National Repository of Grey Literature 47 records found  beginprevious18 - 27nextend  jump to record: Search took 0.01 seconds. 
Wind loading of lightweight bridge-like structure
Hrubý, Pavel ; Kala, Jiří (referee) ; Nevařil, Aleš (advisor)
The present thesis is concerned with air flow over lightweight footbridge. Special attention is paid to flow-induced instabilities. The thesis opens with a theoretical elaboration on the phenomena related to the research matter. The next part investigates air flow over footbridge in a specific situation using numerical simulation in the Ansys CFX software. Finally, results are discussed in the light of chosen theoretical framework and relevant conclusions are presented.
Using Optimization's Algorithms by Designing of Structures
Fedorik, Filip ; Keršner, Zbyněk (referee) ; Haapala,, Antti (referee) ; Dický,, Jozef (referee) ; Kala, Jiří (advisor)
The application of optimization algorithms in the design of many economical and industrial problems currently represents a significant assignment. The development of high-powered computers allows an application of difficult mathematical techniques and physical phenomena to simulate real problems with sufficient accuracy. The optimization techniques used in engineering designs are mostly represented by modified mathematical programming methods with extension of their usability. The aim of the presented thesis "Using Optimization´s Algorithms by Designing of Structures" is to analyze the applicability of optimization procedures which are available in the widely used computing system ANSYS in civil and mechanical engineering practice. The numerical analyses were performed within the frame of multi-extreme, one to three dimensional optimization problems, multi-dimensional problems expressed by minimizing the weight of a truss beam and efficient design of air gap location in wooden studs from the point of view of thermal features of the structure. The analyzed optimization processes are in plurality verified with accurate manual computing and graphical solutions and the accent is put on optimization methods´ possibilities to improve robustness, efficiency and accuracy of the optimization algorithms in civil engineering problems´ designs. The optimization methods represent a suitable approach to improve the efficient design of a wide range of civil and mechanical engineering structures and elements. By combination of their advantages and FEM/FEA method it is possible to achieve very good results, although robustness of the solutions is not guaranteed. The robustness and accuracy of the procedure could be increased by competent exploration of design space and suitable selections of optimization methods´ features.
Wind load on cooling tower
Ehrlich, Tomáš ; Kala, Jiří (referee) ; Nevařil, Aleš (advisor)
Thesis is concerned with modeling fluid dynamics and computing wind load on thin-walled structure of cooling tower. Two models for computational fluid dynamics are presented – one with singleton cooling tower and second with group of four cooling tower. Thesis includes also a structural model of cooling tower and methodology of wind load transfer is presented.
Static analysis of pedestrian bridge stucture
Holada, Jiří ; Kala, Jiří (referee) ; Hradil, Petr (advisor)
The thesis is focused on a static analysis and compiling a computational model of the suspension bridge for pedestrians and cyclists over the Sázavu river in Zbořený Kostelec vilage. The model is constructed according to the real shape of the structure. The length of the footbridge is 135 m and width 4 m. The calculation and compiling a computational model is processed by program ANSYS free Student Software.
Detail analysis of complex connection in the structure
Hokeš, Filip ; Hradil,, Petr (referee) ; Kala, Jiří (advisor)
The main objective of the thesis is to find and describe dependence between load carying capacity of a pin connection and a pin hole drilling. The dependence will be made in according to standard ČSN EN 1993-1-8, by theoretical solution and finally by finite element method in the ANSYS system. The second objective of the thesis is focused on a verification of load test results by numerical methods. Numerical solution will be made up in two analysis with different types of finite elements. The most fiiting model will be used as a basis for description of the relationship between capacity and diameter of drilling.
Wind load analysis of building structures
Ptáček, Václav ; Kala, Jiří (referee) ; Hradil, Petr (advisor)
This bachelor’s thesis is focused on wind load analysis with regard to the dynamic effects caused by wind impact on slender structures. These calculations are conducted for a chimney structure with use of various wind velocities. The thesis includes basic principles of fluid flow modeling in CFD programs like ANSYS CFX.
Statics, dynamics and kinematics of multibody contacts
Štekbauer, Hynek ; Kala, Jiří (referee) ; Krejsa, Martin (referee) ; Němec, Ivan (advisor)
The dissertation deals with the problem of dynamic contact and kinematic constraints between various entities and the related issues of its implementation for static and dynamic finite element analysis. The reason for the development in this area is the increasing demands on functionality of FEM softwares and also accuracy and performance of computational models. Firstly, the problem of enforcing contact conditions in explicit dynamics is addressed. New methods are proposed with respect to the stability of the explicit time integration scheme so that there is no need to reduce the computational time step, adjust the input variables or solve a large system of equations. These methods are based either on basic kinematic principles or on the energy conservation law. Furthermore, attention is paid to different types of constraint conditions having a wide application in civil engineering practice. Understanding them is the starting point for the subsequent definition of the newly designed finite element of the pulley. The correctness of all theoretically proposed methods and their implementation is demonstrated by numerical examples.
Simulation of nonlinear response of construction materials and problem of identitifaction of material parameters
Hokeš, Filip ; Kala, Zdeněk (referee) ; Krejsa,, Martin (referee) ; Kala, Jiří (advisor)
The issue of parameter idenetification within numerical simulations can be considered a necessary step in the use of mathematical models, such as complex material models of building materials utilized in finite element method. The problem is particularly epmhasized in the case of anisothropic materials but also in the case of concrete, which behaves differently in tension and compression and which shows different response under rapid-dynamic and long-term loading. Correct capture of the concrete response in the computation requires usage of plasticity theory, damage theory, visco-elasticity and visco-plasticity or their mutual combinations. It results in development of material models and rheological schemes with large amount of parameters that are not commonly available in standards. The disseration presents application of meta-heuristic algorithm Particle Swarm for parameter identification. The success of the method is demonstrated in a pair of cases, first on the identification of elastoplastic material model parameters from stress strain diagram and then to identify the values of stiffness constants and viscosities of the rheological scheme from a creep curve.
Smoothed Particle Hydrodynamics in Structural Dynamics
Hušek, Martin ; Králik,, Juraj (referee) ; Maňas,, Pavel (referee) ; Kala, Jiří (advisor)
The focus of the thesis is on the application of the Smoothed Particle Hydrodynamics (SPH) method in structural dynamics with an emphasis on usage of quasi-brittle materials. The first part is focused on the introduction, history, and theoretical background of SPH. Numerical examples in which strengths and weaknesses of SPH are shown follow. In addition to pure SPH models, several coupling approaches with the Finite Element Method (FEM) are also discussed. After the introduction of SPH, the focus is on quasi-brittle materials and their reinforced variants. The numerical concept and mathematical background of the Continuous Surface Cap Model are outlined, several benchmarks are presented. Strain-rate effects and their impact on pure SPH and coupled SPH-FEM models are evaluated next. In this section, the author proposes a new approach for SPH models reinforcement with FEM beam elements. The coupling approach was named sublayer coupling and shows a potential in simulations while the SPH tensile instability is alleviated. Since concrete is often associated with heterogeneity and very specific material structure, a unique algorithm for concrete structure generation in combination with SPH is proposed in the next chapter. The concept is based on utilization of coherent noise functions which can bring a variability to numerical models. It has been proved that the algorithm is robust, stable, and easy to implement into the SPH framework. With regard to that, the so-called numerical heterogeneity, a concept of parameters variability implementation, is introduced together with examples. The last part of the thesis is dedicated to the application of SPH in real experiments. The first experiment focuses on a high velocity impact. The second experiment deals with an explosion in which the focus is on both the loaded specimen and charge. Since SPH simulates the explosive, detonation products, and the loaded specimen, it is a fully coupled fluid-structure interaction simulation.
Analysis of railway behavior on vehicles effects
Peňázová, Gabriela ; Kala, Jiří (referee) ; Salajka, Vlastislav (advisor)
The master’s thesis deals with the possibilities of railway track modeling. The computational models were created in ANSYS Classic. Simplified 2D model represents a longitudal half of classic single track construction, 3D models represent classic single track construction and RHEDA 2000 slab track. Static and dynamic response of 2D model was compared with analytical solutions by Timoshenko and Fryba. Static and dynamic responses of 3D models were analyzed and compared.

National Repository of Grey Literature : 47 records found   beginprevious18 - 27nextend  jump to record:
See also: similar author names
1 KALA, Jaroslav
1 Kala, J.
4 Kala, Jakub
4 Kala, Jan
4 Kala, Josef
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