ABSTRACT The selection of the appropriate materials and structures for enhanced energy absorption is paramount in the design of protective gear, regardless of the final application. This research addresses a long‐standing academic debate regarding the effectiveness of auxetic structures in mitigating impacts relative to open‐cell foam counterparts by developing a comparative, energy‐based framework to conclusively establish auxetic structures as the superior option. The framework calculates the energetic performance across the elastic, plateau, and densification regions, utilizing consistent bulk material: polyurea, irrespective of the type of cellular solid (open‐cell foam vs. re‐entrant auxetic). The material properties were found to play a major role in the mechanical performance of open‐cell foams; therefore, they were investigated parametrically. Furthermore, the study examines the critical effect of the auxetic structure's characteristic re‐entrant angle on its energy absorption mechanisms. The results demonstrate that the auxetic structures significantly outperform the open‐cell foams, reporting a four‐fold increase in specific energy absorption. This outcome definitively concludes the discussion in favor of auxetic metamaterials. Crucially, amplifying the initial auxetic angle resulted in a significant seven‐fold increase in energy absorption across the explored re‐entrant range (50° to 85°), providing mechanical designers with a powerful new tool for tailoring energy absorption properties.
Youssef et al. (Sun,) studied this question.