Anti-impact behavior of auxetic sandwich structure with braided face sheets and 3D re-entrant cores

The effectiveness of sandwich structure with auxetic 3D re-entrant lattice core and semi-auxetic braided composite face sheets subjected to high-velocity impact have been investigated. Braided carbon fiber composite used in face sheets of sandwich structure with a through-thickness negative Poisson's ratio significantly improves the impact performance. A semi-analytical Mori-Tanaka asymptotic homogenization, mechanics of structure genome, and multiscale finite element scheme have been applied to study the mechanical properties and auxeticity of the braided composite. The properties obtained at the lower scales are used in a macroscale progressive damage analysis and impact simulations of semi-auxetic braided composite. The results obtained have been compared with experimental data from the literature for validation. The sandwich core holds further scope for tailoring its architecture that can enhance the sandwich performance. The high-velocity steel ball impact response of the sandwich structure with two types of auxetic 3D re-entrant lattice core have been simulated and compared with a non-auxetic core. Parametric studies have been performed at the mesoscale to study the influence of lattice angle on homogenized effective properties of the core. Compared to non-auxetic foam, proposed auxetic sandwich structures are lightweight, have better energy absorption and high stiffness values in the in plane along with out-of-plane directions. A case study of trauma plate for the application of proposed auxetic lattice reinforced polyethylene composite in body armors is presented.