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Analysis of Reinforced Concrete Beams Subjected to Impact Loading
Dvořák, Tomáš
The utilisation of complex nonlinear material models for concrete in numerical simulations is necessary for the accurate representation of structural behaviour. However, the successful modelling of such complex behaviour depends on a good understanding of the material model parameters. This paper deals with the critical issue of material parameter sensitivity in the context of RC beams subjected to impact loading. The objective was to establish relationships between the material parameters and the responses, including deformations and stresses, using sensitivity. This is the main key to understanding the complex interaction of these parameters and their influence on the structure.
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Assessment of impact of arrangement of collagen fibres in arterial wall on its response in tension tests
Kratochvíl, Filip ; Chamrad, Jakub (referee) ; Burša, Jiří (advisor)
This thesis deals with organisation of collagen fibres in human blood vessel walls and with simulation models, which are used to calculate vessel behaviour. Firstly, the thesis focuses on the anatomy of human blood vessel system, mainly on the vessel structure and properties of some vessel components. Next, two models are presented, which can be used for the vessel wall in calculations, specifically models with straight and wavy collagen fibres. Moreover, some methods are described, which can be used to gain information about a vessel. Subsequently, relationships are derived needed for simulation of tension tests of these models, mainly to express the length of collagen fibres. In the practical part simulations of vessel behaviour during uniaxial tension test are carried out and histograms of local direction angles of collagen fibres in the unloaded state are created. In the end, results gained by simulations are compared with real available data.
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Numerical analysis of selected silicate based composites shrinkage
Drbušková, Magdaléna ; Vlk, Zbyněk (referee) ; Keršner, Zbyněk (advisor)
The thesis is divided into two main parts. In the first theoretical part is described the problems of shrinking including a comparison of Czech standard and Model Code 2010, Vol. 1. The second practical part of the master`s thesis is focused on the numerical analysis shrinkage primarily on the initial stage of this process. The experimentally obtained data are set approximations of the relative deformation using ShrCeC. Subsequently the numerical simulation of shrinkage of selected silicate specimens using a computer applications SpatiDist and FyDiK 2D. The real test specimens are modelled as two-component composite consisting of cement paste and aggregates. The result is a parametric study takes into account the influence of type and size of grain aggregate.
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Methods of Space and Spectral Characterization of Light Sources used in Car Industries
Guzej, Michal ; Černý,, Pavel (referee) ; Samek, František (referee) ; Horský, Jaroslav (advisor)
Automotive headlamps work in very variable operating conditions during which the producer have to guarantee their primary function of seeing and being seen. During the development stage of the new headlamps the manufacturers want to eliminate defects which could led to malfunction in operation. The numerical simulations along with the test procedures are appropriate tools for detection of problematic areas. The most appropriate approach is designing of experiment with a view to the subsequent simple implementation of the measured data into numerical simulations software and carefully choosing a measuring method of the monitored physical quantities. The thesis deals with phenomenon of condensation in headlamps, which has a negative effect on the light distribution and their life expectancy. Due to this experimental defog methodology was developed based on evaporation of a specified amount of water into the headlamp and then condensation on the inside surface of the headlamp lens. Pictures are taken during the measurements and the fogged and defogged areas are automatically detected. The results from experiments are used to adjust and verify a numerical model. The next part is devoted to the thermal load of the headlamp components which are mostly heated by waste heat from light sources. This phenomena depends mainly on the type of source, emissivity and thermal conductivity. A methodology of temperature measurement, thermal conductivity measurement, non-stationary method for emissivity determination and spectral characterization of thermal source based on their thermal fluxes to the surroundings has been developed.
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Modelling electron energy-loss spectra of vanadium dioxide nanostructures
Kabát, Jiří ; Křápek, Vlastimil (referee) ; Konečná, Andrea (advisor)
This thesis concerns the characterization of optical modes in vanadium dioxide (VO2) nanostructures, mainly by simulating numerically electron energy loss spectroscopy (EELS) intensity. Among the studied optical modes, there are plasmons, phonons and Mie-type resonances, for which we performed a literature review. VO2 undergoes a phase transition when reaching a temperature of about 67 °C from the insulating phase to the metallic phase. This phase transition is connected to significant changes in optical properties, which offer potential uses in nanophotonics. The main part of the thesis is devoted to numerical simulations, which were firstly performed for thin VO2 slabs and then for VO2 nanoparticles. In simulations of VO2 nanoparticles in the metallic phase, we observed electron energy losses caused by plasmons and localized surface plasmons, which were then characterized and imaged by spacedependent EELS maps. In nanoparticles in the insulating phase, losses caused by phonon excitations and material absorption were observed. A new kind of loss contribution was observed for some geometries, potentially related to the Mie-type resonances.
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Fractal capacitors properties
Chvíla, Ladislav ; Sedlák, Petr (referee) ; Hruška, Pavel (advisor)
This work is focused on computer simulations of fractal capacitors. The geometry of capacitors and its influence is investigated. Simulations are realized in programs Matlab, SolidWorks and Comsol Multiphysics. There are also several specific examples of different geometrics of capacitors their comparisons and assessment.
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NVH of electric vehicles
Dufek, Martin ; Prokop, Aleš (referee) ; Řehák, Kamil (advisor)
There is no internal combustion engine in electric cars and although this is a positive shift in development, it presents new challenges in terms of NVH sources. In these days electric cars seem to be the future of the automotive industry so it is necessary to pay attention to it. In the first part the work is focused on the distribution and description of NVH sources, comparison of their importance in the electric car compared to a car with an internal combustion engine and proposing a possible solution for their damping. The second part of the work is then focused on the importance and implementation of numerical simulations and technical experiments for individual parts of EV used in their development nowadays.
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Numerical simulation of volume changes of selected cementitious composites
Drbušková, Magdaléna ; Veselý,, Václav (referee) ; Keršner, Zbyněk (advisor)
This thesis deals with volume changes of selected cementitious composites. They are divided into two parts, theoretical and practical. The theoretical section describes the volume changes that occur in concrete structures. The practical part is focused primarily on the initial stage of shrinkage specimens of two-component cement composite (cement paste + aggregate) and it´s numerical simulation. For analysis were used SpatiDist and FyDiK 2D computer applications. It was simulating shrinkage of specimens with and without notch to compare. The result is a parametric study which reflects the influence of type and size of grain aggregate and shrinkage degree of cementitious paste.
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Diversion headwork on Smolinka river
Juriga, Jan ; Brázda, Daniel (referee) ; Zachoval, Zbyněk (advisor)
Within the preparation of the dam Vlachovice, it is planned to construct a diversion work on the Smolinka river to ensure the transfer of water from the Smolinka basin to the Vlachovice reservoir. The diversion work is designed by AQUATIS a.s. and is equipped with a sluice gate and a spillway with a crest intake. This thesis deals with the determination of recommendations for the implementation of modifications to the design of the diversion work. Recommendations resulting from the work should lead to reliable functionality of the object both from the point of view of water intake and from the point of view of continuous transport of sediments through the Smolinka river. A two-dimensional numerical model simulating sediment transport and three-dimensional numerical model simulating water flow are used in the thesis to determine recommendations for design modifications. The documents necessary for the creation of the work were provided by company AQUATIS a.s. with the permission of Povodí Moravy, s.p
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Production concept of sink
Bahula, Jan ; Jopek, Miroslav (referee) ; Císařová, Michaela (advisor)
The thesis presents a design for manufacturing a rotary kitchen sink made of a stainless austenitic steel 17 240 with a thickness of 0.8 mm with a production series of 20 000 pieces per year. Based on the analysis of manufacturing variants and necessary calculations, deep drawing without a reduction in the thickness was selected to three operations including calibration. A hydraulic press PO 250 from Dieffenbacher was chosen based on the required forces and available rams. The drawing process was checked using numerical simulations and tools were designed for each operation using a drawing ram, a bottom blank holder, and an upper ejector. In the design of drawing tools, normalised components or easily manufacturable parts were preferred.
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