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Optimalisation of heat treeatment of steel - 27MnCrB5-2
Černín, Jiří ; Němec, Karel (referee) ; Věchet, Stanislav (advisor)
This bachelor’s thesis deal with heat treatment of bor steel, 27MnCrB5-2. The work contains assessment and further proposal of new suitable form fot heat treatment. With request for the most possible hardness and preservation optimal scale of tenacity and reasonable price. Teoretical part describes basic information about heat treatment. In the practical part was investigate sttructure, hardness and chemical composition of six samples.
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Mechanical properties of Nodular Cast Iron prepared by method Tundish and process Initek
Vítek, Radovan ; Hotový, Ivan (referee) ; Věchet, Stanislav (advisor)
This bachelor thesis deals with a properties and production of nodular cast iron. The first section describes the classification, distribution and structure of nodular cast iron. The second part is focuses on the description of nodular cast iron, modification, inoculation and production. A strong effort is made on the production of nodular cast iron using the Tundish Cover method and the Initek process. In conclusion, the structure of the material is evaluated on samples that were delivered for metallographic analysis. The final evaluation of the structure of the material is used to compare the mechanical properties of a nodular cast iron produced by Tundish Cover method and Initek process.
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Design of path planning library for mobile robot
Novotný, Michal ; Marada, Tomáš (referee) ; Věchet, Stanislav (advisor)
This thesis deals with analyses of problems of path planning by means Rapidly-exploring Random Trees (RRT) algorithm. The teoretic part described of basic terms and navigation mobile robots. There are localization, mapping and path planning parts of navigation. Then it is description overview of localization of methods and overview of robot path planning methods. The practical describes implementation of proposed method in Delphi. The best method for path planning of robot using RRT algorithm. For reservation universal communications interface is application creation like dynamic library.
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Development of Models of Al Alloys Behaviour for Applications in Numerical Simulations of Welding and Heat Treatment
Vaněk, Mojmír ; Věchet, Stanislav (referee) ; Neumann, Heinz (referee) ; Daněk, Ladislav (advisor)
The thesis deals with methodology for computational approaches for numerical simulations of welding and heat treatment of aluminium alloys. The thesis describes improvement of the current methodology for metallurgical part of the numerical analysis of welding, which is important mainly for prediction of dimensions of the heat affected zone (and deformations). The improvement was carried out based on CHD diagram that describes precipitation and dissolution of phases during continuous heating. The thesis also describes carried material measurements (measurement of chemical composition, dilatometric tests, tensile tests of several conditions of materials at temperatures up to 500 °C and measurement of aging curves), which allowed to significantly refine analysis results for the alloys EN AW-5083 and EN AW-6082. Based on an evaluation of the measurements, several conclusions were made. They can be useful for creation of material databases of other aluminium alloys. The thesis also describes quantification of dependence between tensile strength and yield strength on the Vickers hardness for different conditions of EN AW-6082. There is also methodology for numerical simulation of the heat treatment process of heat treatable Al alloys in the dissertation. The methodology is completely new approach which has never been published so far. Application of this method is based on user changes of the material database in software Sysweld after relatively easy measurement of aging curves. Therefore, the methodology can be considered as promising for application in industrial practice.
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Fatigue-creep interaction in Ni superalloys and TiAl alloys
Šmíd, Miroslav ; Věchet, Stanislav (referee) ; Kunz, Ludvík (referee) ; Obrtlík, Karel (advisor)
The present doctoral thesis is focused on the effect of dwells on the low cycle fatigue behaviour of advanced high temperature materials. 10 minutes strain holds are introduced into the cyclic straining of cast Ni-based superalloy IN792-5A and cast intermetallic alloy TiAl-7Nb which were chosen as experimental material. Fatigue experiments were conducted in strain control mode with constant total strain amplitude and strain rate. IN792-5A was subjected to continuous cyclic loading test as well as fatigue tests either with tensile peak strain holds or compressive peak strain holds at temperature 800 °C. TiAl-7Nb was experimentally examined by continuous cyclic loading tests and also by fatigue test with tensile peak strain hold times at temperature 750 °C. Cyclic hardening/softening curves, cyclic stress-strain curves, Manson-Coffin curves and Basquin curves were obtained. Stress relaxation data were measured during hold times. Mean stress evolution was observed and documented. Microstructure of both alloys was observed in as-received state and also after cyclic loading by means of SEM and TEM. Surface relief investigation revealed cyclic plastic strain localisation as well as fatigue crack initiation sites. Fatigue crack propagation was described using fracture surface and longitudinal gauge section observations. Dislocation structures developed in the course of fatigue tests were studied and documented.
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Micromouse II mobile Robot
Pavláček, Martin ; Věchet, Stanislav (referee) ; Marada, Tomáš (advisor)
This thesis describes the design and implementation of mobile robot IEEE Micromouse category. The aim is to build a functional design of robot usable to testing methods of mapping and localization. The thesis also deals with the design of electronics for motion control. Electronic design of optical sensors operating on the principle of reflection of infrared light and the signal processing.
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Materials for atypical constructions of bicycle frames
Motl, Daniel ; Věchet, Stanislav (referee) ; Němec, Karel (advisor)
Bachelor’s thesis deals with materials for atypical bicycle frames. At first goes to history of generally bicycles. After gives definition what atypical bicycle is and includes four practical examples this type of bicycle which was real manufactured. Next step is about materials. Firstly about all types of materials uses in bicycles industry. Secondly the most suitable materials for atypical frames were choosen. In the end this materials were described in detail.
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Design of autonomous mobile robot.
Vodrážka, Jakub ; Marada, Tomáš (referee) ; Věchet, Stanislav (advisor)
The thesis deals with design of the device for testing the localization techniques for indoor navigation. Autonomous robot was designed as the most appropriate platform for testing. The thesis is divided into three parts. The first one describes various kinds of robots, their possible use and sensors, which could be of use for solving the problem. The second part deals with the design and construction of the robot. The robot is built on the chassis of the differential type with support spur. Two electric motors with a gearbox and output shaft speed sensor represent the drive unit. Coat of the robot was designed for good functionality and attractive overall look. The robot is also used for the presentation of robotics. Thesis provides complete design of chassis and body construction, along with control section and sensorics. The last part describes a statistical model of the robot movement, which was based on several performed experiments. The experiments were realized to find any possible deviations of sensor measurement comparing to the real situation.
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