Abstract
Knife is the most commonly used single weapon in the UK, being 32% of the weapons employed in a violent incident. Studies reveal that majority (63.3%) of the knife inflicted wounds were slash type and could be disfiguring or life threatening if the blood vessels are ruptured. The stab resistant armours that are currently available do not protect the arms, neck and face as they are very rigid and heavy to be worn comfortably for everyday use for security personnel and are also expensive for the civilian population.
During the research programme, various composite yarns consisting of; a) blends of Spectra® (Ultra High Molecular Weight Polyethylene), glass and polyamide; b) Stainless steel core with wraps of Dyneema® (Ultra High Molecular Weight Polyethylene) and polyester; and c) Kevlar®, in different compositions, were thoroughly investigated to determine the most appropriate yarn for the slash proof materials. The slash proof fabric structures were developed by using knitting technology as it offers significant advantages in terms of cost, design flexibility and versatility. Different fabrics using the appropriate yarn were developed using various knitting criteria. Since there was neither any literature published for slash resistant fabrics nor any comparable fabric availability, the developed fabrics were tested against each other using a test method stipulated for slash proof application. The fabrics were also tested for their thermophysiological and flame resistant properties using a wide range of test methods and procedures. Due to the probable application of slash resistant fabrics, i.e. outer wear in open atmosphere, the developed fabrics were also characterized after exposing 5 years equivalent of UVA/B radiation.
This research programme has led to some extremely successful and innovative outcomes including the granting of a full patent. One of the major findings has been that a two-layered knitted structure produced by using a combination of composite and staple-fibre aramid yarns helps to withstand a higher impact force during the slash attack. It was also established that the designed racked structure in the fabric not only provides resistance to the continuous movement of the knife blade but also increases the overall slash resistance capability of the protective fabric.
The research has also led to some recommendations for further work in order to re-confirm some of the findings established during the study and also to improve the structure by reducing the area density of the slash resistant fabrics further due to the changes in the pass criteria of the slash resistant standard, set as a direct outcome of this research.