Improved buffering performance of negative Poisson's ratio metamaterial based on bamboo bionic design

Hybrid aquatic-aerial vehicle (HAAV) susceptible to tremendous impacts when entering water at high speeds, leading to structural damage and internal component failure. Improving the buffering performance of the head structure of HAAV is crucial. In this work, an impact resistant metamaterial with negative Poisson's ratio (IRMN) was proposed by introducing the pores existing in the microstructure of bamboo into the honeycomb metamaterial. Compression deformation tests and finite element analysis were conducted on the metamaterials fabricated by additive manufacturing. The deformation of IRMN exhibited a nonlinear response with compressive loads. Facing small loads, the presence of pores inhibited the growth of the effective stiffness of IRMN by changing stress distribution, and the structure was more prone to absorb energy through deformation. Facing larger loads, the effective stiffness of IRMN climbed sharply driven by auxetic effect, and the structural stability was enhanced to prevent damage. When the compression amount of samples increased to 20 (mm), the reaction force of IRMN improved by 177.30% compared to traditional honeycomb structure, presenting a better resistance to external force. Therefore, IRMN possessed the potential to be an efficient energy absorption structure due to its greater stiffness, stronger energy absorption and better stability.