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Deformation analysis of the bearing of the main shaft of the wind power plant
Doležel, Miroslav ; Pokorný, Jan (referee) ; Vosynek, Petr (advisor)
This work studies a load distribution in spherical roller bearings of a main shaft in a wind power plant. The effect of the shaft and bearing houses as flexible bodies is considered for a particular geometry. The data are collected and processed by numerical computational modelling using the finite element method. Several complexity levels of models are studied. These analyses are also compared with the data obtained from the software Mesys. The results show that an inclusion of a flexible bearing housing has the greatest effect on the load distribution in the internal geometry of the bearing. The load distribution is also dependent on the direction of the radial load force. The most complex models are dependent on the friction coefficient in the internal bearing geometry, thus revealing the problem of interactions among the bearings. Knowledge of the load distribution contributes to the design of more reliable rolling bearings.
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Impact of residual stresses and uncoiling of arterial specimen on its mechanical response
Sochor, Ondřej ; Lisický, Ondřej (referee) ; Burša, Jiří (advisor)
This thesis examines the impact of residual stresses in the carotid artery wall and the influence of specimen uncoiling on its mechanical response. The introductory part provides basic knowledge about the anatomy and the pathology of blood vessels, as well as overview of common methods used for testing artery samples. The main body of the thesis is divided into two sections. The first section focuses on the impact of specimen uncoiling on its mechanical response during the equibiaxial tensile test. It begins by describing the method used for sample testing and the method used for obtaining material constants from the mechanical response. These constants are then used as input for FEM simulation of the uncoiling and subsequent equibiaxial tensile test simulation on idealized model of geometry. The mechanical behaviour of the uncoiled model is compared to behaviour of the stress-free planar model to determine the influence of uncoiling. In the second section, the influence of residual stresses in the artery wall on its mechanical response is explored. This section includes a description of two methods used to show residual stress release, which are then used for specimen testing. The experiments are used to evaluate input parameters per layer for the model of geometry and subsequent FEM analysis. By comparing results from three levels of modeling, the impact of residual stresses on the artery’s mechanical response is determined.
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Computational modelling and analysis of crack propagation in ceramic composites containing residual stresses
Černý, Hynek ; Majer, Zdeněk (referee) ; Ševeček, Oldřich (advisor)
The diploma thesis dealt with 3D computational modelling of crack propagation in particle and layered ceramic composites. In first part of thesis, all tools for fracture mechanics implemented in software ANSYS were explored for their suitability in given topic. In the next part, crack propagation in particle composites was analysed, where extra focus was applied on influence of different stiffness and thermal expansion of all components of the composite. First, the crack propagation in homogenous material model was set up, then the effect of different stiffness of the composite components was added, and in the last stage, the effect of the residual stresses was also added. From the achieved results, it was possible to describe the influence of the previously listed factors on the energy required for crack propagation. This created model should be applicable to the model of a real composite, thanks to which it should be possible to quantify whether the composite is more resistant to crack propagation then the homogenous material. In the last part of thesis, the crack growth through layered ceramic laminates was analysed, where emphasis was again placed on the different stiffness and thermal expansion of all components of the laminate. In this part, the great advantage of the ANSYS APDL, creating of macros, were used. Using macros, a parametric model was created, which, after the input data was entered, was able to create geometry of the computational model, enter boundary conditions, create a mesh of the computational model, set up the analysis and start the simulation. The created model can be used, for example, to determine the apparent fracture toughness of laminate, thanks to which it is possible to access how much the used configuration is more suitable than the use of a homogenous material.
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Design caclulation of fatigue of tubular condenser
Cablková, Zuzana ; Vincour, Dušan (referee) ; Pernica, Marek (advisor)
The diploma thesis is devoted to the design of the fatigue calculation of the tubular steam condenser with fixed tube sheets, which is in operation as a safety equipment for the steam condenser from the turbine. This device is loaded with temperature and pressure that induces tension. Due to the possibility of frequently starting it up to the operational state and going down to the rest state, stress cycles can occur. The practical part of the thesis is the design calculation, carried out according to ČSN EN 13445–3 standards using the finite element method, abbreviated FEM. The theoretical part of the diploma includes a search of available standards for evaluating the fatigue life of heat exchangers, basic knowledge regarding the issue of fatigue damage and cases of real fatigue damage in practice.
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Strength analysis of the frame for forestry cable yarder
Kovařík, Radim ; Halámka, Tomáš (referee) ; Mergl, Václav (advisor)
This work is focused on the strength analysis of the frame of the Larix Lamako forestry cable yarder rope, as an additional device of a universal agricultural tractor. The theoretical part of the work is focused on the basic description, determination of the area of use of the equipment and the distribution of forest rope transport equipment according to several criteria. The practical part of the work deals with the analytical calculation of force action. Based on the force action, the strength analysis of the original frame structure is numerically calculated. The numerical calculation is followed by structural modifications of the frame and numerical calculation of the modified structure. Assembly drawings of the original and modified structure are processed based on the original and modified equipment models.
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Creation of an application for post-processing results of structural analyses in the space industry
Šprta, Petr ; Silvestri, Riccardo (referee) ; Lošák, Petr (advisor)
Cílem této práce je vytvoření softwarové aplikace pro dodatečné zpracování výsledků strukturálních analýz prováděných metodou konečných prvků v programu Nastran. Náplň a téma této práce vyplývá z požadavků kladených na vývoj konstrukcí v kosmickém průmyslu, kde je pro zaručení bezpečnosti zapotřebí ověřit chování struktury při mnoha zatěžovacích stavech v různých zatěžovacích podmínkách. Díky využívání lineárních statických analýz je možné využít superpozice napětí v rámci dodatečného zpracování výsledků a tím ušetřit cenný výpočetní čas a zvýšit celkovou efektivitu pevnostních výpočtů a vyhodnocování jejich výsledků. Všechny tyto aspekty by měly být zahrnuty při vývoji aplikace, jejímž cílem je načtení výsledků dílčích analýz z programu Nastran, jejich superpozice a vyhodnocení, zapsání výsledků do programu Excel a příprava textových souborů pro vizualizaci v programu HyperView. V úvodní části práce jsou popsány specifika pevnostních výpočtů v kosmickém průmyslu ze kterých vyplývá motivace a požadavky pro vývoj aplikace. V následujících částech je popsán vývoj aplikace a na závěr je její funkčnost ověřena na reálné pevnostní analýze konstrukce vyvíjené v rámci programu Evropské kosmické agenury. Práce byla vytvořena ve spolupráci s firmou SAB Aerospace.
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Design of auxetic structures for the selective laser melting technology
Pchálek, Václav ; Hutař, Pavel (referee) ; Červinek, Ondřej (advisor)
With the development of additive technologies, it became possible to produce auxetic structures with complicated geometries. Despite their intensive study, their potential for high resistance to local loading has not yet been explored. Describing this phenomenon and its causes would enable the effective design of structures with greatly enhanced resistance to foreign object impact. Therefore, this work investigated the deformation behavior of auxetic re-entrant honeycomb structures under local loading. The relationship between the resistance of the structure to local loading and the magnitude of the negative Poisson´s number, which was controlled by the geometry of the basic cell, was investigated. An analytical approach was used to determine the Poisson´s number of the structures. Subsequently, a prediction of the local loading behaviour of the structures was made using the finite element method assuming small and large deformations. This behavior was then experimentally verified for small and large strain rates on structures fabricated by selective laser melting technology. It was found that for the assumption of small deformations, the smaller the Poisson´s number of the structure, the more resistant it is to local loading. However, this does not apply to the assumption of large deformations, where the wall interaction and its buckling were difficult to predict. Furthermore, structures with thinner walls were shown to deform more, thus using their full deformation potential and therefore being more resistant to local loading. When tested at both low and high strain rates, a rearrangement of the structure towards the impact location was observed in two directions, perpendicular and against the direction of loading. It was found that structures with different geometry but the same Poisson's number have the same deformation behavior in terms of strain rate and reaction force. The findings of this work contribute to the understanding of the behaviour of auxetic structures under local loading, which can be used in the design of such loaded structures in specific applications.
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Inverse modelling of stresses in deformed configuration of left ventricle
Zajac, Radim ; Hájek, Petr (referee) ; Vaverka, Jiří (advisor)
The bachelor thesis deals with the development of a FEM model of the left ventricle from a freely available stl model obtained from magnetic resonance images and the modification of this model to make it usable for calculation in Ansys MAPDL. The model was defined with isotropic hyperelastic mechanical properties obtained from the actual myocardial properties obtained from tensile tests described in the accompanying literature. A FEM model corresponding to the stress-free state of the left ventricle was obtained and the stress field of the loaded geometry was reconstructed after loading this null geometry. The reconstructed stress field cannot be considered as real due to the idealization of the material and the neglect of the application of pressures on the epicardium of the left ventricle.
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Analysis of the frontloader arm pin
Smolek, Jan ; Lošák, Petr (referee) ; Hrstka, Miroslav (advisor)
This bachelor's thesis focuses on the dynamic stress analysis of the Stoll FZ 41-33 tractor front loader. It was important to include the inertial effects and loading of the loader in the analysis. For the solution, a program was created in the Python programming language, where the vector and relaxation method of solving mechanisms was used. The result is the courses of forces acting at the nodal points of the loader depending on the time of the analyzed mo-vement. It is possible to simply implement other external influences into the created program or change the characteristic dimensions to a different type of loader. A partial result was also a finite element analysis of the pivot-cantilever node, where the finite element method was used in the Ansys Workbench program. The outputs of this work can find real use in practice in the development of tractor front loaders.
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A research study of plate for the treatment of tumorous mandible
Mäsiar, Matúš ; Valášek, Jiří (referee) ; Marcián, Petr (advisor)
This bachelor’s thesis aims to address the issue of treating tumorous conditions in the lower jaw by implementing a reconstructive plate. The thesis includes an examination of basic anatomy related to the specific problem, along with a research study on the utilization of reconstructive plates based on available literature. Subsequently, a stress-strain analysis of the lower jaw with the two different applied reconstructive plates was performed using computational modeling, specifically employing the finite element method within ANSYS Workbench 22.2. The thesis provides a detailed description of the creation of two variations of the computational model, followed by an evaluation of the stress and deformation exhibited by the system.
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