On the nonlinear evolution of the Poisson's ratio under quasi-static loading for a carbon fabric-reinforced thermoplastic. Part I: Influence of the transverse strain sensor

摘要

When observing or describing the damage state in a composite material, often only Young's modulus or residual deformation are considered. Generally, however, the Poisson's ratio is more sensitive to damage than those properties. Rather than observing the Poisson's ratio as a function of crack density, this article studies the evolution of the Poisson's ratio as function of the longitudinal strain, which has a peculiar shape. In Part 1, multiple experiments, using strain gauges, optical fibres and an extensometer for transverse strain measurement are discussed to determine whether this behaviour is due to the material or to the sensor used. It can be concluded that the hyperbolic-like shape is entirely caused by material behaviour. A theoretical explanation and validation for this behaviour will be given in part II. The material used for this study is a carbon fabric-reinforced PPS.