Polymer nanocomposites for light armour applications

Increasing terrorist activities and the involvement of UK troops in hostile overseas missions has greatly increased the exposure of our soldiers and police force to life threatening situations. A similar danger is also faced by aid workers and other civilian personnel working in hostile areas. The issue of combat survivability is of primary concern in such situations, with a need for high performance, lightweight and cost effective protection for personnel and vehicles. Performance requirements in these applications are highly demanding and protective materials must withstand many different threats, whilst maintaining performance integrity under harsh conditions. To address the challenge of these demanding requirements, new materials, construction methods and designs must be considered. Nanostructured polymeric materials, such as polyurethane nanocomposites for linings for vehicle armour, and ultra-high molecular weight polyethylene and its nanocomposites for light weight body armour, have great potential to improve the combat survivability of both vehicle and body armours, whilst reducing cost and weight. Recent research on polymer nanocomposites has indicated that a nanostructured material architecture can enhance a wide range of physical and engineering properties. Armour with polyurethane (PU) based linings is currently being considered for armed vehicles. Initial research has indicated that a polymer lining can significantly improve the damage resistance of steel armour. For personnel protection, a balance must be made between the needs of high protection and light weight. Ultra-high molecular weight polyethylene (UHMWPE) and its nanocomposites have the potential to raise the effectiveness of protection for troops with the minimal possible weight. The success of using PU nanocomposites for the interior of armed vehicles and UHMWPE and its nanocomposites for body armour will depend on their performance at high strain rates. To date, the only reports in this field for polycarbonate nanocomposites have been on the limited work conducted by the US army. In order to design, predict and optimise the performance of armour under ballistic impact, a detailed knowledge of material behaviour, a material constitutive model that is accurate under the applied time dependent stress fields and an understanding of high rate dynamic modelling, shock wave behaviour, fracture and energy dissipation is needed. Experimental characterisation and modelling of such behaviour is highly challenging, however, recent advances in high rate test equipment, dynamic modelling and the ability to incorporate complex material behaviour into multi-physics finite element models has greatly increased the accuracy and reliability with which this can be done. This project proposes to explore the potential of polymer nanocomposites for light armour applications. Specifically, UHWPE nanocomposites will be investigated for improved lightweight body armour and PU nanocomposites will be investigated for armour linings for armed vehicles. PU based materials are currently of great interest for the interior lining of armed vehicles, to increase the rupture resistance of steel hulls and prevent metal fragments from wounding or killing vehicle occupants. Improved UHMWPE based materials are also urgently required, to provide high damage resistance allied with the lightweight and flexibility that enable the wearer to operate at optimum efficiency. The proposal is aligned with the MoD Defence Technology Strategy. The novelty in this proposal arises from the materials to be developed, the unique high rate characterisation methods and the novel computational methods to be developed. It is also novel in that the proposal aims to combine the expertise of a multidisciplinary team to produce a complete and holistic solution.