Body armour materials: from steel to contemporary biomimetic systems

The history of armour is as old as the evolution of mankind; indeed, it is an intrinsic instinct of humanity to protect and shield ourselves from danger, such as from various critical environments and from other humans, especially in a battlefield setting. The development of high-speed projectiles and explosive materials changed the dynamics of the battlefield and led to an evolution in advanced ballistic personal protection systems, with requirements for the new systems to be damage resistant, flexible and lightweight, and with an efficient energy absorbing capacity. Steel was the preferred material in the battlefield for our ancestors, but in modern days, especially in the last two decades, new design strategies and materials, including fibres, composites, laminates, ceramics and bioinspired materials, have been extensively exploited to accomplish the requirements of modern military operations, and to provide protection appropriate for modern technology-driven war tactics and for protection against current terror threats. The present review covers the general strategies and materials used in armour systems, from felt to metals and composites, which themselves have been further extended, particularly to now include bioinspired materials and utilizing biomimetic conditions. Detailed discussions regarding the various armour materials and any issues in their performance against modern ammunition systems are outlined.