|
|
New trends and material usage in bicycle frame design
Jelínek, Vladimír ; Němec, Karel (referee) ; Juliš, Martin (advisor)
Thesis in its first part summarizes the evolution of the bicycle from the draisine to the low wheels with a focus on the material of the frame of the bicycle. Also discussed in this section is an overview of small structural modifications, which were gradually used on a bike, like Bowden brake or the first type of transmission system. In the second part, the thesis describes the operating principles and types of suspension forks and disc brakes. Mentioned are materials that are currently used for bike frames with a focus on the advantages and disadvantages of each material used and its future anticipated use.
|
|
|
Deposition and analysis of AlCrN coatings
Drásalová, Kateřina ; Juliš, Martin (referee) ; Klakurková, Lenka (advisor)
The topic of this thesis is the deposition process and methods of quality assessment of AlCrN surface coatings produced by methods of (i) magnetron sputtering, (ii) magnetron sputtering with arc enhanced glow discharge, and (iii) high power magnetron sputtering with the movable magnetic field. The main focus is placed on categorizing properties of the produced coatings based on the production method (which vary in the ionization level). Qualities of the surface coatings are assessed by adhesion and cohesion parameters testing of coarseness using AFM (Atomic Force Microscopy), depth measuring using a calotest, measuring internal tension using the Bent Strip Method and Instrumented indentation test for hardness.
|
|
|
Non-destructive testing of gear-wheels
Krejčí, Martin ; Juliš, Martin (referee) ; Čech, Jaroslav (advisor)
This diploma thesis resolves aplication of particular non-destructive testing methods while producing castings of steel wheels and quality control of this process. There are described fundamentals of flaw detection, determination of flaw-generation cause and suggestions for optimalization of casting process and increasing of its quality.
|
|
|
Structure and properties of welded joints of steam turbine rotor
Machala, Jan ; Hutařová, Simona (referee) ; Juliš, Martin (advisor)
This thesis deals with the assessment of the structural-mechanical properties of welded joints of steam turbine rotor. Experimental weld material is low alloy steel 30CrMoNiV5-11 in the state after the artificial degradation. The theoretical part of the literary researches the issue, focusing on the weldability of different types of steel used in the energy industry, the metallurgical processes in welding and provides an overview of the most important methods of welding. Great attention is paid to the evaluation of weld quality in accordance with relevant standards and destructive and non-destructive testing of welded joints. In the experimental part of this work was carried out measurements of hardness and microhardness of the weldment by Vickers and evaluation of the microstructure by light microscopy. The obtained values and information about the properties of the material after artificial degradation were compared with previously obtained experimental results in the default state (after annealing).
|
|
| |
|
| |
|
|
Use of ultrasonic phased array technique for non-destructive testing of the HRK socket at the VVER 440 reactor
Nováček, Jan ; Kusmič, David (referee) ; Juliš, Martin (advisor)
The bachelor's thesis describes the design of a test system for non-destructive ultrasonic inspection of the HRK on the nuclear reactor VVER 440. Using the designed test system, the basic material interface of the HRK 22K steel shell with the weld on ZIO-8 was verified by the advanced ultrasonic Phased array method. The functionality of the designed test system consisting of the TOPAZ 32 device, the 5L64-A32 probe and the STIX manipulator was tested on three standards with variously large artificial defects. The sensitivity of the test system was set using an artificial defect in the form of a groove 0.7 mm high based on simulations in CIVA 2020 software. The functionality and sufficient sensitivity of the system with a deviation of ± 1 mm for the height of the indication and ± 5 mm for the length of the indication were confirmed by performing experimental measurements on standards.
|
|
|
Methods of control of railway wheels in current technical practice
Ondriašová, Patricie ; Ročňáková, Ivana (referee) ; Juliš, Martin (advisor)
The proposed bachelor´s thesis looks into the inspection methods of railway wheelsets in current technical practice. First there is a description of the railway wheelset and the wheel production procedure. The main part of the thesis describes particular categories of wheel inspection. These are described as destructive, non-destructive and final tests. At the end some cases of wheel failure that happened during operation are stated. Finally there is also an outlook for railway transport in the future.
|
|
|
Nondestructive testing in current industrial practice
Jakubcová, Eliška ; Klakurková, Lenka (referee) ; Juliš, Martin (advisor)
The bachelor thesis is focused on personnel certification of non-destructive testing according to valid standards. The theoretical part compares the Czech certification system for non-destructive testing with systems in other countries and evaluates their differences. Problems that occur during certification according to ČSN EN ISO 9712 are also discussed. In the practical part of the thesis the evaluation of the test sample is documented by means of radiographic test, magnetic particle test and leak test. At the end of the thesis the results are evaluated and discussed and also described in the form of measuring protocols.
|
|
|
Optimisation of heat treatment of aluminium alloy AlSi7Mg0,6
Julišová, Martina ; Klakurková, Lenka (referee) ; Juliš, Martin (advisor)
The presented diploma thesis deals with various types of quenching and their respective effects on mechanical and structural properties of AlSi7Mg0.6 alloy castings. Cast with precision casting technology into a self-supporting ceramic shell made by plaster investment technology, flat test bars cast by Alucast were used as experimental samples. Sample castings were used in both cast state and after T6 heat treatment. Air-flow and air-water combination with varying water passage (spraying) were used as the quenching media in the quenching process of the castings. In order to evaluate the effect of five different quenching processes on the structure and mechanical properties of the castings, the method of light microscopy, Brinell hardness test and static traction test were used. Evaluation and porosity and SDAS quantifications were carried out by means of image analysis. Experiments did not prove right the hypothesis holding that low SDAS values inevitably mean higher mechanical properties of the castings. On the other hand, distinct is the negative influence of heterogeneous structure and porosity. Despite the fact that the heat treatment was successful in reducing the influence of structural inhomogeneities, it cannot be concluded that spray quenching has an utterly positive bearing on the mechanical and structural properties of the castings.
|
guest ::
