Quantitative analysis of strain rate and failure modes in sandwich structures under high-velocity impact for ballistic performance optimization

Sandwich structures, known for their high energy absorption capabilities, play a crucial role in enhancing impact resistance in engineering applications. The quantitative relationship between strain rate, peak stress, and energy absorption in aluminum foam core sandwich structures has not been well studied. This research focuses on an aluminum foam core-based sandwich structure to elucidate this relationship through an empirical formula derived from Split-Hopkinson Pressure Bar (SHPB) testing. The formula effectively predicts the dynamic increase factor and energy absorption across various strain rates. Additionally, a finite element model was employed to examine the influence of strain rate on the structure's resistance to high-velocity impacts. It was found that the incidence of failures in the core's rear section escalates with strain rate, primarily due to the convergence of compression waves at the interface. Furthermore, the study investigated the ballistic performance of these structures, noting an increase in shear and tension failures as velocity rises. The combined experimental and numerical analysis presented herein offers a comprehensive understanding and contributes new insights into the design of multilayer sandwich configurations that optimize impact resistance while maintaining lightweight characteristics.