Design and Impact Resistance Analysis of Express Cushioning Materials Based on Biomimetic Gradient Structure

Abstract

With the rapid development of the logistics industry, the contradiction between green packaging and cargo safety has become increasingly prominent. Inspired by the lightweight, high-strength, and graded energy-absorbing microstructure of pomelo peel, this study proposes a novel biomimetic gradient porous cushioning structure. Using the ANSYS Explicit Dynamics module under a constant velocity crushing condition of 4.4 m/s, the impact resistance of three topologies, namely uniform circular holes (U-C), gradient circular holes (G-C), and gradient square holes (G-S), is compared. The simulation results indicate that, compared with the conventional uniform structure, the biomimetic gradient design successfully induces a controllable deformation mode characterized by layer‑by‑layer collapse, effectively reducing the initial impact peak. Among the three structures, G-C exhibits the best overall performance. Its peak contact reaction force is reduced by 16.2% compared with that of the uniform structure, and it avoids the mechanical instability due to stress concentration that occurs in the square-hole structure. Cross-checking the three simulation reports further indicates that the foam masses of the three models are all about 8.76g with only negligible differences. Therefore, the advantage of G-C should be interpreted as better overall cushioning performance under nearly equal-mass conditions, rather than as a direct proof of significantly reduced mass or the highest specific energy absorption. The study demonstrates that the biomimetic gradient circular hole structure has clear potential for impact protection, structural stability, and engineering feasibility in express packaging design.