Defence and Security Accelerator

Blocks of gelatine are used in both lethality and survivability studies for broadly the same reason, i.e. comparison of ammunition effects using a material that it is assumed represents (some part of) the human body. The gelatine is used to visualise the temporary and permanent wound profiles; elements of which are recognised as providing a reasonable approximation to wounding in humans. One set of researchers aim to improve the lethality of the projectile, and the other to understand the effects of the projectile on the body to improve survivability. Research areas that use gelatine blocks are diverse and include ammunition designers, the medical and forensics communities and designers of ballistic protective equipment (including body armour). This paper aims to provide an overarching review of the use of gelatine for wound ballistics studies; it is not intended to provide an extensive review of wound ballistics as that already exists, e.g. Legal Med 23:21-29, 2016. Key messages are that test variables, projectile type (bullet, fragmentation), impact site on the body and intermediate layers (e.g. clothing, personal protective equipment (PPE)) can affect the resulting wound profiles.

There is an interest within forensic science to understand the physical and mechanical properties of human skin and the natural and synthetic simulants used to represent it, particularly with reference to reconstruction studies that consider injury to humans, for example during sharp-weapon and ballistic impact assaults. This paper discusses literature in the broad area of (i) human skin, (ii) animal skin and products such as leather and (iii) synthetic polymeric skin simulants. The physical and mechanical properties of human skin appear to be reasonably well documented in the literature. Animal models discussed appear to be restricted primarily to pig and to a lesser extent goat, plus some data on different types of leather. All skin (human and animal) and derivatives such as leather (from various animal sources) are natural materials and therefore variable in their physical and mechanical properties. The variability of commonly used simulants for human skin such as various types of leather could impact on the confidence of any reconstruction study data obtained by using such simulants. While it is recognized that synthetic simulants (polymers such as silicone and polyurethane) do not have the structure of human skin, their physical and mechanical properties can be manipulated relatively easily to match those of skin and are typically of low variability, providing confidence in the repeatability and reproducibility of reconstruction studies.

With no two gunshot wounds (GSW) being the same, novel research into wound ballistics is challenging. It is evident that the majority of previous wound ballistic research has been conducted without the presence of clothing. Whilst the effect of clothing on wound contamination has been explored, there is a paucity of literature examining the effect of clothing on GSW patterns. The aim of this study was to test the effect of Multi-Terrain Pattern (MTP) UK military clothing on GSW patterns within calibrated blocks of 10% by mass gelatine, using two types of ammunition commonly used in recent conflicts—7.62 × 39 mm and 5.45 × 39 mm. In total, 36 blocks were shot, 18 by each projectile type, further divided into 6 with no clothing layers (Cnil), 6 with a single clothing layer (Cmin) and 6 with maximum clothing layers (Cmax) worn on active duty. Blocks were analysed with high-speed video and dissection to capture measurements of damage, and results compared using analysis of variance (ANOVA). Results showed significantly different damage measurements within blocks with Cmax for both ammunition types compared to the other clothing states. This may result in GSWs that require more extensive surgical management, inviting further study.

Abstract Physical models are required to generate the underlying algorithms that populate computer simulations of the effects of explosive fragmenting devices. These models and simulations are used for understanding weapon performance, designing buildings and optimising personal protective equipment. Previous experimental work has investigated the performance of skin and muscle when subjected to fragmentation threats, but limited evidence exists for the performance of bone when impacted by fragments. In the current work, ballistic testing was conducted using two types of internationally recognised steel fragment simulating projectiles (FSPs): (i) 5.5 mm diameter (0.68 g) ball bearing (BBs) and (ii) 1.10 g chisel nosed (CN). These projectiles were fired at isolated swine ribs at impact velocities between 99 and 1265 m/s. Impact events were recorded using a high-speed camera. Selected specimens were analysed post-impact with plain x-radiographs and micro-CT scanning to determine damage to the bone architecture. Bones were perforated with a kinetic energy density (KED) as low as 0.14 J/mm 2 . Energy transfer to the bone was greater for the CN FSPs, resulting in increased bone damage and the production of secondary bone fragments. The manner in which the bones failed with faster velocity impacts (> 551 m/s; KED > 6.44 J/mm 2 ) was analogous to the behaviour of a brittle material. Slower velocity impacts (< 323 m/s; KED < 1.49 J/mm 2 ) showed a transition in failure mode with the bone displaying the properties of an elastic, plastic and brittle material at various points during the impact. The study gives critical insight into how bone behaves under these circumstances.

There are difficulties associated with mapping gunshot wound (GSW) patterns within opaque models. Depending on the damage measurement parameters required, there are multiple techniques that can provide methods of "seeing" the GSW pattern within an opaque model. The aim of this paper was to test several of these techniques within a cadaveric animal limb model to determine the most effective. The techniques of interest were flash X-ray, ultrasound, physical dissection, and computed-tomography (CT). Fallow deer hind limbs were chosen for the model with four limbs used for each technique tested. Quarantined 7.62 × 39 mm ammunition was used for each shot, and each limb was only shot once, on an outdoor range with shots impacting at muzzle velocity. Flash X-ray provided evidence of yaw within the limb during the projectile's flight; ultrasound though able to visualise the GSW track, was too subjective and was abandoned; dissection proved too unreliable due to the tissue being cadaveric so also too subjective; and lastly, CT with contrast provided excellent imaging in multiple viewing planes and 3D image reconstruction; this allowed versatile measurement of the GSW pattern to collect dimensions of damage as required. Of the different techniques examined in this study, CT with contrast proved the most effective to allow precise GSW pattern analysis within a cadaveric animal limb model. These findings may be beneficial to others wishing to undertake further ballistic study both within clinical and forensic fields.

SYNBONE® spheres were impacted with 7.62 × 39 mm mild steel core ammunition at a mean impact velocity of 654 m/s, SD 7 m/s, to simulate engagement distances of around 50-100 m. The wounds and fracture patterns were assessed by two forensic pathologists familiar with military cranial injury. The overall fracture pattern was assessed as being too comminuted when compared with actual injury. This suggests the SYNBONE® spheres have less utility for simulating military injury than other purposes described in the literature.

Prior to adoption of the pelvic protection system (PPS), one of the signature injuries suffered by H.M. Armed Forces who served in Afghanistan was caused by buried improvised explosive devices (IEDs) accelerating secondary fragmentation from the ground environment into the groin, perineum, genitals, buttocks and legs of personnel. In the current work, a test method was developed which considered the combined effects of explosive blast and fragment loading of targets of Tier 2 PPS. The work identified that it is possible to explosively propel fragments of the ground environment into the specimens of Tier 2 PPS and to analyse each specimen. In doing so, a scenario peculiar to the IED threat faced in Afghanistan was able to be replicated. Such work allows insights into injuries suffered and will assist in the development of future protective clothing systems that require dual blast and fragment protective properties.

INTRODUCTION: On military operations, ballistic impact damage is possible to lithium ion (Li-ion) batteries worn on the body by military personnel and the potential for exothermic reactions may result in injury. This paper investigated the effect of impact on batteries that might be worn in front or behind body armour. METHODS: Li-ion batteries were subjected to ballistic impact both without and in combination with body armour using 7.62×39 mm ammunition (mean velocity=769 m/s) at charge levels up to 40%. The effect of penetrating impacts on charged batteries was also investigated using an outdoor range. RESULTS: The backface signature due to ballistic impact was reduced by including a battery pack between fabric body armour and an armour plate, however the batteries were crushed and mechanically disrupted. Ballistic impacts on batteries mounted in front of an armour plate resulted in perforation of the batteries. Increases in temperature, fire and toxic gas emission were noted when batteries were penetrated by an impact. CONCLUSIONS: Batteries provided limited ballistic protection disproving the hypothesis that batteries could replace or enhance existing body armour solutions. Ballistic impact of charged batteries could lead to injury due to heat/flame and toxic discharge. It is recommended that batteries need to be carried in a position from which they can be rapidly removed from contact with the body.

Abstract Gunshot wounding (GSW) is capable of causing devastating tissue injuries by delivering kinetic energy (KE) through the contact surface area of a projectile. The contact surface area can be increased by yaw, deformation and fragmentation, all of which may be caused by any intermediate layers struck by the projectile prior to entering its target. This study aims to describe whether projectile yaw occurring before penetration of a cadaveric animal limb model causes greater damage with or without clothing layers present using 5.45 × 39 mm projectiles. In total, 12 fallow deer hind limbs were shot, further divided into 4 with no clothing layers (C nil ), 4 with a single clothing layer (C min ) and 4 with maximum clothing layers (C max ) as worn on active duty by UK military personnel. Contrast computed tomography (CT) of limbs was used to measure permanent cavity size and the results were compared using analysis of variance (ANOVA). No significant differences were found among clothing states for each series of measurements taken, with greater cavity sizes noted in all clothing states. This is in contrast to previous work looking at symmetrically flying projectiles in the same model, where a larger permanent cavity was found only with C max present. Projectile yaw is therefore likely to be a key variable with regard to causation of damage within this extremity wound model.

INTRODUCTION: The aim of this paper was to examine any injuries from posterior behind armour blunt trauma ballistic impacts directly over the spine onto typical hard body armours. Due to the spine being close to the surface of the skin and a lack of any previous specific research into this topic, this study was designed to gain preliminary insight into the mechanisms involved and injuries caused. Pigs were chosen as the closest representative of human spine, tissue and skin, although their spines are deeper under the surface than humans. Baseline spine and ribs shots were conducted to ensure that the study was effective. METHOD: This study used a 65 kg cadaveric pig eviscerated torso and 7.62 NATO ammunition (7.62×51; L2A2; mean velocity=838 m/s, SD=4 m/s) impacting hard body armour plates over the spine. Injuries were inspected, and sections were removed for X-ray and micro-CT assessment. RESULTS: There was no visible soft tissue damage under the impact point on the armour over the spine, and no bony injuries were reported. Baseline rib shots resulted in multiple rib fractures; some showed minimal displacement of the bone. Baseline spine shot resulted in damage across the spine involving spinal cord and bone. CONCLUSION: No injuries were noted from the spinal impacts, and the rib shots resulted in injuries consistent with those previously reported. The anatomical differences between pigs and humans does not preclude that bony injuries could occur in a human from these types of spinal ballistic impacts.

This study follows on previous research which investigated the comfort and types of bras worn by UK female police officers when wearing body armour and performing typical activities. This controlled study involved a cohort of 31 female police officers and investigated three main areas. Firstly the effect of professional bra fitting on size and comfort, secondly the effect of wearing an underwired bra or a sports bra on comfort and ability to perform certain actions, and thirdly the effect of an underwired bra and sports bra on key anthropometric data in relation to the fitting of body armour.

One type of clothing system used in the English Civil War, more common amongst cavalrymen than infantrymen, was the linen shirt, wool waistcoat and buff-coat. Ballistic testing was conducted to estimate the velocity at which 50% of 12-bore lead spherical projectiles (V50) would be expected to perforate this clothing system when mounted on gelatine (a tissue simulant used in wound ballistic studies). An estimated six-shot V50 for the clothing system was calculated as 102 m/s. The distance at which the projectile would have decelerated from the muzzle of the weapon to this velocity in free flight was triple the recognised effective range of weapons of the era suggesting that the clothing system would provide limited protection for the wearer. The estimated V50 was also compared with recorded bounce-and-roll data; this suggested that the clothing system could provide some protection to the wearer from ricochets. Finally, potential wounding behind the clothing system was investigated; the results compared favourably with seventeenth century medical writings.

Bloodstained fabrics found at crime scenes are likely to have had processing treatments, such as dyeing or printing, but the effect of the treatments on bloodstain morphology is not always considered. In order to study the effect of digital printing on bloodstain morphology, drip stains were created from five impact velocities (1.9–5.4 ms−1) on three different mass per unit areas (88–226 g/m²) of 100% cotton calico which had been digitally printed using reactive dye. Across all three printed fabrics, the bloodstains appeared visually similar, and no correlation was found between the dry bloodstain area and the impact velocity. When comparing the bloodstains on the printed fabric to those which had been created previously on the same fabric in a dyed and not-coloured state, the dry bloodstains on the printed fabric were statistically significantly larger (e.g. for the calico with the lightest mass per unit area, mean dry bloodstain area was 126.6, 64.4 and 44.3 mm² for the printed, dyed and not-coloured fabrics respectively). Examination of the larger bloodstains on the printed calico with the micro computed tomography scanner and scanning electron microscope, suggested that the printing process increased the wettability of the fabric, so the blood could spread more easily on the surface. This allowed the blood to coat the yarns, and wick into them before wicking along the intra-yarn spaces. The results presented in this paper showed that care must be taken when examining bloodstains at crime scenes. Depending on the fabric and the processing of the fabric the size of the blood stains may not increase with impact velocity as wicking may result in a larger bloodstain from a lower velocity. The bloodstain on the penetrated face of the fabric may be larger than on the impacted face and the same fabrics with different processing will produce different blood stain sizes and shapes.

Military and law enforcement personnel are faced by diverse threats routinely in their employment. Amongst the threats considered in such an analysis are those that require specialized fabrics and clothing systems to provide protection (e.g. ballistic and sharp weapon; flame retardant; and chemical, biological, radiological, and nuclear). This chapter considers these threats and summarizes the fabrics and test methods used. The modification of commodity fibre and fabric properties by innovative finishes could be a cheaper route to high performance than using a high cost fibre with inherent performance properties. Optimum design of protective clothing systems requires knowledge of the threats faced, the tasks to be completed, the anthropometric properties of the persons to be protected, the fabrics that might be used, integration with other fabrics and equipment, and knowledge of appropriate clothing and textile sciences manufacturing techniques and test methods.

Woven fabrics commonly referred to as ‘aerocotton’ and ‘aerolinen’ are frequently used in the conservation of books and manuscripts and are valued for their strength and flexibility. Although textiles have a long history in the production and repair of books, aerocottons and aerolinens are relatively recent materials adopted from early aircraft production. In 2007, the main supplier of these woven fabrics to the UK conservation community ceased production, and new producers started supplying a range of woven fabrics under the labels of ‘aerocotton’ and ‘aerolinen’. Understanding the strength, composition, and longevity of repair materials is central to conservation practice and this investigation tested two linens and two cottons alongside the discontinued cotton to quantify the relative strengths of the fabrics. Each fabric was tested before and after laundering, and in three directions (warp, weft, and bias). The tests conducted measured mass per unit area, thickness, sett, tensile strength, folding endurance, and dimensional change. In tensile strength tests the bias-cut fabrics were weakest but extended the most, whilst those cut in the weft direction were strongest. The cottons lasted longest in terms of folding endurance and the samples cut on the bias were the fastest to break. The dimensional change tests showed that washing affected the linens more than the cottons and that across all fabrics there was a greater amount of shrinkage in the warp direction. It is hoped that these results will provide concrete information to guide conservators in the preparation and use of aerocottons and aerolinens.

Police body armour in the United Kingdom (UK) is designed to provide protection from edged weapons and low-velocity pistol ammunition. Recent events have raised concern about whether UK police body armour and associated personal protective equipment (PPE) provides protection from military threats such as improvised explosive devices (IED) and grenades. In this paper PPE worn by specialised police officers was assessed for its protective performance from a specified grenade threat. The major cause of injury suffered by police officers challenged by a modern military grenade would be from the associated fragmentation which perforated coveralls, boots, helmet and soft body armour, but not hard armour plates.

The majority of fabrics at crime scenes have been coloured in some way. The effect of such treatments on resultant bloodstains has not been considered. In this work, horse blood was dropped onto reactively dyed calico fabrics (100% cotton, plain woven) with three different masses of 91 g m-², 171 g m-² and 243 g m-² and the results compared to previous work on the not-coloured calico fabric. Five impact velocities were used from 1.7 ms−1 to 5.4 ms−1. The use of reactive dye increased the thickness (from 0.38 – 0.56 mm to 0.39 – 0.6 mm) and mass per unit area (from 85.1 – 224.6 g/m² to 91 – 243 g/m²) of the calico fabrics. The reactively dyed fabrics had larger bloodstains (e.g. lightest calico 41.2 – 78.6 mm²) compares to the not-coloured fabrics (e.g. lightest calico 21.4 – 67.5 mm²) across all three mass per unit areas. The dyeing of the fabrics altered the intra-yarn spaces to a more optimum size for wicking blood, increasing the ease with which the blood could wick along the yarns in the dyed calico. The amount of wicking varied depending on individual variations within the fabrics and yarns. More variation in dry bloodstain area was seen among dyed calico specimens than for the not-coloured fabric. The amount of wicking which was seen on the dyed calico meant there was no correlation between dry bloodstain area and impact velocity, a correlation which was seen on the medium and heavy not-coloured calico in the previous work.

The Defence and Security Accelerator (DASA) finds and funds exploitable innovation to support UK defence and security quickly and effectively, and to support UK prosperity. Deb Carr will describe how innovators can work with DASA and the benefits available. She will also present the current competitions being run by DASA and give an overview of the likely future calls.

Personal protective equipment (PPE) is crucial for military personnel who find themselves in hostile situations facing a prolific and focused enemy. PPE is designed to protect the wearer from injury and/or fatality, i.e. the use of PPE increases the likelihood of survivability. Military body armour, which protects the critical organs of the torso, contains multiple layers of para-aramid or ultra-high molecular weight polyethylene (UHMWPE) fabrics. These layers of fabric are often quilted for ease of handling during the construction of the armour and to prevent the slumping of the armour layers in the carrier and protect the wearer from fragmentation which is the major cause of injury in modern warfare. Minimal work has been published on the effect of quilting on the protection offered by military body armour. In this work, the effects of quilting pitch (none; bias direction −10, 20 and 30 mm pitch), sewing thread type (cotton, polyester-cotton, para-aramid, bonded nylon) and the number of layers (one, three) of a Twaron® fabric on the fragment protective performance was investigated with reference to military body armour systems. Evidence of a strain rate effect was noted. Use of 100% cotton or bonded nylon thread for quilting typically resulted in a higher energy dissipated (ED) compared to not-quilted specimens. The greatest improvements were noted with bonded nylon quilted specimens. At slower velocities, this improvement was 94% for one-layer specimens and 32% for three-layer specimens. At faster velocities, this improvement was 41% for one-layer specimens and 32% for three-layer specimens.

Bullet-resistant body armour is used by law enforcement agencies and military personnel worldwide, often in inclement weather. Some fibre types used in body armour perform poorly when wet, resulting in a reduced level of protection; this is why most body armour protective elements are water-repellent treated and/or protected by a water-resistant cover. Some of the users operate in the maritime environment. The effect of salt water on body armour performance has not been previously reported. In this work the effect of soaking body armour in salt water and exposing body armour for up to 10 soaking and drying cycles in salt water was investigated. The effectiveness of the water-resistant cover was investigated by considering three cover conditions: (i) intact, (ii) cut and (iii) removed. Wet armour was heavier and provided significantly less protection from 9 mm Luger FMJ ammunition when compared to not-exposed armour irrespective of cover condition. A degradation in performance of armours exposed to soaking and drying cycles was noted, but this was similar across all regimes considered (one, three, five and ten cycles) and not as great as for wet armours.