Measurement of Negative Poisson's Ratios of CFRP Laminates Using Digital Images

Abstract

In this study, the negative through-the-thickness Poisson's ratio of an angle-ply carbon fiber-reinforced plastic (CFRP) laminate is measured based on a full-field measurement technique using digital images. For this, a [±30] angle-ply CFRP laminate with 11.5 mm thick is prepared. The thickness change of the laminate under tensile loading in the in-plane direction is measured using a digital image correlation (DIC) measurement system and a 3D digital scanner. The through-the-thickness Poisson's ratio of the laminate is then calculated using the observed thickness change. It is shown from the results that the through-the-thickness Poisson's ratio becomes negative, and the negativity becomes stronger with the increase in the inelastic tensile deformation of the laminate.