Tailoring crushing responses of hexagonal crash box filled with additively manufactured lattice structures by assessing the influence of material parameters

Hexagonal crash boxes offer superior crashworthiness compared to other cross-sectional geometries, and their performance can be further enhanced by integrating additively manufactured lattice fillers. This study investigates the quasi-static crushing behavior of hexagonal crash boxes filled with hexagonal close-packed (HCP) lattice structures fabricated via stereolithography (SLA). Finite element models developed in ABAQUS/Explicit, validated against quasi-static compression experiments, show discrepancies below 5%, indicating that polymeric lattice fillers provide modest performance gains, achieving a crushing force efficiency (CFE) of 20%–25%. Replacing polymeric lattices with metallic fillers, namely 316L stainless steel and Ti–6Al–4V titanium alloy, substantially increases energy absorption, with Ti–6Al–4V delivering the highest specific energy absorption ( S E A ) due to its favorable strength-to-weight ratio. The combined experimental–numerical investigation demonstrates that both lattice architecture and material selection critically control crash performance, highlighting the trade-off between total energy absorption and mass efficiency. These findings provide an engineering design strategy for optimizing lightweight, high-performance crashworthy structures using lattice-filled crash boxes, enabling enhanced safety without excessive weight penalties. • Hexagonal close-packed lattice fillers enhance crash box energy absorption. • Finite element models of lattice-filled crash boxes are validated experimentally. • Fracture energy calibration in FE models is required for accurate predictions. • High specific-strength lattice fillers enhance crash box specific energy absorption. • Ti–6Al–4V provides the highest specific energy absorption among studied materials.