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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
431

Modelování podzemních stěn pomocí časově závislého elasto-plastického materiálového modelu / Modelling of diaphragm walls using time-dependent elasto-plastic material model

Šindelářová, Daniela January 2022 (has links)
The goal of this thesis was the verification of the advanced time-dependent elasto-plastic material model for modeling diaphragm walls. Currently, this type of construction is solved usually with a combination of linear-elastic volume and plate elements. To express time-dependent behaviour, there are both, volume and plate, elements active in short-term conditions, then only volume elements in long-term conditions, while plate elements are deactivated. In this thesis, the Shotcrete material model, which can capture the time-dependent behaviour without combining two types of construction elements, is used. First, a theory of time-dependent behaviour is presented and a design of concrete structures by Eurocode 2 is discussed. Next, the Shotcrete material model is described, then used for modeling a biaxial test and calibration of compression and bending test. Following the gained knowledge, a real boundary value problem of deep excavation supported by diaphragm walls with the strut was solved. To calculate values of the internal forces and horizontal deformation in diaphragm walls, three types of material models are used.
432

Návrh a posouzení sanace železničního náspu na Vsetínsku / Design and evaluation of the remedial works of railway embankment in Vsetín area

Vašina, Adam January 2022 (has links)
This document is focused on the elucidation of embankment deformation nearby žst. Valašská Polanka, with subsequent proposal of remediation measures, for which the own software and commercial software Plaxis 2D were used.
433

Statika atypického RD / Statics of an atypical family house

Bartoň, Jakub January 2022 (has links)
The diploma thesis deals with a desing and assessment a prestressed ceiling structure above a family house with a vegetated roof. The creation of the static model was analyzed by the SCIA Engineer program.
434

Návrh a posouzení ŽB konstrukce / Salesian Center

Martinek, Ivo January 2022 (has links)
This final thesis is focused on a reinforcement design and check of selected reinforced concrete structure parts of a church building. A spatial model loaded with dead and live loads is designed in order to carry out a structural analysis in SCIA Engineer software. Serviceability limit state and fire resistance are then checked for some selected load-bearing elements. The drawings are also included in this work.
435

Funkční zkoušení recyklátů do pozemních komunikací / Performance tests of the recycled aggregates to roads

Karásková, Romana January 2012 (has links)
The work is divided into two parts. The practical part deals with the testing properties of soils which are using in new road in Nové Město na Moravě and the testing of recycled materials which could replace this soils from road. The aim this part is to obtain values of elastic modulus which are then inserted into the computational model. In the second part of work the track road is modeled in the software which uses the Finite Element Method to calculate and respect physical properties of different materials and a load. The result of work will be studies with comparison of displacement and stress generated to using existing soils and recycled materials.
436

Stanovení hodnot materiálových parametrů s využitím experimentů různých konfigurací / Determination of values of material parameters using various testing configurations

Michal, Ondřej January 2012 (has links)
The work occupy by inverse analysis based on artificial neural network. This identification algorithm enable correct determine parameters of applied material model on creation of numerical model of construction so it's possible that the results of computerized simulation correspond with experiments. It look's like suitable approach especially in cases with complicated problems and complex models with many material parameters.
437

Numerická simulace proudění nestlačitelných kapalin metodou spektrálních prvků / Numerical simulation of incompressible fluid flow by the spectral element method

Pokorný, Jan January 2008 (has links)
Tato diplomová práce prezentuje metodu spektrálních prvků. Tato metoda je použita k řešení stacionárního 2-D laminárního proudění Newtonovské nestlačitelné tekutiny. Proudění je popsáno stacionarní Navier-Stokesovou rovnicí. Dohromady s okrajovou pod- mínkou tvoří Navier-Stokesův problém. Na slabou formulaci této úlohy je aplikována metoda spektrálních prvků. Touto discretizací se získá soustava nelineárních rovnic. K obrdžení lineární soustavy je použita Newtonova iterační metoda. Podorobný algorit- mus tvoří jádro Navier-Stokeseva solveru, který je naprogramován v Matlabu. Na závěr jsou pomocí tohoto solveru řešeny dva příklady: proudění v kavitě a obtékání válce. Přík- lady jsou řešeny pro různé Reynoldsovy čísla. První od 1 do 1000 a druhý od 1 do 100.
438

STOCHASTIC CRACK PROPAGATION MODELLING USING THE EXTENDED FINITE ELEMENT METHOD / STOCHASTIC CRACK PROPAGATION MODELLING USING THE EXTENDED FINITE ELEMENT METHOD

Nešpůrek, Lukáš January 2010 (has links)
Tato disertační práce vychází z výzkumu v rámci francouzsko-českého programu doktorátu pod dvojím vedením na pracovišti Institut français de mécanique avancée v Clermont-Ferrand a na Ústavu fyziky materiálu AV v Brně. Úvodní výzkumný úkol na brněnském pracovišti se zabýval numerickou analýzou pole napětí v okolí čela trhliny v tenké kovové fólii. Zvláštní pozornost byla zaměřena na vliv speciálního typu singularity v průsečíku čela trhliny s volným povrchem. Těžiště disertační práce spočívá v numerickém modelování a stochastické analýze problémů šíření trhlin se složitou geometrií v dvojrozměrném prostoru. Při analýze těchto problémů se dříve zřídka používaly numerické metody, a to z důvodu vysoké náročnosti na výpočtový čas. V této disertaci je ukázáno, že aplikací moderních metod numerické mechaniky a vhodných technik v analýze spolehlivosti lze tyto problémy řešit s pomocí numerických metod i na PC. Ve spolehlivostní analýze byla využita lineární aproximační metoda FORM. Pro rychlost šíření trhlin se vycházelo z Parisova-Erdoganova vztahu. Pro parametry tohoto vztahu byl použit dvourozměrný statistický model, který postihuje vysokou citlivost na korelaci obou parametrů. Mechanická odezva byla počítána rozšířenou metodou konečných prvků (XFEM), která eliminuje výpočetní náročnost a numerický šum související se změnou sítě v klasické metodě konečných prvků. Prostřednictvím přímé diferenciace bylo odvozeno několik vztahů pro derivace funkce odezvy, čímž se dosáhlo lepší numerické stability a konvergence spolehlivostní analýzy a výrazného zkrácení doby výpočtu. Problém zatížení s proměnou amplitudou byl řešen aplikací transformace zatížení metodou PREFFAS. Využití distribuce výpočtů v síti PC umožnilo další zrychlení analýzy.
439

Bezpečnost dopravního letounu při poškození draku teroristickým útokem / Safety of a Commercial Aircraft after Damage to Airframe due to Terrorist Attack

Lošťák, Miroslav January 2012 (has links)
Modern-day terrorist attacks present a considerable danger for commercial aircrafts. This thesis analyzes potential methods of such attacks with a critical analysis of the most dangerous type: an attack from the outside of the aircraft via a fragmentation missile warhead. Such missiles cause damage to the airframe of the aircraft through fragments created by the explosion. In this thesis, analytical geometry is used to determine the area of the aircraft affected by the fragmentation. The aircraft’s geometry and the fragments’ dispersion are calculated by analytical functions, and the effect of the damage is analyzed. A shooting experiment was also carried out, in which fragments were shot at a reinforced skin panel that was manufactured according to the real design of commercial aircraft. The results of the experiment revealed that only directly hit sections of the structure are damaged. Data obtained by the experiment was then used for the creation and improvement of the model used in the simulation by means of the finite element method. This model is used for the numerical calculation of the damage sustained. Further included in the thesis is an analysis of the change in the load-bearing capacity after such an attack. The relationship between the size of the damage and its effect on the load-bearing capacity of the component as well as the entire structure is defined. First, the effect of component damage is analyzed via the FMEA/FMECA methods. This analysis is then extended using fuzzy logic. Fuzzy logic analysis is based on the determination of the size of the damaged component area and the component’s importance on the structure’s carry loads. Application of the defined approach is described for several parts of an aircraft’s life cycle, including development, operation after the terrorist attack, and assessment of causes after a crash caused by a fragmentation missile warhead.
440

Biomechanická studie zubních implantátů pro sníženou densitu kostní tkáně / Biomechanical Study of Tooth Implants for Low Density Bone

Marcián, Petr January 2012 (has links)
This work deals with problem of dental implant area, where there are many problems at the dental implants application. The essential issue is the bone tissue quality at implant application, which sig-nificantly influences its deformation, tension and the possibility of subsequent implant failure. The knowledge of bone tissue mechanical properties of mandible and mandible with applied implant can significantly affect prediction of dental implant failure. The mechanical interaction can be described by variable determining deformation and tension of solved system. For this reason the computational modeling by using Finite Element Method was used for solving given problem. The computational model creation of solved system on the high resolution level is necessary for biomechanical assessment of implant failure, including bone tissue quality. For this purpose the biomechanical study was performed, which significantly spreads range of solved problem in this work afterwards. In this work the methodology, which describes assessment of bone tissue quality where the implant should be applied as well as mutual interaction, is presented. The results confirm necessity of bone tissue computational models creation on high resolution level including complex trabecular architecture. In this work the creation of trabecular structure computational model from data gained on micro-CT device is described. Further, the trabecular structure computational model was created on the 3D level with dental implant and the stress strain analysis was performed consequently. The last part of this work deals with introductory study of bone tissue modeling and remodeling.

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