On the Influence of Viscous Filler on the Impact Resistance of Flexible Metamaterials with Auxetic Properties

The properties of flexible metamaterials with negative Poisson’s ratio (with an auxetic structure based on a cell in the form of a concave hexagon) to resist penetration by a rigid spherical striker along the normal were experimentally studied. Samples with a chiral structure, manufactured using a 3D printer from thermoplastic polyurethane (TPU 95A plastic), with cells filled with air or gelatin were compared for their ability to reduce the kinetic energy of strikers. The experiments were conducted for two speed modes. It was found that filling auxetic chiral samples made of TPU 95A plastic with gelatin (in contrast to the previously studied rigid metamaterials based on e-PLA plastic) does not lead to an increase in protective properties. According to the results of the experiments for two speed modes, the most effective in terms of resistance to penetration by a striker were flexible and lightweight samples made of thermoplastic polyurethane filled with air.