National Repository of Grey Literature 34 records found  beginprevious21 - 30next  jump to record: Search took 0.00 seconds. 
Comparison of freeware software for estimation of residual fatigue life of bodies
Hanáček, Jan ; Ševčík, Martin (referee) ; Pokorný, Pavel (advisor)
In the first part of this bachelor's thesis the fundamental laws of linear elastic fracture mechanics are described, especially state of stress in bodies with crack and stress intensity factor. Further, the propagation laws of fatigue crack are described and interaction effects of fatigue crack, especially retardation effects are explained. In the second part of this thesis the software NASGRO and AFGROW are described and compared. In the last part of this work the several examples are carried out to compare residual fatigue life obtained by no retardation approach and approach with consideration of retardation effects.
Possibilities of estimation of selected fracture parameters under conditions of LEFM
Zouhar, Petr ; Hutař, Pavel (referee) ; Ševčík, Martin (advisor)
The presented bachelor´s thesis deals with possibilities of estimation of selected fracture parameters under conditions of linear elastic fracture mechanic (LEFM). The aim of this thesis is to quantify the accuracy of specific methods for the estimation of fracture parameters from a known stress and strain field obtained using numerical methods. Thesis is solved using finite element method. The work is divided into two logical parts. The first part of the thesis describes the basic concepts of LEFM and selected methods used for estimation of fracture parameters, namely the stress intensity factor, strain energy release rate and J-integral. A detailed description of the numerical model, a sensitivity analysis of the FEM mesh density and obtained results are described in the second part, focused on the solution of the problem,. The accuracy of each method is expressed by comparing with a known reference value of stress intensity factor. The applicability of selected methods for estimation of the stress intensity factor is shown on a practical example of three-dimensional body containing a crack.
The influence of specimen dimensions on fatigue crack closure
Šebík, Marek ; Ševčík, Martin (referee) ; Poduška, Jan (advisor)
This study is focused on fatigue crack propagation, especially on plasticity-induced fatigue crack closure. The influence of specimen dimensions on fatigue crack closure is assessed by evaluation and consequent comparison of opening and closing stresses on two different fatigue specimen numerical models: compact tension specimen and center cracked plate tension specimen, using nonlinear material model. The numerical modeling of the phenomenon utilized finite element method. The models were created in Ansys programming language, APDL. The first part of the study deals with theoretical research of the subject. The second part consists of description and results of the numerical modeling.
Numerical modeling of crack propagation under conditions of LEFM
Mikula, Jakub ; Hutař, Pavel (referee) ; Ševčík, Martin (advisor)
The presented bachelor’s thesis deals with numerical modeling of crack propagation in general planar body. A user macro was created in APDL programming language for estimation of crack propagation direction and collection of data. Macro allows selection one of the four criteria intended to estimate the direction of the crack and the subsequent listing of the data into a text document. The calculation is based on the finite element method (FEM) using a commercial system ANSYS. The conditions of linear elastic fracture mechanics (LEFM) are expected during the calculation. The first part of this thesis describes the basic concepts of LEFM, including a description of mentioned criteria. The second part is devoted to the created macro. It also describes the algorithm and the necessary conditions for correct processing of data. A comparison with available published data or with experimental data gives a summary of the accuracy and utilization of created macro. In conclusion, the example of estimation of the residual life by different criteria is shown, as its other application.
Multiplatformní mobilní aplikace pro nákup kuponů
Ševčík, Martin
This thesis describes design and implementation of cross platform mobile application for coupon purchasing in the Vykupto company. First part analyzes the existing mobile Vykupto applications. New application's draft including visual application screens is created on basis of requested functional and non-functional requirements. The following part is about selecting appropriate technology to create cross-platform application. The last part covers implementation of a application prototype and user testing.
On a critical geometry of a crack arrested at a bimaterial interface
Ševčík, Martin ; Zouhar, Michal ; Máša, Bohuslav ; Hutař, Pavel ; Náhlík, Luboš
Surface crack propagation in a thin soft protective layer on a massive stiffer substrate is analyzed using generalized linear elastic fracture mechanics. The growth of the initial crack is considered in both forward and sideways directions and the influence of the interface between the protective layer and massive substrate on the final crack configuration is investigated. It is shown that, depending on the elastic mismatch, the part of the crack front can be arrested at the interface protective layer/substrate and the rest of the crack grows continuously sideways only. The effective value of the stress intensity factor is used in order to predict the conditions under which the crack will propagate through the interface into the second material. Corresponding calculations have been made by finite element method.
13th Conference Applied Mechanics 2011 - conference proceedings
Náhlík, Luboš ; Majer, Z. ; Seitl, Stanislav ; Ševčík, Martin ; Zouhar, Michal
Contributions from the field of fatigue of materials, dynamics, biomechanics and structural mechanics were presented on the traditional doctoral conference Applied Mechanics.
Numerical modelling of damage of a particulate composite with polymer matrix
Máša, Bohuslav ; Ševčík, Martin ; Náhlík, Luboš
The main focus of this contribution is estimation of mechanical properties of a composite loaded in tension using finite element method. Investigated composite is composed of matrix in a rubbery state filled by alumina-based particles (Al2O3). Hyperelastic properties of the matrix have been modelled by the Mooney-Rivlin material model. The damage mechanisms of the matrix have also been taken into account. Results of numerical analyses have been compared with experimental data and good agreement between numerical models with damage mechanisms of matrix and experimental data has been found.
Crack stability condition at the interface between two polymer materials
Zouhar, Michal ; Hutař, Pavel ; Náhlík, Luboš ; Ševčík, Martin ; Knésl, Zdeněk
The aim of this work is to study the behaviour of crack with its tip at the interface of two polymer materials. The numerical model of cracked bi-material tension specimen is investigated and a stability criterion was tested. Usually a stability criterion based on general stress concentrator needs the relation between critical value of the generalized stress intensity factor and critical value of the stress intensity factor (fracture toughness). This relation is a function of elastic mismatch between particular materials, fracture toughness of the main material and critical distance d. Estimation of d is usually not straightforward and different authors use different approaches for its determination. Therefore main aim of this study is mutual comparison of published approaches for d estimation and to quantify their effect on the critical loading value. The results of this study can lead to better lifetime prediction and design of layered structures.

National Repository of Grey Literature : 34 records found   beginprevious21 - 30next  jump to record:
See also: similar author names
24 ŠEVČÍK, Martin
3 ŠEVČÍK, Milan
1 Ševčík, Marcel
10 Ševčík, Marek
20 Ševčík, Michal
3 Ševčík, Milan
5 Ševčík, Miroslav
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