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Importance of Upsetting Test for Numerical Simulation of Forming Processes
Tinka, Petr ; Dohnal, Ivo (referee) ; Řiháček, Jan (advisor)
The thesis deals primarily with the creation of a material model for numerical simulation using an upsetting test for steel 17 240, a layer of Delta 144 was applied on the steel. From the obtained values of force and path, a material model was created which serves for characterization material for numerical simulation. The simulation was performed in ANSYS Workbench 19.0. From this, force and path are obtained, which is used to compare with the upsetting test. It is clear from the comparison that the values do not differ too much, and it is possible to use this material for numerical simulation.
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Nonlinear analysis of reinforced concrete structures
Král, Petr ; Salajka, Vlastislav (referee) ; Hradil, Petr (advisor)
The aim is to design and evaluate nonlinear beams analysis, which will be subjected by four – point bending. Nonlinear analysis will be performed and evaluated on three beam models, the first of which will be made from plain concrete, the second of which will be made from reinforced concrete with reinforcement bars in the domain of tensile stress and the third of which will be made from reinforced concrete with reinforcement bars in domains of tensile and compressive stress. The thesis will be included formation of appropriate FE models, performance of nonlinear calculations with using nonlinear material model from a library of nonlinear material models multiPlas in the programming environment of software ANSYS and subsequent evaluation of results. Evaluation of results will consist from evaluation of nonlinear beams analysis and from evaluation of beams analysis according to ČSN EN 1992 – 1 – 1 without reinforcement bars and with reinforcement bars in these variants, next from comparison of nonlinear beams analysis with a beams analysis according to ČSN EN 1992 – 1 – 1 and finally from evaluation of the yield condition, which will be applied to the beams.
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Sandwich structure analysis using Finite Element Methods
Bucňák, Ondřej ; Schoř, Pavel (referee) ; Mališ, Michal (advisor)
This bachelor’s thesis focuses on the analysis of material model core sandwich structures. The behavior of the sandwich core is simulated using Finite Element Method (FEM) in programs MSC.Patran/Nastran. The first part deals with describing the properties of sandwich structures and its components. There are presented examples of the application of sandwich structures. The next section describes the elementary material models. In the last part of bachelor’s thesis is performed FEM analysis of material model sandwich foam core and comparison to the results with the four-point bending test.
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Comparison of two alternatives of deep excavation design
Krejzar, Vojtěch ; Miča, Lumír (referee) ; Chalmovský, Juraj (advisor)
The thesis focuses on numerical modeling of a 30 m deep excavation using the finite element method (FEM). The excavation is situated in Luzern, Switzerland. The subsoil is formed by inclined sandstone or siltstone layers; one of them tends to form a dangerous slip surface. The bachelor’s thesis compares 2 alternatives: Alternative A represents a combination of an anchored pile wall and sprayed concrete in the lower part of the excavation, Alternative B represents a full height anchored pile wall. The thesis comprises of the description of modeling, determination of material parameters and structural members’ inputs, defines calculation phases and predicts the structure deformations. The mathematical model is created using PLAXIS 2D software.
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Car Door Handle FEM Model Creation and Validation for Crash Simulations
Raffai, Peter ; Korouš, Jan (referee) ; Ramík, Pavel (advisor)
The aim of this master’s thesis was to create a component model of a door handle stiffener used by the Volkswagen concern, which can be used for crash computations. Also to tune its parameters the way, its behavior corresponds the most to the real part’s. In the theoretical part the current regulations of the Euro NCAP are presented, concerning the testing and evaluation of the passive safety of new vehicles. Attention is focused on the evaluation of the side impact barrier tests, where the effect of the door handle stiffener’s damage is reflected the most. Shown are the reasons for the effort to simulate the real behavior of the stiffener, the factors, which initialized the born of the studied problem. The practical part starts with the creation of the FEM mesh of the part based on its 3D CAD model, also describes the requirements for the mesh quality, as well as the used tools and methods. Further on investigated are the characters of real damages of the door handle area during side impacts, based on which the component tests are proposed for the validation of the simulation model. Experimental research consists of the stiffener’s testing for simple bend and twist loads, three specimens each. After the execution of the tests the results get compared with the corresponding simulations. Modifications are made on the model according to the acquired results: refinement of the FEM mesh, new material model usage with failure for shell elements and definition of real material characteristics for the used thermoplastics. The latest obtained simulation dependencies are compared with the measured values again, the results are evaluated at last.
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Numerical analysis of stability of retaining structure in cohesive soils
Fejfarová, Aneta ; Račanský, Václav (referee) ; Chalmovský, Juraj (advisor)
The bachelor thesis deals with numerical modeling of excavation using finite element method in the Plaxis 2D software. Triple-anchored retaining structure is founded in a less permeable cohesive soils. There are described loss of stability, types of the calculation and material model (Hardenig soil model used in the mathematical model) in the theoretical section of this bachelor thesis. Mathematical model of the excavation was described in the practical section of this thesis, specifically first limit state. Part of the thesis is an evaluation of the degree of stability over time, pore pressures and critical shear surfaces.
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Modelling of diaphragm walls using time-dependent elasto-plastic material model
Šindelářová, Daniela ; Kotačková, Alena (referee) ; Chalmovský, Juraj (advisor)
The goal of this thesis was the verification of the advanced time-dependent elasto-plastic material model for modeling diaphragm walls. Currently, this type of construction is solved usually with a combination of linear-elastic volume and plate elements. To express time-dependent behaviour, there are both, volume and plate, elements active in short-term conditions, then only volume elements in long-term conditions, while plate elements are deactivated. In this thesis, the Shotcrete material model, which can capture the time-dependent behaviour without combining two types of construction elements, is used. First, a theory of time-dependent behaviour is presented and a design of concrete structures by Eurocode 2 is discussed. Next, the Shotcrete material model is described, then used for modeling a biaxial test and calibration of compression and bending test. Following the gained knowledge, a real boundary value problem of deep excavation supported by diaphragm walls with the strut was solved. To calculate values of the internal forces and horizontal deformation in diaphragm walls, three types of material models are used.
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Verification of nonlinear material models
Prokš, Tomáš ; Němec, Ivan (referee) ; Hradil, Petr (advisor)
The bachelor thesis deals with verification of nonlinear material model of soil FHWA SOIL during shear test. The nonlinear problem was being solved by software LS-DYNA using explicit formulation of finite elements method. The values of horizontal displacements during the direct shear test were compared with the results listed by the developer of the material. The considerable difference in the results led to focusing on the settings of the material model and influence of application of load, geometry and type of finite elements on the monitoring values.
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