Reinforcement of 3D‐Printed Re‐Entrant Structures using Additional Supports under Three‐Point Bending, Experimental and Numerical Analyses

Because of the significant effect of geometry on the mechanical properties of auxetic structures, this work focuses on enhancing the re‐entrant hexagonal honeycomb properties, as an auxetic cellular structure with widespread use, by modifying its unit cell's geometry. Herein, six novel structures with additional struts added as supports to the structure are designed to improve the specific energy absorption capacity and flexural modulus. The results reveal that adding supports significantly increases the maximum force tolerated by the structure in the same undergone displacement as the conventional re‐entrant. Furthermore, the findings indicate that honeycombs with concave curved supports outperform conventional re‐entrant honeycombs, showing a significant enhancement in flexural modulus (Ef) by ≈282%, energy absorption, and specific energy absorption by over 297%. Moreover, angle support structures demonstrate outstanding outcomes compared to simple straight supports and single‐support structures. Additionally, a parametric study is carried out using the validated finite‐element model to analyze the influence of the supports’ thickness and radius as well as the distance between the middle of the unit cell and the support (L3) in honeycombs with concave curved supports and the β angle of angle supports in the double‐angle support structures. Adding supports significantly increases the maximum force tolerated by the structure. Honeycombs with concave curved supports outperform conventional re‐entrant honeycombs, showing a significant enhancement in flexural modulus (Ef) by ≈282%, energy absorption, and specific energy absorption by over 297%.