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Stability analysis of swinging props turbines
Bukovský, Petr ; Navrátil, Petr (referee) ; Skalka, Petr (advisor)
Master thesis deals with a computing simulation of two props turbines lines. The thesis output is gaining maximum possible load, at which a commencement of deformation stability critical state for various geometrical imperfections has not arisen yet. The calculation has been done by FEM in two different ways: linear solution (using a calculation conversion into eigenbuckling) and nonlinear solution (using a FEM deformation option). Result analysis compares both methods outcomes. Safety factor for the props operation has been proposed taking into consideration known influences on operating state.
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Stability and geometrically nonlinear analysis of steel structures
Ondášová, Annamária ; Puklický, Libor (referee) ; Kala, Zdeněk (advisor)
The diploma thesis is dealing with the stability and geometrically nonlinear analysis of a steel structure, explanation of the principles and procedure of the steel structure calculations. The modeled structure is loaded with pressure forces and subsequently the bearing capacity of the structure is calculated using a stability and geometrically nonlinear analysis with initial imperfections. The solution of the frame structure using both approaches can provide slightly different results, which can have an impact on the assessment of the reliability of the structure, its over or under-dimensioning.
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Suspension footbridge over the river Bečva
Sobková, Sára ; Šopík, Leonard (referee) ; Nečas, Radim (advisor)
The subject of this thesis is the design and assessment of a suspended footbridge for pedestrians over the Bečva River. Three variants of the crossing were created. The va-riant with a suspension structure was selected for detailed design. The chosen pede-strian footbridge is composed of two suspension cables supported by an inclined py-lon, anchored by a set of six anchoring cables. The design of the structure relied on finding the ideal geometry of the suspension cables. The computational model was created in the ANSYS Mechanical APDL 2023 R2 software. For the analysis of the deck in the transverse direction, model was created in the SCIA Engineer 21.1 software. The construction was assessed for ultimate limit state of serviceability and load-bearing capacity according to applicable standards, and a dynamic analysis was performed. The work includes clear and detailed drawings and visualizations.
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Programming of the ELSM method for the advanced stability analysis of geotechnical structures
Štetiar, Juraj ; Koudela, Pavel (referee) ; Chalmovský, Juraj (advisor)
This master's thesis addresses the issue of slope stability, which is a key task in the design of geotechnical structures. The study focuses on the Enhanced Limit Strength Method (ELSM), which leverages the advantages of the Finite Element Method (FEM) while allowing the control of the position and shape of the slip surface. ELSM is particularly advantageous for addressing the stability of embankments and aerial slopes of earth-filled water reservoirs. The objective of the thesis is to develop an algorithm for the ELSM method as an additional module for existing FEM solvers. The theoretical part of the thesis explains the principles of commonly used slope stability calculation methods, such as the Limit Equilibrium Method (LEM) and the Strength Reduction Method (SRM). Subsequently, the principles of the ELSM method (determining the factor of safety for the critical slip surface) are introduced, and the optimization algorithm Particle Swarm Optimization (PSO) is briefly described. In the practical section of the thesis, the programmed algorithm for slope stability calculation using the ELSM method with the utilization of the Particle Swarm Optimization (PSO) optimization module is explained. The correctness of the algorithm is verified, and a comparison with the SRM and LEM methods is conducted through three verification studies, including a simple homogeneous slope, a heterogeneous slope with a horizontal material interface, and a real case study assessing the external stability of the dam structure at the Vlachovice waterworks.
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Design of steel-concrete arch structure of footbridge over the river Svratka
Vraňanová, Veronika ; Marván, David (referee) ; Nečesal, Petr (advisor)
The main goal of this diploma thesis was to project a design of arch bridge‘s framework over the Svratka river. This single-span bridge has the span of 52,5m. The framework is constructed from a pair of beams, suspended from the pair of beams bent towards each other. The bridge deck is coupled with steel crosspieces. The construction design was executed in computing programme Dlubal RFEM 5.07. The individual components of the framework were assessed in Microsoft Excel. The calculation considered the load of wind and pedestrians’ movement and their effect on the dynamics of the construction. The phases of development were also considered. Assessments of coupled cross-section, main beams of steel construction, tension systems and selected construction joints were executed in a static calculation. Moreover, a design of a bearing and a bridge plug joint. Finally, a drawing documentation and a final report were prepared in regards with the requirements. The construction design and its assessment were executed according to valid standards.
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Delay differential equations in engineering
Zlámal, Ondřej ; Řehák, Pavel (referee) ; Opluštil, Zdeněk (advisor)
This thesis is about dynamical systems and analysis of their stability. These systems are described using delayed differential equations, whose character is ideal for describing many real life problems. In this thesis it is analysed how size of delay and its rate affects stability of system. Change of stability in system is traced using Hopf bifurcations. Theory of this thesis will be applied on system based on machine tool vibrations and system describing feedback in lasers.
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Localized formulation of bipenalty method in contact-impact problems
Kolman, Radek ; González, J. A. ; Dvořák, Radim ; Kopačka, Ján ; Park, K.C.
Often, the finite element method together with direct time integration is used for modelling of contact-impact problems of bodies. For direct time integration, the implicit or explicit time stepping are gen-\nerally employed. It is well known that the time step size in explicit time integration is limited by the stability limit. Further, the trouble comes with the task of impact of bodies with different critical time step sizes for each body in contact. In this case, this numerical strategy based on explicit time stepping with the same time step size for both bodies is not effective and is not accurate due to the dispersion behaviour and spurious stress oscillations. For that reason, a numerical methodology, which allows independent time stepping for each body with its time step size, is needed to develop. In this paper, we introduce the localized variant of the bipenalty method in contact-impact problems with the governing equations derived based on the Hamilton’s principle. The localized bipenalty method is applied into the impact problems of bars as an one-dimensional problem. The definition of localized gaps is presented and applied into the full concept of the localized bipenalty method.
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