Measurement of kinetic energy dissipation with gelatine fissure formation with special reference to gelatine validation

Various methods for calculating the amount of kinetic energy dissipated by a bullet into ballistic gelatine have been suggested in literature. These methods were compared using the results of thirteen 9 mmx19 mm pistol and five 7.62 mmx 39 mm rifle bullets shot into 10% ballistic gelatine. The Wound Profile Method gave the highest correlation, 0.89, with the measured amounts of dissipated kinetic energy. The Fissure surface area and total crack length method gained 0.51 and 0.52, respectively. The experimental results were also compared with those from pig tests with the same bullet types. Using the z-test at 95% level of confidence no difference between impact velocity normalized bullet decelerations could be determined for the 9 mm bullet used. The same test showed significant difference for 7.62 mm bullets. That, however, can be considered to be the result of the bullet's tendency to tumble in non-homogenous living tissue causing significant dispersion of observed deceleration values. The results add further evidence supporting the validity of 10% gelatine at +4 degrees C as wound ballistic tissue simulant. The study also introduces the use of an elastic "shroud" to hold the gelatine in place, to some extent reduce the effects of asymmetric expansion of the gelatine and to simulate the expansion suppression effect of surrounding tissues.     

Potential Use in Forensics of a Novel Hybrid Gelatin—Dynamic Impact Assessment

Ballistic gelatin as simulant of the human body and organs is a support in forensics. After having obtained very good results for a new gelatin‐based composite in terms of physicochemical and rheological properties, this study focused on this material's mechanical behavior during stabbing and shooting versus bovine and porcine organs and standard ballistic gelatin. The hybrid gelatin has a predominantly elastic behavior at 23°C, whereas the elastic modulus becomes practically constant in the 10–0.1 Hz frequency range. In terms of stabbing behavior, the small variations obtained between porcine organs and surrogate are below 5%, the perforation indicating a good similarity. From the ballistic test results using 10 × 28T rubber balls, it has been seen that the hybrid ballistic gelatin conducts to more reliable and reproducible values of perforation/penetration versus standard gelatin, making from it a real candidate for use in forensic tests.     

Pig Organ Energy Loss Comparison Experiments Using BBs

Torso models for ballistics research require that the mechanical properties of simulant materials must match the heterogeneous nature of tissues/organs within the human thorax/abdomen. A series of energy loss experiments were conducted on fresh porcine organs/tissues at room temperature and 37°C, using steel 4.5 mm BBs fired from a Daisy^® brand air rifle. They were compared to FBI and NATO specification ordnance gelatin and a candidate surrogate material called Simulant “A”. Two CED M2 chronographs measured BB velocity. The resulting energy loss was established using KE = 1/2 mv² before and after target perforation. The combined results at room temperature and 37°C were as follows: FBI specification gelatin was similar (p > 0.05) to heart and lung, spleen was similar to NATO specification gelatin, Simulant “A” was similar to hindquarter muscle, and hindquarter muscle, kidney, and spleen were similar to each other regarding energy retardation. These results can be used as a basis for the development of simulant materials to create an anatomically correct heterogeneous model.     

Evaluating Simulant Materials for Understanding Cranial Backspatter from a Ballistic Projectile

In cranial wounds resulting from a gunshot, the study of backspatter patterns can provide information about the actual incidents by linking material to surrounding objects. This study investigates the physics of backspatter from a high‐speed projectile impact and evaluates a range of simulant materials using impact tests. Next, we evaluate a mesh‐free method called smoothed particle hydrodynamics (SPH) to model the splashing mechanism during backspatter. The study has shown that a projectile impact causes fragmentation at the impact site, while transferring momentum to fragmented particles. The particles travel along the path of least resistance, leading to partial material movement in the reverse direction of the projectile motion causing backspatter. Medium‐density fiberboard is a better simulant for a human skull than polycarbonate, and lorica leather is a better simulant for a human skin than natural rubber. SPH is an effective numerical method for modeling the high‐speed impact fracture and fragmentations.     

Comparison of the terminal ballistics of full metal jacket 7.62-mm M80 (NATO) and 5.56-mm M193 military bullets: a study in ordnance gelatin

Great controversy has surrounded the replacement of the 7.62-mm caliber by the reduced 5.56-mm caliber as the standard U.S. military rifle. Although its relevance to human wounding can be debated, the terminal ballistics of military small arms in ordnance gelatin remains a convenient medium for comparative testing. In the present study, 7- by 10- by 24-in. (18 by 25 by 61 cm) blocks of 20% ordnance gelatin were fired upon from a range of 19 ft (6 m) under high-speed cinemagraphic surveillance. The tendency of the M193 5.56-mm full metal jacket projectile to break up in soft tissue simulant was confirmed as a fundamental difference from the 7.62-mm M80 NATO ball.     

Less‐Lethal Hybrid Ammunition Wounds: A Forensic Assessment Introducing Bullet‐Skin‐Bone Entity

Abstract: Agencies all around the world now use less‐lethal weapons with homogeneous missiles such as bean bag or rubber bullets. Contusions and sometimes significant morbidity have been reported. This study focuses on wounds caused by hybrid ammunition with the pathologists’ flap‐by‐flap procedure. Twenty‐four postmortem human subjects were used, and lesions caused on frontal, temporal, sternal, and left tibial regions by a 40‐mm hybrid ammunition (33 g weight) were evaluated on various distance range. The 50% risk of fractures occurred at 79.2 m/sec on the forehead, 72.9 m/sec on the temporal, 72.5 m/sec on the sternum, and 76.7 m/sec on the tibia. Skin lesions were not predictors of bone fracture. There was no correlation between soft and bone tissue observed lesions and impact velocity (correlated to distance range). Lesions observed with hybrid ammunition were the result of bullet‐skin‐bone entity as the interaction of the projectile on skin and bone tissues.     

The "skin-skull-brain model": a new instrument for the study of gunshot effects

In order to create and study wound morphology, a "skin-skull-brain model" had to be designed which would make the laboratory reproduction of a real ballistic injury possible.To simulate the human skin, an artificial skin (a silicon cap) is used. This silicon scalp contains synthetic fibers (artificial leather) to simulate the collagen and fat of the scalp. The artificial skull is a layered polyurethane sphere (19 cm o.d.; and 5, 6, or 7 mm thick) constructed in a specially designed form with a Tabula externa, Tabula interna, and a porous Diploe sandwiched in between. The periostium of the artificial skull is made of latex. This elastic latex layer prevents the bone fragments from scattering after the model has been struck by gunfire. The brain itself is simulated with ordnance gelatin, 10% at 4 degrees C, a material well known in wound ballistics. Gunshots were fired at a distance of 10 m from the model.During the evaluation of the "skin-skull-brain model", it was possible to show that injuries inflicted to this model are fully comparable to the morphology of equivalent real gunshot injuries.Using the "skin-skull-brain model" has some significant advantages: the model is inexpensive, easy to construct, instantly available for use, and eliminates ethics conflicts. The main advantage of such a model is, in comparison with biological substances, the high reproducibility of inflicted traumas.     

Forensic implications of respiratory derived blood spatter distributions

The nature of blood aerosols produced in physiological studies of an upright subject expiring small volumes through straws, spitting and mouthing sounds, and a semi-prone subject spitting through a bloody mouth or snorting through a single nasal orifice and by a simplified physical model of the respiratory system were investigated. Each manoeuvre produced many hundreds of droplets of a range of size, the vast majority being less than 1mm diameter. Droplets under 1mm dia. travelled over 1m - much further than could be expected if their flight was ballistic, like that of impact spatter. Respired blood aerosol properties are explained in terms of established mechanics of airflow shear induced aerosol production and the fluid mechanics of exhaled air movement.     

The effects of certain intermediary target materials and their proximity to ballistic gelatin on jacketed hollow point bullet expansion

Expanding bullets are preferred by law enforcement because of their wounding potential and ability to avoid over-penetration which could result in unintended targets being struck by bullets that perforate their intended targets. Expansion failure for jacketed hollow point (JHP) bullets is commonly attributed to several causes including damage to the bullet's cavity, velocity loss, bullet destabilization and materials from intermediate targets filling the bullet's cavity which can cause expansion failure when the bullet subsequently impacts a soft, fluid-based target such as human tissue or ballistic gelatin. In this study, JHP bullets were fired into ballistic gelatin after passing through selected intermediate targets representing items common to shooting incidents. Velocity loss and bullet destabilization were not factors that contributed to the JHP bullets that experienced expansion failure; however, materials obstructing the bullets' cavities and damage to the bullets' cavities were considered causes for some of the JHP bullet expansion failures. It was determined through this research that most of the target materials caused JHP bullet expansion failure when shored against the ballistic gelatin, but when placed at distances of 7 ft. from the ballistic gelatin, bullets fired through the same target materials did expand. This original and unique study produced findings that are of significant value to shooting incident reconstruction experts and other forensic professionals as shooting incidents can call into question a victim's proximity to a wall or door when a bullet(s) perforated such a target material.     

Injuries of the Head from Backface Deformation of Ballistic Protective Helmets Under Ballistic Impact

Modern ballistic helmets defeat penetrating bullets by energy transfer from the projectile to the helmet, producing helmet deformation. This deformation may cause severe injuries without completely perforating the helmet, termed “behind armor blunt trauma” (BABT). As helmets become lighter, the likelihood of larger helmet backface deformation under ballistic impact increases. To characterize the potential for BABT, seven postmortem human head/neck specimens wearing a ballistic protective helmet were exposed to nonperforating impact, using a 9 mm, full metal jacket, 124 grain bullet with velocities of 400–460 m/s. An increasing trend of injury severity was observed, ranging from simple linear fractures to combinations of linear and depressed fractures. Overall, the ability to identify skull fractures resulting from BABT can be used in forensic investigations. Our results demonstrate a high risk of skull fracture due to BABT and necessitate the prevention of BABT as a design factor in future generations of protective gear.     

Experimental study of the expansion dynamic of 9 mm Parabellum hollow point projectiles in ballistic gelatin

We study in this paper the expanding behaviour of hollow point 9 mm Parabellum projectiles (Hornady XTP(?) and Speer Gold Dot(?)). We defined a deformation rate that takes into account both the diameter increase and the length reduction. We plotted the behaviour of this parameter versus impact velocity (we refer to this curve as the expanding law). This expanding law has been plotted for different gelatin weight ratios and different gelatin block lengths. We completed our experiments with a set of high speed movies in order to correlate the deceleration to the state of expansion and size of the temporary cavity. Our results pointed out that full expansion is reached shortly after the projectile fully penetrates the gelatin. This result shows that the key point to accurately simulate human body interaction with a hollow point projectile is to accurately simulate the interface (skin, skull, clothes thoracic walls). Simulating accurately organs is only an issue if a quantitative comparison between penetration depths is required, but not if we only focus on the state of expansion of the projectile. By varying the gelatin parameters, we discovered that the expanding law exhibits a velocity threshold below which no expansion occurs, followed by a rather linear curve. The parameters of that expanding law (velocity threshold and line slope) vary with the gelatin parameters, but our quantitative results demonstrate that these parameters are not extremely critical. Finally, our experiments demonstrate that the knowledge of the expansion law can be a useful tool to investigate a gunshot in a human body with a semi-jacketed projectile, giving an estimation of the impact velocity and thus the shooting distance.     

Area-specific increased density of mu-opioid receptor immunoreactive neurons in the cerebral cortex of drug-related fatalities

In animal experiments and in cell culture, chronic morphine treatment has been followed by "up-regulation" as well as "down-regulation" of the mu-opioid receptor (OR) number. The present postmortem morphometric study of morphine-related fatalities of drug-addicts (n=13, 20-35 years old, with blood unconjugated morphine levels from 27.1 ng/ml to 458 ng/ml, m.v. 198.5 ng/ml) versus a non-addicted control group (n=13, 10-44 years old) was intended to examine, whether chronic opiate exposure affects the numerical density of mu-OR expressing neurons in the human neocortex (areas 11, 24 and 25 according to Brodmann). For the immunohistochemical procedure, vibratome sections (100 microm) were incubated with a monoclonal antibody against the mu-OR, diluted 1:100, and immunolabelled sites were visualized using an immunoperoxidase protocol. The numerical densities of OR immunoreactive neuronal profiles and Nissl-stained central profiles were assessed morphometrically (camera lucida-drawings). In both groups, the anti-mu-OR-immunoreactivity was mainly localized in pyramidal neurons of layers (L) II/III and V and in multiform neurons of L VI. In the areas 24 and 25, the density of the immunoreactive neuronal profiles did not display a significant difference between the two examined groups. In the area 11, however, the number of immunolabelled neuronal profiles amounted to 2777+/-206 mm(3) in the drug-related fatalities and to 2320+/-124 mm(3) in the control group and thus was significantly increased.     

Effects of Re‐heating Tissue Samples to Core Body Temperature on High‐Velocity Ballistic Projectile–tissue Interactions

Damage produced by high‐speed projectiles on organic tissue will depend on the physical properties of the tissues. Conditioning organic tissue samples to human core body temperature (37°C) prior to conducting ballistic experiments enables their behavior to closely mimic that of living tissues. To minimize autolytic changes after death, the tissues are refrigerated soon after their removal from the body and re‐heated to 37°C prior to testing. This research investigates whether heating 50‐mm‐cube samples of porcine liver, kidney, and heart to 37°C for varying durations (maximum 7 h) can affect the penetration response of a high‐speed, steel sphere projectile. Longer conditioning times for heart and liver resulted in a slight loss of velocity/energy of the projectile, but the reverse effect occurred for the kidney. Possible reasons for these trends include autolytic changes causing softening (heart and liver) and dehydration causing an increase in density (kidney).     

利用尸体软组织生物力学性状时序性变化推断死亡时间

目的探讨尸体软组织生物力学性状时序性变化规律及其推断死亡时间的可行性。方法将实验大鼠用颈椎脱臼法处死,放置25℃恒温培养箱内即刻、6、12、18、24、30、36、42、48、60、72、96、120、144、168、192h,定时、定位、定向、定形切取大鼠胸部正中皮肤、腹壁肌肉、胸主动脉、结肠和小肠的生物力学试件,用电子万能材料试验机检测各试件的极限载荷、应变、应力生物力学参数。结果除主动脉外,尸体皮肤、肌肉、小肠、结肠的各项软组织生物力学参数均呈明显的死后时序性下降趋势。各参数下降趋势具有显著性差异的＂窗口期＂分别为：极限载荷：死后18h内皮肤、小肠呈下降趋势;24h内肌肉、结肠呈下降趋势;96～168h肌肉呈下降趋势;72～192h结肠呈下降趋势。应变：各组织在24h内均呈下降趋势,其结肠72～192h缓慢下降趋势。应力：皮肤18h内呈下降趋势,肌肉、小肠24h内呈下降趋势,结肠36h内呈下降趋势。结论大鼠尸体软组织各生物力学性状在不同的＂窗口期＂存在时序性变化规律,综合各指标可用于推断相应＂窗口期＂内的死亡时间。     

Laminated safety glass as an intermediate target: a wound ballistic study

Various 9‐mm ammunitions (A1, A4, A5, ST, GS, GSb, P.E.P., SeCa, HP, PTP/s, VM, McVG, DM41, PTP, SX2, PT, and MEN frangible) were tested regarding their velocity, energy, angle of impact, and potential wound channel after penetrating a car window at 30° and 90°. Test materials were gelatine, soap, and pig cadavers. The velocities of the projectiles were between c. 288 and 430 m/ses, the energy spread between 394 and 564 J. Handgun bullets fired through vehicular side window glass lose substantial energy reducing the effectiveness of the ammunition. This effect is greater when fired at an angle of 30° compared to 90°. At a shooting angle of 90°, none of the different projectiles showed remarkable differences considering its wound ballistic features. Accuracy is maintained at a 90° angle but seriously impaired at 30°. None of the examined ammunition complied with the demanded wound channel effectiveness of 30–60 J/cm.     

Experimental blowgun injuries, ballistic aspects of modern blowguns

Slender thin arrows blown through modern blowguns can cause serious injuries. In this paper we present some data regarding the terminal ballistics of such an arrow when blown by a young male who had no previous experience with the weapon. The penetration depth into wood was similar to that of an arrow fired from a pistol-crossbow. Further, the blowgun arrow could pass through more than 7 mm of porcine bone. The velocities at a distance of 2 m from the blowgun of three different types of arrows having weights of 1-1.6 g and diameters between 1 and 5 mm were between 22 and 32 m/s, giving an energy of 0.3 to 0.6 J. When blown from a blowgun, these slender modern arrows can thus penetrate human skin and even the cranial bone of a child and cause serious injury.     

Investigation of the variability in the tool marks produced by modified blank firing pistols on fired 7.65 mm projectiles

Firearms identification has an important place in forensic ballistic investigations since the weapons are widely used in criminal offences. Firearm examiners resolve many case files, through the use of automatic systems or comparison microscopes. Advanced forensic technologies like BALİSTİKA helps to record and analyze non standard ballistic evidence. In today's world, with the ease of access to materials and production technique information, pistols modified from blank firers are frequently encountered as crime tools. In this study, the characteristics of 7.65 mm fired cartridge cases obtained by controlled shots from blank firing modified pistols were examined, and their detection performances were compared by means of the Balistika system. Although distinctive differences are not expected after successive test shootings, balistically important changes were seen after the use of blank firing modified pistols and the 3D imaging system proved to be useful in observing such differences. The analyses showed that the modifications in weapons lead to variation in the ballistic characteristics and reduce the accuracy of the detection performance, which may result in flawed forensic decisions. It was also found that the deviations in ballistic impressions of modified blank firing pistols were greater than that of standard fabricated and hand-made pistols. This unique study contributed to the forensic sciences literature by focusing on the impact of modified weapons on ballistic characteristics.     

The influence of physical properties and lipid content of bile on the human blood/bile ethanol ratio

The relationship between ethanol levels in blood and bile was determined in human postmortem specimens. The influences of several physical properties--surface tension, specific gravity and viscosity--and bile lipid content on the blood/bile ethanol ratio were evaluated. A gas chromatographic direct injection technique was employed to determine the ethanol concentrations in postmortem blood and bile specimens. A positive correlation was established between the levels in the two fluids. No correlation could be found between the blood/bile ethanol ratios and the aforementioned physical properties of bile. Correction of the observed bile ethanol for lipid content had an insignificant effect on the ratio. The average blood/bile ethanol ratio was 1.03 +/- 0.29 (range: 0.32-2.91). The wide range observed makes it undesirable to use bile ethanol concentrations to predict specific blood ethanol concentrations. However, under certain conditions, bile ethanol levels may be used to estimate blood concentrations within a range of values.     

Minimum velocity necessary for nonconventional projectiles to penetrate the eye: an experimental study using pig eyes

To satisfy the Criminal Code of Canada's definition of a firearm, a barreled weapon must be capable of causing serious bodily injury or death to a person. Canadian courts have accepted the forensically established criteria of "penetration or rupture of an eye" as serious bodily injury. The minimal velocity of nonconventional ammunition required to penetrate the eye including airsoft projectiles has yet to be established. To establish minimal threshold requirements for eye penetration, empirical tests were conducted using a variety of airsoft projectiles. Using the data obtained from these tests, and previous research using "air gun" projectiles, an "energy density" parameter was calculated for the minimum penetration threshold of an eye. Airsoft guns capable of achieving velocities in excess of 99 m/s (325 ft/s) using conventional 6-mm airsoft ammunition will satisfy the forensically established criteria of "serious bodily injury." The energy density parameter for typical 6-mm plastic airsoft projectiles is 4.3 to 4.8 J/cm2. This calculation also encompasses 4.5-mm steel BBs.