Influence of Specimen Geometry on Apparent Poisson’s Ratio Evaluated under the Compressive Loading of Quasi-Isotropic CFRP Laminate

Abstract

The effects of specimen geometry on the Poisson’s ratio of a quasi-isotropic carbon fiber reinforced polymer laminate under compression tests were examined experimentally. In particular, the divergence of the apparent Poisson ratio from the theoretical value was measured experimentally for a decreasing specimen width/thickness ratio (b/t). The observed tendency was then confirmed by simulations using finite element analyses (FEAs). FEAs using a 3D model of the specimens were performed to investigate the strain and stress distribution. Moreover, it was confirmed that the width-direction strain in evaluating the apparent Poisson’s ratio varies with the condition of a low b/t specimen. It was confirmed from the FEA results that the cause of an increasing or reducing width strain was sectional deformation under compressive loading, resulting from differences in the layer angles and stiffness between the outermost and inner layers.