National Repository of Grey Literature 538 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Temporal-spatial dispersion analysis of finite element method in implicit time integration
Kruisová, Alena ; Kolman, Radek ; Mračko, Michal ; Okrouhlík, Miloslav
The temporal-spatial dispersion analysis for the linear finite element method with implicit time integration is presented. The Newmark method with β = 1/2 and γ = 1/4 is used as well as the consistent\nmass matrix. The temporal-spatial dispersion relationships are derived in the closed form and analyzed due to errors in numerical wave speed of propagation of harmonic wave. Based on this temporal-spatial dispersion analysis, a suitable mesh size and time step size for allowed errors in phase speed are mentioned as well as we present the polar dispersion graphs.
Bi-penalty stabilized explicit finite element algorithm for one-dimensional contact-impact problems
Kolman, Radek ; Kopačka, Ján ; Tkachuk, A. ; Gabriel, Dušan ; Gonzáles, J.A.
In this contribution, a stabilization technique for finite element modelling of contact-impact problems based on the bipenalty method and the explicit predictor-corrector time integration is presented. The penalty method is a standard method for enforced contact constrains in dynamic problems. This method is easily implemented but the solution depends on numerical value of the stiffness penalty parameter and also the stability limit for explicit time integration is effected by a choice of this parameter. The bipenalty method is based on penalized not only stiffness term but also mass term concurrently. By this technique with a special ratio of mass and stiffness penalty parameters, the stability limit of contact-free problem is preserved. In this contribution, we also present a modification of the explicit time scheme based on predictor-corrector form. By meaning of this approach, spurious contact oscillations are eliminated and the results do not depend on numerical parameters.
Concrete slab roof of underground parking garage
Řihošek, Jan ; Strnad, Jiří (referee) ; Perla, Jan (advisor)
Bachelor thesis deals with the roofing of the underground parking garage with reinforced point-supported slab. The aim of the work is to find out the internal forces on reinforced slab for two of the construction variants, design and check one construction variants. The replacement frame method and Finite Element Method were used for calculation internal forces using 2D model in the Dlubal RFEM 5.17. The work also includes the design and check of one column.
Concrete flat slab of a hospital building
Lehoťák, Roman ; Švaříčková, Ivana (referee) ; Perla, Jan (advisor)
The bachelor thesis deals with the analysis of internal forces and the design of the shape and reinforcement of the reinforced concrete monolithic slab, the ceiling above the 6th floor of the University Hospital in Bohunice. The calculation of internal forces was performed by the substitute frame method and the finite element method in the Nemetschek Scia Engineer 18.0 program. The work deals with the design and assessment of the board and adjacent stairs.
Static analysis of the cylindrical tank
Kunčáková, Eva ; Martinásek, Josef (referee) ; Vlk, Zbyněk (advisor)
This bachelor thesis describes structural analysis of cylindrical tank. The goal of this thesis is creating a computational algorithm in a software called MATLAB, using which the structural analysis on idealized models of cylindrical tank is solved. These models are the rod model and the model with plane elements. This bachelor thesis is divided in several parts. Firstly, there is defined the structure, material and load of cylyndrical tank. Second part is about rod model, stiffness method and the calculation using this method. Next part is about model with plane elements, finite element method and its calculation. In the last part, there are results from each part and their comparison.
Passive axial magnetic bearing
Dostál, Patrik ; Štěpánek, Vojtěch (referee) ; Pruša, Radomír (advisor)
The goal of the bachelor thesis is to measure the characteristics of a passive magnetic bearing. The practical part of the thesis consists of two segments – experimental measurement of properties of a passive axial magnetic bearing and a simulation of this bearing using the finite element method in the FEMM application. The simulation also dealt with the effects of temperature on the bearing. It was discovered that high temperatures considerably lower the axial stiffness of the magnetic bearing. Other effects on the stiffness of the bearing were taken into consideration, especially the dimensions of used magnets and the distance between them. The values that were determined by the experimental measurement and the FEMM simulation were mutually compared. The analysed bearing was built for use in a seal-less centrifugal pump. The values determined by the simulation and the measurement were applied to practical use in pumps. A part of the thesis was concerned with a research on passive magnetic bearings. The research dealt with the principle of the bearings, their structure and their application.
Analysis of Thermoplastic Pipes in a Soil Environment
Ekr, Jan ; Kuklík,, Pavel (referee) ; prof. Ing. Alois Materna, CSc., MBA (referee) ; Gratza, Roman (advisor)
The doctoral thesis deals with an analysis of thermoplastics pipes in a soil environment, in particularly, pipes performed by using trenchless technologies. In the doctoral thesis, experiments of polyethylene pipes loaded by external hydrostatic pressure were performed. The aim of the experiments was to determine a behaviour and load-bearing capacity of the polyethylene pipes loaded by external hydrostatic pressure. For the experiments, a steel pressure chamber was designed and produced which allowed loading and observing a pipe during its loss of the stability. Mechanical properties of the pipe material were determined based on the tensile and bending tests. The series of detailed numerical analyses of the pipe experiments were performed. Various material models which take into account elastic, plastic and viscous behaviour of thermoplastic materials were used. In addition, series of standardized calculations of polyethylene pipes installed using trenchless technologies were performed. The aim was to create new design diagrams for practical assessment of these pipes placed in the partially deteriorated old pipes. In the case of the deteriorated old pipe, a numerical model for determination of design coefficients was created. These design coefficients were verified with standard values. Then, the results of the numerical model were compared with the results of the more complex numerical model which better take into account pipe-soil interaction of various soil types.
Design of test rig for long-term testing of couplings intended for railroad applications
Machálek, Ondřej ; Prokop, Aleš (referee) ; Řehák, Kamil (advisor)
The master thesis deals with design of test rig for long-term testing of coupling appointed to railway vehicles. At first, there is made a brief research which is related to railway coupling used for transmitting a torque. This is followed by an analysis of the most used power devices to derive real loads conditions of tested couplings. There is chosen the most appropriate conception based on made analysis and it is followed by the description of designed components. There is made a verification of modal properties non-purchased components which is necessary part of the thesis. Numerical modal analysis was performed in ANSYS Workbench software. In the end of the thesis there are included stress-strain analysis of the chosen designed components.
Influence of hardening model on the results of cros-roll straightening simulation
Meňhert, Samuel ; Kubík, Petr (referee) ; Petruška, Jindřich (advisor)
This diploma thesis deals with simulation of cross-roll straightening using computational modeling with finite element method in software ANSYS. The main goal of this thesis is to quantify the influence of inaccurate knowledge of mechanical properties on the straightening process and correct setting of machine. It also aims for comparison of hardening models and their influence on the final curvature and residual stresses in the cross section of the bar.
Pulse flow of liquid in flexible tube
Komoráš, Miroslav ; Šedivý, Dominik (referee) ; Klas, Roman (advisor)
This master’s thesis is dealing with analysis of fluid flow pulse in a flexible tube representing e.g. an artery in a human body. In ANSYS program, 3D simulations were performed, and these are so-called interrelated FSI analysis. In Maple software, 1D simulations of fluid flow in the tube were performed for various thin-walled and thick-walled variants. The aim is using these programs to determine the flow rates and pressures in the tube, its wall deformation and stress. Therefore, the theoretical part deals mainly with basic equations of flow dynamics, linear and nonlinear models and rotationally symmetric vessels. In the computational part are described individual procedures in the mentioned programs.

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