Elastoplasticity of auxetic materials

Materials exhibiting a negative Poisson’s ratio (auxetics) have drawn attention for the past two decades, especially in the field of lightweight composite structures and cellular media. Studies have shown that auxeticity may result in higher shear modulus, indentation toughness and acoustic damping. Although elastic properties of such materials have been extensively investigated, the effect of plasticity on auxetic behavior has not been discussed. In particular, does the auxetic character of the material remain while entering the plastic domain? The present work aims at modeling the nonlinear mechanical response of auxetics. Full-field simulations are performed using the finite element method with periodic boundary conditions. Macroscopic modeling of auxetics is attempted using an anisotropic compressible plasticity framework.