Ballistic performance and failure modes of woven and unidirectional fabric based soft armour panels

This study presents the ballistic protection performance and failure modes of soft armour panels (SAPs) made from different structures, including woven fabrics and unidirectional (UD) laminates. SAPs made from para-aramid woven fabrics and UD laminates, and ultra-high molecular weight polyethylene (UHMWPE) UD laminates were developed and subjected to ballistic impact against 9 mm lead core bullets at an average velocity of 430 m s(-1). Ballistic performance of SAPs was evaluated in terms of back face signature (BFS), perforation ratio (PR) and expansion of bullet. UD laminate-based SAPs outperformed their counterparts based on para-aramid woven fabric. While among the UD laminates, UHMWPE variants surpassed their para-aramid counterparts. Microscopic images and scanning electron micrographs showed extensive thermal degradation and melting in first few layers of SAP made from UHMWPE UD laminates, whereas para-aramid panels failed mainly due to fibre rupture, fibrillation along with debonding and delamination in their UD variants. Therefore, an ideal SAP design should incorporate a heat resistant material in the front layers followed by high-modulus ballistic materials in subsequent layers. Use of spacer fabric as backing material can partially replace high-cost ballistic materials without compromising ballistic performance.