DEVELOPMENTS IN LIGHTWEIGHT COMPOSITE BALLISTIC HELMET MANUFACTURE

The design and manufacturing considerations for modern lightweight military helmets are discussed by an original equipment manufacturer (OEM.). The core functional requirements of contemporary military helmets are outlined, describing the performance measures that are routinely requested to quantify these requirements within specifications. The challenges for OEM and end-user are highlighted, as there are many ways of measuring this performance and many different levels of performance desired by different end users. The OEM states the compromises that are made in order to maximise helmet performance whilst balancing the complex and competing requirements of military helmets. The use of lightweight fibre-reinforced composite structures in modern military helmets is described. The composite materials commonly used in these helmets are discussed, highlighting the key properties of the materials used and the use of hybridised shell constructions using many different materials in order to achieve optimum helmet shell performance. The challenges faced when hybridising helmet constructions in this way, using often incompatible materials is considered. The two most common helmet manufacturing processes are also outlined, and the paper discusses how careful selection of processing parameters is key to realise the full potential of the materials used: how the increased use of ultra-high molecular weight polyethylene in ballistic helmets has led to the use of new manufacturing processes, such as deep draw, for the manufacture of fibre reinforced composite helmets rather than the traditional compression moulding. These preferences and the experience gained during the development initiatives are considered to provide insight and guidance to those specifying requirements for their own helmets, such as the technical representatives of international Ministries of Defence