Sustainable polycarbonate hierarchical square honeycomb structures for energy absorption

• Introduced a new sustainable hierarchical honeycomb for superior energy absorption. • 2nd order HSHS achieves 78.1 % higher energy absorption than 1st order HSHS. • Interlocking HSHS rivals non-interlocking in energy absorption efficiency. • HSHS offers a sustainable, cost-effective alternative to 3D printing, EDM cutting. • Enhanced HSHS outperforms popular cellular structures in energy absorption. The study presents a new approach to repurpose polycarbonate panels in designing sustainable hierarchical square honeycomb structures (HSHS) with enhanced energy absorption. The proposed structures are fabricated using a multi-wall polycarbonate sandwich panel combined with interlocking mechanisms. The 1 st order HSHS is constructed with a single sandwich panel, while the 2 nd order HSHS employs double sandwich panels, leveraging the hierarchical design and interlocking features to significantly enhance mechanical properties and energy absorption performance. To evaluate the performance of the proposed structures, a comprehensive investigation was conducted using quasi-static compression tests and finite element analysis. Experimental results and parametric studies demonstrated that the 2 nd order HSHS significantly outperforms the 1 st order HSHS and conventional square honeycomb structures in terms of energy absorption capacity. Specifically, the 2 nd order HSHS exhibits a 78.1 % higher energy absorption compared to the 1 st order HSHS and a 53 % higher specific energy absorption compared to the conventional square honeycomb. Additionally, its specific energy absorption is 20–30 % higher than other bio-inspired structures such as bio-hierarchical circular honeycombs (BHCH) and cuttlebone-like architectures. The parametric study further revealed that the specific energy absorption of the HSHS with interlocking mechanisms is comparable to that of non-interlocking HSHS, highlighting the effectiveness of the interlocking approach. This finding suggests that interlocking mechanisms are a viable alternative to traditional fabrication methods such as 3D printing and wire EDM cutting, offering a more efficient and potentially cost-effective solution. In addition to energy absorption, the HSHS demonstrated superior relative energy absorption compared to other popular cellular structures. This research paves the way for sustainable advancements in material design and engineering, contributing to safer and more efficient structural solutions across various industries.