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Standardization of the copper technological forming process
Březina, Tomáš ; Císařová, Michaela (referee) ; Jopek, Miroslav (advisor)
The thesis focuses on the optimization of bending copper busbars in the Brno branch of the company ABB s.r.o. Busbars serve to conduct electricity and are used in high-voltage switchgears. The semi-finished busbar products are made of electrolytic copper that complies with the EN 13601 standard. Busbars are produced in various shapes and sizes according to the specifications of the switchgear. Part of the thesis involves a tensile test to determine the mechanical properties of electrolytic copper. A practical bending test was performed on a bending machine for bars with different mechanical properties. The entire bending process was simulated in Ansys Workbench software. Using the simulation, the tool stroke was optimized to achieve the desired deviation from the nominal angle. The optimized stroke was subsequently used on the bending machine to achieve the required bending accuracy.
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Determination of residual stresses by hole-drilling method considering finite body boundaries
Began, Jakub ; Ščerba, Bořek (referee) ; Halabuk, Dávid (advisor)
The diploma thesis analyses the impact of the finite dimensions of a body on residual stresses by means of the hole-drilling method which was derived for bodies of dimensions large enough not to affect the measurement. To assess the impact of the finite dimensions of a body on measured residual stresses, a computational model simulating the hole drilling method was created using the finite element method. The assumptions made during the creation of the computational model included a desired geometric shape and an uniform residual stresses along the depth of the drilled hole. The computational model was subsequently parameterised so that it could be used to simulate different combinations of the finite dimensions of a body, whose impact on measured residual stresses was analysed. In the next part of the thesis, the impact of the biaxiality of residual stresses on the accuracy of their measurement was assessed. Subsequently, three correction algorithms were proposed to minimise the errors of measured residual stresses caused by the finite dimensions of a body. The first correction algorithm is supposed to correct calibration coefficients, the second one to correct input strains, and the third one to correct the assessed residual stresses. In the last part of the thesis, the individual correction algorithms were tested and compared. The outcomes of the diploma thesis suggest the possibility to correct the errors in the analysed residual stresses due to finite dimensions of a body, on the condition of a desired geometric shape and an uniform stresses along the depth of the drilled hole.
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Development of a test specimen carrier for a symmetrical impact test
Hoffman, Petr ; Forejt, Milan (referee) ; Jopek, Miroslav (advisor)
The thesis focuses on the development and optimization of a wooden specimen carrier for the symmetric Taylor test. It includes a detailed description of dynamic material tests, internal ballistics of the projectile, and labyrinth seal. The thesis summarizes the history of the carrier development for the Taylor test and analyzes its current state. A new carrier for the symmetric Taylor test and wooden specimens with a square cross-section was developed. Using simulations and tensile tests, the ultimate strength for the given carrier was determined. Subsequently, the thesis addresses the design and impact of the labyrinth seal on the carrier's velocity, which was designed based on simulations in the ANSYS program and practically tested in the Taylor test
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Analysis of software solutions for particle motion in moving fluids
Bohuslav, Marek ; Vacula, Jiří (referee) ; Novotný, Pavel (advisor)
The issue of particle motion in moving fluids is a more frequently discussed topic in the automotive industry concerning the new EURO 7 emission standards. Requirements include particles from brakes, tire wear and exhaust gases and their limitations. To limit them, it is possible to capture them and for that, the behaviour of the particles needs to be predicted. Particle behaviour can be simulated using the right software, which requires an understanding of flow physics to be set up. The bachelor's thesis offers a complete overview of the CFD principles of flow and particle motion in fluids. In the second part, the thesis provides an overview and analysis of usable software for particle flow solutions with examples of their practical use in this matter. The third part focuses on the demonstration of particle flow in the numerical simulation in the software Ansys CFX, particularly in a simulation of particle motion in oil in a slide bearing. The demonstration includes an analysis of the results and provides useful insights and tips for creating a simulation in Ansys CFX.
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Exploring Bubble Dynamics with VOF Method Simulations: Insights from Two Fundamental Gas-Liquid Flow Case Studies
Harrandt, Václav
The present study focuses on the flow of Taylor bubbles, representing the interaction between the channel wall and the gas phase, and the collision of\na bubble with a vortex ring, serving as a model liquid-gas interaction. Understanding the former case can be essential to prevent the membrane\nfouling or the flow induced corrosion. The dynamics of the latter case is the predictive criterion for whether the initial mother bubble will break up into the daughter bubbles or not2 and this process can therefore be used as an idealized model of turbulent bubble flow.
Plný tet:  PDF
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Optimization of Thermally Activated Building Structures
Oravec, Jakub ; Kalousek, Miloš (referee) ; Čekon, Miroslav (referee) ; Šikula, Ondřej (advisor)
The thesis deals with the modelling, analysis and optimization of thermally activated foundation piles using the in-house developed numerical software Epile. A sensitivity analysis of short energy piles was performed and a deep regression neural model was developed to predict the energy gain of the pile. A Bayesian optimization method was implemented to find the optimal parameters of the energy piles in order to maximize the financial and energy gain.
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Porušování jemnozrnného cementového kompozitu v blízkosti rozhraní plniva a matrice
Vyhlídal, Michal ; Kabele,, Petr (referee) ; Profant, Tomáš (referee) ; Keršner, Zbyněk (advisor)
The Interfacial Transition Zone (ITZ) between the aggregate grain/reinforcement bar and the matrix is considered to be the weakest element in cementitious composites and is, according to some authors, directly responsible for the nonlinear (more precisely, quasi-brittle) behavior of the composites. The aim of this work is verification of the generally accepted paradigm of the weakest element by means of fracture experiments and corresponding numerical simulations. In the experimental part, in addition to traditional fracture tests, modern methods of 3D scanning, scanning electron microscopy, chemical analysis using an electron microprobe and nanoindentation were used. In the numerical part, models based on generalized linear elastic fracture mechanics as well as modern models intended for the simulation of cement composites, namely crack band model with smeared cracks and the Microplane model, were used. Based on the results, the numerical part was complemented by the Cohesive Zone Material model simulating the behavior of the interface. All results are discussed and put into context with already published work. The main conclusion of the work is that the properties of the ITZ do not have such an influence on the behavior of cement composites as the adhesion between the inclusion and the ITZ, i.e. the matrix.
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Mould Risk on Wall Surface in Partly Underground Technical Room
Nováková, Iva ; Šikula, Ondřej
This conference article aims at the indoor climate in the technical room of an underground water reservoir. This indoor climate is specific by high relative humidity (average 75.2% r.h.) and low air temperature (average 13.6 °C). Therefore, this research study focuses on surface condensation and mould risk on the partly underground wall in the technical room. The experimental research combines long-term monitoring (22 months). Long-term of indoor climate and thermal numerical simulation. The experimental measurement shows condensation risk on the indoor wall surface, and the unsteady 2D numerical simulation in software Calculation Area 4.0e shows temperature fluctuation on indoor wall surfaces. Finally, the empirical VVT model predicts mould risk on the indoor wall surface for the over-terrain part in autumn and summer for the under-terrain part.
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Energy Balance of Smart Ventilated Facade
Salajka, Radek
This article explains the function and basic energy balance for a smart facade system that is being researched at Brno University of Technology. This system is an upgrade to an already well-known ventilated facade. The upgrade is mainly presented by efficient control over built-in shut-off dampers inside the ventilated gap. The main goal is to reduce the energy consumption of buildings and create a healthy and comfortable indoor thermal microclimate in a much more ecological way. Numerical calculations are being used to present the energy use of a given facade in comparison with other conventional facade systems on the same building with identical boundary conditions. FSVM software which provides these calculations has been developed by the same research team. It can calculate the energy balance of conventional facades, ETICS and prototype of smart facades as well. This article presents ongoing research and results of the simulation of the heat flow of these three main facade systems throughout the year. Significant variables for facade heat flow calculations are weather and outdoor boundary conditions. They are used in this article as conditions for the Czech Republic which has a mild climate and four different seasons of the year.
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