Novel negative-zero-positive Poisson's ratio graded mechanical metamaterials for enhanced energy absorption: Performance investigation and design optimization

A novel gradient mechanical metamaterial with a variable Poisson's ratio (VPR) integrated with thin-walled skin is proposed for enhanced energy absorption, demonstrating potential for impact mitigation applications. Constructed by stacking layers of a varying cellular structure, the proposed VPR structure exhibits the collapse permeability resistance of auxiliary materials and the lateral expansion of positive Poisson's ratio (PPR) materials in different regions. The concept is analyzed through numerical simulations of the impact loading on the proposed VPR structure, followed by experimental validation using 3D-printed specimens. To further enhance the energy absorption performance, the influential parameters of the VPR structure are rigorously optimized within a multi-objective optimization framework. The results demonstrate that the optimal VPR structure is more resistant to global buckling instability compared to a uniform negative Poisson's ratio (NPR) structure. Additionally, during compression energy absorption, the VPR structure distributes impact forces more evenly over a longer duration than the NPR structure of the same mass. Specifically, the DD-VPR type can increase specific energy absorption (SEA) by 60 % with only an 11 % increase in peak loading force (PLF), while the AD-VPR type can boost SEA by up to 67 % with a 20 % increase in PLF. • A novel structure with variable Poisson’s ratio (VPR) metamaterial and thin-wall skin designed. • Numerical model developed and specimen fabricated for thorough experimental validation. • Integrated multi-objective optimization framework established for effective design. • Optimized solutions with enhanced specific energy absorption and peak loading force.