Negative Poisson's ratio from pentagons: A new auxetic structure combining three different auxetic mechanisms

S Winczewski and J Rybicki, COMPUTATIONAL MATERIALS SCIENCE, 201, 110914 (2022).

DOI: 10.1016/j.commatsci.2021.110914

A novel class of two-dimensional auxetic structures based on the pentagon motif is proposed. Their mechanical properties are investigated by combining molecular mechanics simulations with a simple three- parameter mechanical model which assumes perfectly elastic behavior. It is predicted that the proposed structures - termed as double re-entrant honeycomb - may possess unique mechanical characteristics, which include complete and perfect auxeticity, as well as the negative Poisson's ratio observed in both the tensile and compressive regimes. The behavior of the considered structures is explained in relation to well-known auxetic models. It is shown that the considered structures simultaneously implement three different mechanisms leading to a negative Poisson's ratio: the opening of the re-entrant units, the rotation of the squares, and the flattening effect.

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