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Design of tester of piezoelectric PVDF layers
Sijková, Simona ; Rubeš, Ondřej (referee) ; Hadaš, Zdeněk (advisor)
The diploma thesis deals with a design of a tester device, a selection and verification of a suitable method for comparing the piezoelectric properties of tested PVDF samples. In the introduction, a basic overview of the theory is important to understand the issue and the various branches of use of PVDF in the field of energy harvesting. The tester device includes a unimorph piezoelectric cantilever beam with tip mass, whose properties are described by three models: a model with N degrees of freedom reduced to one degree of freedom (NDOF), a single degree of freedom model (SDOF), both created in Matlab and a model for verifying results in FEM ANSYS Workbench program. The voltage time response and the voltage frequency response of the models is compared with each other. For two different PVDF samples, the voltage response to harmonic excitation is measured using a tester device, and the piezoelectric properties of one of them are determined using the NDOF and SDOF models.
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Mechanical analysis of historical systems
Bilík, Pavel ; Ševeček, Oldřich (referee) ; Fuis, Vladimír (advisor)
This work thesis deals with historical machine systems from the period of antiquity and the Middle Ages. The basic concepts, quantities and phenomena related to the operation of machines are defined. Technically important inventions are described in more detail herein. In the practical part, two selected assemblies are examined, their dimensions and properties are designed. Furthermore, calculations from mechanical analysis are performed on selected systems. Numerical solutions are implemented using scripts in Matlab.
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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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Application of boundary value problems for ordinary differential equations in engineering
Zapoměl, Jakub ; Šremr, Jiří (referee) ; Opluštil, Zdeněk (advisor)
This bachelor thesis deals with the determination of the shape of the deflection line for boundary value problems in strength of materials. There are several methods for solving boundary value problems. This thesis focuses on the Green's function method. It provides a basic review of the properties of ordinary differential equations, an introduction to the Green's function method and the actual application of the findings to beam bending models. The concrete models are solved using an interactive program developed in Matlab software.
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Solution of the exact differential equation of deflection curve
Šikl, František ; Fuis, Vladimír (referee) ; Vaverka, Jiří (advisor)
This bachelor thesis deals with the deformation of a beam loaded with a basic bend using the differential equation of the deflection curve. The work is divided into four parts, where in the first part the general form of the differential equation of the deflection curve, which is based on simple geometry and mathematical approximations, is derived. In the second part, we will describe the basic methods of solving the differential equation of the deflection curve for large deformations for simple cases, where we must use the nonlinear form of the already mentioned equation. However, we will also mention methods that can be used for specific cases. In the third part, two numerical methods, which can be used to solve large deformations of beams, are being programmed. The last part describes the difference between the linear equation of the deflection curve, which is simplified and taught commonly, and the nonlinear differential equation of the second order. The fundamental task of the work is a comparison of commonly used methods to determine the deformation of the beam and to determine the degree of load, when it is possible to use a simplified differential equation of the deflection curve, and when not. However, it is important to mention that the numerical solution cannot always be used, so the example will be embedded in a simple case.
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Piezoelectric vibration energy harvester
Klásek, Matyáš ; Rubeš, Ondřej (referee) ; Hadaš, Zdeněk (advisor)
The first goal of this bachelor’s thesis is to give an overview of piezoelectric materials and their utilization in energy harvesting applications. The second goal is to examine the effect of altering model parameters on generated power and natural frequency of the system using analytical model of a bimorph piezoelectric cantilever beam in MATLAB/Simulink.
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Discrete modeling of nonlinear beams under uniform external load
Folorunsho, Sodiq Sunday ; Tomášek, Petr (referee) ; Giorgio, Ivan (advisor)
The concept of Beam theory is extensively studied in the fields of computational and structural mechanics, with widespread applications in both industry and academia. However, the existing body of knowledge lacks the derivation of important deformation equations due to the overly constrained assumptions made by early researchers in this area. This research aims to overcome these limitations by investigating beam deformation through the study of the centerline beam deformation theory, thus relaxing the previously adopted assumptions. To achieve this goal, the energy functionals variational formulation was employed to derive a classical formulation that avoids the inherent assumptions of the Euler-Bernoulli and Timoshenko beam model equations. A discrete approach, known as Hencky-Type, was utilized to verify the inextensibility constraint of the nonlinear Euler-Bernoulli Beam. Furthermore, the linearized case was derived using variational methods applied to its nonlinear counterpart. The derived models were then applied to two types of beams: the cantilever or clamped-Free (CF) beam and the simply supported beam (SS). A comparison was made to evaluate the superiority of these models. The nonlinear model formulation was solved using the weak formulation math model of COMSOL Multiphysics software. This study aims to pave the way for more accurate model formulations and the development of novel numerical schemes that can effectively handle nonlinear models, which are often avoided due to their complexity. The findings from this work hold the potential to significantly advance the field and facilitate the exploration of various practical applications.
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Mechanical analysis of historical systems
Bilík, Pavel ; Ševeček, Oldřich (referee) ; Fuis, Vladimír (advisor)
This work thesis deals with historical machine systems from the period of antiquity and the Middle Ages. The basic concepts, quantities and phenomena related to the operation of machines are defined. Technically important inventions are described in more detail herein. In the practical part, two selected assemblies are examined, their dimensions and properties are designed. Furthermore, calculations from mechanical analysis are performed on selected systems. Numerical solutions are implemented using scripts in Matlab.
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Application of boundary value problems for ordinary differential equations in engineering
Zapoměl, Jakub ; Šremr, Jiří (referee) ; Opluštil, Zdeněk (advisor)
This bachelor thesis deals with the determination of the shape of the deflection line for boundary value problems in strength of materials. There are several methods for solving boundary value problems. This thesis focuses on the Green's function method. It provides a basic review of the properties of ordinary differential equations, an introduction to the Green's function method and the actual application of the findings to beam bending models. The concrete models are solved using an interactive program developed in Matlab software.
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Solution of the exact differential equation of deflection curve
Šikl, František ; Fuis, Vladimír (referee) ; Vaverka, Jiří (advisor)
This bachelor thesis deals with the deformation of a beam loaded with a basic bend using the differential equation of the deflection curve. The work is divided into four parts, where in the first part the general form of the differential equation of the deflection curve, which is based on simple geometry and mathematical approximations, is derived. In the second part, we will describe the basic methods of solving the differential equation of the deflection curve for large deformations for simple cases, where we must use the nonlinear form of the already mentioned equation. However, we will also mention methods that can be used for specific cases. In the third part, two numerical methods, which can be used to solve large deformations of beams, are being programmed. The last part describes the difference between the linear equation of the deflection curve, which is simplified and taught commonly, and the nonlinear differential equation of the second order. The fundamental task of the work is a comparison of commonly used methods to determine the deformation of the beam and to determine the degree of load, when it is possible to use a simplified differential equation of the deflection curve, and when not. However, it is important to mention that the numerical solution cannot always be used, so the example will be embedded in a simple case.
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