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Influence of degassing parameters on quality of Al castings
Jeřábek, Petr ; Horenský, Jiří (referee) ; Vašťák, Patrik (advisor)
This master’s thesis is focused on optimalization of degassing parameters in the foundry plant and effect of these parameters on mechanical properties of Al-Si alloys. In practical part is used factorial experiment to research effect of degassing parameters on mechanical properties and dichte index. After optimalization the new process is validated by comparing with the previous one. This experiment was taken on AlSi7Mg0,6 alloy in foundry plant MESIT foundry, a.s.
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Atomic force microscopy of soft materials
Šudáková, Anna ; Havlíková, Martina (referee) ; Smilek, Jiří (advisor)
This bachelor thesis focuses on atomic force microscopy (AFM), mainly on studying the measurement procedure and optimalization of measurement conditions with future perspective on imaging hydrogels and measuring mechanical properties (such as adhesion or stiffness) of hydrogels and semi-rigid materials at the microlevel. Atomic force microscopy is gaining significant importance in research due to its versatility, when it can provide topographical image of conductive and non-conductive samples while measuring mechanical properties of the samples, such as adhesion, elasticity or stiffness. Advantage of AFM method is that it can provide mechanical properties of the samples not only on macro levels as we are used to, for example, from rheology, but also on local level. Optimalization was performed on standard sample, one micrometre polystyrene nanoparticles , when the individual modes were measured, such as non-contact (AC Mode Imaging) mode and quantitative mode (QITM Advanced Imaging). This was followed by the measurement of a PVA foils, the measurement was performed because they are xerogels and will be studied more in the future. They were made with polyvinyl alcohol and chitosan. The internal environment of the hydrogels has been modified by adjusting the pH (NaOH) or by changing the ionic strength (NaCl). Furthermore, the effect of freezing on the PVA foils was observed, it is one of the possible ways of preparation of physically linked hydrogels. This work also examines the effect of porosity on concentration of physically linked thermoreversible agarose gels.
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Quantification of Hydraulic Descaling Mechanisms
Hrabovský, Jozef ; Toman,, Zdeněk (referee) ; Dobeš, Ferdinand (referee) ; Horský, Jaroslav (advisor)
The issue of descaling is an important part of the forging and heat treatment of steel and semi products of steel production. Rising of new information and study of this process can increase efficiency and improve the surface quality after descaling. This thesis is focused on the mechanisms of the high pressure hydraulic descaling qualification and study of the chemical compounds of which the scales grown. To achieve all goals of this work and to get a comprehensive view of descaling process, few experimental measurements and numerical analyses were performed. All experimental measurements were focused on obtaining data about fundamental parameters and effects of the hydraulic descaling. The data obtained from measurements were applied to numerical analyses, which aimed to discover a deeper relation and to confirm the experimental results. This thesis can be divided into two main parts. The first part is devoted to parameters of the water jet study. The main studied characteristics of the high pressure hydraulic water jet were heat transfer coefficient and impact pressure at different modes such as standard or pulsating water jet. Experimentally measured data of these parameters were applied in numerical analyses. The numerical analyses were focused on studying the impact of the water jet parameters on the stresses in the oxide scale layers. A further water jet analysis was focused on the influence of the individual parts of the hydraulic system (such as water chamber or stabilizer) on its characteristics. In this part different types of the water chambers in combination with different types of stabilizers on the impact pressure values were investigated. These measurements were supported by fluid flow analysis through the hydraulic system. The second part of this work was focused on getting mechanical properties of the oxide scales from specimens prepared from standard structural steel and specimens from silicon steel. In this thesis, the influence of various parameters and characteristics was studied on these two types of steel. Mechanical properties of oxide scale structures were carried out by the Small Punch Test method. To obtain the fundamental mechanical properties such as Young´s modulus, yield strength and ultimate strength, material parameters based on the measured data were optimized. The whole work was carried out in order to get valuable and comprehensive results about high pressure hydraulic descaling process and influencing factors as well as about oxide scales themselves.
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Stress strain analysis of the femur based on the CT data collection
Nečas, David ; Marcián, Petr (referee) ; Vosynek, Petr (advisor)
The area of clinical biomechanics is a rapidly growing engineering discipline in the world of today. This master's thesis is concerned with the stress-strain analysis of human femoral neck. In the first place it emphasizes the creation of computational model, especially the model of bone material, because of its high level of inhomogeneity. The creation of the computational model has been tested using several software packages, which are often mentioned in connection with the biomechanical tasks. The latter part of the thesis contains finite element method analysis for several material models, which are based on extensive analysis of relations used to transfer the information from computed tomography data to material model properties. Subsequently, the realization of experimental measurement is described. The final part of the thesis contains evaluated results obtained from the FEM analysis, which are also compared with the experiment.
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Heterogeneous bipolar membrane and the influence of composition on its properties
Kvasničková, Lucie ; Válek, Robert (referee) ; Neděla, David (advisor)
This work is focused on the preparation of heterogeneous bipolar membranes and studies the influence of different composition on mechanical and physical properties. The main feature of this approach is optimalization of composition following gained data. Theoretical part contains new piece of knowledge in the field of heterogeneous bipolar membranes. Experimental part engages preparation of bipolar ion-exchange membranes on one face cation-selective and on the other one anion-selective. In this case are used variant types of polyethylene.
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Preparation and characterization of cosmetic emulsion with addition of active compounds
Zinkovska, Natalia ; Smilková, Marcela (referee) ; Smilek, Jiří (advisor)
In the theoretical part, this bachelor’s thesis focuses on the overview of the basic characteristics and properties of the emulsion. Great attention is paid to choosing the type of emulsifier and the calculation hydrophilic-lipophilic balance. The mechanisms andcauses of instability of emulsions and their possible prevention and methods of stabilization are analyzed. The present state of the problem aimed to the analysis of existing methods for determination of emulsion stability and their use in practice is also part of this thesis. The experimental part of the work is primarily focused on the preparation of O/W cosmetic emulsions with additive of active substances such as UV absorbers. To characterize the prepared samples, pH values were measured and viscosities determined. The stability of the emulsion was carried out using an analytical centrifuge, and these results were further correlated with the standard gravitational stability tests (change of storage temperature of the formulation) according to the SÚKL methodical guidelines (REG-49, REG 51), which are the Czech version of the 75/318 /: Stability tests on active ingredients and finished products. Methods of preparation and composition of individual samples are described, which is further correlated with the stated characteristics of prepared creams.
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Effect of cellulose ethers on mechanical properties of lime mortar
Skoupil, Jakub ; Bayer, Patrik (referee) ; Vyšvařil, Martin (advisor)
The subject of the thesis is to conduct an extensive literature review on the topic of effect of cellulose ethers on the mechanical properties of lime mortars. The theoretical part is devoted to the composition and production of cellulose ethers, which are available on the industrial market. On the basis of the review, the design of lime mortars using different kind of cellulose ethers has been conducted and after curing the tests of mechanical properties of mortars were performed and evaluated.
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The mechanical properties of AlSi9Cu3 aluminum alloy processed by SLM technology
Koutný, Filip ; Skřivánková, Vendula (referee) ; Paloušek, David (advisor)
This bachelor thesis aims to compare mechanical properties of cast AlSi9Cu3 aluminium alloy with its state after processing by the selective laser melting (SLM) technology. The theoretical part of this work presents general characteristics of aluminium alloys, focusing on their classification, mechanical properties and heat treatment as well as SLM technology processing. In the second part, we further discuss optimal processing parameters of the SLM 3D printing technology and compare mechanical properties of the conventionally cast AlSi9Cu3 alloy and the alloy processed by the SLM technology.
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Determination of the Mechanical Properties of Weld Materials based on Hardness Test
Stodola, Martin ; Španiel, Miroslav (referee) ; Dlouhý, Ivo (referee) ; Junek, Lubomír (advisor)
This dissertation thesis deals with determination of the mechanical properties of weld materials based on instrumented hardness test. This work was caused by the research project between IAM Brno Ltd and CEZ corp., when the task was to develop a methodology for evaluation of mechanical material properties using NDT methods. For these reasons the development of methodology is reflected especially for use in practice focusing to determining the mechanical properties of the heterogeneous weld joint on the assembled equipment. The mechanical material properties are determined by carrying out non-destructive tests of the instrumented Vickers hardness. The developed methodology for determining of basic mechanical properties is based on the principle of inverse FEM modeling of the instrumented hardness tests, when output of the testing is indentation curve and measured surface imprint after unloading. The basic material mechanical properties are achieved by comparing the outputs of the experimental instrumented hardness tests and the outputs of the modeled hardness test using FEM.
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Design of structures with FRP reinforcement
Matušíková, Anna ; Vácha, Jaroslav (referee) ; Štěpánek, Petr (advisor)
This diploma thesis presents available FRP software for calculating load bearing capacity of the structures reinforced with FRP and compares them between each other. Furthermore theory and algorithm of my own software is presented here. Load bearing capacity of structures which are reinforced with non-metallic reinforcement and loaded by combination of normal force and bending moment can be solved by my programme. Effects of high temperatures on the concrete structures can be included in the calculation. In the second part of the thesis is calculated load-bearing capacity and deflection of the real beam reinforced with FRP reinforcement and load-bearing capacity of member with FRP reinforcement with effect of elevated temperature. This has been done using my software. Comparison of results from hand calculation and laboratory load-bearing testing is done at the end. This laboratory testing was accomplished by Institute of Concrete and Mansory Structures at our faculty.
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