This final work deals with the evaluation of a truss structure and its wooden elements of St. James church located in Brno. The building is enrolled to the list of a National cultural monuments. The aim was to detect the damage done as well as to determine its range to particular elements. The evaluation of a truss was based on a survey made by sensoric and instrumental methods. Two devices were used for these measurements - Arborsonic Decay Detector and Fakopp UltraSonic Timer at which the spike and cylindrical sensors were used. To compare and determine the conformity or differentiation of the above said ultrasonic devices were used statistical analysis of the results. The structure was found infested with wood decaying insects and wood-destroying fungi mainly in tie beams, collar ties and pentagonal purlins. This damage was evaluated and the level of damage was determined together with its range. The result was recorded in drawings (top view plan). This drawing together with other results will serve as a basis for further phase of reconstruction which is planned to be made to this historically valuable structure.

This doctoral thesis was written under supervision of my supervisor Prof. Ing. Přemysl Janicek, DrSc. and under supervision of my specialist supervisor Ing. Petr Skalka, Ph.D. The thesis deals with the influence of various operating conditions on crack behaviour in in a wheel rim and/or tire. The dissertation topic was motivated by cooperation with Pardubice University, Faculty of Jan Perner. The first part of the thesis presents a literature search, which provides a current state-of-art in the field of contact loading, crack propagation behaviour under mixed-mode and thermal field generated during braking. The next part of thesis deals with the solution of the given problem and the obtained results are presented. Specifically, crack behaviour under various operating conditions including the crack growth rate is simulated. Also, an influence of thermal field on crack is investigated. The linear elastic fracture mechanics approach is considered to treat the above mentioned problems. Last part of thesis summarizes the obtained results which are discussed in a broader context.

Diplomová práce se zabývá metodou hybridních (hranových a uzlových) konečných prvků ve frekvenční i časové oblasti. Tato metoda je použita pro analýzu vlnovodu parallel-plate, v kterém jsou umístěny dvě dielektrické vrstvy. Jako ukončení vlnovodu je implementována dokonale přizpůsobená vrstva označována PML. Projekt řeší možný výběr PML vrstvy v časové oblasti. Metoda je programována v programu MATLAB a výsledky jsou porovnány s programem COMSOL Multiphysics.

Tato práce se zabývá problematikou aneurysmat břišní aorty a možností využít konečnoprvkovou deformačně-napěťovou analýzu těchto aneurysmat ke stanovení rizika ruptury. První část práce je věnována úvodu do problematiky, popisu kardiovaskulární soustavy člověka s důrazem na abdominální aortu, anatomii, fyziologii a patologii stěny tepny s důrazem na procesy vedoucí ke vzniku aneurysmatu. Dále se práce věnuje rizikovým faktorům přispívajících ke vzniku aneurysmat spolu s analýzou současných klinických postupů ke stanovení rizika ruptury spolu se srovnáním navrhovaného kritéria maximálního napětí. Dominantní část této disertace je věnována identifikaci faktorů ovlivňujících napjatost a deformaci stěny aneurysmatu spolu s návrhem nových postupů, prezentací vlastních poznatků vedoucích ke zpřesnění určení rizika ruptury pomocí deformačně- napěťové analýzy a metody konečných prvků. Nejprve je analyzován vliv geometrie, vedoucí k závěru, že je nezbytné používání individuálních geometrií pacienta. Dále je pozornost zaměřena na odbočující tepny, které ve stěně působí jako koncentrátor napětí a mohou tedy ovlivňovat napjatost v ní. Jako další podstatný faktor byl identifikován vliv nezatížené geometrie a bylo napsáno makro pro její nalezení, které bylo opět zahrnuto jako standardní součást do výpočtového modelu. Mechanické vlastnosti jak stěny aneurysmatu, tak intraluminálního trombu jsou experimentálně testovány pomocí dvouosých zkoušek. Také je zde analyzován vliv modelu materiálu, kde je ukázáno, že srovnávání maximálních napětí u jednotlivých modelů materiálu není vhodné díky zcela rozdílným gradientům napětí ve stěně aneurysmatu. Dále je zdůrazněna potřeba znalosti distribuce kolagenních vláken ve stěně a navržen program k jejímu získání. Intraluminální trombus je analyzován ve dvou souvislostech. Jednak je ukázán vliv jeho ruptury na napětí ve stěně a jednak je analyzován vliv jeho poroelastické struktury na totéž. Posledním identifikovaným podstatným faktorem je zbytková napjatost ve stěně. Její významnost je demonstrována na několika aneurysmatech a i tato je zahrnuta jako integrální součást do našeho výpočtového modelu.Na závěr jsou pak navrženy další možné směry výzkumu.

This thesis is devoted to the problem of finding a suitable geometrical de- scription of the domain for the Finite Element Method (FEM). We present the most important methods used in generation and improvement of unstructured triangular meshes (grids) for two dimensional FEM. Possible measures of mesh quality are discussed with respect to their usage in linear Lagrange FEM. The relationship between mesh geometry (especially angles of particular triangles), discretization error and stiffness matrix condition number is examined. Two methods of mesh improvement, based on Centroidal Voronoi Tessellations (CVT) and Optimal Delaunay Triangulations (ODT), are discussed in detail and some results on convergence of CVT based methods are reviewed. Some aspects of these methods, e.g. the relation between density of boundary points and interior mesh vertices and the treatment of the boundary triangles is reconsidered in a new way. We have implemented these two methods and we discuss possible im- provements and new algorithms. A geometrically very interesting idea of recent alternative to FEM, Isogeometric Analysis (IGA), is outlined and demonstrated on a simple example. Several numerical tests are made in order to the compare the accuracy of solutions of isotropic PDEs obtained by FEM on bad mesh, mesh improved...

This thesis deals with the design of a container carrier with interchangeable superstructures up to 3000 kg of technical weight. The introduction renders a critical review of similar devices and consecutive review of the device in terms of legislative matters. A dynamic simulation was used to calculate the loaded states. The outcome of the simulation was used to set the border conditions, which were then used for strength analysis calculations using finite element method (FEM). Blueprints of the final design are a part of the thesis.

In the present thesis we study and compare different viscoelastic rate-type fluid models capable of describing response of geomaterials such as asphalt. Using new thermodynamic approach proposed by Rajagopal and Srinivasa (2000) we derive several classes of non-linear viscoelastic models that generalize standard Oldroyd-B and Burgers models. We show that the new models achieve better results in fitting experimental data with asphalt than the previously considered models (Oldroyd-B, Burgers, Rajagopal and Srinivasa (2000)). In particular they are able to capture the behavior of asphalt observed recently in experiments (torque overshoot and two relaxation mechanisms), which is not possible to describe by the other models. Using both the standard and the newly derived models we compute full simulations of viscoelastic flow with the finite element method in fixed domains and incorporating the Arbitrary Lagrangian-Eulerian description also in deforming domains. For example, we study rolling of asphalt or creation of ruts in the road with the real material parameters obtained by fitting the experiments. Powered by TCPDF (www.tcpdf.org)

This work is devoted to the analysis of wood with imperfection in tension, digital image correlation method and finite element method. It is investigated the comparability of the results of these two methods on the example of behaving of the wood in tension with imperfection. The imperfection could be for example any weakening of the wood structure. It could be natural (knots, cracks and so on). The example of artificial imperfection here is a drilled hole. In this work an experiment with plastic sample in the same manner was also conducted in order to validate the analytical procedure for calculating the stress and practically demonstrate the difference between isotropic and anisotropic material. The work also includes general information from the literature, theoretical assumptions, methodologies, measured results and the comparison of these results each other and with the literature. The result of this work is to evaluate the behavior of wood with a hole in the tension and the comparison of these two methods of measuring deformation. In the end there are the advantages and disadvantages of each method.

This Diploma Thesis is dedicated to a proposal of a carrier swap bodies hooked up to a agrotruck 6x6 with a maximum technical weight 38000 kg and has been worked out in corporation with ZDT Nové Veselí company. The first section of the Thesis is occupied with legislation and then especially with a description of available agrotrucks and similar constuction solutions not just of the carrier swap bodies. In the following part of the Thesis the own carrier swap bodies construction proposal has been described, based on which the stress analysis has been done in the final part of the Thesis. Also the technical drawing forms an integral part of the Thesis.

This master’s thesis deals with a strength analysis of the main frame and loading arms of a skip loader. For a calculation of load states is used a dynamic simulation and its results are used as a boundary conditions for the strength analysis using finite element method (FEM). The results of the analysis is evaluated and on theirs basis are designed a construction improvements. The part of the thesis is drawings documentation of the construction improvements.