Energy absorption performance study of bio-inspired hierarchical honeycomb structures with curved cell walls under Quasi-static loading

Abstract The mechanical performance and energy absorption capability of honeycomb structures are strongly influenced by their geometric configuration. However, conventional honeycombs with straight cell walls often suffer from premature buckling and high peak crushing force (PCF), limiting their crashworthiness efficiency. In this study, a novel grass stem-inspired hierarchical honeycomb structure with curved cell walls was developed by modifying the conventional hexagonal geometry to enhance energy absorption performance. The axial crushing behavior of the proposed structures was investigated through quasi-static compression experiments and validated finite element (FE) simulations. Two configurations, including a conventional straight cell-wall honeycomb and a convex curved cell-wall honeycomb, were fabricated using 3D-printed polylactic acid (PLA) and evaluated experimentally. The results demonstrated that the convex curved cell-wall honeycomb improved specific energy absorption (SEA) while reducing PCF compared with the conventional design. The FE models showed good agreement with experimental results, confirming their reliability for further analysis. Parametric investigation revealed that wall thickness mainly controls load-carrying capacity, whereas curvature radius influences deformation stability and energy absorption behavior. Furthermore, multi-objective optimization was performed to maximize SEA and minimize PCF. The optimized design achieved a 2.18% increase in SEA and a 19.75% reduction in PCF compared with the conventional honeycomb, demonstrating its potential for lightweight crashworthiness applications.