Mechanical performance of 4D-printed honeycombs with various Poisson’s ratios under quasi-static and low-velocity compression

Abstract

Four-dimensional (4D) printing provides a promising route for prototyping reusable energy-absorbing metamaterials that can recover their geometry after large deformation. However, the cyclic performance of 4D-printed shape-memory honeycombs remains governed by topology, loading direction, loading rate, and cold programming history. This study investigates the rate-dependent compressive response and cyclic reusability of 4D-printed polylactic acid honeycomb metamaterials with positive, negative, and zero Poisson’s ratios. The as-printed specimens were tested along two orthogonal directions at crosshead velocities of 0.025 and 25 mm/s. The X-direction specimens were then subjected to six severe deformation–recovery cycles to evaluate cyclic mechanical retention and shape-memory recovery. The results show mechanical anisotropy, with compression along the principal cell-alignment direction yielding higher structural stiffness, plateau force, and specific energy absorption. Increasing the loading velocity enhances plateau force and energy absorption, whereas the structural-stiffness response depends on topology and loading direction. By Cycle 6, SEA retention remained at least 69.60% across all tested conditions, with the zero-Poisson’s-ratio honeycomb showing the most balanced retention across the quantified cyclic mechanical metrics. These findings provide design guidance for additively manufactured reusable shape-memory metamaterials for impact mitigation and protective applications.