dwell), which has a fundamental influence on mechanical properties of ADI. Problems of fatigue properties are described at the end of this part. The experimental part contains a chemical composition of studied samples and their metallographic analysis. Among others the basic mechanical static properties were determined as well as the Wöhler curves including values of fatigue limits for ten on seventh cycles. Wöhler curves were obtained by a mathematical processing using data reached by fatigue tests.
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Low Cycle and High Cycle Fatigue Properties of Austempered Ductile Iron
Zapletal, Josef ; Bokůvka, Otakar (referee) ; Kunz, Ludvík (referee) ; Věchet, Stanislav (advisor)
The thesis is focused on assessment of fatigue behaviour of austempered ductile iron with nodular graphite. Optimal period of transformation was determined based on the best combination of stress and strain characteristics established by tensile test. Cyclic response and low-cycle fatigue life were studied under both stress-control and longitudinal strain-control mode at room temperature. For both modes, shapes of cyclic hardening curves are dependent on stress amplitude. Cyclic deformation curves (CDC) were fitted by power regression function. Results were compared with CDC established by multiple step test in both modes with verification of the influence of cyclic creep (high stress levels, stress-control mode). Experimental data of S-N curves are in agreement with the Manson-Coffin and the Basquin law. Fatigue and cyclic parameters were compared. Fatigue life time in high-cycle fatigue region was determined. Experimental data were fitted by suitable regression functions. Regression parameters and fatigue limit were established by means of each regression function. Experimental data in low- and high-cycle fatigue regions were used to construct S-N curve and to determine relevant parameters. Discontinuity of experimental data was not observed. Low-cycle fatigue behaviour was predicted. Approximation of tolerance bands was realized in high-cycle and both high and low cycle fatigue regions.
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Static and Fatigue Properties of Selected Al - alloy
Skoumalová, Zuzana ; Němec, Karel (referee) ; Věchet, Stanislav (advisor)
The present bachelor thesis focuses on material properties of wrought aluminium alloy AlZn4Mg1. The thesis deals with the interrelations between the alloy structure and its static as well as fatigue properties, especially with the latter. The first part of the thesis provides a summary of current knowledge in the studied field, experimental results can be found in the second part. Static properties of the alloy were examined with the help of measurements of hardness and a tension test, fatigue properties on the basis of experiments in high- and low-cycle regions.
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Hardness testing of metallic materials
Dufková, Hana ; Věchet, Stanislav (referee) ; Němec, Karel (advisor)
The aim of this thesis is to define and describe the hardness of material, possibilities of its testing, including the history and development of individual tests of hardness. The practical part of this work consists of the application of some of these tests on selected samples, including the evaluation of the results.
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RFID based attedance system design
Krejzek, Jakub ; Mašek, Petr (referee) ; Věchet, Stanislav (advisor)
This thesis describes the design of applications for attendance system. The first part describes today's modern applications and basic information about RFID technology. The second part deals with the design, of SQL database applications and own attendance system application. The last part describes the instructions and suggestions for possible improvements and expansion, which is described in the conclusion.
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Haigh diagram of selected spring steel
Zejdová, Lucie ; Kohout, Jan (referee) ; Věchet, Stanislav (advisor)
This master’s thesis focuses on the fatigue properties of spring steel 54SiCrV6. The theoretical part deals with the properties and use of spring steel and metal response to cyclic loading. The main aim of this work was to obtain the basic mechanical properties as well as the hight cycle fatigue data. Additional metallographical evaluation of microstructure.
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Design of quadcopter contol sytem with visual guidance
Pokorný, Ondřej ; Věchet, Stanislav (referee) ; Andrš, Ondřej (advisor)
Tato práce pojednává o návrhu a implementaci systému řízení kvadrokoptéry s vizuálním naváděním k vytištěné značce. Systém se skládá výhradně z komerčně dostupného hardwaru a open source nebo uživatelského softwaru. Jednotkami jsou například mikropočítač Raspberry Pi 3 Model B, mikrokontrolér Arduino Nano, letový kontrolér Omnibus F3 atd. V první části je nastíněna struktura navrhnutého systému a popsány vlastnosti a funkce jednotlivých komponent. Následuje přehled použitých druhů komunikací a jejich verzí specifických pro létající platformy. Nakonec je popsána architektura uživatelského softwaru společně s fungováním jednotlivých částí a důvody pro jejich přítomnost v kódu. Druhá část se zaměřuje na použití knihovny pro augmentovanou realitu ArUco za účelem odhadování polohy, dále se zaměřuje na opatření zavedená pro kompenzaci nedostatků spjatých s použitím tohoto systému. Tato část také obsahuje popis vývoje řídícího algoritmu a následného testování implementovaného řešení. Na závěr jsou navženy možné další kroky ve vývoji.
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The design of control unit for UAV robot.
Arnošt, Petr ; Marada, Tomáš (referee) ; Věchet, Stanislav (advisor)
This diploma thesis is focused on the design of the control software for the unmanned aerial vehicle. Parrot Ar.Drone quadrocopter was a representative of the unmanned aerial vehicle. This thesis describes the way of control and communication with the unmanned aerial vehicle. Based of this information the flight control software for Ar.Drone quadrocopter is created.
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Differential chassis mobile robot trajectory planning
Chochel, Michael ; Věchet, Stanislav (referee) ; Krejsa, Jiří (advisor)
This work speaks about a suggestion of trajectory of mobile robot with nonholonomic movement limits and differential chassis while passing through a “T“ shaped crossroad. In the theoretical part some methods generally used to solve this task of planning a trajectory of the robot will be explained. In the practical part this task will be solved by an algorithm for searching the optimal trajectory to pass through the crossroad.
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Design and realization of data processing system from environmental sensors in IoT environment
Maraczek, Patrik ; Bastl, Michal (referee) ; Věchet, Stanislav (advisor)
The master’s thesis deal with design and realization of measuring station, which process data from environmental sensors in IoT environment. Thesis includes research of sensors, cloud services for IoT, microcontrollers and environmental data available online. Thesis contains detailed procedure for realization of designed system, including code description for microcontrollers STM32W55 and STM32 B-L475E-IOT01A2 Discovery kit, configuration of IBM Watson IoT Platform cloud service and procedure for correct programming of Node-RED application responsible for logic of whole system. Source code, which might be used for simple implementation of designed system, is attached to the master’s thesis.
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