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Fracture Parameters of AAAS composites with ceramic precursor
Šimonová, H. ; Rozsypalová, I. ; Kumpová, Ivana ; Trčka, T. ; Frantík, P. ; Rovnaníková, P. ; Keršner, Z.
The paper deals with alkali-activated aluminosilicate composites based on ceramic precursors with respect to their characterization by fracture-mechanical parameters. Three composites made of brick dust as a precursor and alkaline activator with silicate modulus Ms = 1.0, 1.2 and 1.4 were investigated. After 28 days of maturation, specimens with nominal dimensions of 40 × 40 × 160 mm were provided by an initial notch to 1/3 of the body height in the middle of the span. At least 6 samples were tested from each composite. Specimens were subjected to three-point bending tests during which force vs. deflection at midspan (F–d) and force vs. crack mouth opening displacement (F–CMOD) diagrams were recorded. By processing these diagrams, the values of the static modulus of elasticity, the effective fracture toughness (including its initiating component) and the specific fracture energy were determined using the effective crack model, Work-of-Fracture method, and Double-K fracture model. After the fracture experiments had been performed, compressive strength values were determined for informational purposes from one part of each specimen that remained after testing. All evaluations included the determination of arithmetic means and standard deviations. To obtain information about the internal structure of composites before and after mechanical testing, the selected body was examined by micro-tomography. Tomographic measurements and image processing were performed for qualitative and quantitative evaluation of internal structure changes with an emphasis on the calculation of porosimetric parameters as well as visualization of the fracture process zone. The fractal dimension of fracture objects was determined.
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Conditioning of Primary Systems for Solving by Flexibility Method
Sabelová, Katarína ; Mašek, Jan (referee) ; Frantík, Petr (advisor)
This bachelor thesis deals with effect of chosen basic determinate structure on solution of statically indeterminate structures obtained by using force method. Evaluation of basic determinate structure is based on conditioning of flexibility matrix, defined by three different condition numbers. Each of the four analyzed structures is examined in different way, due to their individual characteristics. As a result, few findings about dependence of conditioning of used basic structure on structures parameters and its effect on solution by force method were obtained.
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Design and Analysis of Structure of Spherical House
Kolodzej, Ján ; Zídek, Rostislav (referee) ; Frantík, Petr (advisor)
This bachelor thesis is dedicated to designing of two different versions of the construction for a spherical house. The design was developed upon an interest of the investor, with whom were both versions also consulted and is supposed to lead to an actual project and realization. The two versions will differ in usage of building materials and the construction geometry.
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Experimental Verification of Optimal Shape of Beam
Uríček, Matúš ; Keršner, Zbyněk (referee) ; Frantík, Petr (advisor)
The thesis deals with design of beams of optimized shapes, which are than manufactured by 3D printer and their features are experimentally verified. When the limit strength of a given component is reached, ways of fracture development are observed. Information obtained from the experiments are then compared with assumptions generated by numerical methods.
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Simulation of Idiofonic System
Múčka, Martin ; Keršner, Zbyněk (referee) ; Frantík, Petr (advisor)
The thesis deals with dynamic simulation of real bell behavior over time. The model is created according to principles of physical discretization as a spring in the FyDiK3D software. In order for the model to be declared as relevant, it is necessary to prove the behavior of the structures used in the elementary tasks of the mechanics. It shows the correlation between the stiffness of normal and diagonal springs. Describes how to use software import tools to create a model. The resulting model approaches its real bell behavior.
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Experimental and Numerical Analysis of the Volume Changes of Fine-grained Concretes
Odstrčil, Štěpán ; Frantík, Petr (referee) ; Kucharczyková, Barbara (advisor)
This diploma thesis deals with the experimental and numerical analysis of volume changes of fine-grained concrete. Experiments were carried out, measuring both the length changes as well as the mass losses and the internal temperature of the test specimens made from fine-grained concrete. The measurements were divided into two parts (phases). The first phase took approx. 72 hours. The second phase was focused on the long-term measurements and will be completed after stabilization of the mass losses and length changes. In the diploma thesis, the first phase of measurement was elaborated in detail, both in terms of experimental and numerical analysis. In addition, a C # .NET program was created to facilitate the processing of raw measurement data from the data logger. Finally, a comparative calculation was performed according to the model B4, where the result of the calculation was compared with the results of the experiment.
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Three-dimensional Spring Networks and Their Applications
Štafa, Michal ; Brožovský, Jiří (referee) ; Keršner, Zbyněk (referee) ; Frantík, Petr (advisor)
The presented work highlights the remarkable potential of physical discretization – lattice model FyDiK in three-dimensional modelling of non-linear problems in structural mechanics. To achieve the objectives a software application, that implements the model FyDiK along with the 3D graphical user interface has been developed and thus is able to assemble a spring network model. Such a model was used for modelling the formation of cracks and fracture in the concrete specimens and also to model a plastic behaviour of steel I-beam. The calculations were performed by a massive parallelization on CUDA platform. In the first part the basic principles on which the work is based are introduced. Subsequently, a detailed description of individual parts of the model and the issue of parallelization by graphics cards are presented. In the next part the creation of the required software and improving of the model properties of mentioned materials are described. That is followed by evaluation of the achieved results with the comparison of other modelling software. The conclusion summarizes the achievements and suggestions for the further development possibilities of the presented method of modelling.
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