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Homogenization of open foam structures using Kelvin cell
Barančík, Milan ; Navrátil, Petr (referee) ; Skalka, Petr (advisor)
The bachelor thesis deals with homogenization of open foam structures using Kelvin cell. A computational model of the foam structure was created and converted into a computational model of solid with corresponding material characteristics in ANSYS software. Subsequently, a parametric study of the effect of Kelvin cell proportions on solid material characteristics was done. The output of the study was a generalization of the dependence of solid material characteristics on Kelvin cell proportions. Lastly, the suitability of the generalization was verified and achievements were evaluated.
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Determination of the elastic characteristics of highly-porous materials by means of the impulse excitation technique
Kollmann, Marek ; Lošák, Petr (referee) ; Ševeček, Oldřich (advisor)
The bachelor thesis dealt with the application of pulse excitation technique (IET) to determine the elastic characteristics of highly-porous materials. The first part explained the principle of this method together with the arguments for use outside the conditions given by the standard. In the next part, a model of foam structure with open porosity based on Kelvin cell was created in ANSYS software. The influence of porosity and cell size on its elastic characteristics was determined on the model. It was showed to agree with the theory according to Gibson and Ashby. The result of the work was the evaluation of the possibility of using IET to determine these characteristics, these results were then compared with the experimental values. It turned out that the IET provides the correct information about the stiffness of the model.
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Determination of mechanical properties of open ceramic foam structure using finite element method
Barančík, Milan ; Navrátil, Petr (referee) ; Skalka, Petr (advisor)
The thesis is concerned with creating of a computational model of open-cell ceramic foam and determining mechanical properties of open-cell ceramic foam using computational modeling. The geometry of Kelvin cell was used for creating the model of geometry of the foam. The model of geometry of ceramic foam structure was meshed with solid elements, with beam elements and with combination of rigid beam and beam elements. Elastic properties of the foam were determined by two types of mechanical loading. Young´s modulus and Poisson´s ratio were determined by tensile/compressive mechanical loading and shear modulus was determined by shear mechanical loading. The relationship between mechanical properties of the foam and the ratio of diameter of strut D and length of strut L was analysed in the thesis. A good agreement was found out between Young´s modulus determined by solid element based and Young´s modulus determined by modified beam based model of geometry of the foam structure – for ratio D/L up to 0,6. In the case of Poisson´s ratio a good agreement was determined up to D/L = 0,4. In conclusion the value of Young´s modulus 1,97 GPa which was determined by computational modeling was compared with the value 1,56 GPa which was determined experimentally on ceramic foam. This difference was caused by idealization of geometry of the real ceramic foam material. In addition, mechanical properties of the ceramic foam material are influenced by structural imperfections of the material.
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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.
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Determination of the elastic characteristics of highly-porous materials by means of the impulse excitation technique
Kollmann, Marek ; Lošák, Petr (referee) ; Ševeček, Oldřich (advisor)
The bachelor thesis dealt with the application of pulse excitation technique (IET) to determine the elastic characteristics of highly-porous materials. The first part explained the principle of this method together with the arguments for use outside the conditions given by the standard. In the next part, a model of foam structure with open porosity based on Kelvin cell was created in ANSYS software. The influence of porosity and cell size on its elastic characteristics was determined on the model. It was showed to agree with the theory according to Gibson and Ashby. The result of the work was the evaluation of the possibility of using IET to determine these characteristics, these results were then compared with the experimental values. It turned out that the IET provides the correct information about the stiffness of the model.
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Determination of mechanical properties of open ceramic foam structure using finite element method
Barančík, Milan ; Navrátil, Petr (referee) ; Skalka, Petr (advisor)
The thesis is concerned with creating of a computational model of open-cell ceramic foam and determining mechanical properties of open-cell ceramic foam using computational modeling. The geometry of Kelvin cell was used for creating the model of geometry of the foam. The model of geometry of ceramic foam structure was meshed with solid elements, with beam elements and with combination of rigid beam and beam elements. Elastic properties of the foam were determined by two types of mechanical loading. Young´s modulus and Poisson´s ratio were determined by tensile/compressive mechanical loading and shear modulus was determined by shear mechanical loading. The relationship between mechanical properties of the foam and the ratio of diameter of strut D and length of strut L was analysed in the thesis. A good agreement was found out between Young´s modulus determined by solid element based and Young´s modulus determined by modified beam based model of geometry of the foam structure – for ratio D/L up to 0,6. In the case of Poisson´s ratio a good agreement was determined up to D/L = 0,4. In conclusion the value of Young´s modulus 1,97 GPa which was determined by computational modeling was compared with the value 1,56 GPa which was determined experimentally on ceramic foam. This difference was caused by idealization of geometry of the real ceramic foam material. In addition, mechanical properties of the ceramic foam material are influenced by structural imperfections of the material.
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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.
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Homogenization of open foam structures using Kelvin cell
Barančík, Milan ; Navrátil, Petr (referee) ; Skalka, Petr (advisor)
The bachelor thesis deals with homogenization of open foam structures using Kelvin cell. A computational model of the foam structure was created and converted into a computational model of solid with corresponding material characteristics in ANSYS software. Subsequently, a parametric study of the effect of Kelvin cell proportions on solid material characteristics was done. The output of the study was a generalization of the dependence of solid material characteristics on Kelvin cell proportions. Lastly, the suitability of the generalization was verified and achievements were evaluated.
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