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Properties of ceramics foam filters needed for numerical simulation software
Boček, Vítězslav ; Láník, Boris (referee) ; Záděra, Antonín (advisor)
Final thesis, elaborated within the master study field of Foundry technology, deals with determination of some parameters of ceramic foam filters that are necessary for using numerical simulation during foundry practice. Thesis foccuses on defining methodology, manufacturing messuring device and measuring pressure drop on several type sof ceramic foam filters in dependence on flow rate of measuring medium. Measuring medium selected is water, mening this thesis deals also with water simulation in foundry technology.
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Cavitating jet
Kotoulová, Helena ; Kozák, Jiří (referee) ; Rudolf, Pavel (advisor)
Předložená diplomová práce se zabývá kavitujícím paprskem a je rozdělena do tří hlavních částí. Teoretická část popisuje základní principy kavitace a její negativní účinky na povrch obtékaných těles (např. hydraulických strojů). Rozsáhlá kapitola je také věnována popisu samotného kavitujícího paprsku včetně mechanismů jeho vzniku, růstu a kolapsu. Další podkapitola je zaměřena na modely kavitační eroze, které mají velký význam pro predikci kavitační eroze ve fázi výpočtové simulace. V experimentální části je popsáno testování vzorku mědi inspirované normou ASTM G134 a následné vytvoření grafů kumulativního hmotnostního úbytku a rychlosti úbytku hmotnosti. Dále byla také provedena vizualizace pomocí vysokorychlostní kamery, aby bylo možné podrobně prozkoumat dynamické chování kavitujícího paprsku. Poslední část je zaměřena na numerické simulace pomocí výpočtového modelování proudění, tzv. Computational Fluid Dynamics (CFD), a na predikci kavitační eroze. Z důvodu optimalizace úlohy bylo provedeno více výpočtů na různých typech sítí s různými modely turbulence. Následně byly výsledky ze simulací vyhodnoceny a společně s výsledky z experimentu byly použity pro predikci kavitační eroze.
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Problems of critical wall narrowing in high pressure hydroforming
Drška, Jan ; Řiháček, Jan (referee) ; Lidmila, Zdeněk (advisor)
Bachelor's thesis deals with narrowing metal sheet wall by high-pressure-fluid forming technology on a practical example. This thesis is working on an issue from practice while using a non-standard problem solving method. Theoretical part outlines classical methods of hydroforming and the theories of sheet metal forming. Practical part consists of proposed solution and an elaborated simulation. Subsequently is described the ideal machine for hydroforming and technological procedure. Last part is devoted to technical and economical evaluation.
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Analysis of fracture of quasibrittle materials using numerical modelling and acoustic/electromagnetic emission
Vodák, Ondřej ; Vořechovský, Miroslav (referee) ; Veselý, Václav (advisor)
This master thesis gives overview of non-destructive tests of concrete and provides detailed information concerning the acoustic and electromagnetic emission during monitoring of concrete failure. Conducted loading tests of plain concrete specimens are described in the thesis together with the performed numerical simulations of these tests in the software ATENA. The simulation results of concrete failure are analysed in detail and compared with the experimental results recording failure processes with the help of acoustic and electromagnetic emission. The majority of simulation results in software ATENA 3D show good agreement with the recorded data.
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Car cabin passive cooling system performance study
Viščor, Petr ; Hejčík, Jiří (referee) ; Fišer, Jan (advisor)
The work is focused on issue of passive cooling in a cabin of a car. The basic principles and mechanisms of heat transfer are described in the theoretical part and the quality of cabin environment in terms of thermal comfort and air quality is discussed as well. Next part of the work describing the principles of ventilation and air conditioning of cabins and possible methods of passive cooling are discussed. Passive cooling means decrease of temperature of cars interior, without need of energy supply from car battery, or fuel. The last part of the work includes numerical simulation of selected methods of passive cooling using the THESEUS-FE 3.0 software. Simulations were performed on model of Volkswagen Polo car and primarily were focused on testing of functionality of various methods of passive cooling.
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The use of hydraulic disc brakes for road bikes
Dvořáková, Barbora ; Lošák, Petr (referee) ; Šebek, František (advisor)
This bachelor's thesis is focused on the usage of hydraulic disc brakes on road bikes. The thesis is divided into two parts. In the first part, there is a research focused on differences in construction and properties of hydraulic disc brakes in comparison with rim brakes. The main emphasis is placed on evaluating all advantages and disad-vantages of the hydraulic disc brakes in comparison with rim brakes. Evaluation is conducted both from the functional point of view and user point of view with taking different requirements of both recreational level cyclist and professional cyclist into account. The aim of the second part is the numerical simulation of loading of the frame and fork for both types of brakes. The goal of this part is an overall assessment of suitability of hydraulic disc brakes for the road bikes.
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Utilization of Hydroforming Technology to Create a Structured Surface of Solar Panel
Řiháček, Jan ; Mašek, Bohuslav (referee) ; Lidmila, Zdeněk (referee) ; Mrňa, Libor (advisor)
The doctoral thesis deals with utilization of hydroforming technology for manufacturing of a new type of solar absorber, which has directly flow meandering structure and a structured surface consisting of pyramidal elements. Austenitic stainless steel X5CrNi18-10 is used as a material for absorbers production. At the beginning of the thesis, a literary research is performed, which is focused on particular methods of hydroforming technology, their applicability for this problem, forming limits determination and usability of numerical simulation. Based on the literature study, the production technology was developed by using parallel hydroforming technology and it was optimized by using a numerical simulation in the ANSYS software. Hydroforming parameters for two variants of the structured surface with pyramidal cavities with apex angle of 90° and 60° were determined from the calculations and the material tests.
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Development and use of non-destructive testing methods from the point of view of forensic engineering
Bílek, Petr ; Vala, Jiří (referee) ; Vodička, Jan (referee) ; Hobst, Leonard (advisor)
Concretes reinforced by, using distributed steel reinforcements (fibres) are known as fibre-concrete. In case of disturbances or accidents of concrete structures reinforced with wires, it is necessary to carefully examine the actual implementation of dispersed reinforcement. Fibre concretes belong to modern building materials whose possible applications have not been fully utilized so far. Have been mainly used for floor structures loaded with factory halls and warehouses. Recently, thanks to well-known physical and mechanical properties of fibre-concrete, there were numerous attempts of designers, and namely investors, to utilize this kind of materials for support structures either. Favorable properties of wire-concrete can be utilized if there is a necessity to increase the resistance of concrete to stresses exceeding its strength, cyclic stress or impact stress. Daily practice shows to prove that the applications of fibre-concrete in such structures lead to the economic success. Necessary condition for successful application of steel fiber reinforced concrete in constructions however consists in its uniform dispersion, a homogeneous distribution of the wires throughout the volume of the structure. In case of inappropriate processing and deposition of the mixture during the manufacturing process fiber-concrete structures, the fibers are often unevenly distributed. Wires itself represent unfavourably shaped mixture components and they are extremely deteriorating its workability. A grouping of wires may be encountered as well, which reduces the overall homogeneity and the quality of steel fiber-concrete structures. If the homogeneity of fibre-concrete is not kept, the material possess different properties in various parts of the structure (for example, tensile strength), which can lead to defects in the structure (generation and development of cracks). The relevant lower reliability of the structure which is caused by unequal distribution of fibres (wires) in concrete volume can lead to damage of the property as well as the safety and the human lives can be jeopardized. Hence it is necessary to secure the effective control of the fibre-concrete homogeneity in ready support fibre-concrete structures. Contemporary homogeneity control is still ongoing on fresh blends, but if the fibre-concrete hardened and is a part of the construction, no known reliable methods are currently in available to test the homogeneity of the fibre-concrete on the structure without its destruction. The methods developed to control the concentration of wires in wire-concrete structures are based mostly on magnetic or electromagnetic properties of wires. The thesis deals with the development of the magnetic method in situ using permanent magnets for monitoring the distribution of fibers in hardened steel fiber-concrete structures. The test principle is based on measurements of the changes in magnetic field strength of permanent magnets which are induced by a change in wire distribution in steel fibre-concrete structure. Test is characterized as a so called local- failure- test using a small diameter core drill. In this sense it is a semi-destructive method.
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Defects and properties of heavy castings
Sobotka, Petr ; Carbol, Zdeněk (referee) ; Záděra, Antonín (advisor)
A diploma thesis was objected to a figure analyzing and a figure interpretation of ingot processing. The described figures were obtained from samples which were taking from feeder-heads of ingot of lower ram, produced in Vitkovice Machinery Group. The thesis was focused on ingot solidification and segregation processes which were associated with this procedure. The figures obtained from numeric simulation of ingot solidification in defined places were analyzed using statistic method – linear regression, as well as linear regression was used for evaluation of explored samples, their chemical compositions and mechanical properties. In conclusion all acquired results were summarized.
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Part Manufacturing by Using Hydroforming and Its Optimization
Chrz, Jan ; Jopek, Miroslav (referee) ; Řiháček, Jan (advisor)
The thesis presents an analysis and optimization of the manufacturing process of a part using the technology of parallel hydroforming. Two circular blanks made of DC01 steel with a thickness of 1 mm serve as a semi-manufactured part. In one of the blanks, the supply of the forming medium is constructed using Flowdrill technology. Subsequently, the two blanks are laser welded together and then formed. Numerical simulation using PAM-STAMP software was used to analyse the manufacturing process. This analysis provided information on wall thinning, deformation size, critical points on the product and springback. The numerical simulation was verified on the basis of comparison with an experiment. The criterion for verification was the course of the thickness of the part. Based on the results of the simulation, an optimization is performed in the thesis. It consists in determining the minimum required pressure of the forming medium for pressing the part, particularly for different distances between the two formed sheets.
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