|
|
Influence of Friction to the Shear Stress State in the Crack-Front Vicinity
Vlach, Jiří ; Hutař, Pavel (referee) ; Horníková, Jana (advisor)
The aim of this master thesis is to explore the influence of frictional forces to the stress and strain on the straight crack tip loaded in shear modes. The first section summarizes the most important things from the field of fracture mechanics. Especially theoretical knowledge about fracture parameters (stress intensity factor, J – integral) and their determination in computational environment ANSYS Workbench. The second part deals with computational modeling. At the beginning, is created the model of material, the model of geometry, the model of loads, etc. Then it is possible to solve the direct problem outlined in the introduction. A result of this thesis is the assessment of how the friction influences the fracture parameters in shear modes II and III.
|
|
|
Residual fatigue life estimation of railway wheelset
Pokorný, Pavel ; Zouhar, Michal (referee) ; Náhlík, Luboš (advisor)
The first part of this master's thesis deals with the high cycle fatigue of materials, especially on growing cracks using linear elastic fracture mechanics. Much of this work is focused on the concept of stress intensity factor. This concept is nowadays one of the most widely used concepts for describing a body with crack. The first part ends with theoretical approaches to determine the residual fatigue life of the body with a crack. The second part of this master's thesis is focused on the determination of residual fatigue life of a specified railway wheelset. An existence of crack-like defect is assumed at the railway wheelset. The goal of this master's thesis is to estimate how long it will take to grow from initial defect to a critical crack length. The last part of this master's thesis is devoted to addiction order load cycles on crack growth rate.
|
|
|
Description of Stress and Strain States at Front of Inclined Cracks Loaded by Shear Modes
Roh, Marek ; Majer, Zdeněk (referee) ; Horníková, Jana (advisor)
The primary objective of this masters thesis is to assess the eects of the length of crack and the angle, of which is this crack inclined on the stress and strain states at its front for the test sample loaded under shear. The rst part of this thesis will analyze the individual approaches that lead to the description of the aforementioned conditions. The second part deals with the FEM model assembly, which will lead to the fracture parameters, the values of which will be compared in part three.
|
|
|
A study of the stress field near the stress concentrator at the bi-material interface
Krepl, Ondřej ; Klusák, Jan (referee) ; Profant, Tomáš (advisor)
The aim of this work is the solution of problems of the stress distribution near bimaterial notch tip or eventually the crack impinging orthogonaly the bimaterial interface, determination of stress singularity exponent. The first part is concerned with basics of linear elastic fracture mechanics, i.e. Irwin's concept of stress intensity factor. The second part is devoted to description of anisotropic materials by complex potencial theory. The final part is focused on calculation of eigenvalues of both isotropic and anisotropic materials and application of LES formalism on the calculation of stress singularities of the bimaterial ortotropic notch or the crack impinging orthogonaly the bimaterial interface.
|
|
|
Crack path calculation using linear elastic fracture mechanics
Bónová, Kateřina ; Malíková, Lucie (referee) ; Eliáš, Jan (advisor)
This diploma thesis deals with the different possible calculations of crack path. Specifically, it focuses on criteria based on maximum tangential stress, minimal strain energy density, crack tip displacement, and local symmetry. These criteria are used for calculations in ANSYS software to estimate possible crack paths on four simple structures. The thesis also contains the codes created in ANSYS. Using these, the crack trajectory of a given structure can be calculated by any of the four criteria described.
|
|
|
Numerical support for wedge splitting test on non-traditional geometry
Juhászová, Tereza ; Malíková, Lucie (referee) ; Seitl, Stanislav (advisor)
Bachelor thesis is focused on numerical support of wedge splitting test with non-traditional geometry. Numerical analysis takes place in program Ansys, defining behavior of models with modified entry parameters. Attention is focused on values of parameters characteristic for fracture mechanics; stress intensity factor and T-stress and functions describing their relationship to length of crack, evaluation of which is graphically illustrated.
|
|
|
Basic features of aggregate-matrix-interface fracture of selected building composites
Vyhlídal, Michal ; Seitl, Stanislav (referee) ; Keršner, Zbyněk (advisor)
The aim of this work is to analyze the behavior of cement composite, depending on the features of ITZ. The first part of the thesis is theoretical and deals with the origin and features of ITZ, defines the basic relationships and concepts of continuum mechanics and linear elastic fracture mechanics and presents crack tips posibilities in the three-phase composite, including their short characterization. The second part is practical and describes creation of numerical model in the ANSYS software, presentation of partial results and compare of them. The result of this work is a comparison of the mean values of stress and amplitude of stress depending on the features of ITZ.
|
|
|
Fracture Toughness of Metallic Materials and its Testing
Kosek, Lukáš ; Zapletal, Josef (referee) ; Němec, Karel (advisor)
The purpose of the work is to introduce the basic of the fracture toughness of metallic materials and its measuring under the conditions of the plane strain. There are shown essential concepts of the linear elastic fracture mechanics, which is used for the description of the material behavior at fracture of the material with a crack. It defines stress intensity factor and describes the main elements influencing the fracture toughness. Furthermore, the work contains the particular testing methods, specimens and testing equipments. In the conclusion it recapitulates the availability and the application of the linear elastic fracture mechanics.
|
|
|
Influence of a Notch on Stress-Strain States at the Front of Cracks Loaded by Shear Modes
Ščotka, Martin ; Žák, Stanislav (referee) ; Horníková, Jana (advisor)
This diploma thesis deals with influence of a notch on stress-strain states at the front of cracks by shear modes. Starting with fracture mechanics and its division, followed by stress intensity factor and calculate its by finite element method. Calculation is solved for two types of notches, U-notched and V-notched, both notches were modeled parametrically so their geometry was changeable and stress intensity factor were calculated for all configurations. Subsequently was solved next calculation of stress intensity factor but for shaft without notch. Finally, was evaluated influence of notch on stress intensity factor. Software for finite element method has been used ANSYS. Others calculation was provided in software MATLAB
|
|
|
Analysis of the three-dimensional shape of the crack in the cantilever beam
Ozimák, Eduard ; Ševeček, Oldřich (referee) ; Majer, Zdeněk (advisor)
The bachelor thesis deals with the numerical calculation of the stress intensity factor using the finite element method and the subsequent modelling of the crack face shape on a simple beam in the ANSYS Mechanical APDL computational environment. In the introductory part of the thesis, the history and beginnings of fracture mechanics are described. Then, the basic theoretical knowledge and relationships needed when working with a body containing a crack are described. This is followed by an introduction to the finite element method. In the second part of the bachelor thesis, the procedure of performing numerical calculations and modelling in the ANSYS environment is described in detail.
|
guest ::
