Smoothed Particle Hydrodynamics ve strukturální dynamice
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Vysoké učení technické v Brně. Fakulta stavební
Abstract
Disertační práce je zaměřena na aplikaci metody Smoothed Particle Hydrodynamics (SPH) ve strukturální dynamice s důrazem na použití kvazi-křehkých materiálů. První část je zaměřena na úvod, historii a teoretické pozadí SPH. Numerické příklady, kde jsou ukázány silné a slabé stránky SPH, následují. Diskutovány jsou rovněž metody tvorby kombinovaných modelů s Finite Element Method (FEM). Po úvodu do SPH se práce soustředí na kvazi-křehké materiály a jejich vyztužené varianty. Nastíněny jsou numerické koncepty a matematické pozadí Continuous Surface Cap Model spolu s několika benchmarky. Následuje rozbor vlivu rychlosti přetvoření na modely SPH a na kombinované modely SPH-FEM. V této sekci autor představuje nový způsob vyztužení modelů SPH s pomocí nosníkových prvků FEM. Tento způsob spojení byl nazván vazba podvrstvou a ukazuje potenciál v simulacích, zatímco je tahová nestabilita SPH zmírněna. Jelikož je beton často spojován s heterogenitou a velmi specifickou materiálovou strukturou, unikátní algoritmus pro generaci struktury betonu v kombinaci s SPH je představen v následující kapitole. Koncept je založen na využití koherentních funkcí šumu, které mohou přinést variabilitu do numerických modelů. Bylo prokázáno, že algoritmus je robustní, stabilní a jednoduchý na implementaci do SPH. S ohledem na to, takzvaná numerická heterogenita, koncept implementace parametrové variability, je představena spolu s příklady. Poslední část práce je zaměřena na aplikaci SPH ve skutečných experimentech. První experiment se soustředí na náraz ve vysoké rychlosti. Druhý experiment se zabývá výbuchem, kde zaměření je na zatěžovaný vzorek a nálož. Vzhledem k tomu, že SPH simuluje nálož, plyny výbuchu a zatěžovaný vzorek, jedná se o plně svázanou simulaci interakce tekutiny a struktury.
The focus of the thesis is on the application of the Smoothed Particle Hydrodynamics (SPH) method in structural dynamics with an emphasis on usage of quasi-brittle materials. The first part is focused on the introduction, history, and theoretical background of SPH. Numerical examples in which strengths and weaknesses of SPH are shown follow. In addition to pure SPH models, several coupling approaches with the Finite Element Method (FEM) are also discussed. After the introduction of SPH, the focus is on quasi-brittle materials and their reinforced variants. The numerical concept and mathematical background of the Continuous Surface Cap Model are outlined, several benchmarks are presented. Strain-rate effects and their impact on pure SPH and coupled SPH-FEM models are evaluated next. In this section, the author proposes a new approach for SPH models reinforcement with FEM beam elements. The coupling approach was named sublayer coupling and shows a potential in simulations while the SPH tensile instability is alleviated. Since concrete is often associated with heterogeneity and very specific material structure, a unique algorithm for concrete structure generation in combination with SPH is proposed in the next chapter. The concept is based on utilization of coherent noise functions which can bring a variability to numerical models. It has been proved that the algorithm is robust, stable, and easy to implement into the SPH framework. With regard to that, the so-called numerical heterogeneity, a concept of parameters variability implementation, is introduced together with examples. The last part of the thesis is dedicated to the application of SPH in real experiments. The first experiment focuses on a high velocity impact. The second experiment deals with an explosion in which the focus is on both the loaded specimen and charge. Since SPH simulates the explosive, detonation products, and the loaded specimen, it is a fully coupled fluid-structure interaction simulation.
The focus of the thesis is on the application of the Smoothed Particle Hydrodynamics (SPH) method in structural dynamics with an emphasis on usage of quasi-brittle materials. The first part is focused on the introduction, history, and theoretical background of SPH. Numerical examples in which strengths and weaknesses of SPH are shown follow. In addition to pure SPH models, several coupling approaches with the Finite Element Method (FEM) are also discussed. After the introduction of SPH, the focus is on quasi-brittle materials and their reinforced variants. The numerical concept and mathematical background of the Continuous Surface Cap Model are outlined, several benchmarks are presented. Strain-rate effects and their impact on pure SPH and coupled SPH-FEM models are evaluated next. In this section, the author proposes a new approach for SPH models reinforcement with FEM beam elements. The coupling approach was named sublayer coupling and shows a potential in simulations while the SPH tensile instability is alleviated. Since concrete is often associated with heterogeneity and very specific material structure, a unique algorithm for concrete structure generation in combination with SPH is proposed in the next chapter. The concept is based on utilization of coherent noise functions which can bring a variability to numerical models. It has been proved that the algorithm is robust, stable, and easy to implement into the SPH framework. With regard to that, the so-called numerical heterogeneity, a concept of parameters variability implementation, is introduced together with examples. The last part of the thesis is dedicated to the application of SPH in real experiments. The first experiment focuses on a high velocity impact. The second experiment deals with an explosion in which the focus is on both the loaded specimen and charge. Since SPH simulates the explosive, detonation products, and the loaded specimen, it is a fully coupled fluid-structure interaction simulation.
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HUŠEK, M. Smoothed Particle Hydrodynamics ve strukturální dynamice [online]. Brno: Vysoké učení technické v Brně. Fakulta stavební. .
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cs
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Konstrukce a dopravní stavby
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práce byla úspěšně obhájena
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