Analysis of Negative Poisson's Ratios of Re-Entrant Honeycombs

Abstract

Materials or structures that contract in the transverse direction under uniaxial compression, or expand laterally when stretched are said to have negative Poisson's ratios. A theoretical approach to the prediction of negative Poisson's ratios of re-entrant honeycombs has been developed which is based on the large deflection model. The equations of the deflection curves of the inclined member of the re-entrant cell, strains and Poisson's ratios of re-entrant honeycombs in two orthogonal directions have been derived. The deformed shapes of the inclined members of the re-entrant cell are calculated. The negative Poisson's ratios of re-entrant honeycombs are no longer a constant at large deformation. They vary significantly with the strain. The effect of the geometric parameters of the cell on the Poisson's ratios is analyzed.