Computational Simulations of Regular Open-cell Cellular Structures with Fillers

M. Vesenjak, Prof. Z. Ren, Prof. A. Öchsner (University of Maribor) Cellular structures are often used as crash absorbers due to their high capability of impact energy absorption. During the impact the intercellular walls buckle and cells collapse which results in impact energy absorption through deformation. Cell fillers might be used to additionally increase the impact energy absorption capability. The filler is pushed out of the open-cell cellular structure during the compression and thus dissipates additional energy. The paper presents results of parametric computational simulations of impact behaviour of cellular structures with open-cell morphology accounting for fluid fillers. A regular cellular structure has been modelled with the finite element method, while the fluid filler flow was modelled with the meshless method Smoothed particle hydrodynamics (SPH). Fully coupled fluid-structure interaction between the cellular structure base material and the fluid filler was considered. The cellular structure has been subjected to uniaxial compressive impact loading. The computational model has been analyzed with the explicit code LS-DYNA. Additional simulations have been performed also with the ANSYS CFX code in order to validate the SPH fluid models. The computational results have shown that the fluid fillers in cellular structures can significantly influence the capability of impact energy absorption. It was observed that the filler influences are more pronounced in cellular structure with higher relative density than in cellular structures with lower relative density. With further computational simulations it was also determined that the increase of the filler viscosity results in increase of cellular structure stiffness which contributes to higher capability of deformational energy absorption.

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