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Opis: This paper proposes an innovative multi-material approach for introducing auxetic behaviour to syntactic foams (SFs). By carefully designing the size, shape, and orientation of the SFs, auxetic deformation behaviour was induced. Re-entrant hexagon-shaped SF elements were fabricated using expanded perlite (EP) particles and a plaster of Paris slurry first. Then, an auxetic pattern of these SF elements was arranged within a stainless-steel casting box. The empty spaces between the SF elements were filled with molten aluminium alloy (A356) using the counter-gravity infiltration casting technique. The cast auxetic composite had a bulk density of 1.52 g/cm3. The cast composite was then compressed under quasi-static loading to characterise its deformation behaviour and to determine the mechanical properties, especially the Poisson’s ratio. The cast composite deformation was auxetic with a Poisson’s ratio of −1.04. Finite Element (FE) simulations were conducted to understand the deformation mechanism better and provide means for further optimisation of the geometry.
Ključne besede: auxetic cellular structure, syntactic foams, experimental tests, mechanical properties, Poisson’s ratio
Objavljeno v DKUM: 28.03.2024; Ogledov: 222; Prenosov: 30
Celotno besedilo (8,46 MB)
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Opis: Rigid metallic fiber structures made from a variety of different metals and alloys have been investigated mainly with regard to their functional properties such as heat transfer, pressure drop, or filtration characteristics. With the recent advent of aluminum and magnesium-based fiber structures, the application of such structures in light-weight crash absorbers has become conceivable. The present paper therefore elucidates the mechanical behavior of rigid sintered fiber structures under quasi-static and dynamic loading. Special attention is paid to the strongly anisotropic properties observed for different directions of loading in relation to the main fiber orientation. Basically, the structures show an orthotropic behavior; however, a finite thickness of the fiber slabs results in moderate deviations from a purely orthotropic behavior. The morphology of the tested specimens is examined by computed tomography, and experimental results for different directions of loading as well as different relative densities are presented. Numerical calculations were carried out using real structural data derived from the computed tomography data. Depending on the direction of loading, the fiber structures show a distinctively different deformation behavior both experimentally and numerically. Based on these results, the prevalent modes of deformation are discussed and a first comparison with an established polymer foam and an assessment of the applicability of aluminum fiber structures in crash protection devices is attempted.
Ključne besede: aluminum fiber, fiber structure, orthotropy, sintering, compression, static loading, dynamic loading, energy absorption, numerical simulation
Objavljeno v DKUM: 21.06.2017; Ogledov: 1148; Prenosov: 575
Celotno besedilo (23,30 MB)
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