Strain-rate dependence for Ni/Al hybrid foams
1 Saarland University, Institute of Applied Mechanics, Campus A4.2, 66123 Saarbrcken, Germany
2 European Commission, Joint Research Centre (JRC), Institute for the Protection and Security of the Citizen (IPSC), European Laboratory for Structural Assessment, via E. Fermi 2749, 21027 Ispra (VA), Italy
3 Academy of Sciences of the Czech Republic, v.v.i., Department of Biomechanics, Institute of Theoretical and Applied Mechanics, Prosecka 76, 190 00 Prague 9, Czech Republic
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Published online: 7 September 2015
Shock absorption often needs stiff but lightweight materials that exhibit a large kinetic energy absorption capability. Open-cell metal foams are artificial structures, which due to their plateau stress, including a strong hysteresis, can in principle absorb large amounts of energy. However, their plateau stress is too low for many applications. In this study, we use highly novel and promising Ni/Al hybrid foams which consist of standard, open-cell aluminium foams, where nanocrystalline nickel is deposited by electrodeposition as coating on the strut surface. The mechanical behaviour of cellular materials, including their behaviour under higher strain-rates, is governed by their microstructure due to the properties of the strut material, pore/strut geometry and mass distribution over the struts. Micro-inertia effects are strongly related to the microstructure. For a conclusive model, the exact real microstructure is needed. In this study a micro-focus computer tomography (μCT) system has been used for the analysis of the microstructure of the foam samples and for the development of a microstructural Finite Element (micro-FE) mesh. The microstructural FE models have been used to model the mechanical behaviour of the Ni/Al hybrid foams under dynamic loading conditions. The simulations are validated by quasi-static compression tests and dynamic split Hopkinson pressure bar tests.
© Owned by the authors, published by EDP Sciences, 2015
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