Mechanical Behavior Analysis of Porous Nested Structures with Negative Poisson’s Ratio

The deformation behavior and energy absorption characteristics of multilayer nested auxetic hexagonal single-cell structures and tandem configurations with different angles, spacing and connection modes were analyzed through quasi-static uniaxial compression experiments, cyclic compression experiments and finite element simulations. The results show that the multilayer nested structure exhibits predominant shear deformation with localized stress concentration at diagonal bar connections, demonstrating lower stress magnitude distribution. The single-cell structures featuring alternating connections with larger angle and reduced spacing exhibit extended plateau phase duration. The specimen with α=65° achieves better energy absorption, where the isotropic connection and increasing spacing enhance the energy absorption capacity. The angle and spacing present analogous effects on the plateau period of both tandem and single-cell structures, while the connection mode demonstrate contrasting influences. Meanwhile, the energy absorption is positively correlated with increased angles and spacing, as well as the variation of the connection mode. Cyclic compression testing induces progressive delamination and plastic fracture in the specimen, predominantly initiating from the second cycle onward, accompanied by stress softening and energy dissipation behaviors that intensify with cycle repetition.