National Repository of Grey Literature 15 records found  1 - 10next  jump to record: Search took 0.00 seconds. 
Analysis of influence of length dimensions on stress-strain states of press-fitted thin-walled and thick-walled cylindrical bodies
Janýška, Jakub ; Kovář, Jaroslav (referee) ; Šebek, František (advisor)
This work deals with the analysis of the influence of length dimensions on the stress-strain states of pressed-fitted thin-walled and thick-walled cylindrical bodies. It includes a research of press-fit connections and their use. Derivation of basic analytical models of axisymmetric bodies that can be used to solve the problem of press-fitted hub to shaft. Analytical solution of the problem and its comparison with the numerical solution in ANSYS. The comparison includes both frictionless and friction model.
Computational modelling of the nanoindentation with Berkovich indenter
Fiala, Lukáš ; Fuis, Vladimír (referee) ; Kovář, Jaroslav (advisor)
This diploma thesis deals with computational modelling of the nanoindentation of tungsten with Berkovich indenter. In the beginning of thesis, research about nanoindentation test and Oliver-Pharr analysis is performed. The next part of thesis deals with deformation-stress analysis of the nanoindentation test with the linear-elastic model of material of tungsten and with comparison of results obtained with a diamond indenter and with an ideal rigid indenter. In the following model, plastic deformation is already considered. On the computational model with elasto-plastic model of material a sensitivity analysis of the influence of specimen and indenter dimensions and the influence of the penetration on results determined using the Oliver-Pharr analysis is performed. Furthermore, the applicability of the correction factors which were founded in the literature is assessed on this model and their exact value is determined. The last part of the work deals with the analysis of the influence of blunting of the indenter on results of the nanoindentation test and the comparison of different approaches for determining the projection of the contact surface.
Computation modelling of the nanoindentation test with the axisymmetric indenters
Ballo, Igor ; Fuis, Vladimír (referee) ; Kovář, Jaroslav (advisor)
This diploma thesis deals with the nanoindentation test, which is increasingly used to determine the mechanical properties of materials. The entire process of nanoindentation and its advantages, such as the possibility of testing thin layers or different coatings, are described in more detail in the thesis. In addition, the basic methods of analytical processing of the resulting data using Sneddon’s, Hertz’s and Oliver-Pharr analysis are presented. The practical part of this thesis is focused precisely on the verification of these simplified analytical relationships using numerical models of the nanoindentation test of conical and spherical indenter created using the finite element method. In this part, not only the accuracy of the methods themselves is verified, but also the applicability and necessity of using modifications and corrections associated with these analyses. The test body consisted of tungsten material, the model of which was considered in one case as linear elastic and in the other as elasto-plastic. Knowledge from this work can be useful for further research in this area as well as for various applications of nanoindentation testing.
Stress and deformation analyses of the bridge near the Jedov mill
Hort, Michal ; Kovář, Jaroslav (referee) ; Fuis, Vladimír (advisor)
Bridges serve to many people every day, so it is necessary to be concerned about theirsafety. Analysis of bridge superstructures are used to increase their safety - and this is also the mainsubject of this thesis. Specifically, it is the analysis of the pedestrian bridge located near Jedov Mill on the Oslava river. For the stress and strain calculations, the method of joints is used, and that iscompared with the finite element method. During the comparison of the methods which hadbeen used, it was found, that the method of joints is suitable for identifying critical points, but cannot accurately determine stress values. While the finite element method can both, identify critical locations and determine the exact stress values. These calculations determinedthe critical locations on the footbridge, which are in the outmost members of the structure. By enlarge their cross-section would increase the safety of the structure. Among the critical trusses do not belong trusses damaged by the footbridge crash. The safety factor of the pedestrian bridge to the elasticity limit state, which is k = 1.74, provides a sufficient reserve for the further use of the footbridge, even if the cross-sections of the above mentioned members are not increased.
Analýza škodlivého kódu ve virtuálním prostředí
KOVÁŘ, Jaroslav
The diploma thesis deals with analysis of malware that attempts to evade many kinds of analyses in virtual environments (so-called evasive malware). The thesis includes a designed implementation of the analysis environment, experiments and assessment of the malware analysis in virtual environment, which validates the benefits of protective measures making the analysis environment less obvious to evasive malware. An important source of inspiration for creating the basis of some of the protective measures were findings about biological viruses.
Stress-strain analysis of stadium lighting mast
Tokoš, Richard ; Kovář, Jaroslav (referee) ; Fuis, Vladimír (advisor)
The bachelor thesis contains an analysis of a steel structure that serves as lighting in a football stadium. The main goal is to create a bar system, the equation of static equilibrium and the deformation condition and I will analytically solve the stress and strain. Then I will create a model in ANSYS and calculate the stress and strain numerically. The bachelor thesis contains a comparison of the results of these methods.
Calculation of the probability of the endoprosthesis ceramic head with shape deviation
Kučerková, Miroslava ; Fuis, Vladimír (referee) ; Kovář, Jaroslav (advisor)
The main content of the diploma thesis is to determine the probability of failure of the hip joint endoprosthesis ceramic head. The assumption is the three-axis state of stress. To calculate the probability of failure three principal stresses, which are determined numerically using finite element method, are needed. Ceramic materials, hip joint endoprosthesis and Weibull weakest link theory, which describes the calculation of the probability of failure of ceramic components, are described in the first part of the thesis, after that, the second part with calculations follows. The first model, for which the stress and probability of failure were calculated, is a cylindrical body. The stress distribution in it was determined numerically as well as analytically. Its primary goal is to verify the developed algorithm of calculating the probability of failure. This algorithm is also used in calculations of probability of failure of ceramic femoral head. The suitability of using averaged principal stress values was also verified here. In the next part of the thesis, a model of an ideal ceramic head was created and its probability of failure was calculated. The impact of friction, penetration and the size of elements used for discretization of the model on the value of probability of failure were all analysed. The evaluated findings were subsequently used in the calculations of the model of ceramic head with an deviation from the ideal ovality. The impact of this change on the resulting probability of failure in comparison with the ideal state was evaluated in the conclusion.
Mechanical analysis of lift
Tesař, Jakub ; Kovář, Jaroslav (referee) ; Fuis, Vladimír (advisor)
The bachelor thesis deals with analysis of the system with seven solids with consideration of passive effect. In the first part of thesis describes the basics of statics and dynamics. Description of neutral and passive links, release method and reduction method. In the second part of the work are describing effects of passive effects on the movement state of the elevator. The individual bodies were released in the GeoGebra program. The aim of the example is to determine the contract forces in the links, check functionality of the links and state of motion. The solution took place in the computer program Matlab
Stress-strain analysis of the Gbely drilling tower
Vizváry, Peter ; Kovář, Jaroslav (referee) ; Fuis, Vladimír (advisor)
The content of the bachelor's thesis is focused on the stress-strain analysis of a drilling tower located in Gbely. Its main goal is to compile equations of static equilibrium for the analytical solution of the structure and its subsequent numerical verification using the created 3D computational model based on various static loads or changes in the degree of static determinacy. The first part of this work summarizes the theory of the bar and of bar systems, the basic limit states and the finite element method (FEM). The second part contains a search on the history of oil production in Slovakia, its discoverer and the development of deep drilling and production technologies. The third part describes the drilling tower in Gbely. The content of the fourth part is the creation of a 3D computational model of a real structure, which should represent the drilling tower as accurately as possible. The most comprehensive is the fifth part, which consists of the design of a simplified structure, writing the equations of static equilibrium for the analytical solution, creating a 3D computational model for numerical verification of the analytical solution and evaluating the conclusions to which the individual variants of the solution led.
Calculation of the probability of the ceramic component failure according to the Weibull’s weakest link theory
Kučerková, Miroslava ; Fuis, Vladimír (referee) ; Kovář, Jaroslav (advisor)
Weibull weakest link theory is used to determine the probability of failure of ceramic components. This bachelor thesis examines the cylindrical body, beams and rotating circular and intercircular disc. In these bodies it is possible to identify course of the stress in an analytical way. The research part of the work approaches ceramic materials in terms of their structure, composition, method of production or mechanical properties. From a theoretical point of view, Weibull weakest link theory for uniaxial and triaxial stress in the body is described and required relations for further calculations are given here. In the second part, the probability of failure of previously mentioned models is calculated. Beams are stressed by a simple and four - point bending. The impact of the body size on the probability of failure is also analyzed. The cylindrical body is solved for different variants, which are compared afterwards. At last, the effect of operating speed on the probability of failure of the rotating circular and intercircular disc is investigated.

National Repository of Grey Literature : 15 records found   1 - 10next  jump to record:
See also: similar author names
12 KOVÁŘ, Jakub
44 KOVÁŘ, Jan
9 KOVÁŘ, Jiří
9 Kovár, Jiří
7 Kovář, J.
12 Kovář, Jakub
44 Kovář, Jan
7 Kovář, Jaromír
5 Kovář, Jaroslav
2 Kovář, Jindřich
9 Kovář, Jiří
4 Kovář, Josef
5 Kovář, Jáchym
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