|
|
Application of the Williams expansion near a bi-material interface
Malíková, Lucie ; Seitl, Stanislav
A simplified model of a crack approaching a bi-material interface is modelled by means of the finite element method in order to investigate the significance of the higher-order terms of the Williams expansion for the proper approximation of the opening crack-tip stress near the bi-material interface. The discussion on results is presented and the importance of the higher-order terms proved.
|
|
|
Comparison of calibration functions for short edge cracks under selected loads
Seitl, Stanislav ; Miarka, Petr ; Malíková, Lucie ; Krejsa, M.
Attention to the fatigue cracks in steel structures and bridges has been paid for long time. In spite to efforts to eliminate the creation and propagation of fatigue cracks throughout the designed service life, cracks are still revealed during inspections. Note, that depending on location of initial crack, the crack may propagate from the edge or from the surface. The theoretical model of fatigue crack progression is based on linear fracture mechanics. Steel specimens are subjected to various load (tension, three- and four-point bending, pure bending etc.). The calibration functions for short edge cracks are compared for various load and the discrepancies are discussed.
|
|
|
Basic features of aggregate-matrix-interface fracture of concrete: pilot modelling
Vyhlídal, M. ; Šimonová, H. ; Veselý, V. ; Keršner, Z. ; Klusák, Jan ; Malíková, Lucie
In this paper, the attention is paid to investigation of the importance of the Interfacial Transition Zone (ITZ) in concrete for the global fracture behaviour. A simplified cracked geometry (consisting matrix, ITZ and aggregate) is modelled by means of the finite element method with a crack terminating at the matrix-ITZ interface. Numerical studies assuming two various ITZ thicknesses and several various ITZ elastic moduli are performed. Based on the values of the opening stress ahead of the crack tip (its average value and stress range) a few conclusions are discussed. The pilot analyses dealing with the effect of ITZ on the stress distribution should contribute to better description of toughening mechanisms in silicate-based composites.
|
|
|
Assessment of Crack Stability in a Quasi-brittle Particle Composite
Malíková, Lucie ; Klusák, Jan ; Keršner, Z.
Fracture behaviour of a crack in a particle (silicate based) composite is studied. The crack propagation depends not only on mutual elastic mismatch of matrix and aggregate but also the influence of the interfacial transition zone (ITZ) between the matrix and the aggregate is discussed. Various combinations of materials and geometry of matrix, aggregate and ITZ can improve or degrade fracture properties of the composite. Extensive numerical simulations on a basic 3-point-bending cracked specimen via the finite element method are performed in order to analyze the stress field near the crack tip. Linear elastic fracture mechanics approach is utilized in order to assess the crack stability and summarize several conclusions.
|
|
| |
|
|
Fracture of selected building composites in the vicinity of aggregate-matrix-interface
Vyhlídal, Michal ; Malíková, Lucie (referee) ; Keršner, Zbyněk (advisor)
The interface between aggregate grains and matrix in cementitious composites is their weakest element. The topic is particularly significant in the case of high performance and high strength concrete technology for which the eliminination or reduction of these weak links are necessary. The aim of this thesis is to determine the influence of the interface on the fracture behaviour of the cementitious composites. The fracture experiments were performed for this purpose and were complemented by the nanoindentation’s results and scanning electron microscopy results. Numerical model was created in ANSYS software on the basis of these data and the fracture toughness values of the interface were evaluated by means of the generalized fracture mechanics principles. Conclusion of the thesis is proof that the interface properties have a significant influence on the fracture behaviour of cementitious composites.
|
|
|
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.
|
|
|
High temporal satellite data assimilation for vegetation spectral characteristic assignment
Malíková, Lucie ; Langhammer, Jakub (referee) ; Štych, Přemysl (advisor)
The application of high temporal satellite image data for designation of the spectral characteristic of vegetation Abstract The objektive of this paper is to evaluate possibilities of high temporal satellite data assimilation for continuous monitoring of the spectral characteristic of vegetation. There is also given the suggestion of metodology for processing MERIS data and for continuous monitoring of spectral characteristic of landscape objects. Finally, vegetation cover database for the Czech Republic in the year 2009 is created from sectorial analysis. In the paper there is used the LSU classification and thresholding of vegetation indicies histograms. The universal decision algorithm for classification of vegetation landscape component are described and particular thresholding values for the year 2009 given. The finally product of this paper is Czech vegetation cover database for the year 2009 with overall accuracy of 63,35 %. Accuracy for forest is even over 80 %. Keywords: remote sensing, MERIS, vegetation, spectral reflectance, LSU, BEAM
|
|
|
Company Marketing Strategy
Malíková, Lucie ; Baksa, Jiří (referee) ; Schüller, David (advisor)
The main aim of this diploma thesis is to design a marketing strategy for an advertising agency / design studio. The theoretical part contains a comprehensive overview of the marketing issues, marketing mix and marketing strategies. There is also included a creation of the analysis of external and internal company environment, project management and STP process. The current situation is discussed in the analytical part of the diploma thesis. The appropriate recommendation are defined according to realization of the marketing research through questionnaires and afterwards suitable marketing strategy is created for two years.
|
|
| |
guest ::
RSS feed.