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Introduction of loadcase „Creeping“ to a multi-body simulation
Volek, Matěj ; Lošák, Petr (referee) ; Březina, Lukáš (advisor)
Tato diplomová práce je zaměřena na implementaci procesu simulace zatěžovacího zatížení do stávajícího rozhraní používaného pro multi-body simulace hnacího vozidla. „Creeping“ bylo definováno jako řízení vozidla bez nárazu na plynový pedál v nízkých převodech. Bylo rozhodnuto simulovat tento stav zavedením sil Jízdních odporů – Aerodynamická odporová síla Fa, síla Valivého odporu Fr a horizontální část Gravitační síly Fgx. Tyto síly byly modelovány v softwaru SimulationX a byl definován model pro zatížení „Creeping“ – ten byl založen na změně stoupání kopce, což dalo výsledky potřebné pro analýzu chování při stavu „Creeping“. Poté byly vytvořeny soubory v softwaru Matlab potřebné pro běh a následné zpracování simulace, které analyzují výsledky v závislosti na čase nebo průměrném točivém momentu motoru. Potom byla správnost procesu kontrolována ve srovnání s experimentálními daty. Toto srovnání ukázalo, že proces pracuje bez velkých problémů; výsledky vykazovaly podobný trend, byly ale ovlivněny nedostatkem vstupních dat z experimentu.
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Simulation of Noise Emitted by a Single-stage Gearbox
Motl, Daniel ; Hadaš, Zdeněk (referee) ; Lošák, Petr (advisor)
The level of noise and vibration of gearboxes is one of the most important parameters for today´s customers. This thesis deals with mathematical acoustic behavior modelling and its contribution to the gearbox design using finite element method. The process is presented at three computations models. Two of those were validated with experimental measurement. Acoustic analysis were performed with software FFT ACTRAN.
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Using Calculix computing environment to solve problems of solid mechanics
Lukáš, Jan ; Lošák, Petr (referee) ; Vosynek, Petr (advisor)
Submitted bachelor thesis is focused on a solution of solid mechanics problems in a computing environment of the Calculix program. In the opening of the thesis there are briefly described theoretical foundations of finite element method. Subsequently there are analyzed particular parts of the program environment of Calculix. The main part of the thesis deals with solutions of three selected problems of solid mechanics. There are three different types of analyzes: static structural, modal dynamic and explicit dynamic. In the first assignment there is discovered deformation and stress in a fixed compressed squared timber. The second assignment deals with modal properties of the fixed squared timber. The last assignment discovers effect of loading velocity on the deformation of fixed compressed squared timber. In the conclusion there are briefly evaluated advantages and disadvantages of the Calculix program and there are compared solutions of the Calculix program and commercial program.
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The use of hydraulic disc brakes for road bikes
Dvořáková, Barbora ; Lošák, Petr (referee) ; Šebek, František (advisor)
This bachelor's thesis is focused on the usage of hydraulic disc brakes on road bikes. The thesis is divided into two parts. In the first part, there is a research focused on differences in construction and properties of hydraulic disc brakes in comparison with rim brakes. The main emphasis is placed on evaluating all advantages and disad-vantages of the hydraulic disc brakes in comparison with rim brakes. Evaluation is conducted both from the functional point of view and user point of view with taking different requirements of both recreational level cyclist and professional cyclist into account. The aim of the second part is the numerical simulation of loading of the frame and fork for both types of brakes. The goal of this part is an overall assessment of suitability of hydraulic disc brakes for the road bikes.
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An application of Python language to some problems of the mechanics
Horák, Filip ; Lošák, Petr (referee) ; Profant, Tomáš (advisor)
Programming language Python is currently a very powerful and widely used programming tool. Its availability, simplicity and versatility makes it a popular choice among both beginners and experienced programmers. Although Python is not primarily designed for calculations, it is easy to program a calculator software when proper libraries are used. The aim of this bachelor thesis is to get to know the Python programming language, to apply it to chosen tasks of mechanics and to present the results using the Jupyter web application.
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Multi-body model of a motorcycle suspension
Kotas, Jakub ; Lošák, Petr (referee) ; Březina, Lukáš (advisor)
This bachelor's thesis deals with the rear wheel suspension of a motorcycle. Theoretical basics of the suspension design and terms, essential for the understaning of the work, are breifly explained. A review of contemporary used spring, shock-absorber and suspension system types is presented.
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Analysis of Smart Materials
Rašner, Martin ; Lošák, Petr (referee) ; Hadaš, Zdeněk (advisor)
The bachelor's thesis "Smart Materials Analysis" deals with the description of intelligent materials in the way of usability in technical practice. At first, the research of smart materials is carried out, which is further elaborated on a detailed description of shape memory materials. In order to investigate the functionality of the material and the description of its behaviour in terms of non-linear oscillation, a simplified model is proposed. The practical part deals with the application of passive damping of Nitinol. The solution is accomplished by modelling program MATLAB / Simulink.
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Use of Neural Networks for the Stiffness Calculation of a Spur Gear Transmission
Planka, Michal ; Krpalek, David (referee) ; Lošák, Petr (advisor)
The aim of this master's thesis is to build artificial neural network that is able to calculate varying single tooth-pair mesh stiffness of spur gear for given input parameters. The training set for this network was determined by computational modelling by finite element method. Therefore, creating of computational model and mesh stiffness calculating were a partial aim of this thesis. Input parameters for stiffness calculation were number of driving and driven gear teeth and gear loading. Creating of computational model and performing series of simulations was followed by creating artificial neural network. Multilayer neural network with backpropagation training was chosen as a type of the network. Created neural network is sufficiently efficient and can determine varying mesh stiffness in input set range for learned input parameters and for values of parameters that are not included in training set as well. This neural network can be used for varying single tooth-pair mesh stiffness estimation in input set range.
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Determination of the mechanical properties of the multilayer structure materials with utilization of the sonic resonance method and modal FE analysis
Fodor, Ján ; Lošák, Petr (referee) ; Ševeček, Oldřich (advisor)
Thesis deals with determination of layerwise mechanical properties of composite ceramics by indirect method, namely Youngs modulus. Based on literature review, it was found that a method to determine elastic properties of one or more components of multi layered composites based on experimental modal analysis and finite element modal analysis, or analytical approach exists. Method based on FE modal analysis was applied to ceramic laminate, where it was attempt to determine youngs modulus of one component. Beyond that, it was attempt to determine Youngs moduli of both components using first two bending resonant frequencies. Results were unsatisfying. Sensitivity analysis showed that layers with unknown Youngs modulus were overly sensitive to small changes in input parameters due to their small relative thickness with respect to thickness of laminate and due to location in laminate. Based on this conclusion, recommendations were made with respect to suitable geometry of test specimens.
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