|
|
Computational simulation of the compression test of the open cell metal foam
Homola, Václav ; Skalka, Petr (referee) ; Ševeček, Oldřich (advisor)
The thesis presents computational simulation of compression test of a nickel foam and the 3D reconstruction of micro-CT images was utilized to generate the foam’s model of geometry. Explicit FEM is used to simulate compression test using software tool LS-DYNA and the stress–deformation curve is obtained together with deformed model’s mesh used for subsequent analysis. Sensitivity analyses were performed to configure the model and ensure best fit with values obtained during real-life experiment. The ANSYS Classic environment was then used to simulate tensile test of the foam compressed to various thicknesses. The tensile moduli in three mutually perpendicular directions of nickel foam were computed and the results were compared to experimental values as well. The results of tensile test simulation revealed considerable anisotropy of the foam’s elastic behavior. It can be said that the measured experimental data correspond very well with the elastic properties obtained from simulation up to certain level of compression. Analysis of the relationship between the element size and tensile moduli showed a significant difference between fine and coarse mesh. The optimal level of discretization and the overall model configuration ensuring high level of accuracy is proposed in this thesis.
|
|
|
Stress-strain analysis of the axial turbine of turboprop engine
Kolárik, Matej ; Ing. Petr Navrátil, Ph.D (referee) ; Skalka, Petr (advisor)
This diploma thesis deals with a creation and subsequent analysis of the computational model of the turboprop engine's turbine designed by Prvá Brněnská Strojírna Velká Bíteš. The computational model is created and solved in the finite element model system ANSYS. A cyclic symmetry is taken into account during the solution. The static analysis of the turbine was carried out in objective to quatify prestress effects which are caused by a rotation, higher temperature and an excitation from stator blades. These prestress effects were used in the modal analysis of the turbine. Harmonic analysis were calculated to simulate an operation conditions and a resonance state. The results of these analysis indicate that the higher temperature has the biggest impact on the properties of the turbine. It is also shown, that during the operation of the engine the turbine runs in the mode which is not even close to the resonance state.
|
|
|
Homogenization of closed foam structures using Kelvin cell
Škoviera, Jozef ; Navrátil, Petr (referee) ; Skalka, Petr (advisor)
The bachelor‘s thesis deals with creating calculation model of the foam structure based on Kelvin cell with closed porosity. First aim of this work is homogenization of the foam structure by identical deformation response in foam structure and continuum. Second aim is follow-up parametrical study of influence of characteristic measures of Kelvin cell on material characteristics. Task was solved in ANSYS software by method of final elements. Resultant dependences rendering was done in MATLAB software.
|
|
|
Micro-cellular impact absorbers
Rakušan, Jakub ; Ševeček, Oldřich (referee) ; Skalka, Petr (advisor)
This bachelor thesis focuses on micro-cellular impact absorbers. The micro-cellular absorber converts the kinetic energy of the impacting object into the strain energy of the internal structure of the absorber. The thesis focuses on two types of absorbers, namely the absorber with internal auxetic structure and the absorber with internal non-auxetic structure. The same porosity has been kept for both internal structures for further comparison of the characteristics of both the absorbers. As part of this thesis, an impact test was simulated. In this test, objects (cylinders) of different diameters, the same length (identical to the absorber thickness), and different kinetic energy were impacted into the absorber. The finite element method (explicit solution) was used to solve this problem. The output of the study was a comparison of simulations of the impact test into auxetic and non-auxetic structures.
|
|
|
Stress-strain analysis of front seat folding mechanism
Gergeľ, Erik ; Gašparec, Andrej (referee) ; Skalka, Petr (advisor)
This master thesis deals with creation of computational model for stress - strain analysis of front car seat folding mechanism. The calculation has been done using FEM for static and dynamic load case. The results displayed the critical area of mechanism and determined the value of force when the safety of mechanism is not guaranteed and the force when the mechanism failure occurs. According to results from both load cases was made a statement that is necessary to model the dynamic load cases respecting the load time course.
|
|
|
Radial turbine runner design with reduced moment of inertia
Votava, Ondřej ; Skalka, Petr (referee) ; Fuis, Vladimír (advisor)
This master’s thesis deals with topological optimization of the impeller of a radial turbocharger turbine. It focuses on reducing the moment of inertia with unchanged aerodynamic properties. The optimization was carried out using CFD, thermal and structural analysis. The computational modeling was performed using the finite element analysis in ANSYS. The work proposes models of the impeller with the topological modification of the internal structure. Based on the values of moment of inertia, the stress and the strain the most suitable model was selected.
|
|
|
Frequency modal analysis of blade package of steam turbine
Přikryl, František ; Skalka, Petr (referee) ; Malenovský, Eduard (advisor)
This thesis deals with comparison the results of the frequency modal analysis of blade package of steam turbine with stiffening or damping bounding elements. Computational model was created through the finite element method, using cyclical symmetry. The results were compared with experimental analysis and analysis in VIPACK programme. Thesis also contains creating the solid blade model, using the reverse engineering.
|
|
|
Finite element simulation of stresses in plasma-sprayed thermal barrier coating
Lacina, Zdeněk ; Slámečka, Karel (referee) ; Skalka, Petr (advisor)
Bachelor‘s thesis focuses on the study of stress states in thermal barrier coatings. A two-dimensional computational model of thermal barrier coating was created using ANSYS software, on which the process of cooling of thermal barrier from working temperature to room temperature was simulated .The stress distribution in ceramic layer was studied then. The output of this thesis is a description of the influence of roughness, amplitude and TGO layer on the stresses in a ceramic layer of thermal barrier. Matlab software was used to process the results.
|
|
|
Computational analysis of auxetic structures application potential in impact absorbers
Dohnal, Jakub ; Skalka, Petr (referee) ; Ševeček, Oldřich (advisor)
Master thesis deals with the analysis of the application potential of auxetic materials in the field of shock absorption (absorption of impact energy). Due to their cellular structure and specific geometry, these materials are characterized by a negative Poisson’s ratio, which means that they are able to reduce their transverse dimension under compressive stress in the longitudinal direction. The aim of this work is to use this interesting property for the absorption of kinetic energy. After the introduction, devoted to the theoretical basis and research in the field of auxetic structures, a numerical FEM model is described in detail. The task of the model is to study the mechanical response of auxetic and conventional cellular structure to an impact loading. An explicit solver in the commercial software LS-DYNA is used to numerically simulate fast processes. The results of the analyses are used to compare auxetic and conventional structures and quantify the differences in their ability to dampen the kinetic energy of the impact effectively and gently. It also serves to demonstrate the influence of individual geometric or material parameters on impact attenuation. At the end of the work, numerical simulations are confronted with available experiments in order to verify the informative value of computational models and to point out the application potential of auxetic structures in the discussion. There are also partial recommendations for their design so that they best serve the intended purpose.
|
|
|
Stress - strain analysis of bridge structure during the train passage
Kolárik, Matej ; Navrátil, Petr (referee) ; Skalka, Petr (advisor)
The bachelor’s thesis concerns the stress-strain determination of the rail bridge in Komárov during the train crossing. The task was solved in the program ANSYS which uses the finite element analysis. The following factors were taken into consideration: a non-loaded state, the state of a train assembly load, and detailed observation of a continual crossing of diesel train. Following the series of results the most dangerous state was defined and the safety calculated.
|
guest ::
