Analysis of Mechanical Properties of 3D-Printed Auxetic Reentrant Structures

Objective: The aim of this study is to investigate the mechanical behavior of auxetic polymeric metamaterials, especially reentrant structures compared to honeycomb structures, through compression tests in order to understand the differences between auxetic and non-auxetic behaviors and how the cell arrangement influences the Poisson's ratio and energy absorption. Theoretical Framework: The fundamentals of metamaterials stand out, with a focus on auxetic materials, which are characterized by a negative Poisson's ratio and can be designed by modifying the architecture of the unit cell. These structures offer advantages such as greater impact resistance, specific rigidity, and vibration absorption. Method: The methodology consists of modeling cellular geometric structures (reentrant and honeycomb) with the use of SolidWorks software and manufacturing of cubes by additive manufacturing (FDM) with PLA polymer. Samples with both structures were printed and subjected to compression tests, where longitudinal and lateral deformations were measured to calculate Poisson's ratio, considering the average of measurements with digital calipers and analysis software. Results and Discussion: The results obtained revealed distinct behaviors between the structures. The honeycomb presented lateral expansion under compression, confirming its positive Poisson's ratio, while the reentrant structure contracted transversally, evidencing auxetic behavior. The reentrant structure required greater forces to achieve similar deformations, demonstrating greater rigidity and energy absorption. Research Implications: The practical and theoretical implications of this research include advancing the application of auxetic structures in areas such as biomedical, automotive and aerospace engineering, enabling lighter, more resistant and sustainable devices.