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Comparison of approaches to the assessment of buckling of variously long and supported columns
Ostratická, Klára ; Pokorný, Jan (referee) ; Šebek, František (advisor)
The bachelor's thesis deals with assessment of the buckling stability. The differences between elastic and inelastic buckling and effects on the critical force are described. The effect of material, supports and length of the column is described in more detail. During buckling, the character of deformation changes, the compressed column starts to bend at a definite point. This point is called bifurcation point and the limit is amount of critical force. The calculation of critical buckling force is carried out analytically for selected examples using the Euler and Johnson methods. The results are numerically checked by the finite element method in Ansys. The results for linear buckling are identical. Examples of nonlinear buckling are also calculated numerically. The difference is found in critical force for contact surfaces without friction and with friction. Defining the critical force can prevent the collapse of the entire structure, thus avoiding catastrophic incidents.
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Study of crack retarders geometry modification effect on integral structural panel stability with the use of Finite Element method
Moštěk, Daniel ; Augustin, Petr (referee) ; Katrňák, Tomáš (advisor)
The master’s thesis concerns itself with evaluating the impact of four dimensional parameters of a specific type of crack retarder on improving the compressional buckling strength of an integral wing panel, using the finite element method. The improvements in buckling strength were particularly assessed with concerns to the added mass of the crack retarders. The crack retarders are composed of a so-called terminal section and so-called side branches. The thesis includes a literature review on the buckling of skin-stringer panels and an overview of crack retarder types. In the practical part of the thesis created FEM models of the examined variants are described along with the achieved results, which are subsequently evaluated. It was concluded that the examined parameters related to the terminal section significantly influence the increase of buckling strength of a given variant and are efficient concerning added mass. On the other hand, the examined parameters related to the side branches were deemed less significant and their alteration was inefficient in terms of added mass.
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Buckling analysis of the load-bearing system
Majer, Tomáš ; Löffelmann, František (referee) ; Šplíchal, Jan (advisor)
The research part of the work summarizes the knowledge in the field of calculation of buckling stability and methods of heat transfer. The next part deals with the calculation of the buckling stability of two types of samples using an analytical approach, finite element method, and verified using experimental measurements. Finally, the work deals with CFD calculation for determining the temperature field on the examined samples, which is used to calculate the buckling stability with temperature influence.
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Buckling Length of Steel Columns in Frame Structures Stressed by Fire
Červenka, Roman
Fire resistance is crucial for load-bearing structures. However, current rules in structural Eurocodes may not cover all fire design situations. In EN 1993-1-2, fire design rules exist only for braced steel frames, treating each floor as a separate fire section. Unbraced frames lack specific fire design rules and use regular temperature design buckling lengths. This article presents an analysis of the behaviour of columns in braced and unbraced frames and compares it with the procedures of some other authors.
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Stability Analysis of Thin-Walled Cold-Formed Sigma Profiles Using the Finite Strip Method
Venzara, Mikuláš
The stability analysis of cold-formed thin-walled profiles often benefits from the effective application of the finite strip method. Among the software tools based on this method is the CUFSM program. This article provides an overview of the principles of the finite strip method and the use of the CUFSM program for conducting parametric studies. Specially, the focus is on investigating the influence of the geometry of web intermediate stiffeners in Sigma-sections on the buckling capacity of flanges with edge stiffeners during distortional buckling. The parametric studies are automated through appropriate modifications of the CUFSM program source code.
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Methods of Static Buckling Analysis
Svoboda, Filip ; Eliáš, Jan (referee) ; Frantík, Petr (advisor)
The aim of this theses is to create application, which is able to calculate buckling load of structure made from 1D bar elements, using finite element method. introduction is devoted to basic principles of buckling and derivation of necessary formulas. Then are described all operations and numerical methods needed for the application. At the and is in detail analyzed few structures and results are compared with known solutions or with other applications.
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Finding kinematic quantities of a mechanism and a structural analysis of its members after blockage
Zvozil, Ondrej ; Vosynek, Petr (referee) ; Fuis, Vladimír (advisor)
Diplomová práca, ktorá vznikla v spolupráci so spoločnosťou AUFEER DESIGN (AFD), sa zaoberá analýzou konkrétneho stieračového mechanizmu automobilu. Najprv je uvedená stručná história stieračov. Stieracie sústavy sú potom rozdelené podľa ich usporiadania a spôsobu pohonu. V nasledujúcej kapitole je formulovaná problémová situácia, problém a systém podstatných veličín. Kinematické veličiny kľúčových bodov mechanizmu sú určené analytickým aj numerickým prístupom. Výpočtový model pre kinematickú analýzu je vyvinutý v Matlabe a SimMechanics. Ďalšia časť je venovaná vytváraniu konečno-prvkového modelu v programe ANSA. Všetky deformačne-napäťové analýzy sú vykonané v programe Abaqus. Prvá z nich je parametrická štúdia, ktorá odhaľuje kritické polohy mechanizmu z hľadiska tlakového namáhania určitých súčastí. Mechanizmus v kritických polohách je potom zaťažovaný so zablokovanými ramenami stieračov. Nakoniec sú urobené lineárne analýzy straty vzpernej stability súčastí, u ktorých môže nastať, nasledované nelineárnymi analýzami so zahrnutými imperfekciami.
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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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Strength design of the aircraft spur
Profota, Martin ; Vosynek, Petr (referee) ; Vrbka, Jan (advisor)
This master thesis deals with computational stress-strain analysis of the tailskid of airplane L410 NG with main focus firstly the check current design of the tailskid and then the design another design solution with the able to absorb as much as possible the deformation energy. Solution of this problem is performed using computational modeling utilizing numerical simulation of quasi-static and crash deformation load of the tailskid with using explicit Finite Element Method (FEM) in program ABAQUS v6.14. After the introduction with problem situation and tailskid assembly introductory part is devoted to the research study of various designs of the tailskid for different types of airplanes. There follows these theoretical general principles of thin-walled structures and buckling of them. Before the creating of the computational model itself, the explicit form of the Finite Element Method is better described. The conclusion of this thesis deals with the mutual comparison of the most advantageous design variants of the tailskid and the selection of the most suitable one of them for the airplane L410 NG.
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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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