COUPLED 2025

Improving the mechanical properties of 3D-printed auxetic structures through design modifications

  • Dialami, Narges (CIMNE-UPC)
  • Farshbaf, Sima (CIMNE-UPC)
  • Cervera, Miguel (CIMNE-UPC)

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Auxetic structures gained significant attention due to their distinctive mechanical properties, including negative Poisson’s ratio and outstanding energy absorption. These unique characteristics make them advantageous for a wide range of engineering applications, including impact protection components and biomedical implants. Despite their advantages, auxetic structures need to be further optimized to maximize their mechanical performance and energy absorption efficiency. In this study, we introduce three novel in-plane auxetic structures derived from modifications of the traditional re-entrant unit cell. The primary objective of these designs is to significantly enhance energy absorption capacity while maintaining fundamental auxetic properties. The structures are fabricated using thermoplastic polyurethane (TPU) through additive manufacturing. Compression tests are conducted to evaluate their mechanical behavior, providing insights into their structural response and deformation mechanisms. To complement the experimental investigations, numerical simulations are performed using an in-house finite element model to validate and further understand the mechanical behavior of the proposed designs. The numerical models utilize hyperelastic with rate-independent plasticity constitutive equations, calibrated with experimental uniaxial tensile test data. Large deformation analyses are carried out using multi-field displacement-pressure elements. Additionally, a contact domain method is implemented to capture self-contact effects and interactions between the structure and supporting plates. The numerical models are calibrated with experimental data. Among the three design proposals, two demonstrate remarkable improvements in energy absorption performance. The most significant enhancement is observed in one design, which exhibits a 1250% increase in energy absorption capacity and an 860% improvement in the energy absorption-to-weight ratio compared to the conventional re-entrant structure. These findings highlight the potential of our newly developed auxetic structures as a next-generation solution for applications requiring high energy absorption. The integration of experimental and numerical approaches provides a comprehensive understanding of their behavior, paving the way for further advancements in the design and application of auxetic metamaterials.