Topology-Driven Mechanical Tuning of FDM-Printed TPU Tubular Lattices with Auxetic Architectures

Auxetic tubular lattices provide a potential structural platform for simultaneously tuning radial support, axial dimensional stability, and bending flexibility; however, the coupled effects of topology and geometric parameters on these mechanical responses remain insufficiently understood. In this study, a topology-driven design framework was established for fused deposition modeling (FDM)-printed thermoplastic polyurethane (TPU) tubular lattices. Five auxetic topologies were designed by regulating curvature polarity and structural symmetry, while planar porosity and wall thickness were selected as geometric control parameters. Numerical simulations combined with experimental validation were employed to systematically evaluate axial bending stiffness, radial support force, Poisson's ratio, and stress distribution. The results demonstrate that geometric curvature promotes radial load transfer through an arch-like mechanism and contributes to stress redistribution, whereas structural symmetry strongly influences axial compliance and auxetic deformation. Planar porosity acts as the dominant macroscopic tuning parameter for overall mechanical performance, while wall thickness provides a secondary fine-tuning mechanism with greater sensitivity to local stress variation. Based on these findings, a hierarchical design strategy integrating topology, planar porosity, and wall thickness is proposed, providing a generalizable approach for tailoring the mechanical performance of FDM-printed elastomeric tubular lattices.