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Evaluation of geometry effect on structural panel stability with the use of Finite Element Methods
Klepiš, Daniel ; Augustin, Petr (referee) ; Katrňák, Tomáš (advisor)
This bachelor thesis deals with the problem of loss of stability of a reinforced wing panel. Within the research part of the thesis, an overview of the types of instabilities is created, thanks to which it is possible to verify the phenomena occurring in the whole area of progressive loading of the panel. The classical concept of longitudinal section reinforcement is enriched by an unusual type of so-called tree reinforcement inspired by the bionic structure of the leaf. For the panel modified in this way, two models are created in which selected dimensional parameters are changed. All the variations are numerically calculated using nonlinear analysis in MSC Patran/Nastran. For comparison of the calculated panels, a series of graphs are produced showing the force transfer and the percentage increase in the maximum force transfer with loss of stability. The selected variant of the parametric model is also compared in terms of mass increase. This allows a better verification of the appropriate panel for further detailed analysis.
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Collection of solved examples from Elasticity and Strength
ŠIMANOVÁ, Petra
The thesis is designed as a brief teaching text for the course Technical Mechanics II at the Faculty of Education of the University of South Bohemia in České Budějovice. The topics included in the thesis are simple tension, simple compression, simple shear, simple bending, simple torsion, buckling. The theory is supplemented by examples with annotated solutions for each type of stress. The thesis also contains several complex problems on dealing with multiple types of stresses on a structure. The work can be used by teachers of the subject in preparation for classes and by students in self-study or in preparation for various examinations or tests.
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ACT - according Palaščáková Špringrová - Influence on Backeche during the Pregnancy and Puerperium
Baranová, Eva ; Vondráková, Ivana (advisor) ; Hylmarová, Ludmila (referee)
Author: Eva Baranová Institution: Department of Rehabilitation, Faculty of Medicine, Charles University in Hradec Králové Title of Bachelor's thesis: ACT® - Influence on Backache during the Pregnancy and Puerperium Supervisor: Mgr. Ivana Vondráková Number of pages: 105 Number of pictures: 40 Number of charts: 24 Year of defense: 2014 Keywords: ACT® - Acral coactivation therapy® /Ingrid Palaščáková Špringrová, acra, buckling, straightening, ontogenetic, positions, pregnancy, puerperium Bachelor thesis deals with the method ACT® - acral coactivation therapy and its application of back pain in pregnancy and in the postpartum period. In the theoretical part of this thesis is the anatomy of the spine, planes and dimensions of the pelvic stabilizing system of the spine and the importance of muscle systematization . Another chapter is a method of ACT® - acral coactivation therapy, which describes its principles. The last chapter is about pregnancy itself, change of it and nourishment. The practical part included two case reports of pregnant patients with back pain. Both attended the outpatient rehabilitation. They were treated conservatively, one with low back pain, the one with a sore a lower thoracic and upper lumbar spine. Each of the patients there is done input and output kinesiology examination,...
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Stress-strain analysis of the railway bridge in Zahrádky near Česká Lípa
Abdul moghni, Abdul rahman ; Vosynek, Petr (referee) ; Fuis, Vladimír (advisor)
Cílem této bakalářské práce je využití deformačně napěťové analýzy na Železniční most v Zahrádkách u České Lípy. Konstrukce mostu byla zjednodušena a vymodelována jako nosníková konstrukce. První část bakalářské práce byla věnována získávání vstupních dat a základních informacích z technické dokumentace mostu. V nosníkovém modelu bylo využito několik zjednodušení. První model považujeme za staticky neurčitý, zatímco druhý jako staticky určitou konstrukci. Každý model tedy obsahuje zátěž z důvodu vlastní váhy a zatížení způsobeno projíždějícím vlakem. Z důvodu objemnosti rovnic, využíváme k výpočtu software Maple. Zkontrolovali jsme i mezní stav vzpěru pro oba modely, avšak jsme uvažovali pouze zatížení vlastní váhou a zatížení způsobeno vlakem. Po získání analytických dat bylo důležité tyto výsledky ověřit. Toto bylo docíleno využitím metody konečných prvku za pomocí programu Ansys. Veškeré výpočty byly provedeny pro 2D modely. Jediná výjimka je numerická sekce, kde byl přidán 3D model za účelem porovnání s 2D modelem.
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Construction of equipment for thin walled L-profiles instability testing
Polčák, Marek ; Vaněk, František (referee) ; Horák, Marek (advisor)
Bachelor’s thesis deals with the loss of stability of axially loaded thin-walled aluminium profi-les, which make up an important part in the aircraft structures. The loss of their stability is tes-ted by the compression test, which is used to determine the buckling load. Compression test may be influenced by many factors, which are related to the fixing to the testing machine. The aim of the thesis is to design a fixture, which would fix a specimen to the testing machine and improve the results of the test.
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Napjatostně deformační analýza mostu ve Starém Městě u Frýdku-Místku
Janík, Rostislav ; Profant, Tomáš (referee) ; Fuis, Vladimír (advisor)
The bachelor thesis analyses stress and strain of real railway bridge. Construction of bridge is modelled as plane bar system. The fisrt part of the thesis deals with a research, which includes obtaining information from theory, which is necessary for the right solution of the task. Next part dedicates to analytic solution of statically determinate and indeterminate variation of structure for load by own weight and also for load during passage of the train. In the next part are the results of analytic solution verified by numerical solution in program ANSYS. In the last part is evaluated the risk of buckling for all variations of the load.
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Sensitivity analysis of stability problems of steel structures
Valeš, Jan ; Vičan,, Josef (referee) ; Kučerová,, Anna (referee) ; Melcher, Jindřich (referee) ; Kala, Zdeněk (advisor)
The doctoral thesis is focused on evaluation of global sensitivity analysis of load-carrying capacity of steel hot-rolled beams. These beams are subjected to lateral-torsional buckling, weak axis buckling and strong axis buckling. Very comprehensive computational models which were both geometrically and materially nonlinear were created in Ansys software using solid finite elements to calculate the load-carrying capacity. The computational models allowed modelling of random initial imperfections such as initial curvature, deviations of cross-section dimensions and steel properties. Sensitivity analysis quantified their influence on the load-carrying capacity. Simulation runs of random imperfections were generated using the Latin Hypercube Sampling method. Since the evaluation of sensitivity analysis of load-carrying capacity of all finite element models would cost an extreme amount of computer time, the thesis aimed at developing a meta-model (also known as surrogate model) based on approximation of FEM model. The approximation polynomial then facilitated the evaluation of sensitivity indices using a high number of simulation runs. At the end, the relationships between the slenderness and the first and second-order sensitivity indices are plotted in graphs. Those random input imperfections that influence the variability of load-carrying capacity the most are pointed out.
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Stability problems of laminated structural glass members
Pešek, Ondřej ; Lokaj,, Antonín (referee) ; Brodniansky,, Ján (referee) ; Melcher, Jindřich (advisor)
Transparent and subtle structures are features of modern architecture. Structural glass is constructional material that provides to realize architect's visions and ideas. Glass as a constructional material is more often used as a material for primary load-bearing structures. Realization of safe, reliable and economic glass structure is real challenge for structural engineers because of absence of standards for designing of glass members and elements. Compressed members (columns), bended members (beams) and members loaded by compression and bending (beam-columns) were analysed in the frame of the doctoral thesis whereby the emphasis is being placed on the lack of stability – flexural buckling, lateral-torsional buckling and flexural-lateral-torsional buckling. Measuring of shape and amplitude of initial geometrical imperfections is a part of doctoral thesis. The theoretical analysis describes the behaviour of the member by means of solving the differential equations. The solution according to the second order theory developed for metal members is applied on structural laminated glass members with use of effective cross-sectional characteristics. Numerical analysis is focused on the use of commonly available software based on finite element method in order to predict the load-bearing resistance of laminated glass members. Actual behaviour of laminated and monolithic structural glass members was found within experimental program. The correctness of FEM model and analytical solutions were evaluated by comparing with test results. The goal of the doctoral thesis was determine of buckling curves for calculation of flexural buckling and lateral-torsional buckling resistances by the same calculation procedure as for metal members. Because of small number of experimentally tested specimens the Monte Carlo simulation was performed.
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Strengthening of axially loaded steel members under load
Vild, Martin ; Wald,, František (referee) ; Křivý,, Vít (referee) ; Bajer, Miroslav (advisor)
Dissertation focuses on strengthening of axially loaded steel members strengthened under load. Strengthening under load using welding is time and financially efficient. Plastic design can be used for members without stability problems. However, the design of members susceptible to buckling is difficult and opinions of researchers differ on this matter and there are only several experiments. The dissertation is focused on strengthening under load of members with selected cross-sections susceptible to flexural buckling. It is necessary to check the resistance of the base member weakened by the elevated temperatures caused by welding. The preload and welding – residual stress and deformations – must be taken into account for the determination of the buckling resistance of the member strengthened under load. The aim of this dissertation is to provide the load resistance of selected compressed members strengthened under load. Author performed experiments on members with the H and L shaped cross-sections and seamless tubes. Other experiments were performed on members with H shaped cross-section and rectangular hollow sections to determine the resistance of base member during welding. These served to validate numerical models which helped to increase the number of specimens for statistical evaluation. Analytical models to determine the load resistances of the base member during welding and the strengthened member were developed using experiments from literature and author’s experiments and numerical models. The simplified model is conservative and suitable for practical design. The complex model is suitable for scientific purpose and it provides both deformation and load resistance using modified imperfection factor. It provides a good agreement with the experiments. Doctoral thesis also includes practical recommendations for design and execution of strengthening under load using welding.
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