Radial Buckling‐Harnessed Auxetic Effect for Enhanced Energy Absorption in Snowflake‐Perforated Honeycomb Metamaterials

Advancing multifunctional mechanical metamaterials requires harmonizing auxetic behavior (negative Poisson's ratio, NPR) with high‐energy absorption (EA) capabilities. This study presents a snowflake‐perforated honeycomb metamaterial where radial buckling activates NPR‐driven EA enhancement. Plastic hinges at 45° ligaments initiate auxetic contraction, while NPR‐induced transverse compression forces hierarchical folding, delaying densification and amplifying energy dissipation. Geometric parameters ( a/b , d ) tune this cooperative mechanism within an optimal design window, enabling NPR to intrinsically reinforce EA. Integrated experiments and simulations confirm that NPR actively elevates EA through biaxial strain constraints and extended folding sequences. Parametric studies establish aspect ratio ( a/b ) as the primary regulator of NPR‐EA synergy, while inscribed diameter ( d ) governs structural stability. A gradient design strategy further leverages NPR‐induced compaction through spatially coordinated parameters, maximizing multifunctional performance. This work pioneers a tunable metamaterial paradigm where NPR fundamentally fortifies impact protection.