17 January 2012
Impact face of glazing panel after impact
Image by Defence Materials Group, Cranfield University
Transparent armour is designed to withstand impact by one or more ballistic rounds depending on the thickness of the glass and the weapon being fired. It is conventionally made by laminating a sandwich of a clear plastic film (typically polycarbonate) between two thick layers of glass. Transparent armour is typically between 7 and 75 mm in thickness (depending on the ballistic resistance required). A ballistic round fired at a sheet of transparent armour will pierce the outer layer of glass, but the underlying laminated polycarbonate and glass material is able to absorb the round's energy before exiting the final layer.
The ability to stop ballistic projectiles is a critical function, however, one outcome of an impact event is a loss in optical clarity (see photograph), a situation that can only be remedied by total replacement of the component. While this may be a practical solution if extensive logistical support is nearby, an impact event during a patrol or prolonged engagement may compromise the ongoing optical function of the transparent armour protection.
The funding has been awarded as a result of the Ministry of Defence’s Armour and Protection Science and Technology Centre call for proposals back in July 2011, in which proposals were sought for long term research in the area of innovative and novel protection systems, with the aim to provide a significant, possibly revolutionary, advance on current technologies.
