Gradient Design Enhances Energy Absorption of 3D‐Printed Bio‐Inspired Functionally Graded Honeycombs

Functionally graded structures are prevalent in nature and recognized for their excellent mechanical properties. Inspired by this, this article proposed a novel bio‐inspired functionally graded honeycomb (FGH) with varying wall thickness, fabricated by 3D printing, to enhance structural energy absorption under bending loads. First, a finite element model incorporating the elastic‐plastic behavior, damage, and failure of the FGH was developed and validated against three‐point bending tests. Subsequently, the effects of gradient pattern, gradient ratio ( n ), and maximum wall thickness ( t _max ) on the energy absorption performance of FGH were systematically investigated using statistical methods. The results indicated that the ascending gradient pattern (A‐FGH) exhibits significant potential for enhancing energy absorption. Furthermore, the gradient ratio exerted a more pronounced influence on the energy absorption of A‐FGH than the maximum wall thickness. Response Surface Methodology (RSM) surrogate model and the Nondominated Sorting Genetic Algorithm II (NSGA‐II) were used to simultaneously maximize specific energy absorption (SEA) and minimize peak force ( F _max ) of FGHs. The optimized FGH ( n = 2.15, t _max = 3.17 mm) exhibited a remarkable 51.9% enhancement in SEA compared to uniform honeycomb (UH) without an excessive increase in F _max .