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Evaluation of elastic parameters for models of isolated cells
Krbálek, Jaroslav ; Fuis, Vladimír (referee) ; Burša, Jiří (advisor)
This diploma thesis focuses on computational modeling of the cell mechanical tests. The goal of this thesis is to build a cell model and to simulate compression test on this model. If necessary, the model should be adjusted so the model reflects real cell behavior. It was created the cell model reflecting cytoplasm, nucleus, membrane and cell cytoskeleton. Cytoskeleton was modeled as tensegrity structure. After this, the pressure test was simulated on this model. The behavior of the cell model and real cell was compared using the stress force. The stress force - cell deformation curve was markedly different for the cell model and the real cell. For this reason, the cytoplasm material model was adjusted. The difference between the curves was acceptable after this modification. It was found during computations that the cytoskeleton model influence on the cell load is minimal. These results does not reflects real cell behavior, which means that the model is considered inadequate for performing stress load simulation.
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The role and differences of traditional international trade centers
Plaček, Lukáš ; Sato, Alexej (advisor) ; Dvořák, Jiří (referee)
The thesis discusses the differences and the role of the traditional centers of international trade. It is conducted through comparative analysis of the two ports in the open and closed economy - Rotterdam and Alexandria. In the first chapter, that is based on the theoretical and analytical frame, are specified the relevant facts and empirical findings in the field of international trade, centers of the international trade and maritime transport. The second chapter named Characterization and comparison of national economies deeper investigates the environment in which are the selected ports located. Chapter three and four deal with the Rotterdam respectively Alexandria in the detail view consisting of a historical context, profile and description of the port, the commodity structure, current development, future plans, related industrial regions and areas. The last chapter contains a comparison of the Rotterdam and Alexandria, including SWOT analysis.
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City House – Mixet Use Architecture
Mertlíková, Klára ; Urbášková,, Hana (referee) ; Menšíková, Naděžda (advisor)
The subject of the thesis is an architectural project of urban structure - a town house in Brno - Zábrdovice. The design uses the principle of multiplicity, which is characterized by multiplying of the site, using of roof planes and highlighting the object above the ground. The material of object is formed by the gradual reduction of the structure consisting of four blocks arranged around a central atrium. The building respects the height of the surrounding buildings, on the west side it has 5 floors, towards the river Svitava the height of the building gradually decreases. A significant feature is the use of greenery on roofs. Ventilated facade of the building will consist of perforated steel sheets Cor-ten and facade panels Cembrit.
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Initial stages of fatigue failure of polycrystalline materials
Man, Jiří ; Petrenec, Martin ; Obrtlík, Karel ; Polák, Jaroslav
Geometry of persistent slip markings (PSMs) formed during cyclic loading of polycrystalline stainless steels and superalloy was studied using atomic force microscopy (AFM) and high-resolution scanning electron microscopy (SEM-FEG). Internal dislocation structure was investigated using transmission electron microscopy (TEM). Persistent slip bands with dislocation structure corresponding to the cyclic strain localization were identified and correlated with PSMs observed on the specimen surface.
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A possible approach for assessment of general singular stress concentrators on the basis of linear elastic fracture mechanics
Náhlík, Luboš
This paper studies a stress distribution around a general singular stress concentrator tip on the basis of linear elastic fracture mechanics. A procedure for development of stability criteria of general singular stress concentrators is shown. Three different methods for determination of an essential critical stress for crack propagation from the stress concentrator tip are introduced. Each of used method is useful for different mechanism of crack propagation. The described procedures are based on three dissimilar physical basis: on the energetic ground – the generalized strain energy density factor is mentioned, on the failure stress of material grain ahead of concentrator tip and on the size of plastic zone in front of concentrator tip. The numerical results can contribute to better understanding of general stress concentrators behaviour and can be used for design of engineering structures with mentioned type of stress concentrator
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Determination of threshold values of components with protective layers
Náhlík, Luboš ; Bareš, Pavel
The contribution is focused on the influence of existing fatigue cracks in protective layers on fatigue life of structures with protective layers. The problem is solved under conditions of linear elastic fracture mechanics with help of finite element method. Is shown, that in the case of the hard protective layer on the ductile substrate represents existing crack with its tip on the bi-material interface dangerous singular stress concentrator, because of decrease of threshold values of applied loading necessary for crack propagation. Knowledge of crack propagation in protective film is of paramount importance when studying potential failure of the substrate.
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Study of the synthesis and structure of ceramic perovskite materials for energy applications
Strejček, Josef ; Bartoníčková, Eva (referee) ; Cihlář, Jaroslav (advisor)
Method, so called “glycin- nitrate process”, combined with high temperature solid state reaction, of preparation multi- component ceramic perovskite materials was studied. Two types of perovskite systems were prepared by this method. Firs one, based on LaNiO3 doped by calcium and aluminium and second one, based on SmFeO3 doped by calcium and nickel or cobalt. This method made possible preparation of one phase perovskite or perovskites with few percent of nickel in form of oxide. In systems containing both nickel and calcium another phases rich in calcium and nickel appeared.
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Propagation of inclined cracks to the interface of ceramic laminates
Novotná, Lenka ; Trunec, Martin (referee) ; Chlup, Zdeněk (advisor)
Composite materials with laminated structure provide advantages which are utilised during component design. Low density, temperature and chemical stability are the profitable properties predetermining application of ceramic laminates. The main obstacle for wide spread of ceramic materials is their inherent brittleness. Therefore, in this thesis, the crack propagation in ceramics laminates has been extensively studied. Laminated structures with various volume fractions of components (alumina and zirconia) were prepared by electrophoretic deposition. Evaluation of crack propagation through the interface and determination of basic mechanical properties was conducted on the basis of extensive literature search. Crack deflection originated in both presence of internal stresses and differences in elastic modulus during the crack interface passing was monitored. A special type of specimen geometry was employed with the aim to set arbitrary angle between crack and interface. It was experimentally found that the degree of crack deflection is dependent on entering angle and volume fraction of components. Higher crack deflection was already found in the bulk of the test piece comparing to the test piece surface. The 3D fracture surface reconstruction generated using laser confocal microscopy was used in this detailed crack propagation study. Further basic elastic and strength characteristics of laminates were determined and compared to those obtained from monolithic materials. The validity of the mix rule for elastic characteristics was confirmed by comparing of elastics modulus. The most reliable method for elastic modulus determination was marked the dynamic resonance method due to low scatter and consistency in measurement. The flexural strength of all laminates tends to be close to the flexural strength of the weakest component. Therefore the mix rule is not applicable for flexural strength estimation on the contrary of elastic characteristics. The change of component volume fraction leads only to change of flexural strength scatter. Thanks to gained knowledge about crack propagation and basic characteristic determination will be possible to design ceramic laminates more efficiently for given needs of application.
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Modelling of lumpy clay fills
Najser, Jan ; Boháč, Jan (advisor) ; Herle, Ivo (referee) ; Doležalová, Marta (referee)
of the dissertation An extensive open cast mining of brown coal has been taking place in NW Bohemia since 1940's. During the mining process, overburden clay is placed in the form of irregularly shaped lumps of typical dimensions up to 500 mm into large spoil heaps. The total thickness of the lumpy clay landfills is usually 20-50 m. Their material has a double porosity structure: the porosity of intact clay (intragranular porosity) and the voids between clay lumps (intergranular porosity). The total porosity of the fresh fill can be up to 70%. This soil presents special challenges for geotechnical design, primarily because of its high and non-uniform settlement. Further, the progressive tranformation from the "granular" to "fine-grained" material makes the lumpy clay difficult to characterise and model. The aim of the presented thesis is to describe the behaviour of the landfill and the change of its structure by means of field measurements, the centrifuge and numerical modelling. During site investigation for a motorway over a 20-30 years old landfill, two trial embankments were built and 1 monitored over the period of 3 and 6 years respectively. The subsoil of the embankments was instrumented by hydrostatic levelling profiles, pore pressure transducers and depth reference points installed in...
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