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Experimentální určení tlumení nosníku
Fučík, Ondřej ; Hadraba, Petr (referee) ; Rubeš, Ondřej (advisor)
This bachelor thesis deals with structural damping of metallic materials. The first part is research of damping properties, ways how to discover damping properties and short description of how to simulate viscoelasticity of materials, using mathematical models. The second part is focused on an experiment with beams of different lengths and materials. Mathematical models making is also part of solution. The third, last part is focused on results processing. Using mathematical models, damping ratios of beams are determined.
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Analysis of passive and semi-active damping of cantilever oscillation
Václavík, Tomáš ; Tofel, Pavel (referee) ; Hadaš, Zdeněk (advisor)
In this thesis passive and semi-active damping methods on a model of cantilever beam with piezoelectric patch are analyzed. Explanation of piezoelectric effect, classification of damping methods used for vibration control, description of their properties, their benefits and disadvantages, and lastly the challanges of their implementation is presented. Models of specified methods are carried out in MATLAB Simulink and the results are compared. Basic concept of electrical design of circuits for semi-active damping by SDDNC and SSD methods is introduced.
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Analytical model of composite cantilever with SMART layer
Dostal, Vojtěch ; Ševeček, Oldřich (referee) ; Majer, Zdeněk (advisor)
This bachelor's thesis deals with analytical modelling of composite cantilever with smart layer. The structure is based on the real piezoelectric generator, which is a solid cantilever beam with a layer of piezoelectric material attached to its bottom and top. The first part of this bachelor's thesis summarizes the knowledge of the energy harvesting, the process under which harvesting of electric energy from the piezoelectric generator belongs. Some piezoelectric materials are mentioned and described afterwards. At first, analytical modelling is implemented on the homogeneous cantilever beam. Then, the relations for required characteristics are derived for laminate structure, which is structurally similar to the piezoelectric generator. One chosen parameter will be changeable. Due to the ties of relations, the required characteristics will change as well, which are for the piezoelectric generator strain and deflection.
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Dispersion relation of magnonic crystals with nontrivial spatial distribution of magnetic anisotropy
Wojewoda, Ondřej ; Hamrle,, Jaroslav (referee) ; Flajšman, Lukáš (advisor)
Magnonics is a novel field of research dealing with the physics of spin waves, which are collective excitations of a magnetization. Magnonic crystals, the basic building blocks of magnonic circuits, allow extended control over the spin-wave dispersion. The periodic structure of magnonic crystals results in the formation of a complex band structure with a gap of forbidden frequencies. Periodic structures are conventionally prepared by a local modulation of material thickness or by a step change of saturation magnetization. The presented work deals with the theoretical verification of dispersion relations of magnonic crystals, where the periodicity of the system is achieved by the modulation of the direction of uniaxial magnetic anisotropy and by continuous change of saturation magnetization. For a better insight into the propagation of spin waves in a material with non-homogeneous magnetic properties, a theory describing the refraction and reflection of spin waves at the interface is presented and further verified by numerical simulations.
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Analysis of passive and semi-active damping of cantilever oscillation
Václavík, Tomáš ; Tofel, Pavel (referee) ; Hadaš, Zdeněk (advisor)
In this thesis passive and semi-active damping methods on a model of cantilever beam with piezoelectric patch are analyzed. Explanation of piezoelectric effect, classification of damping methods used for vibration control, description of their properties, their benefits and disadvantages, and lastly the challanges of their implementation is presented. Models of specified methods are carried out in MATLAB Simulink and the results are compared. Basic concept of electrical design of circuits for semi-active damping by SDDNC and SSD methods is introduced.
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|
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Experimentální určení tlumení nosníku
Fučík, Ondřej ; Hadraba, Petr (referee) ; Rubeš, Ondřej (advisor)
This bachelor thesis deals with structural damping of metallic materials. The first part is research of damping properties, ways how to discover damping properties and short description of how to simulate viscoelasticity of materials, using mathematical models. The second part is focused on an experiment with beams of different lengths and materials. Mathematical models making is also part of solution. The third, last part is focused on results processing. Using mathematical models, damping ratios of beams are determined.
|
|
|
Dispersion relation of magnonic crystals with nontrivial spatial distribution of magnetic anisotropy
Wojewoda, Ondřej ; Hamrle,, Jaroslav (referee) ; Flajšman, Lukáš (advisor)
Magnonics is a novel field of research dealing with the physics of spin waves, which are collective excitations of a magnetization. Magnonic crystals, the basic building blocks of magnonic circuits, allow extended control over the spin-wave dispersion. The periodic structure of magnonic crystals results in the formation of a complex band structure with a gap of forbidden frequencies. Periodic structures are conventionally prepared by a local modulation of material thickness or by a step change of saturation magnetization. The presented work deals with the theoretical verification of dispersion relations of magnonic crystals, where the periodicity of the system is achieved by the modulation of the direction of uniaxial magnetic anisotropy and by continuous change of saturation magnetization. For a better insight into the propagation of spin waves in a material with non-homogeneous magnetic properties, a theory describing the refraction and reflection of spin waves at the interface is presented and further verified by numerical simulations.
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|
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Analytical model of composite cantilever with SMART layer
Dostal, Vojtěch ; Ševeček, Oldřich (referee) ; Majer, Zdeněk (advisor)
This bachelor's thesis deals with analytical modelling of composite cantilever with smart layer. The structure is based on the real piezoelectric generator, which is a solid cantilever beam with a layer of piezoelectric material attached to its bottom and top. The first part of this bachelor's thesis summarizes the knowledge of the energy harvesting, the process under which harvesting of electric energy from the piezoelectric generator belongs. Some piezoelectric materials are mentioned and described afterwards. At first, analytical modelling is implemented on the homogeneous cantilever beam. Then, the relations for required characteristics are derived for laminate structure, which is structurally similar to the piezoelectric generator. One chosen parameter will be changeable. Due to the ties of relations, the required characteristics will change as well, which are for the piezoelectric generator strain and deflection.
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