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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.
71

Návrh zařízení pro měření výškové polohy těžiště automobilu / Design of Device for Vehicle Center of Gravity Height Measurement

Rektořík, Jiří January 2017 (has links)
The objective of this diploma thesis is the design of a device that measures the vehicle’s centre of gravity height position. The first part defines individual methods of measurement using various measuring equipment. The next part deals with the definition of requirements for the device and the definition of the design. A stress-strain analysis was executed for selected components. This diploma thesis describes the preparation process of the vehicle and the device for the measurement. The next part is dedicated to the design of the measuring chain and to the evaluation of the results. The thesis concludes with a theoretic analysis of the measurement inaccuracy.
72

Deformačně napěťová studie Burch-Schneiderovy dlahy / Strain Stress Study of Burch-Schneider Split

Řehák, Kamil January 2018 (has links)
This thesis deals with problems of the hip endoprosthetics area, namely total endoprosthesis (TEP) with Burch-Schneider (BS) split, in which there are many problems in clinical practice. The hip joint load depends on the patient weight and the performed activity. Sedentary job, little exercise, a lot of stress or poor eating habits and overweight associated with it affect negatively hip joint. Increasing hip joint wear and its pain in movement is necessary in several cases to be solved by a surgical procedure in which TEP is applied. When selecting and subsequently applying individual TEP, it is important to pay attention to creating conditions which will allow good fixation. In case of worse mechanical properties of bone tissue, it is very problematic to ensure stability of the implant. Based on several classifications which assess the degree of hip joint damage, it is possible to select a suitable TEP. The BS split, on which this work is focused, is dominantly used in cases of large defects in the acetabulum area. The use of this cage allows to bridgelarge defects and create a new centre of rotation of the hip. Knowledge of the mechanical properties of hip bone tissue can significantly affect the prediction of BS split damage. For this purpose, it was necessary to perform a biomechanical study, which is focused on the influence of worse mechanical properties of bone tissue on BS split failure. The computational modelling using finite element method implemented in the ANSY S software was used for the solution, which enables to solve the mechanical interaction between bone tissue and TEP with BS split. Due to the absence of bone tissue data before application of TEP with BS split, the variants before application of TEP and after application of resurfacing and standard TEP were solved. All variants were solved with the material properties of bone tissue that were determined based on CT images. In addition, all variants were solved for the case of degraded mechanical properties. Based on the numerical simulations results and the Mechanostat hypothesis, a bone tissue analysis of the hip joint was performed before and after application of TEP and TEP with BS split. The results show the influence of the computational model level, which considers the distribution of bone tissue through the inhomogeneous model of the material. Therefore, the degraded mechanical properties have a major impact on the stability and strain of the BS split, particularly in the cranial part of the acetabulum.
73

Deformačně a napěťová analýza čelisti se zubním implantátem BOI / Stress - strain analysis of jaw with tooth implant type BOI

Marcián, Petr January 2008 (has links)
Submitted master thesis deals with stress - strain analysis of jaw, with dental implant. The implant serve as a suitable pillar for crown or dental bridge, when one or more teeth are lost. The project is oriented on BOI (basale - oseo - integrable) dental implant type, which is produced by DENTALIHDE company. Stress – strain condition of the mandible system with implant have been established by computational simulation, with use of the final elements method. Important part of down jowl is simulated on with EDS and EDDS applied types of implants. After implementation the implant begins to heal. Therefore the special attention is paid to stress - strain states on various level of osteointegration. There is a detail description of production of single part computational model and his solving in the master thesis. Presentation of large chapter with results and subsequent alteration stress - strain analysis is part of the master thesis. Program SolidWorks 2005 was used to create the geometric model. Computational model and the actual solving was accomplished with use of ANSYS 11.0 and ANSYS Wor-kbench systems.
74

Deformační a napěťová analýza dolní čelisti s fixátorem / Stress-Strain Analysis of Mandible with Fixator

Semerák, Jaroslav January 2018 (has links)
This diploma thesis deals with fixation of the lower jaw fractures using commercially produced fixators. The topic was researched on the basis of the available literature. The thesis also indicates basic anatomy of the surveyed area and nowadays the most commonly used materials. Subsequently, the stress-strain analysis of the lower jaw with the applied angular stable fixation plate was performed. The solution was performed for the lower jaw with a fracture in the area of the condyle with different types of fixation plates made of CP-Ti Grade 4. In addition, the strain analysis of the healed lower jaw with the fixators after the defect in the area of chin and angle was performed. The mechanical interaction analysis of the lower jaw with defect and applied fixation plate was solved by using computational modeling with variational approach, in use of the finite element method in Ansys Workbench 18.1. The thesis also describes in detail the creation of a computational model of the system and the subsequent solution.
75

Analýza vlivu směrové distribuce kolagenních vláken ve stěně tepny na její mechanické vlastnosti / Analysis of impact of direction distribution of collagen fibres in arterial wall on its mechanical properties

Fischer, Jiří January 2020 (has links)
The aim of this thesis is to analyse literature with focusing on literature about directional distribution of collagen fibres. This knowledge is very important for computational modelling and FEM analysis of arterial wall. Comparison of suitability of different models of directional distribution of collagen fibres is made by fitting of different types of probability density functions. Impact assessment of different collagen fibres distribution on mechanical properties of the arterial wall and impact assessment of wall anisotropy is solved with finite element method. FEM analysis is done on three loading types – uniaxial tension, equibiaxial tension and inflation of artery by internal pressure. Output of this thesis is evaluation of results for various types of collagen fibres arrangement in arterial wall.
76

Pevnostně deformační analýza uchycení filtru pevných částic na traktoru / Stress-strain Analysis of Diesel Particulate Filter Support on Tractor

Ježek, Přemysl January 2012 (has links)
The subject of this thesis is to carry out stress-strain analysis of diesel particulate filter support on tractor. So it describes sequence of steps for the analysis model, such as geometry description, mesh generation, applied forces definition and others. Result of the analysis is assessed in terms of strength and improvement was proposed.
77

Pevnostně deformační analýza uchycení filtru pevných částic na traktoru Zetor Forterra / Stress-strain Analysis of Diesel Particulate Filter Support on Tractor Zetor Forterra

Kučera, Petr January 2014 (has links)
The subject of this master's thesis is the FEM analysis of the construction of the diesel particulate filter support on the tractor Zetor Forterra. The introduction of this thesis is about the theoretical part dealing with the issue of emissions from diesel engines and ways to reduce them. The following part describing the creation of the computational model. Then, the static stress-strain analysis, modal analysis and fatigue analysis are solved in the ANSYS Workbench software. The assessment of the safety of the structure in terms of limit states, that may occur during the operation of the tractor, based on the results of calculations is in the conclusion of the thesis.
78

Deformačně-napěťová analýza tenkostěnné skříně vystavené rázovému zatížení od výbuchu / Stress-strain analysis of the thin wall structure subjected to impact load

Tatalák, Adam January 2016 (has links)
This master thesis deals with stress-strain analysis of simplified model of the thin wall transformer case subjected to impact load of electrical blast. Electrical blast is replaced by chemical blast (detonation of high explosive). The problem is solved using computational modeling utilizing the Finite Element Method (FEM) and LS-DYNA solver. After the introduction where detonation and shock wave propagation is explained the analytical approach is presented. This approach serves to results verification. In the next chapter is conducted research of applicable methods from which ALE method is chosen. In preliminary study is performed the mesh size analysis that is focused on finding the size of element which is both computational effective and gives accurate results. Next the infulence of input conditions (shape, location and parametres of high explosive, location of detonation point, boundary conditions) on distribution and time progress of pressure is investigated. Then influence of the opening on upper side of the case on overall pressure redistribution and strain and stress of the case is analysed. The stress-strain analysis of the case´s door which are connected to case by various types of contact models is performed as well as stiffness analysis of these types of contact.
79

Návrh metodiky výpočtu životnosti valivého ložiska / Design of the computational lifetime prediction methodology for the roll bearing

Vaculka, Miroslav January 2016 (has links)
This master’s thesis deals with a fatigue analysis of a roller bearing. The fatigue analysis consists of determining service-life of a roller bearing using a stress-strain analysis with finite element method and subsequent numeric calculation using software fe-safe with application of Brown-Miller multiaxial fatigue criterion. Service-life of a roller bearing is determined by number of cycles to failure in the form of pitting formation which is consequence of contact fatigue. According to calculations was found an inappropriateness of Brown-Miller criterion for high-cycle contact fatigue. Test of other available criteria was performed. Principal-Strain criterion provided the best match with ISO 281 standard.
80

Pevnostní posouzení konstrukce výřezu dveří přetlakovatelného habitatu pro extrémní prostředí / Pevnostní posouzení konstrukce výřezu dveří přetlakovatelného habitatu pro extrémní prostředí

Sláma, David January 2017 (has links)
Main goals of this master thesis are following: to perform the state of the art research of overpressure constructions (especially space habitats, plane fuselages); to create an own concept of the functional inside ending (hole) in the sandwich panel for a door; to perform stress-strain analysis of this concept; to perform the design optimalization of this concept in order to minimise the weight. To solve the problems above software Ansys 17.2 is chosen, because it allows to: model the material of the honeycomb core of sandwich panel as homogenous linear orthotropic material; evaluate reserve factors of all critical limit states; perform the design optimalization; perform Monte Carlo simulation. First and second design optimalizations discover, that with defined parameters: 0,635 mm width of aluminium sandwich face sheets and inner overpressure 0,1 MPa, a creation of the model, that would be safe by changing the values of design variables is not possible. Specifically, the maximum value of shear stress on the glued areas between aluminium face sheets and honeycomb core is higher than the shear strength of the glue. Therefore, two new concepts are created. First for inner pressure 0,03 MPa and bigger width of aluminium face sheets 3,175 mm, second for inner pressure 0,02 MPa and same width of aluminium face sheets 0,635 mm. For both these concepts, an overall reserve factor is calculated. First, the value of an overall reserve factor is calculated deterministically. Secondly, the value of an overall reserve factor is calculated stochastically considering the variance of material properties of the honeycomb core ± 10 % by Monte Carlo simulation. An overall reserve factor of the concept with inner pressure 0,02 MPa is determined as 1,21. An overall reserve factor of the concept with inner pressure 0,03 MPa is determined as 1,20. The weight of the concept for inner pressure 0,03 MPa is though 4 times bigger than the weight of the concept for inner pressure 0,02 MPa. In the concept for inner pressure 0,02 MPa the maximum value of HMH stress in aluminium components is critical, stochastically considered material properties of the honeycomb core don’t have a significant influence on this value. In the concept for inner pressure 0,03 MPa the value of maximum shear stress on the glued areas between aluminium face sheets and the honeycomb core is critical, stochastically considered material properties of the honeycomb core have a significant influence on this value. In the concept for inner pressure 0,03 MPa an absolute error of overall reserve factor is 8 % (overall reserve factor calculated deterministically was 1,28) which is significant. Monte Carlo simulation is also used to find that the value of Poisson ratio XY of the honeycomb core doesn’t have statistically significant influence on all limit states. Value of the reserve factor of the honeycomb core is higher than 2 in both concepts. Monte Carlo simulation discovers that this value can be significantly lower. Using Tsai-Wu failure criteria the reserve factor in the concept for inner pressure 0,02 MPa is determined as 2,72 deterministically x 2,41 stochastically (absolute error 31 %), in the concept for inner pressure 0,03 MPa the reserve factor is determined as 6,85 deterministically x 6,17 stochastically (absolute error 68 %).

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