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Stress-Strain Analysis of Shotgun Barells
Běhal, Josef ; Majer, Zdeněk (referee) ; Slažanský, Martin (advisor)
This bachelor’s thesis deals with stress-strain analysis of the shotgun barells. Gun was designed by company Česká zbrojovka a.s. Thesis contains an introduction to the functionality of weapons folowed by chapter dealing with shot from small shot shotgun. Stress-strain analysis was performed by finite element method. The final section shows the evaluation of achieved results.
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Description of Stress and Strain States at the Front of Cracks Loaded by Shear Modes
Žák, Stanislav ; Majer, Zdeněk (referee) ; Horníková, Jana (advisor)
The main goal of this work is the comparison of the size of the plastic zone at the crack tip for two analysis methods: an analytical linear method and an elastic-plastic analysis employing the Finite Element method (ANSYS software). All calculations were made for a crack loaded under pure shear modes. These types of loading are not sufficiently described in the literature. The first part of this work introduces the problem with the crack tip plastic zone using both linear and nonlinear fracture parameters. The second part is dedicated to the construction of the Finite Element model in the ANSYS software. The geometry of the samples and the loading levels were chosen to match an existing experimental test of the impact of shear modes on the crack behavior. In the third part of this thesis, the plastic zone radii for pure shear modes II and III are estimated using several methods and the results are compared. In the last part of this work, the same procedure as in the previous part is applied on a mixed-mode II+III loading. A result of this thesis is the assessment of the application limits of the linear analysis method used to estimate the size of the plastic zone at the crack tip for a specific geometry and material model.
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Assessment of impact of production inaccuracies on characteristic of a helical conus-shaped spring in compression
Sitte, David ; Majer, Zdeněk (referee) ; Burša, Jiří (advisor)
This bachelor thesis deals with the possible influence of production inaccuracies on the characteristics of the helical conus-shaped spring in compression. In the first part of the thesis there is a search for a given problem of the helical conus-shaped spring in compression calculation according to the algorithm created in the bachelor thesis „Určení charakteristiky kónické vinuté tlačné pružiny“ created by Libor Loveček. The remaining part of the thesis focuses on a concrete the helical conus-shaped spring in compression, namely on taking its variable pitch into consideration to achieve a better correspondence of the numerical model to the experimental characteristics.
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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.
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Design of the axial dendritic suspension of steam turbine rotor blade
Vrbka, Dušan ; Majer, Zdeněk (referee) ; Dušek, Daniel (advisor)
This master thesis deals with axial dendritic suspension of steam turbine rotor blade. The initial shape of the suspension was design on the basis of available data. There was performed stress-strain analysis of this shape and most dangerous spots were picked. There were made several geometrical changes of the shape of suspension. Their affection on stress-strain responding of the suspension was examined. The best shape was chosen which was used to perform analysis of infinite life according to ASME code and due to loading low cycle fatigue analysis. According to results of low cycle fatigue analysis the maximum loading was established. At the end of this work the further steps were suggested.
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Modelling and analysis of the contact failure of ceramic materials
Machů, Zdeněk ; Majer, Zdeněk (referee) ; Ševeček, Oldřich (advisor)
This bachelor thesis deals with contact damage of ceramic materials. The purpose of this work is to create an analytical and FEM model of contact between a sphere and flat plate and subsequently use these models to analyse loading conditions that lead to crack initiation in the ceramic plate. The research part contains description of contact failures in ceramic materials with strong emphasis on Hertzian cone crack, followed by Hertzian theory of contact between two spheres and Hertzian stress field equations for flat plate. The next part of research chapters describes how contact problems are modelled in FEM software ANSYS Mechanical APDL and introduces the basics of fracture mechanics, which are necessary for the prediction of ring crack initiation. The next chapter contains information about the creation of analytical and FEM model and includes illustrative results of both models, which are then compared between these two models. The last chapter of this work deals with fracture mechanics FEM model that can simulate the ring crack initiation. This chapter also contains analysis of ideal crack position, where the crack has the best conditions for its initiation and growth. The last part of this chapter contains parametrical study where critical loading conditions are analysed in relation to radius of indentation sphere and different mechanical properties of used ceramic plate. In the final part of this work, the results of fracture mechanics FEM model are compared to experimental results of real specimens.
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Mutual interaction of multiple cracks growing in the particulate composite with brittle matrix under conditions of sub-critical crack growth
Slávik, Ondrej ; Ševeček, Oldřich (referee) ; Majer, Zdeněk (advisor)
In the first part of the submitted diploma thesis, the knowledge in the sphere of the fracture mechanics, related to the practice part of this thesis are summarized. In that the 2D parametrical numerical model of the particle composite with multiple cracks was created, using the finite elements method. Thanks to this model it is possible to find specific configurations which are showing the existance of multiple mutual interactions between these cracks, just by simple manipulation of the input data. In the calculations the influence of the residual stresses was considered which are formed during production of the material. The effect of the subcritical crack growth was taken into account as well in this thesis.
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Integration of SMART Material within Mechanical Structure
Běhal, Josef ; Majer, Zdeněk (referee) ; Hadaš, Zdeněk (advisor)
This diploma thesis deals with the modelling of the piezoelectric composite material using the finite element method. The thesis is divided into three parts. Research study is done in the first part. It focuses on the possibility of use of the piezoelectric layers as sensors. The second part concerns the homogenization of MFC (macro fiber composite). Material and piezoelectric parameters are obtained by modelling elementary structural cell under different loading conditions. Determined characteristics are verified with experimental data. The third part proposes the design of the experimental device, which allows the simulation of the rotor excitation by rotating unbalance. Excitation responses of MFCs placed in specific locations are calculated using FEA model of the device. The conclusion includes the description of the suitability to vibration measurement on the device.
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