The design, matching and manufacture of auxetic carbon fibre laminates

Either an in-plane or out-of-plane negative Poisson's ratio, nu, in continuous carbon fibre/epoxy resin composites can be achieved, providing the fibre volume fraction and anisotropy are high enough, by selecting suitable stacking sequences. This paper examines the use of specially designed software which allows the designer to match the mechanical properties of laminates with predicted negative nu to those with similar mechanical properties but positive nu. This has allowed auxetic and matched carbon fibre/epoxy resin laminates to be specifically designed. These laminates were then fabricated and tested, with good agreement found to theoretical predictions. This study, then, provides a route to evaluating the effect of a negative nu alone on properties such as fracture toughness and impact resistance.