Auxeticity due to elastic instabilities

Abstract

Elastic instabilities are usually deleterious and needed to prevent. In this study, we use elastic instabilities as helpful mechanisms to show auxeticity. Firstly, using atomistic simulations we show that some face-centered-cubic metals under tensile loading exhibit a large value of negative Poisson’s ratio as the applied strain beyond a critical strain. This auxetic phenomenon is associated with the Born-Hill elastic instability. In addition, using atomistic simulation as well as finite element method calculation, we show that periodic porous metallic structures can also exhibit auxeticity at finite strains. Another elastic instability mechanism, Euler buckling of the microscopic elements leads to the auxetic behavior of the porous metallic structures.