Ballistic performance of a novel auxetic core in sandwich structures under impact loading

To enhance energy absorption and ballistic resistance, a novel auxetic unit cell is incorporated into sandwich structures and evaluated in this work. Starting from a perforated design domain and tested under regulated compressive and impact loading conditions, a topology optimization technique is used to create a re-entrant braced auxetic (REBA) geometry with auxetic behavior. When compared to traditional designs, the resultant unit cell significantly improves specific energy absorption under quasi-static compression and shows a negative Poisson’s ratio. Finite element simulations confirm that the optimized core offers enhanced mechanical performance compared to conventional lattice designs. Using a hemispherical shell, the new unit cell is further incorporated into a sandwich design with many layers, mimicking the use of ballistic impact. Superior ballistic resistance and energy dissipation over conventional core designs are demonstrated by high-velocity impact simulations, highlighting the suggested structure’s potential for defensive applications. The results demonstrate how well topology-driven design works to customize cellular materials for impact loads.