Energy absorption and indentation resistance of re-entrant arched honeycomb reinforced by circular ribs

Abstract To enhance the mechanical properties while keeping controlled auxetic performance, a novel circular reinforced re-entrant arched honeycomb (CRRAH) structure is developed. CRRAH specimens were additively manufactured, and quasi-static compression tests were conducted to evaluate their performance. Results demonstrate that superior mechanical performance is presented by comparing to the conventional re-entrant arched honeycomb structures, including a remarkable 208% increase in specific energy absorption (SEA). The finite element model, validated against experimental results, was further used to explore the deformation mechanism and auxetic performance of CRRAH structures with varying thickness ratios (γ). Results indicated that integrating circular rib within the re-entrant cells effectively restricts the continuous rotational stretching of inclined ligaments, resulting in a two-stage collapse process. This significantly enhances the deformation stability and energy absorption capacity. Moreover, adjusting the thickness ratio γ shifts the deformation mode from localized shear band formation to uniform global deformation with slight lateral expansion. Moreover, the dependence of deformation and the indentation resistance performance on thickness ratio were explored and the underlying mechanism was revealed. These findings provide valuable insights into the design of advanced re-entrant honeycomb structures, combining improved crashworthiness with controlled auxetic effects.