Performance study of two-ways gradient octagonal hierarchical honeycomb with excellent energy absorption and crashworthiness properties

The demand for lightweight structures with outstanding energy absorption capabilities is increasingly critical. Inspired by the stability inherent in triangular configurations, this study introduces an Octagonal Self-similar Hierarchical Honeycomb (OSHH), designed by integrating multiple triangles into a hierarchical system within an octagonal framework. To further enhance its performance, gradient strategies and hierarchical strategies are applied. This research systematically evaluates the energy absorption capacity and crashworthiness of the Two-Way Gradient Octagonal Hierarchical Honeycomb (TWGOHH) through experimental and numerical simulation methods. The study explores the effects of various gradient distribution strategies, angular gradient coefficients, length gradient coefficients, dual-parameter gradients (angle and length), and hierarchical strategies on structural performance. Results from numerical simulations reveal significant performance improvements driven by both gradient and hierarchical strategies. The gradient strategy enhances the energy absorption (EA), specific energy absorption (SEA), and crush force efficiency (CFE) by approximately 15 %, while the hierarchical strategy achieves increases exceeding 35 %. Additionally, the hierarchical strategy substantially reduces the Poisson's ratio under impact, which is crucial for performance enhancement. By integrating gradient and hierarchical strategies, the honeycomb structures exhibit notable improvements, offering fresh perspectives for advanced honeycomb structure design.