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Assessment and evaluation of safety in power. machines
Hromek, Lukáš ; Janda, Marcel (referee) ; Veselka, František (advisor)
This thesis is focused on the security and improving of electrical rotating machines service life, especially asynchronous motors. Work includes a description of the most common disorders, short description of the asynchronous motor cage casting, analysis of provided decommissioned motors with photo documentation. The last part of this thesis is focused to vibrodiagnostic of asynchronous motor with simulated imbalance and motor emplacement by laser.
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Development of Endoprosthesis.
Řehák, Kamil ; Houfek, Martin (referee) ; Florian, Zdeněk (advisor)
This bachelor’s thesis deals with the problems of the development of total endoprosthesis. The work contains the history of endoprosthesis and the present day description of made and used types of endoprosthesis. In the conclusion there is foreshadowed the development of joints’ surgical implants.
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Cost Analysis of Repairs and Maintenance of an Apartment Building in Brno
Staňková, Pavla ; Hobst, Leonard (referee) ; Klika, Pavel (advisor)
The aim of this diploma thesis will be to create a plan for maintenance and repairs of the building on the street of the brothers Čapků in Brno. The first part will describe the individual concepts dealing with the life of individual structural elements, maintenance and repair and revisions of dedicated technical equipment. The second part will be focused on practice. A plan for maintenance and repairs of the building structures and a plan for revisions and inspections on the dedicated technical equipment will be prepared for the given building. The proposed plan will be designed to spread the funds over the whole period considered.
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Vibration of rolling bearing
Otoupalík, Jan ; Ripel, Tomáš (referee) ; Krejsa, Jiří (advisor)
The thesis deals with vibrations caused by geometric defect and fatigue damage of rolling element bearing. Hardware for vibration measurement is tested on 25 new pieces of NJ 304. Second part of the thesis examines if measuring of bearing vibration can help to detect a geometric defect. Geometric defects are detected according to a spectrum of vibration but the results are not absolutely exact. The possibility to detect geometric defects by measuring vibration has not been proven. The end of project tests diagnostic methods for rolling element bearings. The bearing defect was simulated to demonstrate bearing failure frequencies, envelope method and vibration spectrum.
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Examination of degradation frequently repaired shearing and forming tools
Izák, Josef ; Kubíček, Jaroslav (referee) ; Sigmund, Marian (advisor)
The diploma thesis is focused on the renovation of forming tools made of tool steel, their weldability and assessment of the quality of tool repairs. The damaged tool was a part of the cutter from the progressive cutting tool made of Caldie steel. We used micro TIG technology to repair the damage. A total of three types of additional materials were used and investigated to restore the geometry of the damaged edge. One of the main purposes was to evaluate the possibility of extending the life of tools and reducing the implementation of already inefficient repairs. A number of destructive tests were performed for the assessment - macrostructure, microstructure, hardness measurement and EDS analysis.
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OPTIMIZATION OF ANALYTICAL METHOD FOR CALCULATING THE WEAR OF BUILDINGS
Hlavinková, Vítězslava ; Matějka, Libor (referee) ; Abraham, Karel (referee) ; Bradáč, Albert (advisor)
The dissertation focuses on the problems associated with determining the amount of wear (finding the remaining technical values) that are being addressed. It deals with an overview of the different methods used. The basic premise of the thesis is a comprehensive overview of the calculation procedure and the methods used. This area of wear does not except the price regulation precisely defined procedure, nor are they addressed the circumstances in which that would be the method to be used. Various possible methods or inaccuracies may result in questioning the expert opinions as at trial. In conclusion of this dissertation is shown how the calculation procedure should wear for what purpose should be used and it is also proposed several alternatives.
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HEAT – MECHANICAL DEGRADATION OF SURFACES AT THE HIGH TEMPERATURES
Zahradník, Radek ; Hajduk, Daniel (referee) ; Čecho, Ladislav (referee) ; Toman,, Zdeněk (referee) ; Raudenský, Miroslav (advisor)
The Ph.D. thesis is focused on a surface degradation mechanisms under combined heat and mechanical load. The objects of examination are work rolls from hot rolling mill which suffer such a load. In first chapter, the hot rolling process, the design, the manufacturing process and present materials of work rolls are described. The state-of-the-art study of work roll surface degradation mechanisms – wear, oxidation, thermal and contact fatigue are described in the second chapter. The characterization, the formation, the mechanisms of progression and the effects of each surface degradation mechanism is described step by step. The state-of-the-art study of analytical and numerical models which are related to hot rolling process is described in third chapter together with their limitations and flaws. The next chapters contain design of an analytical, an optimized macroscopic and a microscopic model for study of the work roll stress state. The macroscopic and the microscopic model is based on finite element method and they are implemented in ANSYS Programming Design Language. The models are used to process several case study which are based on previous experimental work of the Heat transfer and fluid flow laboratory. The results from case studies specify and expand the knowledge of work roll stress state. The results show the portion of each loading factor on the whole stress state. In addition, time and depth depended distribution of stress state is presented. The results from macrosferic model illustrate the cause of spalling and a rupture of the work roll. The results from the microsferic model show the cause of creation of the to-surface-parallel cracks within carbides of high chromium irons. Last chapter summarized of all results gathered from case studies together with the goals for further research definition. The necessary steps for further cognition are stated. The thesis contains a large set of appendixes with deeper discussion of several related topics. These appendixes represent the one third of whole the thesis.
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Influence of Residual Stress on Lifetime Prediction of Polymer Pipelines
Poduška, Jan ; Nezbedová, Eva (referee) ; Malíková, Lucie (referee) ; Hutař, Pavel (advisor)
The lifetime of plastic pipes for water supply and other applications is demanded to exceed at least 50 years. Such a long lifetime is difficult to prove by standard testing methods like the hydrostatic pres-sure test. However, it is possible to calculate an estimation of the lifetime, as the most frequently oc-curring mechanism of failure of plastic pipes is the creep crack propagation and subsequent failure. The method is based on describing the crack propagation by parameters of the linear-elastic fracture mechanics. An important part of this method is a finite element simulation of crack propagation in a pipe loaded by various types of loads. Residual stress, a side product of solidification after extrusion, is one of these loads. This thesis begins with an introductory part and literature review of the relevant topics – most of all the typical material properties of the pipe materials, mechanisms of failure, methods of residual stress determination suitable for plastic pipes and their results, methods of testing the materials and calculating lifetime. After the introduction, the problems to be solved are defined. The description of the residual stress state in the wall of various plastic pipes is the main topic. Both tangential (hoop) and axial residual stress in pipes of different dimensions and materials are determined using a combination of experiments and numerical simulations. Also, a simplified method of tangential residual stress is designed that can provide a sufficiently precise description of the tangential resid-ual stress state and is not difficult to carry out. A method to include the residual stress in the lifetime calculations and its influence on the lifetime is also dealt with. Apart from residual stress, the influence of soil loads in case of a buried pipe is studied. The residual stress can also influence the experimental determination of crack growth rate. If the CRB (cracked round bar) test is used to measure the crack growth rate, the crack can propagate asymmetrically due to the presence of residual stress in the specimens, which affects the results. Based on a finite element simulation of crack propagation in a CRB specimen, the severity of the influence is assessed.
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Lifecycle of selected building
Smečková, Veronika ; Aubusová,, Alena (referee) ; Tichá, Alena (advisor)
In this thesis, the main objective is to determine the price of selected construction project during its life cycle and assess operational costs. As a selected object is a family town house built in 1982 as a building type okal. The theoretical part is devoted to professional concepts and detailed information regarding the lifecycle, durability, budget, and wear-related issues. The practical part includes an itemized budget and the actual award of a selected object by using the software on valuation. The resulting values of individual valuation methods are then compared and graphically displayed. Furthermore I judge the actual operating costs incurred during the period.
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