Hybrid Composite Laminates using an AUXETIC Steel Core: A Numerical Investigation

Abstract

The use of Fiber Metal Laminates (FMLs) provides a high-stiffness fibre-reinforced polymer (FRP) with ductile properties derived from metals; however, few studies have attempted to create hybrid FMLs that incorporate auxetic (negative Poisson's ratio) materials to enhance energy absorption characteristics. To investigate the mechanical behaviour of hybrid laminates composed of perforated steel metamaterials sandwiched between layers of Glass Fiber Reinforced Polymer (GFRP) and Carbon Fibers, a series of parametric studies using Finite Element Analysis (FEA) in SIMULIA Abaqus were conducted. This analysis focused on the development of a metallic core with a non-convex rotating unit geometry and a theoretical Poisson's ratio of -1. A Uniaxial Tensile Test was conducted to find the effective elastic properties of the Hybrid Material Structure. The results of this study showed that the Hybrid Laminate, a form of the Hybrid Structure, did not retain any auxetic characteristics found in its separate component, the Metal Core. This is contrary to the original theory used to develop these Hybrid Laminates, as the Hybrid Structure's Ultimate Poisson’s Ratio increased rather than decreasing as expected. The results further demonstrate that the high in-plane stiffness of the Composite Face Sheets, when bonded together with other sheet layers in the Hybrid Structures, limits the rotational mechanism necessary for producing the auxetic effect. This finding concludes that for the hybrid Fiber Metal Laminates to achieve the auxetic characteristics inherent in their Metal Core components, the interface design must be such that enough freedom is allowed for geometric variations. The Guidelines established in this study are intended to assist in the development of next-generation Metamaterial Composite Fabrics with sufficient geometric freedom.