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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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CNC turning of shaped stainless steel parts.
Vostřel, Jan ; Polzer, Aleš (referee) ; Píška, Miroslav (advisor)
This diploma thesis is focused on a CNC turning operation of form parts made of stainless steels. The first part of the diploma thesis is focused on a theoretical analysis of stainless steels material characteristics. The second part is focused on a concept of experiment of complex form experimental stainless steel components. In this thesis the new CNC technology is defined in a new operation system Sinumerik 840D/ShopTurn V06.04 with an application for a new multi-purpose turning centre SP280SY. The final part comprehends technical documentation, CNC programs of shaped components, their verification and overall photographic documentation.
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Verifikation of machine component strain
Novák, Tomáš ; Dočkal, Aleš (referee) ; Drápela, Miloslav (advisor)
The thesis deals with a comparative analysis of strain of parts using finite element method (FEM) and measurement of the optical system Pontos. Part was used the reflector of Volkswagen Polo. The subject of comparing were the values of deviations optical shield of reflector which excitation random vibration described power spectral density. The thesis presented describes of experimental measurements to obtain the boundary conditions using optical systems. FEM analysis was performed using software ANSYS Workbench 12.
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Turbulentní charakteristika uvnitř městské křižovatky
Kellnerová, Radka ; Jaňour, Zbyněk
The wind-tunnel experiment checked the central symmetry for the inlet conditions and the flow inside an one case of symmetric model. For approaching flow, central asymmetry of y- and z-component of velocity between the right and left side of tube was detected. Nonetheless, the model of urban intersection has a dominant role in flow up to the 1.5 height of building and just mild asymmetry was found here. For elimination of these discrepancies the influence of wind direction and model arrangement suppressing the lateral flow was tested. The main reason for asymmetry was appeared to be a position of the mounted probe of LDA measuring facility. The turbulent characteristics obtained inside the model were analysed using Quadrant analysis technique. This helped to understand the structure of momentum flux in lower surface layer called the roughness sublayer.
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Proposal of a tool for radial expanding of axial symetrical components
Střílka, Vlastimil ; Forejt, Milan (referee) ; Samek, Radko (advisor)
STŘÍLKA VLASTIMIL, Proposal of a tool for radial expanding of axial symetrical components Diploma work, 5th year, School year 2008/2009, educational group 5O/61, FS VUT in Brno, Institute of Manufacturing Technology, department of forming, May 2009 An object of this diploma work is location suitable manufacturing proposal for production engaged part of form ring from materials 17 246 segments tool. As a half- finished product of this part will be use a weldment metal plate from materials 17 246.1, the used welding technology is butt weld by laser beam. Choice of suitable manufacturing variety will be made from more construction proposal tool. Appearance to financial costs, mode of radial expanding and so from aspekt functionality and next processing part. We choice variety NO. 3. I implemented calculation usefull forming power and process factor. I affixed to the dokument plan configuration choose variety.
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Pokusy o rozlišení podjednotek trimerních a hexamerních forem purinnukleosidfosforylázy pomocí krystalové struktury komplexů purinových bází nukleosidů, acyklonukleosidů a jejich fosfonátových analogů
Bzowska, A. ; Stepniak, K. ; Olasek, M. ; Dlugosz, M. ; Wielgus-Kutrowska, B. ; Antosiewicz, J. ; Holý, Antonín ; Koellner, G. ; Stroh, A. ; Raszewski, G. ; Steiner, T. ; Frank, J.
Attempts to demonstrate and interpret differences between subunits forming biologically active oligomers of low-(calf spleen) and high-molecular mass (E. coli) purine nucleoside phosphorylases (PNP) yielded new crystal structures of both enzymes complexed with ground-state analogue ligands in space groups and with two full trimers and one full hexamer in the asymmetric unit, respectively.
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