numerical analysis of core geometry and material influences on the impact performance and dissipated energy of composite sandwich helmets

This study numerically investigates the influence of core material and internal geometry on the dynamic response of multi-layer composite helmet liners under impact. unlike prior work focusing on single materials or geometries, this research performs a systematic parametric analysis of sandwich-style helmets combining five core materials—aluminum, carbon fiber, fiberglass, kevlar, and polyurethane foam—with three cellular geometries (hexagonal, triangular, square). using finite element simulations in abaqus 6.14 per iranian standard 875, the cores (6 mm thick) are sandwiched between 3 mm carbon fiber/epoxy skins and subjected to uniform impact loads. results show honeycomb-like carbon fiber cores in hexagonal geometry achieve superior energy absorption and minimal displacement (2.995 mm), outperforming aluminum (8.338 mm) and polyurethane foam (23.61 mm) by 35% and 55%, respectively. however, square aluminum cores exhibit the highest structural stability across materials, indicating stable performance regardless of geometry. sensitivity analysis reveals carbon fiber cores’ effectiveness depends strongly on geometry, while aluminum cores are less sensitive, underscoring the importance of matching materials to topology. based on these findings, a hybrid design is proposed combining carbon fiber skins with an aluminum honeycomb core to optimize impact resistance and minimize deformation. this study highlights pathways for engineering helmet liners that balance energy dissipation and structural integrity. future work should explore hybrid cores, full-scale drop tests, and injury modeling to advance helmet designs for civilian, military, and sports applications.