The Critical Role of a Backing Material in Assessing the Performance of Soft Ballistic Protection

Abstract

Penetrating trauma by energised fragments is the most common injury from an explosive event. Fragment penetrations to the truncal region can result in lethal haemorrhage. Personal armour is used to mitigate ballistic threats; it comprises hard armour to protect from high-velocity bullets and soft armour to protect against energised fragments and other ballistic threats (such as from a hand gun) with low impact velocities. Current testing standards for soft armour do not focus on realistic boundary conditions, and a backing material is not always recommended. This study provides a comprehensive set of evidence to support the inclusion of a backing used in testing of soft body armour. Experiments were performed with a gas-gun system using fragment-simulating projectiles (FSPs) of different shapes and sizes to impact on a woven aramid and a knitted high-performance polyethylene ballistic fabric, with and without the ballistic gelatine soft tissue simulant as the backing material. The results showed statistically significant differences in the impact velocities at 50% risk (V50) of fabric perforation across all test configurations when the gelatine backing was used. Furthermore, the backing material enabled the collection of injury-related metrics such as V50 of tissue-simulant penetrations as well as depth of penetration against impact velocity. The normalised energy absorbed by the fabric could also be calculated when the backing material was present. This study confirms that a backing material is essential, particularly when assessing the performance of single layer fabrics against FSPs of low mass. It also demonstrates the additional benefits provided by the backing for predicting injury outcomes.

Evaluation of soft tissue simulant performance against economic and environmental impact

“…Although depth of penetration is a key attribute in understanding material performance and lethality of projectiles, it is the response of the simulant and ability to assess temporary and permanent cavitation that is most important. [52][53][54][55] The depth to which the projectile can travel is therefore not signicantly important so long as the material has been constructed to depths calculated from kinetic energy density and therefore is sufficient to capture a wound ballistics prole. For this reason, the depth penetration measurement within this study was scored at 30% of the swing during the direct weighting procedure.…”