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Modelling and analysis of auxetic materials response on the mechanical loading
Vítek, Tomáš ; Skalka, Petr (referee) ; Ševeček, Oldřich (advisor)
This bachelor’s thesis is focused on auxetic materials, especially on their response on the mechanical loading. Historical development, significant mechanical properties, different ways of modelling and possible practical applications of these materials are described in the research part of the thesis. The computational part deals with the detailed analysis of selected auxetic structures in order to evaluate their elastic properties depending on different geometric parameters and also on the magnitude of applied deformation. Computational modelling is primarily performed using the software ANSYS Mechanical APDL based on the finite element method (FEM). This method is briefly explained in one chapter. In the following part of the thesis the process of creating a parametric model and reducing the whole structure to a minimum geometry size (a part of a basic unit) is described. A detailed explanation of generating the mesh and setting appropriate boundary conditions is also included together with the results evaluation. Elastic properties obtained by numerical simulations are then compared to available analytical model. Dependencies of elastic properties are presented for a wide range of values of selected geometric parameters and applied deformations of the structure considering small and large deformation regimes. An influence of these parameters on a structure response during the mechanical loading is discussed based on these dependencies. At the end of the thesis the values of elastic properties computed using a finite element method are confronted to the experimental data available in the literature and the validity of the computational model is considered based on this comparison.
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Engine Conecting Rod Analysis Inluding Bolts Influence
Cseh, Csaba ; Svída, David (referee) ; Ramík, Pavel (advisor)
Csaba CSEH Engine Connecting Rod Analysis Including Bolts Influence DW, ITE, 2008, 75 pp, 88 fig. The aim of my diploma work is a stress analysis in the material of a connecting rod during a stationary engine regime. Dynamic forces from the connecting rod‘s motion and the forces acting on the bolts are included in the calculations. The whole stress analysis is based on a FEM designed application on a model, that was created in a CAD system package according to the real component.
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Cranktrain of three-cylinder in-line disel engine
Kovář, Pavel ; Ramík, Pavel (referee) ; Píštěk, Václav (advisor)
This master’s thesis describes design and comparison of three variants of the crankshaft in-line diesel engine for commercial vehicles. The work focuses on working with programs for 3D modelling and analysis proposed models, to be able to work under difficult conditions. Part of this work is a computational modal and strength analysis.
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Computational analysis of the electro-mechanical characteristics of ferroelectric/dielectric composite material
Vítek, Tomáš ; Marcián, Petr (referee) ; Ševeček, Oldřich (advisor)
This diploma thesis deals with the computational modeling of ceramic ferroelectric/dielectric particle composites. The literature review section explains the principle of the piezoelectric phenomenon, describes the quantities defining the piezoelectric behaviour of materials, and provides characteristics of commonly used piezoelectric materials, including the mentioned ferroelectric/dielectric composites. The computational part of the thesis begins with the homogenization of particle composites consisting of a ferroelectric matrix and dielectric particles. Available analytical models for determining the effective electromechanical properties of the composite are tested, and parametric finite element models of the particle composite are assembled using Ansys Mechanical APDL software. The algorithm for creating these models is described, and the procedure for computing the relevant effective properties of the composite based on the obtained results is explained. Subsequently, the results obtained from the analytical and finite element models are compared, and the usability of the chosen analytical models is assessed based on the composite parameters. Sensitivity analyses are then performed using the assembled finite element models to evaluate how specific geometric and material parameters affect the effective electromechanical properties of the composite. These properties predicted by the finite element method are compared to the provided experimental results in the next part of the thesis. A computational analysis of residual stresses induced in the composite during sintering follows, and the output of this analysis provides recommendations for the manufacturing of these composites, aiming to reduce residual stresses and, thus, the risk of crack formation. Finally, various designs of ferroelectric/dielectric composites that can be manufactured using 3D printing are proposed and analysed, with the presented results serving as a basis for future research.
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Selected aspects of diagnostics of the reinforced concrete structure of the interwar period of the 20th century
Žítt, Petr ; Bílek,, Vlastimil (referee) ; Pěnčík, Jan (referee) ; Daněk, Petr (advisor)
The dissertation deals with diagnostics and load tests of a reinforced concrete ceiling structure built in the interwar period of the 20th century. The theoretical part of the work is an excerpt from standard regulations for the design of structures in terms of material properties of concrete and reinforcement, the implementation of load tests and measuring equipment used. Furthermore, static calculations according to relevant standards, numerical and stochastic analysis of selected members. The practical part of the work is then focused on performing experimental load tests of selected elements of the ceiling structure with appropriate diagnostic work, which includes determining the geometry of the supporting structure, reinforcement of elements and determining the quality of built-in materials. An integral part of the practical part of the work is based on the data obtained from the performed load tests and diagnostic work to perform a static assessment of the affected structures and to compile a deterministic and stochastic FEM model of the selected member. The conclusion is a comparison of measured data with FEM analyzes, analysis of the justification of the use a load tests in the context of classical diagnostic methods and the methodology of the optimal number of test samples for objective evaluation of the actual state of the structure.
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Modelling and analysis of auxetic materials response on the mechanical loading
Vítek, Tomáš ; Skalka, Petr (referee) ; Ševeček, Oldřich (advisor)
This bachelor’s thesis is focused on auxetic materials, especially on their response on the mechanical loading. Historical development, significant mechanical properties, different ways of modelling and possible practical applications of these materials are described in the research part of the thesis. The computational part deals with the detailed analysis of selected auxetic structures in order to evaluate their elastic properties depending on different geometric parameters and also on the magnitude of applied deformation. Computational modelling is primarily performed using the software ANSYS Mechanical APDL based on the finite element method (FEM). This method is briefly explained in one chapter. In the following part of the thesis the process of creating a parametric model and reducing the whole structure to a minimum geometry size (a part of a basic unit) is described. A detailed explanation of generating the mesh and setting appropriate boundary conditions is also included together with the results evaluation. Elastic properties obtained by numerical simulations are then compared to available analytical model. Dependencies of elastic properties are presented for a wide range of values of selected geometric parameters and applied deformations of the structure considering small and large deformation regimes. An influence of these parameters on a structure response during the mechanical loading is discussed based on these dependencies. At the end of the thesis the values of elastic properties computed using a finite element method are confronted to the experimental data available in the literature and the validity of the computational model is considered based on this comparison.
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Engine Conecting Rod Analysis Inluding Bolts Influence
Cseh, Csaba ; Svída, David (referee) ; Ramík, Pavel (advisor)
Csaba CSEH Engine Connecting Rod Analysis Including Bolts Influence DW, ITE, 2008, 75 pp, 88 fig. The aim of my diploma work is a stress analysis in the material of a connecting rod during a stationary engine regime. Dynamic forces from the connecting rod‘s motion and the forces acting on the bolts are included in the calculations. The whole stress analysis is based on a FEM designed application on a model, that was created in a CAD system package according to the real component.
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Cranktrain of three-cylinder in-line disel engine
Kovář, Pavel ; Ramík, Pavel (referee) ; Píštěk, Václav (advisor)
This master’s thesis describes design and comparison of three variants of the crankshaft in-line diesel engine for commercial vehicles. The work focuses on working with programs for 3D modelling and analysis proposed models, to be able to work under difficult conditions. Part of this work is a computational modal and strength analysis.
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