Continuous ultrahigh molecular weight polyethylene fibre as through-thickness reinforcement for sandwich-structured composites

Abstract

This thesis describes the design and fabrication of continuous ultra-high molecular weight polyethylene (UHMWPE) fibre as through-thickness reinforcement for sandwich-structured composites consisting of mechanically frothed epoxy foam as the foam core material. It was found that the introduction of continuous UHMWPE fibres into an epoxy foam core increased its core shear, flatwise compressive, as well as edgewise tensile properties. More importantly, the failure of the continuous UHMWPE fibre-reinforced epoxy foam in tension was delayed. This thesis also discusses the properties of sandwich-structured composites with UHMWPE fibres weaved through both the facesheets and the epoxy foam core. It was found that sandwich-structured composites consisting of continuous UHMWPE fibres performed significantly better than their discontinuous fibre-reinforced counterparts in both core shear and flatwise tension. Charpy impact test further showed that continuous UHMWPE fibre-reinforced sandwich-structured composites improved the impact toughness of the resulting sandwich-structured composites. A set of strain energy based analytical equations was derived to estimate the upper bound mechanical properties of these reinforced epoxy foams and sandwich-structured composites and compared with experimentally measured values.