Behavior of sandwich structures with 3D-printed auxetic and non-auxetic cores under low velocity impact: Experimental and computational analysis

In recent years, impact-resistant structures are highly sought after in various fields such automotive and aerospace applications as they proved notable performances, garnering significant success. The aim of this study is to assess the behavior of the 3D-printable honeycombs subjected to low velocity impact, for providing insights into absorbed energy for different core designs: hexagonal, auxetic, and rectangular, considering an equal number of cells across all designs. This work reports the computational and experimental studies conducted for sandwich structures under different impact loading. The experimental impact tests are carried out using a drop weight impact-testing machine. The examined specimen comprises two face-sheets and architected cell core fabricated through the Fused Filament Fabrication (FFF) process made of polylactic acid (PLA). Variations in the geometric design of the cells result in the formation of cores with auxetic and non-auxetic topologies. Uniaxial tensile tests are performed to identify the mechanical properties of the involved biopolymer. The second attempt consists on comparing three architectural core structures under impact test using experimental and computational methods. Our findings highlight the specific influence of core topology on energy absorption in 3D-printed sandwich structures. Results indicate that while all three configurations (hexagonal, re-entrant, and rectangular) demonstrate comparable energy absorption values, the specific mechanisms and efficiencies vary, with re-entrant cores exhibiting distinct behaviors under impact.