Research on Shape Memory Properties of PETG Based on 4D-Printed Negative Poisson’s Ratio Structures

This research systematically investigates the shape memory properties of re-entrant hexagonal negative Poisson’s ratio (NPR) honeycomb structures fabricated via 4D printing, using polyethylene terephthalate glycol (PETG) and polylactic acid (PLA) as comparative materials. Periodic honeycomb models with varied wall thicknesses and structural unit angles were designed, and their effects on shape recovery time and recovery rate were examined. Response surface methodology (RSM) based on a Box–Behnke