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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.
161

Pomocný podvozek pro nosič výměnných nástaveb s návěsovým čepem / Auxiliary chassis for swap bodies with king pin

Felcman, Miroslav January 2015 (has links)
Main purpose of the thesis is to carry out a design and a check up of an auxiliary chassis for swap bodies with king pin. The thesis contains pictures of auxiliary chassis made by different producers, followed by my own design. The design contains my own concept of the chassis with purchased parts included. The design of a frame of the auxiliary chassis has been taken in for stress analysis during a number of test loads. Last part of the thesis contains results of stress analysis. Drawings of selected parts are also included. The thesis has been made in cooperation with ZDT Nové Veseli s.r.o.
162

Discontinuous Galerkin method for the solution of boundary-value problems in non-smooth domains / Discontinuous Galerkin method for the solution of boundary-value problems in non-smooth domains

Bartoš, Ondřej January 2017 (has links)
This thesis is concerned with the analysis of the finite element method and the discontinuous Galerkin method for the numerical solution of an elliptic boundary value problem with a nonlinear Newton boundary condition in a two-dimensional polygonal domain. The weak solution loses regularity in a neighbourhood of boundary singularities, which may be at corners or at roots of the weak solution on edges. The main attention is paid to the study of error estimates. It turns out that the order of convergence is not dampened by the nonlinearity, if the weak solution is nonzero on a large part of the boundary. If the weak solution is zero on the whole boundary, the nonlinearity only slows down the convergence of the function values but not the convergence of the gradient. The same analysis is carried out for approximate solutions obtained with numerical integration. The theoretical results are verified by numerical experiments. 1
163

Pasivní kompenzace teplotních deformací u obráběcího stroje / Passive compensation of a thermal deformation for a machine tool

Šabart, Adam January 2017 (has links)
This master thesis deals with passive compensation of a thermal deformation for a binder of portal machining center. The problem is solved by computational modeling with finite element method using ANSYS Workbench software. Afterwards mathematical optimization (also using ANSYS Workbench software) is used for finding binder parameters in order to reduce thermal deformation and its weight. The output is two new versions of binder which are compared to the original configuration.
164

Vliv mechanických vlastností intraluminálního trombu na napjatost v aneurysmatech abdominální aorty / Effect of the mechanical properties of intraluminal thrombus on wall stress of abdominal aortic aneurysms

Hřičiště, Michal January 2017 (has links)
The aim of this thesis is the problematic of abdominal aortic aneurysm wall stress in relation to a different material behavior of intraluminal thrombus, which is in most cases present in the aneurysmal volume. In this thesis, the influence of neglecting the patient-specific material properties of the intraluminal thrombus, on the aneurysmal wall stress, obtained from finite element stress-strain analysis, is investigated. In terms of solution method selection, a system approach was applied so that the solution method was selected in order to respect a system of essential variables as much as possible. The first part of this thesis is focused on a description of the problematic and the human cardiovascular system with important aspects contributing to development and growth of the abdominal aortic aneurysm. Next, this part of the thesis includes chapters devoted to the intraluminal thrombus in terms of its basic characteristics (anatomy, physiology, pathology), structure and its influence on processes within the abdominal aneurysm. The second part of this work is devoted to the accomplishment of the first and second goal of this thesis, which is analyzing the available literature to obtain mean population stiffness values of the intraluminal thrombus and conducting biaxial experimental tests of provided samples of intraluminal thrombus. The experimental testing was conducted in order to obtain the patient-specific mechanical properties, which are used as the inputs in the finite element analysis. The experimental testing confirmed the stiffness negligibility of the intraluminal thrombus’s outer layer, which is mentioned is several studies, however, the influence of this layer on resulting aneurysmal wall stress has been to this date not tested. The dominant part of this thesis is focused on the third goal of this work, which is a comparison of aneurysmal wall stress obtained from the finite element computation that included mechanical properties of intraluminal thrombus obtained either from the literature analysis of experimental testing. This part includes discerption of idealized geometry model development, which was used to analyze the sensibility of computed stresses on a number of ILT layers representing different material properties. In order to obtain this analysis, a macro was created prescribing each element of the intraluminal thrombus finite element mesh with material properties derived from its distance from the lumen. Next, this chapter contains description of patient-specific geometry models development, material models, and boundary conditions selection. In the end of this part, results of the finite element computations are presented together with their statistical analysis. Within the last part of this thesis, discussion of results and conclusions of this thesis is included. Also, an overview of important aspects entering computational modeling of abdominal aortic aneurysms is presented.
165

Numerická simulace růstu trhliny v keramických kompozitních materiálech ve 3D / Numerical simulation of crack propagation in ceramic composites in 3D

Svoboda, Josef January 2017 (has links)
The strength of materials such as glass and ceramics can be influenced by the environment (stress corrosion). Under applied stress defects (cracks) can grow sub-critically below fracture toughness K_Ic. The aim of this work was to develop a three-dimensional finite-element model to analyze the subcritical crack growth behavior of ceramic-based particulate composites. The maximum tangential stress criterion (MTS) was used to predict the direction of the crack propagation in the framework of linear elastic fracture mechanics. The modeled material was a Low Temperature Co-fired Ceramics (LTCC), containing alumina particles embedded in a glass matrix. The main aim of this work was to develop a 3D model describing the crack growth. Conclusions from this work can contribute to a better understanding of subcritical crack propagation in particle composites.
166

Deformační a napěťová analýza dentálního implantátu zavedeného v horní čelisti / Stress-strain analysis of dental implant inserted in maxilla

Dušková, Tereza January 2017 (has links)
Variety of problems can appear when introducing dental implants, especially to in the maxilla. Biggest problems are caused by insufficient quality and volume of the bone tissue of the alveolar process. This thesis focuses on stress-strain analysis of an implant introduced in the maxilla. Mechanical interaction between the implant and bone tissue is solved using computational modelling with the finite element method. From analysis of results, it was discovered that deformation and tension of the implant are influenced by the direction of the load, osseointegration and thickness of the cortical bone tissue. In the anterior region, it is necessary to work with other types of load than axial.
167

Tepelná analýza servo motoru / Thermal analyses of servo motor

Kratochvila, Lukáš January 2017 (has links)
This Master’s thesis is focused on thermal analyses of servomotors per computational modeling with finite element method. The goal was to set the model for the analyses and verify it with experiment and evaluate achieved results.
168

Blok vznětového motoru 2.0L / Engine Block for Diesel Engine 2.0 L

Kudlík, Michael January 2017 (has links)
This diploma thesis describes the problems of the engine block and crankcase. As a one of the most imprortant and first part of this task is creating a 3D simulation model of a engine block and calculating load forces of engine block. The simulation and evaluation of the solution are calculated by using method finite element, software Ansys. The conclusion and ending point of the od the diploma thesis construction desing of stiffness increase.
169

Optimalizace konstrukce korečkových dopravníků / Design Optimization of Bucket Conveyors

Jonák, Martin January 2018 (has links)
This thesis deals with a study of methods sufficient to describe the behavior of bulk materials (homogeneous and non-homogeneous) during their transport by bucket elevators in the application focused on the optimization of the bucket shape and also on the optimization of operating parameters of whole elevator. More specifically, this thesis is based on the studying and creating analytical and numerical computational models which are used for description of flows and deformations especially of particulate materials. Firstly, the thesis is focused on the process of discharging the bucket – the relationship among the shape of the surface of a particulate material and geometry, position and movement of the bucket. The beginning and way of discharge of the bucket will be determined. Secondly, the thesis includes the overall computational model of a bucket elevator which is based on discrete element method and presented in the case study. The goal is to determine the limits of some classical physical and mathematical descriptions.
170

Napjatostní analýza šachet zhotovených z tryskové injektáže / Stress analysis of jet grouted shafts

Tarbajová, Mária January 2018 (has links)
The subject of the diploma thesis is the stress analysis of the circular and elliptical shaft from material jet grouting. A new advanced constitutive Shotcrete model will be applied on the material jet grouting. In the thesis, the shaft tensile strength factor and the size of the ground pressures will be primarily examined. The practical part of the diploma thesis is completed by the comparison of the analytical and numerical calculation of the normal force of the circular and elliptical shafts.

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