Effects of Fiber Arrangement on Negative Poisson’s Ratio of Angle-Ply CFRP Laminates: Analysis Based on a Homogenization Theory

Abstract

The effects of fiber arrangement on the negative through-the-thickness Poisson’s ratios of angle-ply carbon fiber-reinforced plastic (CFRP) laminates are investigated based on a homogenization theory. First, angle-ply CFRP laminates are modeled three-dimensionally with $+\theta$- and $-\theta$-laminae in which carbon fibers are distributed in a hexagonal arrangement. Then, a homogenization theory for nonlinear time-dependent composites is applied to the laminates. Using the present method, the elastic-viscoplastic Poisson’s ratios of angle-ply carbon fiber/epoxy laminates are analyzed. The analysis results are then compared with those of the previous study, in which a square fiber arrangement in each lamina was assumed. It is shown that the fiber arrangement affects the negative through-the-thickness Poisson’s ratios of the laminates in both elastic and viscoplastic regions, though they have little effect on the macroscopic stress-strain relationships of the laminates.