A novel modified re-entrant honeycomb structure to enhance the auxetic behavior: Analytical and numerical study by FEA

Auxetic materials or structures on the application of a tensile or compressive load expand or contract laterally, respectively. Over the years, multiple auxetic structures have been proposed. The most studied type is the re-entrant honeycomb model. In this work, a novel modified re-entrant honeycomb model is proposed to improve the elastic properties of the structure by adding additional members to the unit cell. Analytical equations for the Poisson’s ratio, strain, deflection and Young’s modulus are derived in two orthogonal directions. The proposed model provides significantly higher values of Negative Poisson’s Ratio (NPR) for the same relative density in loading in one direction at the cost of other orthogonal direction when compared to the existing re-entrant honeycomb model. The results are evaluated for multiple geometric parameters for the calculation of NPR.