CERES :: Browsing by Author "Carr, Debra J."

Browsing by Author "Carr, Debra J."

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Open Access
Ballistic extremity wounding : quantifying tissue damage associated with military firearms
(2018) Stevenson, Tom; Carr, Debra J.; Harrison, K.; Critchley, Richard; Shortland, Andrew J.
Gunshot wounding (GSW) is often the second most common mechanism of injury after explosive in war. With a large proportion of survivors typically suffering with extremity wounds, the clinical burden is often substantial. Following the recent Iraq and Afghanistan conflicts, this work set out to ascertain the clinical burden of GSW suffered by UK military personnel. A critical literature gap uncovered was pertaining to the effect of clothing on GSW patterns. A synthetic limb model was used to test the effect of UK military clothing on GSW patterns in a maximal and minimal state, as worn by front-line service personnel, using 7.62 x 39 mm and 5.45 x 39 mm ammunition types. Further work was then undertaken to develop a technique to facilitate precise examination of GSW patterns within an opaque target. Lastly, this led to the development of a cadaveric animal limb model to test the same military clothing states as with the synthetic model. Increased damage was found in the presence of the maximal clothing state within both models, which would translate clinically into a wound requiring more extensive surgical intervention. The relevance of these findings, along with critical appraisal of each model used are then discussed, with further work proposed.
Open Access
Ballistic impacts on an anatomically correct synthetic skull with a surrogate skin/soft tissue layer
(Springer, 2017-11-28) Mahoney, Peter F.; Carr, Debra J.; Arm, Richard; Gibb, Iain; Hunt, Nicholas; Delaney, Russ J.
The aim of this work was to further develop a synthetic model of ballistic head injury by the addition of skin and soft tissue layers to an anatomically correct polyurethane skull filled with gelatine 10% by mass. Six head models were impacted with 7.62 x 39 mm full metal jacket mild steel core (FMJ MSC) bullets with a mean velocity of 652 m/s. The impact events were filmed with high-speed cameras. The models were imaged pre- and post-impact using computed tomography. The models were assessed post impact by two experienced Home Office pathologists and the images assessed by an experienced military radiologist. The findings were scored against real injuries. The entry wounds, exit wounds and fracture patterns were scored positively, but the synthetic skin and soft tissue layer was felt to be too extendable. Further work is ongoing to address this.
Open Access
The ballistic performance of bone when impacted by fragments
(Springer, 2020-05-02) Caister, A. J.; Carr, Debra J.; Campbell, P. D.; Brock, Fiona; Breeze, John
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/mm2. 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/mm2) was analogous to the behaviour of a brittle material. Slower velocity impacts (< 323 m/s; KED < 1.49 J/mm2) 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.
Open Access
Ballistic protective properties of materials representative of English civil war buff-coats and clothing
(Springer, 2020-07-21) May, Brian; Critchley, Richard; Carr, Debra J.; Peare, Alan; Dowen, Keith
One type of clothing system used in the English Civil War, more common among 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 to 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 to seventeenth century medical writings
Open Access
Ballistic research techniques: visualizing gunshot wounding patterns
(Springer, 2020-02-14) Stevenson, Tom; Carr, Debra J.; Harrison, Karl; Critchley, Richard; Gibb, Iain E.; Stapley, Sarah A.
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.
Open Access
The ballistics of seventeenth century musket balls
(Brill Academic Publishers, 2019-07-14) Miller, David P.; Allsop, Derek; Carr, Debra J.
This paper investigates the firing of seventeenth Century musket balls. Prior to this research, the main concerns with making range predictions were associated with the deformed shape of the musket balls affecting their drag coefficient and therefore their distance to ground impact. However, the distance due to bounce and roll after initial impact has been unknown. In this work, the distance travelled after the first ground impact greatly exceeded expectations, with the musket balls approximately doubling the distance to their final resting positions. From these findings the initial factors thought to have had high relevance to the final resting position of the musket ball (velocity variation and drag co-efficient) become less significant and factors such as ground hardness become more prominent. The knowledge gained during this investigation will allow more accurate information to be obtained on the firing positions of opposing forces during conflicts in the English Civil War.
Open Access
Comparison of porcine thorax to gelatine blocks for wound
(2016-02-04) Mabbott, A.; Carr, Debra J.; Champion, Stephen M.; Malbon, Christopher
Tissue simulants are typically used in ballistic testing as substitutes for biological tissues. Many simulants have been used, with gelatine amongst the most common. While two concentrations of gelatine (10 and 20 %) have been used extensively, no agreed standard exists for the preparation of either. Comparison of ballistic damage produced in both concentrations is lacking. The damage produced in gelatine is also questioned, with regards to what it would mean for specific areas of living tissue. The aim of the work discussed in this paper was to consider how damage caused by selected pistol and rifle ammunition varied in different simulants. Damage to gelatine blocks 10 and 20 % in concentration were tested with 9 mm Luger (9 × 19 full metal jacket; FMJ) rounds, while damage produced by .223 Remington (5.56 × 45 Federal Premium® Tactical® Bonded®) rounds to porcine thorax sections (skin, underlying tissue, ribs, lungs, ribs, underlying tissue, skin; backed by a block of 10 % gelatine) were compared to 10 and 20 % gelatine blocks. Results from the .223 Remington rifle round, which is one that typically expands on impact, revealed depths of penetration in the thorax arrangement were significantly different to 20 % gelatine, but not 10 % gelatine. The level of damage produced in the simulated thoraxes was smaller in scale to that witnessed in both gelatine concentrations,though greater debris was produced in the thoraxes.
Open Access
Degradation of fabrics used in military fragment protective clothing due to selected laundering regimes
(2018) Helliker, M.; Carr, Debra J.
With the introduction of fragment protective fabrics into combat clothing, there was a need to understand the effect of laundering on the performance of these fabrics. This thesis investigated the effect of typical laundering regimes on selected ballistic protective fabrics representative of those suitable for clothing applications. This study presents evidence that knitted silk and felted ultra-high molecular weight polyethylene retained their ballistic protective performance after laundering. The para-aramid fabrics showed significant improvement from laundering. The dimensional stability of the selected fabrics was affected by laundering and the effect was cumulative. The damage imparted to the fibres was determined to be due to mechanical wear. This mechanical wear was significantly increased when the fabrics were wet. This was due to the water increasing the friction between fibres during the laundering process. The fabrics investigated were shown to be suitable for use in fragment protective clothing, and were more robust than was generally considered.
Open Access
Development of a synthetic bone and tissue model to simulate overmatch military ballistic head injury
(2018) Mahoney, Peter F.; Carr, Debra J.; Harrison, K.; Critchley, Richard
A synthetic bone and tissue head model was built using sequential experiments and tested against impacts with 7.62 x 39 mm MSC ammunition. The key experiment in this series was a forensic reconstruction of two military head injury gunshot wounds. One of the models produced a good representation of the incident. The other was less accurate but did produce a good representation of tangential gunshot wounds. Further work assessed the model against a contact gunshot injury with 5.56 x 45 mm ammunition and looked at the effects of intermediate glass and transparent thermoplastic targets on the wounds produced by 7.62 x 39 mm impacts. Strengths and weaknesses of the model are discussed and further work suggested.
Open Access
Does preliminary optimisation of an anatomically correct skull-brain model using simple simulants produce clinically realistic ballistic injury fracture patterns?
(Springer, 2017-03) Mahoney, Peter F.; Carr, Debra J.; Delaney, Russ J.; Hunt, N.; Harrison, S.; Breeze, J.; Gibb, I.
Ballistic head injury remains a significant threat to military personnel. Studying such injuries requires a model that can be used with a military helmet. This paper describes further work on a skull-brain model using skulls made from three different polyurethane plastics and a series of skull ‘fills’ to simulate brain (3, 5, 7 and 10% gelatine by mass and PermaGel™). The models were subjected to ballistic impact from 7.62 × 39 mm mild steel core bullets. The first part of the work compares the different polyurethanes (mean bullet muzzle velocity of 708 m/s), and the second part compares the different fills (mean bullet muzzle velocity of 680 m/s). The impact events were filmed using high speed cameras. The resulting fracture patterns in the skulls were reviewed and scored by five clinicians experienced in assessing penetrating head injury. In over half of the models, one or more assessors felt aspects of the fracture pattern were close to real injury. Limitations of the model include the skull being manufactured in two parts and the lack of a realistic skin layer. Further work is ongoing to address these.
Open Access
Early spears as thrusting weapons: Isolating force and impact velocities in human performance trials
(Elsevier, 2016-10-01) Milks, Annemieke; Champion, Stephen M.; Cowper, Elizabeth J.; Pope, Matt; Carr, Debra J.
Human hunting has been a cornerstone of research in human evolutionary studies, and decades worth of research programmes into early weapon systems have improved our understanding of the subsistence behaviours of our genus. Thrusting spears are potentially one of the earliest hunting weapons to be manufactured and used by humans. However, a dearth of data on the mechanics of thrusting spear use has hampered experimental research. This paper presents a human performance trial using military personnel trained in bayonet use. Participants thrusted replicas of Middle Pleistocene wooden spears into PermaGel™. For each spear thrust, impact velocity was recorded with high-speed video equipment, and force profiles were recorded using a force transducer. The results demonstrate that training improves performance when compared with previous experimental results using untrained participants, and that the mechanics and biomechanics of spear thrusting are complex. The trial confirms that previous spear thrusting experiments firing spears as projectiles are failing to replicate the entire spear thrusting event, and that crossbows are too powerful to replicate the low velocities involved in spear thrusting. In order to better understand evidence of spear thrusting in the archaeological record, experimental protocols accurately replicating and recording the mechanics of spear thrusting in the past are proposed.
Open Access
The effect of breast size and bra type on comfort for UK female police officers wearing body armour
(Elsevier, 2019-12-05) Malbon, Christopher; Knock, Clare; Critchley, Richard; Carr, Debra J.
Within the Police service of England and Wales the wearing of ballistic and stab resistant body armour is common, with most police forces mandating its usage when away from the police station. Of all the serving police officers in England and Wales 29.1% are female (Hargreaves et al., 2017). A survey was developed and then distributed by the Police Federation of England and Wales to all servicing police officers up to the rank of Inspector. The survey returned 2633 responses after cleaning of the data. From the responses it was seen that the predominant bra type worn is underwired (71%) and the predominant UK bra size is 34B (9%). It was also determined that the predominant areas where the body armour either rubbed or caused discomfort were the left and right anterior mammary regions and the posterior lateral sacral region. By understanding the distribution of bra size, type of bra worn and areas of discomfort or rubbing it helps further understand the issues faced by female police officers and how body armour design could be improved.
Open Access
The effect of fabric mass per unit area and blood impact velocity on bloodstain morphology
(Elsevier, 2019-05-09) Dicken, Anthony; Knock, Clare; Beckett, Sophie; Carr, Debra J.
This paper discusses the effects of thickness, mass per unit area, sett, yarn linear density and twist of calico fabrics (100% cotton, plain woven) on the morphology of passive bloodstains. Horse blood was dropped vertically onto three calico fabrics with different mass per unit areas (85.1 g/m², 163.5 g/m² and 224.6 g/m²). Six different impact velocities were used (1.7 ms-1, 2.9 ms-1, 4.1 ms-1, 4.9 ms-1, 5.1 ms-1 and 5.4 ms-1). The dry bloodstains were largest on the calico with the lightest mass per unit area. The low yarn linear density and large inter-yarn spaces meant that the blood could wick into the yarns from all directions and along the intra-yarn spaces. The calico with the middle mass per unit area had the smallest mean dry bloodstain area for four out of the six velocities. The twist level for this calico was greater than for the calicos with a heavier or lighter mass per unit area. This reduced the amount of wicking which occurred along the yarns due to the tighter yarn structure. The calico with the heaviest mass per unit area had the highest yarn linear density resulting in a thicker fabric, so the blood could not as easily penetrate into the fabric. This resulted in a thicker wet blood layer remaining on the fabric surface, where it gradually wicked vertically into the yarns under gravity. Less wicking along the yarns occurred, resulting in a smaller bloodstain than on the fabric with the lightest mass per unit area. The correlation between impact velocity and mean dry bloodstain area was greater for the calicos with the medium and heaviest mass per unit area than for the calico with the lightest mass per unit area. For the calicos with the medium and heaviest mass per unit area, the distance the blood spread laterally at impact, which increased with the increase in impact velocity, had a greater influence on the dry bloodstain area than the amount of wicking.
Open Access
The effect of helmet materials and simulated bone and tissue layers on bullet behaviour in a gelatine model of overmatch penetrating head injury
(Springer Verlag, 2017-08-16) Mahoney, Peter F.; Carr, Debra J.; Miller, D.; Teagle, M.
The aim of this work was to simulate an overmatch ballistic event against a head wearing a helmet. The experiments were designed to understand how layers of bone (or synthetic bone), synthetic skin and currently used helmet materials influence the behaviour of full metal jacket mild steel core (FMJ MSC) 7.62 × 39 mm bullets, impacting on targets with a mean velocity of 650 m/s. Bullet behaviour within 10% (by mass) gelatine blocks was assessed by measurements made of the temporary cavity within the blocks using high-speed video and of the permanent cavity by dissecting blocks post firing. While ANOVA did not find significant difference at the 0.05 level in the mean values of most of the measurements, there was a significant difference in neck length within the gelatine blocks. The addition of material layers did produce greater variability in the temporary cavity measurements under some of the conditions. One of the synthetic bone polymers with a synthetic skin layer produced similar results within the gelatine blocks to the horse scapulae (with residual tissue) and may be suitable for future ballistic experiments.
Open Access
The effect of military clothing on gunshot wound patterns in a cadaveric animal limb model
(Springer, 2019-08-14) Stevenson, Tom; Carr, Debra J.; Gibb, Iain E.; Stapley, Sarah A.
The majority of injuries in survivors of gunshot wounds (GSW) are typically to the extremities. Novel wound ballistic research is encouraged to try and capture corporate knowledge on the management of these injuries gained during recent conflicts and understand the wounding patterns seen. With recent work examining the effect of UK military clothing on extremity GSW patterns in a synthetic model, a model with greater biofidelity is needed for ballistic testing. The aim of this study was to assess the effect of UK military clothing on GSW patterns within a cadaveric animal limb model using two types of ammunition commonly used in recent conflicts—7.62 × 39 mm and 5.45 × 39 mm. In total, 24 fallow deer hind limbs were shot, 12 by 7.62 mm projectiles and the remaining 12 shot by 5.45 mm projectiles, further divided into four with no clothing layers (Cnil), four with a single clothing layer (Cmin) and four with maximum clothing layers (Cmax) as worn on active duty by UK military personnel. Limbs were analysed after ballistic impact using contrast CT scanning to obtain measurements of permanent cavity damage, and results were compared using analysis of variance (ANOVA). Results showed significantly different damage measurements within limbs with Cmax for both ammunition types compared with the other clothing states. This may result in GSWs that require more extensive surgical management, and invites further study.
Open Access
The effect of military clothing on gunshot wounding patterns in gelatine
(Springer Verlag, 2018-11-28) Stevenson, Tom; Carr, Debra J.; Stapley, Sarah A.
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.
Open Access
The effect of reactive dyeing of fabric on the morphology of passive bloodstains
(Elsevier, 2022-04-30) Dicken, Lisa; Knock, Clare; Carr, Debra J.; Beckett, Sophie
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.
Open Access
The effect of the digital printing of fabric on the morphology of passive bloodstains
(Elsevier, 2022-11-10) Dicken, Lisa; Knock, Clare; Carr, Debra J.; Beckett, Sophie
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.
Open Access
The effect of underwired and sports bras on breast shape, key anthropometric dimensions, and body armour comfort
(Sage, 2021-04-23) Malbon, Christopher; Knock, Clare; Critchley, Richard; Carr, Debra J.
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.
Open Access
Effects of salt water on the ballistic protective performance of bullet-resistant body armour
(SAGE, 2018-11-09) Dodd, S.; Malbon, Christopher; Critchley, Richard; Lankester, Claire; O’Rourke, S.; Corke, T.; Carr, Debra J.
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.