Multimaterial 4D printing of adaptive and reconfigurable auxetic metastructures

Purpose This study investigates the application of multimaterial additive manufacturing to design auxetic metastructures with tunable mechanical properties and energy absorption (EA) capabilities. By integrating stiff and compliant polymers within a single architected lattice, the aim is to understand how localized variations in material distribution influence deformation behavior, structural adaptability and reconfigurability. The overarching goal is to demonstrate how multimaterial auxetic designs can be leveraged to create adaptive and multifunctional structures. Design/methodology/approach An auxetic lattice exhibiting a negative Poisson’s ratio was designed in multiple multimaterial configurations and fabricated using a dual-nozzle fused deposition modeling (FDM) process. Polylactide (PLA) and polycaprolactone (PCL) were selected as the hard and soft phases, respectively, providing mechanical contrast while enabling thermally induced shape reconfiguration through shape memory behavior. Compression testing was conducted to characterize the force–deformation behavior, densification response and EA of the material. The influence of material arrangement within each unit cell was evaluated by comparing circular, line and cross-distributions of PLA and PCL. Findings An auxetic lattice exhibiting a negative Poisson’s ratio was designed in multiple multimaterial configurations and fabricated using a dual-nozzle FDM process. PLA and PCL were selected as the hard and soft phases, respectively, providing mechanical contrast while enabling thermally induced shape reconfiguration through shape memory behavior. Compression testing was conducted to characterize the force–deformation behavior, densification response and EA of the material. The influence of material arrangement within each unit cell was evaluated by comparing circular, line and cross-distributions of PLA and PCL. Originality/value This work provides an experimentally validated demonstration of geometry–material coupling as a design strategy for creating adaptive, reconfigurable metastructures. By exploiting the contrasting properties of soft and hard materials within an auxetic architecture, the study highlights how multimaterial 4D printing can be used to achieve tailored mechanical performance and functional programmability. The presented approach offers broad potential for future applications in soft robotics, impact mitigation systems and thermally responsive devices.