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Energy absorption of cellular foams in high strain rate compression test
Králík, V. ; Němeček, J. ; Jíra, A. ; Fíla, Tomáš ; Zlámal, P.
Aluminum foams are structural materials with excellent energy absorption capacity jointed with very low specific weight and high stiffness. Products of aluminum foams are used in a wide range of structural and functional applications (e.g. as a part of composite protection elements) due to its attractive properties. Full characterization of deformation behaviour under high-strain rate loading is required for designing these applications. The aim of this study is to compare stress-strain behaviour and energy absorption of the aluminium foam structure with conventional energy absorbing materials based on polystyrene and extruded polystyrene commonly used as protective elements. The compressive deformation behaviour of the materials was assessed under impact loading conditions using a drop tower experimental device.
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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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Dynamic impact tester of hard thin coatings
Grossman, Jan ; Dupák, Libor ; Fořt, Tomáš ; Sobota, Jaroslav
An impact test has been used to evaluate the impact wear resistance of nanostructured hard coatings using a system developed at the Institute of Scientific Instruments in collaboration with the Brno University of Technology. After the test, wear scars were evaluated by means of scanning electron microscope, spectral analyses and profilometer. The impact test offers an important new method for the determination of both the fracture toughness and wear behaviour of hard thin coatings.
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Institute of Scientific Instruments: An Overview Presenatation
Kolařík, Vladimír ; Zobač, Martin ; Fořt, Tomáš ; Vlček, Ivan ; Dupák, Libor ; Mikmeková, Šárka ; Mikmeková, Eliška ; Mrňa, Libor ; Horáček, Miroslav ; Sobota, Jaroslav
The aim of this contribution is to present the Institute of Scientific Instrument of the Academy of Sciences of the Czech Republic, mainly from the potential of applied research viewpoint. It covers mainly the six application fields including material study of metals and alloys, nano layer residual stress observation methods, 2 kW fibre laser, impact testing of hard coatings, e-beam welding, machining and engraving, and finally e-beam lithography. Recently achieved results as well as the new application potential are presented. Furthermore, each topic is assumed to have a separate presentation prepared in more details within this event. A brief overview follows. Scanning low energy electron microscopy (SLEEM) is increasingly becoming recognized as a valuable analytical tool in the field of materials science. The SLEEM is also used for observation of compressive stress in nano layers that leads to wrinkling and film delamination. Using the fibre laser, we can offer 3D laser welding and cutting of various type of materials and laser surface hardening too. For the hard coatings testing and evaluation of their impact resistance a new method was suggested (Dynamic Impact Wear Test). During testing the specimen is cyclically loaded by tungsten carbide ball that impacts of the coating/substrate surface. In house e-beam welding machine allows for welding, machining, engraving and other utilizations of intense electron beam. The group of micro lithography is able to prepare micro and nano structures in thin layers of metals and other materials; including the characterization of the realized structures
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Simulace rázové zkoušky v ohybu na oceli R7T
Severa, Martin
Rázová zkouška v ohybu dle Charpyho je dynamická zkouška, kterou zjišťujeme chování materiálu při rázovém zatížení. Tato metoda se používá k určení křehkolomového chování. V této práci byl použit Johnsonův -Cookův materiálový model, který předpovídá dynamické chování zkoušeného materiálu. Bylo prezentováno srovnání experimentálních dat a numerických výsledků.
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Hodnocení mechanických vlastností tenkých vrstev a povlaků systémem NanoTest™ NT600
Čtvrtlík, Radim ; Stranyánek, Martin ; Boháč, Petr ; Jastrabík, Lubomír ; Hrabovský, Miroslav
Systém NanoTest™ NT600 je univerzální zařízení určené pro vyšetřování mechanických vlastností tenkých vrstev a povlaků, jež umožňuje měřit tvrdost, vyhodnocovat elastický modul, adhezi, únavové, lomové, ale také dynamické vlastnosti.
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