Investigation of low-velocity impact response of AlSi10Mg auxetic structures fabricated with different build orientations by SLM

This study was conducted to clarify the combined effects of build orientation and unit-cell topology on the low-velocity impact response of selective laser melted AlSi10Mg auxetic lattice structures, since further comparative experimental evidence under identical design conditions is still valuable. Re-entrant, arrowhead, star-shaped, and missing-rib structures fabricated at 0°, 45°, and 90° were tested at impact energies of 20, 40, and 60 J. The impact response was evaluated using contact force-time, force-displacement, and energy-time histories, along with image-processing-based surface damage assessment, radiographic inspection, and cross-sectional analysis. The absorbed energy was primarily governed by the applied impact energy, ranging from 18.67–19.48 J at 20 J, 38.70–39.88 J at 40 J, and 59.84–61.38 J at 60 J. In contrast, peak contact force and deformation behavior strongly depended on build orientation and unit-cell geometry. The arrowhead structure exhibited the highest load-carrying capacity, reaching 19877 N at 60 J and 0° build orientation, whereas the re-entrant and missing-rib structures showed higher deformation, with a maximum displacement of 11.20 mm. Increasing build orientation reduced peak contact force and promoted a transition from stiffness-dominated to deformation-controlled behavior. Damage evolved from localized indentation to progressive cell collapse and distributed internal damage with increasing impact energy. RSM analysis further confirmed that impact energy dominated absorbed energy, whereas cell geometry and build orientation mainly governed peak contact force and deformation response. The most favorable impact performance was obtained for the arrowhead geometry fabricated at low build orientation.