High-velocity impact response of 3D-printed composite mechanical metamaterials

This study explores the high-velocity impact response of 3D-printed composite mechanical metamaterials through a combination of experimental testing and numerical simulations. Auxetic structures demonstrated a marked reduction in transmitted force and an extended force duration, both of which are advantageous for mitigating impact-related injuries. Specifically, the double arrowhead auxetic geometry reduced the transmitted force by 44% compared to conventional hexagonal structures, albeit at the cost of 17% greater deformation. Novel hybrid designs, integrating auxetic and conventional geometries, achieved a decoupled control of deformation and force responses. For instance, a re-entrant auxetic structure on the impact face, transitioning into a hexagonal configuration, led to a 10% increase in deformation compared to the reverse orientation while maintaining a similar transmitted force. Additionally, a comprehensive parametric study was conducted to examine the influence of cell size and relative density on the overall impact performance of these metamaterials. • Validated impact model for 3D-printed auxetics aligns closely with experimental data. • Auxetic designs drastically minimise transmitted impact forces. • Ballistic performance shaped by cell geometry, size, and density variations. • Hybrid auxetic layouts enable tailored control over impact force and deformation.