Energy absorption enhancement in reinforced reentrant auxetic structures through primary to secondary strut interaction

Abstract Re-entrant auxetic lattices exhibiting negative Poisson’s ratio behaviour are attractive for lightweight energy-absorbing applications. However, traditional re-entrant and hexagonal auxetic designs often exhibit low stiffness and premature cell collapse under compressive or impact loading. In this research, the effect of the thickness ratio between primary and secondary struts on the mechanical properties of reinforced re-entrant auxetic lattices produced using fused deposition modelling is investigated. Quasi-static compression testing and numerical analysis using finite element methods are carried out to validate the mechanical performance of these lattices. The optimised reinforced lattice has shown an improvement of approximately 73% in energy absorption and 28% in specific energy absorption compared to the unreinforced lattice. This improvement is mainly attributed to a transition in the deformation mechanism from localized hinge buckling to stable progressive crushing. The optimum thickness ratio between primary and secondary struts (t/t* ≈ 1.0) is found to achieve a balance between mechanical properties. The research provides a design guideline for high-performance lightweight auxetic lattices. Graphical abstract Graphical abstract illustrating the design, experimental–numerical methodology, and performance enhancement of reinforced re-entrant honeycomb auxetic structures