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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.
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Aluminium foams and their applications in engineering practice
Belák, Kristián ; Čížek, Jan (referee) ; Němec, Karel (advisor)
Bachelor thesis includes knowledge of aluminum foams and their practical use. The first part of the thesis is focused on the basic characteristics of aluminum and its alloys, consequently, there are characterized metal foams and stated their basic division. Further, there is also devoted considerable attention to selected methods of its manufacturing. Also, properties of these foams are mentioned, mainly the most important ones – mechanical. Thesis deals even about technological processing of foams and the last part contains description of selected applications of metal foams in technical practice.
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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.
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Semi-automated assessment of micromechanical properties of the metal foams on the cell-wall level
Krčmářová, Nela ; Šleichrt, J. ; Doktor, T. ; Kytýř, Daniel ; Jiroušek, O.
Metal foams are innovative porous material used for wide range of application such as deformation energy or sound absorption, filter material, or microbiological incubation carrier. To predict mechanical properties of the metal foam is necessary to precisely describe elasto–plastic properties of the foam on cell–wall level. Indentation with low load is suitable tool for this purpose. In this paper custom designed instrumented microindentation device was used for measurement of cell-wall characteristics of two different aluminium foams (ALPORAS and ALCORAS). To demonstrate the possibility of automated statistical estimation of measured characteristics the device had been enhanced by semi-automatic indent positioning and evaluation procedures based on user-defined grid. Vickers hardness was measured on two samples made from ALPORAS aluminium foam and one sample from ALCORAS aluminium foam. Average Vickers hardness of ALPORAS foam was 24.465 HV1.019 and average Vickers hardness of ALCORAS was 36.585 HV1.019..
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Aluminium foams and their applications in engineering practice
Belák, Kristián ; Čížek, Jan (referee) ; Němec, Karel (advisor)
Bachelor thesis includes knowledge of aluminum foams and their practical use. The first part of the thesis is focused on the basic characteristics of aluminum and its alloys, consequently, there are characterized metal foams and stated their basic division. Further, there is also devoted considerable attention to selected methods of its manufacturing. Also, properties of these foams are mentioned, mainly the most important ones – mechanical. Thesis deals even about technological processing of foams and the last part contains description of selected applications of metal foams in technical practice.
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Investigation of deformation behaviour of aluminium foam under high-strain rate loading and comparison with conventional energy absorbing material
Zlámal, P. ; Fíla, Tomáš ; Jiroušek, O. ; Králík, V.
The aim of this study is proper description of stress-strain behaviour of the metal foam structure Alporas under high-strain rate loading. Stress-strain response of Alporas specimens is measured during an impact test using a drop tower experiment. Strain of the specimens is evaluated by two independent approaches: i) double numerical integration of acceleration data and ii) digital image correlation technique. Thus, experimental setup is equipped with triaxial accelerometer and high speed camera. Resulting stress-strain curves are compared with behaviour of polystyrene material samples (polystyrene material is commonly used as a shock absorber) obtained from the same testing procedure and with stress-strain function determined from Alporas quasi-static compression testing.
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Experimental study on size effect in quasi-static compressive behavior of closed-cell aluminium foams
Koudelka_ml., Petr ; Zlámal, Petr ; Kytýř, Daniel ; Fíla, Tomáš ; Jiroušek, Ondřej
The size effect in compressive deformation behaviour of commercially available aluminium closed-cell foam Alporas was studied under quasi-static loading conditions with different boundary conditions. Dimensions of the specimen’s cross-section were selected to match those of sufficient representative volume element (RVE) obtained by spectral analysis of the macroscopic structure whereas different heights of specimens were tested to examine size-scaling factor. Mechanical properties were derived from three different data sources: I) using data captured by load-cell, II) by digital image correlation (DIC) of displacement of contact faces, III) by DIC of the specimen’s structure. Mechanical testing was performed in custom-built loading device as well as in Instron 4301 electromechanical testing system with custom computer control software.
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