|
An aplication of the mathematical dislocation theory to the problem of the crack in the vicinity of the bi-material interface
Padělek, Petr ; Hrstka, Miroslav (referee) ; Profant, Tomáš (advisor)
The presented diploma thesis deals with a problem of the determination of the stress intensity factor of the finite length crack in the vicinity of the bi-material interface solved by the distributed dislocation technique. The work is divided into several parts. The first part is theoretical and includes basic concepts of the fracture mechanics, the crack behaviour at the bi-material interface, the formulation of the singular integral equation by virtue of the distributed dislocation technique, the Bueckner's principle, complex potentials and consequently the determination of the stress intensity factor. The second part is the theory application to the specific configuration of the crack of the finite length with respect to the bi-material interface and in the third part, there is carried out the solution of this problem for various configurations of the bi-material solved by the distributed dislocation technique and its comparison with the results obtained from the FE analysis.
|
|
Stress distribution near sharp orthotropic bi-material notch tips
Krepl, Ondřej ; Klusák, Jan (referee) ; Hrstka, Miroslav (advisor)
Presented diploma thesis is concerned with problems of a stress singularity exponent and a generalized stress intensity factor determination, by dint the stress field in the vicinity of the stress concentrator can be consecutively determined. This task is possible to sectionalize into three parts. The first part summarizes basic information about linear anisotropic materials, deals with fundamentals of the linear elastic fracture mechanics and introduces its generalization to the case of the generalized stress intensity factors. The second part is dedicated to a special theory of anisotropic elasticity - Lekhnitskii-Eshelby-Stroh formalism (LES). Furthermore, a theory of the psi-integral is introduced, by dint the stress intensity factor is determined. The final part applies the LES theory and the psi-integral to the concrete material configuration of a crack on the bimaterial interface, a special example of a sharp bimaterial notch. By means of analytical-numerical algorithm in ANSYS and Silverforst FNT95 software the stress singularity exponents and generalised stress intensity factors are consecutively computed.
|
|
Crack propagation in ceramics laminates with strongly bonded interfaces
Hadraba, Hynek ; Chlup, Zdeněk ; Maca, K. ; Bermejo, R.
Crack propagation through layered composites based on Al2O3 and ZrO2 was studied. The strongly bonded laminates with single-component layers and laminates with two-component layers were prepared via electrophoretic deposition and slip casting respectively. Laminates of different pre-defined thicknesses and composition contained different magnitudes of residual stress. Cracks, produced by an indentation technique, propagated towards layer interfaces deflected towards the interface in the compressed layers and away from the interface in the layers containing tension stress. Changes in the direction of crack propagation were described for the whole range of angles of incidence (0° - 90°). The biggest change in the crack propagation was observed, irrespective of the magnitude of residual stress in the layers.
|
|
Positioning System for Sound Intensity Probe
Sedlář, Pavel ; Kouřil, Jiří (referee) ; Schimmel, Jiří (advisor)
This bachelor thesis deals with a development of a 2-dimensional positioning equipment for an acoustic measurement using modules of linear positioning axises MAXS1BR and PAS41BR and stepping motors ILS1R573PB1A0 by Schneider Electric. These motors include integrated power stage and interface RS485. An interface converter using integrated curcuit MAX232 by MAXIM for interconnection between these motors and a control computer was designed. The circuit of the converter was built and tested in a solderless breadboard at rst. Afterwards, a printed circuit board was developed using software EAGLE Layout Editor. This thesis also includes a documentation of mechanic parts, which are necessary to grip measuring appliances.
|
|
Audio Interface for Signal Procesor Using IEEE 1394 Bus
Staroň, Martin ; Přinosil, Jiří (referee) ; Schimmel, Jiří (advisor)
The scope of bachelor’s thesis is a design of the connection between the Freescale digital signal processor DSP56300 family and the DFM Audio DICE II iKit interface by way of the TDM bus. The DICE II iKit interface uses serial IEEE1394 FireWire bus that transmits an audio stream from a host computer. This signal receives the DICE II iKit interface that converts audio data from IEEE1394 FireWire to the TDM bus. The signal processor that process the sended audio data in a real time is connected to this TDM bus. The theoretical part of this work describes the theory of the digital signal processor, in detail DSP56300 Freescale family. After that there is a basic specification of the IEEE1394 FireWire bus. The theoretical part of this bachelor‘s thesis is ended by a description the TDM bus, the I2S interface and the AudifiedDSP Solution system. A connection of the signal processor and the DICE II interface was solved in the practical part, included the debbuging and the operating of the hadle subroutine for the duplex communication. The results of this thesis is might utilise for the duplex communication between the signal processor and aplication software working on the host computer.
|
|
Crack stability analysis of the crack in surface protective layers based on crack mouth opening displacement
Bareš, Pavel
Paper deals with stability analysis of a crack in a coating on a substrate. It is considered that the crack is perpendicularly oriented to the interface between the coating and the substrate and the crack tip lies directly on the material interface. The simple method based on crack mouth opening displacement parameter CMOD is proposed here for a critical stress calculation in the case of through coating crack in very thin coatings. The method is then applied herein on the model example and the critical stresses for different material combinations of the coating and the substrate are calculated. Note that under these stresses the crack will start propagate across the interface to the substrate. All calculations are performed by a finite element method FEM in the system ANSYS.
|
|
Coupling atmospheric chemistry/aerosols to regional climate models
Huszár, Peter ; Halenka, Tomáš (advisor) ; Macoun, Jan (referee) ; Eben, Kryštof (referee)
Title: Coupling atmospheric chemistry/aerosols to regional climate models Author: Peter Huszár Department: Department of Meteorology and Environment Protection Supervisor: doc. RNDr. Tomáš Halenka, CSc. Supervisor's e-mail address: tomas.halenka@mff.cuni.cz Abstract: In this thesis, the connections between air quality and climate are studied. For this purpose, regional climate model RegCM3 and chemistry transport model CAMx has been coupled offline with one- and two-way interaction. Our work represents a first attempt to connect RegCM3 not only with CAMx, but with any other chemistry transport model. As a first step, an offline one way couple of RegCM3 and CAMx has been developed, meaning that the climate model drives the transport, emission, chemical transformation and deposition of species while the radiative feedbacks of gases and aerosols are not considered. A meteorological interface has been developed at our department in order to convert the meteorological data generated by RegCM3 to fields required by CAMx. For those parameters that are essential for CAMx but the regional climate model does not supply them, diagnostic methods were implemented into this interface. Further, it is used to calculate biogenic emissions. Regarding anthropogenic emissions, a simple utility has been developed to...
|
|
Studium defektů v kvazikrystalech metodou pozitronové anihilační spektroskopie
Vlček, Marián ; Čížek, Jakub (advisor) ; Smola, Bohumil (referee)
In the present work positron lifetime spectroscopy and coincidence spectroscopy of Doppler broadening of annihilation radiation were employed for investigations of defects in Mg alloys with icosahedral phase. Samples of WE43 alloy and WE43 alloy modified by addition of zinc were investigated. Positron trapping at vacancy-like defects associated with interface between the icosahedral phase Mg3Zn6Y1 and Mg matrix was observed. Investigations of MgZnAl-based alloys were performed as well. Vacancy-like defects were not detected in MgZnAl- based alloys by positron lifetime spectroscopy. However, coincidence spectroscopy of Doppler broadening of annihilation radiation revealed that positron trapping in the vincinity of icosahedral Mg44Zn41Al15 phase occurs. Several hypotheses ex- plaining different nature of positron trapping in WE43-based and MgZnAl-based alloys were proposed. Keywords: quasicrystals; positron annihilation spectroscopy; positron trapping; open-volume defects
|
| |
|
Webová aplikace pro vytváření logických herních úloh a jejich sdílení
Vlachovský, Jakub
Web application for logic games creation and sharing. Bachelor thesis. Brno: Mendel University, 2016. This thesis contains the concept of implementation and description of executing a web application providing a general interface to create and play certain types of logic games. It also includes the description of technology applied to create the application.
|
guest ::
