Search

The ballistic impact response of Kevlar textiles is significantly influenced by the friction between the yarns. It increases the dissipation of energy when yarns begin to displace relative to one another and it also results in to transfer of load to a larger area during ballistic impacts. In the present work, a novel sulfonyl aryl group containing monomer acrylic acid-2-(toluene sulphonyl amine)-ethyl ester (AATSAEE) was synthesized by a three-step process with ethanol amine and p-toluene sulfonic acid as starting material. The monomer was homopolymerized and grafted on Kevlar fabric by UV-induced free radical polymerization technique. Benzoyl peroxide (BPO) was used as initiator. Utilizing spectroscopic and thermal gravimetric methods, the monomer, precursor, and the homopolymer were characterized. The yarn pull-out tests on unmodified and AATSAEE grafted Kevlar fabrics were performed on Universal Tensile Tester at a steady speed of the upper jaw of 50 cm min−1. Increases in yarn pull out force have been noted with grafting of AATSAEE on Kevlar fabric. The peak force increases around 284% with grafting which indicates an increase in friction forces. When these yarns start to move apart from one another due to friction factors, the fabric's energy dissipation increases and it may results in to increase in energy absorption at the time of ballistic impacts. [ABSTRACT FROM AUTHOR]

In this work, the finite element software (ABAQUS) was used to build a single-cell model based on three-dimensional woven reinforced composite and investigate the propagation of stress waves in the composite. The experimental results of the edge part of the bullet after impact with the results of simulations were compared, and the final damage pattern of three-dimensional woven reinforced composite with commonly used laminates were also comparatively studied. The results indicated that the peak stress of the bullet in the three-dimensional woven reinforced composite increased with increasing incident velocity and was reflected back and forth. The fracture of the reinforcement yarn was rougher after the bullet was ejected from the lower surface of the three-dimensional woven reinforced composite than from the incident upper surface. Delamination did not occur within the three-dimensional woven reinforced composite, and the observed damage holes were generally consistent with the graphs simulated using finite element software. The research in this paper provides a design method for the application of three-dimensional orthogonal hybrid woven reinforced composites in ballistic protection. The experimental results and corresponding calculation methods can guide the design of high-performance protective armor. [ABSTRACT FROM AUTHOR]

As a parameter important ballistic, the research about polygonal and grooved barrels' behavior has not been widely carried out. The pressures, velocities, stresses, deformations, and strains generated by the firing of 9 mm × 19 mm ammunition in weapons with polygonal barrels are analyzed numerically and experimentally, compared with those generated in pistols with grooved barrels. The Finite Element Method with equal boundary and loading conditions was used in both types of guns, specifying the actual materials of the projectile and the barrels. Subsequently, experimental tests were carried out on various weapons with 9 mm ammunitions of 115, 122, and 124 gr. The results show that the 9 mm bullet fired in a polygonal barrel undergoes a maximum deformation towards its exterior of 0.178 mm and interior of 0.158 mm, with stress up to 295.85 MPa. Compared with 0.025 mm maximum external deformation and 0.112 mm internal deformation of 9 mm projectiles fired in a grooved barrel, with stress up to 269.79 MPa. The deformation in the polygonal barrel is in a greater area, but the rifling impression left is less deep, making its identification more difficult. Although there are differences in the stresses and strains obtained, similar velocity and pressure parameters are achieved in the two types of barrels. This has application in the development and standardization of new kinds of barrels and weapons. [ABSTRACT FROM AUTHOR]

Here in Canada, we often think of gun violence as confined to conflict zones, terrorism, and more of a problem for our southern neighbor. However, in recent years, it has also become a Canadian problem with increased gun violence related to criminal activity presenting in daily practice. Radiologists play a critical role in the evaluation of ballistic trauma and must therefore be familiar with both the common and uncommon patterns of ballistic injury. In this article, we review the mechanisms of ballistic trauma as well as their resultant injury patterns in order to guide image interpretation. [ABSTRACT FROM AUTHOR]

High-performance ultra-high molecular weight polyethylene (UHMWPE) soft ballistic sub-laminates ([0/90]n, SBSL) are stacked to build a soft body armor pack (SBAP) that can defeat handgun projectiles. Transverse impact on single-layer [0/90] SBSL of different size is modeled with shell elements and is solved using LS-DYNA composite material model MAT54. The finite element (FE) model is validated using 1D and 2D theories for transverse impact. The validated FE models are then used to study the perforation behavior of a [0/90] SK76/PU SBSL under constant and variable velocity impact. Results show that the basal shape of the transverse deformation cone has a diamond shape; the cone wave speed along primary material direction agrees well with 2D membrane theory, there exists a minimum perforation velocity below which the SBSL will not perforate, the peak perforation force reduces with the size of the SBSL, and the work of perforation decreases with increasing speed. Detail perforation mechanics of [0/90] SK76/PU SBSL is presented for the first time. [ABSTRACT FROM AUTHOR]

In this paper, the behaviour of laminated GFRP composite plate under ballistic impact has been studied with experimental as well as numerical model. Variation of residual velocity, energy absorption, damaged area and modes of damages have been studied. A simplified three dimensional FE model for composite plate and impactor with gap interaction and Lagrangian mesh has been presented. Material characterization of GFRP composite for progressive damage analysis based on material stress/strain failure criteria has been carried out. Shock effect with nonlinear volumetric response of laminated composite during impact is also considered. Pressure wave propagation in composite plate due to impact is also studied. Numerical results from present FE model are validated with those of experimental results showing close agreements in terms of damaged length, energy absorption and variation of residual velocities. [ABSTRACT FROM AUTHOR]

Projectile injury represents an estimated 14% of reported animal cruelty cases in the United States. Cases involving projectiles are complicated by gross similarities to other common types of injury, including bite wounds and motor vehicle injuries, by weapons and ammunition not commonly recognized or understood by veterinary medical professionals, and by required expertise beyond that employed in routine postmortem examination. This review describes the common types of projectile injuries encountered within the United States, as well as firearms and ammunition associated with this form of injury. The 3 stages of ballistics—internal, external, and terminal—and wounding capacity are discussed. A general understanding of firearms, ammunition, and ballistics is necessary before pursuing forensic projectile cases. The forensic necropsy is described, including gunshot wound examination, projectile trajectories, different imaging procedures, collection and storage of projectile evidence, and potential advanced techniques for gunpowder analysis. This review presents aspects of projectile injury investigation that must be considered in tandem with standard postmortem practices and procedures to ensure reliable conclusions are reached for medicolegal as well as diagnostic purposes. [ABSTRACT FROM AUTHOR]

Decades before Newton’s Principia ushered in the age of modern science, Aristotelian physics faced a serious challenge against its weakest point, in the quest to construct a new theory of projectile motion. Yet how were such new principles of motion conceived, without reference to an established theory of mechanics? This paper explores the conceptual space between the rejection of Aristotle’s physics and the appearance of Newton’s physics in which people such as Harriot and Galileo sought new ways to understand mechanical phenomena. This paper seeks to show that both Harriot and Galileo looked to the (early seventeenth-century) zeitgeist of accepting the law of reflection as a law of oblique projection-rebound for all material bodies, for their foundational (non-Aristotelian) conceptual resource. The kinematics and dynamics of light’s compound, oblique motion had been developed over centuries within optics, and constituted the ‘ideal’ resource for novel analyses of oblique projectile motion. Whereas Harriot’s inclusion of air resistance restricted the generalizability of optical principles to his simplest case, the upright parabola, Galileo’s idealized analysis of projectile motion in a vacuum represented all cases of projectile motion as upright parabolas. He was thus able to generalize these optical principles to projectile motion per se. [ABSTRACT FROM AUTHOR]

A new penetration equation for ballistic limit analysis (BLA) of a projectile–target pair is developed and presented. A critical review of the classic BLA (CBLA) has identified that the CBLA penetration equations do not satisfy the conservation of momentum and energy principles simultaneously and completely. It has also been found that the classic definition of residual velocity of the projectile does not quantify the instantaneous rigid body velocity of the projectile at ballistic limit. A new definition of the projectile relative velocity with respect to the target in contact (and in motion) is defined, and this new definition is used to define the projectile instantaneous velocity at ballistic limit. With this new definition of the projectile instantaneous velocity, the new penetration equation is derived satisfying both the conservation of momentum and energy principles simultaneously. A general functional form of the new penetration equation is used in analyzing experimental data and the results are found to match well with the experiments. The new equation is shown to be able to explain projectile residual velocity at and around ballistic limit, can predict the jump velocity at ballistic limit (if any), and is applicable to experimental ballistic data of a wide range of thin and thick targets. The present work sets the background for further development of theoretical penetration models incorporating material properties and parameters of the projectile–target pair. [ABSTRACT FROM PUBLISHER]

An analytical formulation is presented for the prediction of ballistic impact behavior of fabric targets. The formulation is based on stress wave propagation in porous medium and energy balance between the rigid projectile and the fabric target. During the ballistic impact event, energy lost by the projectile is absorbed by the fabric target through various damage and energy absorbing mechanisms such as compression of the fabric target directly below the projectile, compression in the region surrounding the impacted zone, shear plugging, stretching and tensile failure of yarns/layers in the region consisting of primary yarns, tensile deformation of yarns/layers in the region consisting of secondary yarns, conical deformation on the back face of the fabric target, in-plane friction between the warp and fill yarns and through the thickness friction between the moving projectile and the fabric target. The formulation presented considers both shear plugging and tensile failure of yarns during conical deformation and is valid for a wide range of fabric target thicknesses. Solution procedure for the evaluation of ballistic impact performance is presented. Further, experimental results are presented for the validation of analytical predictions. A good match is observed between the analytical predictions and the experimental results. [ABSTRACT FROM PUBLISHER]

Multi-axial aramid fabrics have a wide range of applications in the construction of composite structures for body armor. Nanoparticles, which include nanosilica, are one of the most common nanofillers for these structures. The particles of nanosilica possess nanometer dimensions with high specific surface area. Silane coupling agents are mostly used for modifying nanosilica surface in order to prevent silica agglomeration. Incorporation of nanosilica treated with silane adhesion promoter, in the matrix part of the hybrid composite form, leads to increased resistance to the bullet shock impact. In this study, the resistance to penetration of a shot bullet was tested for four samples of the aramid fabric composite forms. All fabrics were coated with γ-aminopropyl triethoxysilane (AMEO silane)/ethanol solution. Two samples were impregnated with poly (vinyl butyral) (PVB)/ethanol solution, while the other two were impregnated with the same solution, but with the addition of the 30 wt.% AMEO silane modified silica nanoparticles as reinforcement. The samples were both hard and flexible options. The bullet-shooting test was applied to all the composites by two different bullet types. The structural design of the samples improved the ballistic resistance after the bullets were shot. Some ballistic image analyses for print and penetration depth of the samples were performed using Image Pro-Plus software. [ABSTRACT FROM AUTHOR]

The aim of this study was to understand the stick–slip (Sk-Sp) properties of para-aramid woven fabrics. For this reason, pullout test was conducted on para-aramid Twaron CT® 716 (CT716) and Twaron CT® 716 (CT714) woven fabrics. The Sk-Sp region and accumulative retraction force region were defined based on the single- or multiple-yarn pullout force–displacement curve. It was found that Sk-Sp force and accumulative retraction force depend on the fabric density and the number of pulled ends in the fabric. Sk-Sp force in the multiple-yarn pullout test was higher than that of the single-yarn pullout test. Sk-Sp force in single- and multiple-yarn pullout tests in the dense CT716 fabric was higher than that of the loose CT714 fabric. In addition, long fabric samples showed high Sk-Sp force compared to that of the short fabric samples. On the other hand, the amount of Sk-Sp force was related to the number of interlacement points in the fabric, whereas the amount of accumulative retraction force was related to fabric structural response. [ABSTRACT FROM PUBLISHER]

How accurate are explicit judgements about familiar forms of object motion, and how are they made? Participants judged the relations between force exerted in kicking a soccer ball and variables that define the trajectory of the ball: launch angle, maximum height attained, and maximum distance reached. Judgements tended to conform to a simple heuristic that judged force tends to increase as maximum height and maximum distance increase, with launch angle not being influential. Support was also found for the converse prediction, that judged maximum height and distance tend to increase as the amount of force described in the kick increases. The observed judgemental tendencies did not resemble the objective relations, in which force is a function of interactions between the trajectory variables. This adds to a body of research indicating that practical knowledge based on experiences of actions on objects is not available to the processes that generate judgements in higher cognition and that such judgements are generated by simple rules that do not capture the objective interactions between the physical variables. [ABSTRACT FROM AUTHOR]

An analytical model is presented for the ballistic impact behavior of ceramic-composite armors. The model is based on wave theory and energy balance between the kinetic energy of the projectile and the energy absorbed by different mechanisms. The armor analyzed consists of front composite cover layer, ceramic plate, rubber layer and the composite backing plate. The projectile is cylindrical. The major damage and energy-absorbing mechanisms are compression of the target directly below the projectile, compression in the surrounding region around the point of impact, formation of ring cracks and radial cracks in the ceramic leading to tensile failure, shear plugging, pulverization of the ceramic, tension in the yarns, delamination and matrix cracking in the composite, bulge formation on the back face of the composite backing plate and friction between the target and the projectile. Projectile erosion and deformation are also considered. Kinetic energy, velocity and deceleration of the projectile, distance traveled by the projectile and the contact force are presented as a function of time. Ballistic limit velocity, contact duration and damage progression are also given. Further, solution procedure is presented for the study of ballistic impact behavior of ceramic-composite armors. Analytical predictions are validated with the experimental results. Finally, performance of a typical ceramic-composite armor is presented. [ABSTRACT FROM PUBLISHER]

A combined theoretical–semiempirical penetration model of ballistic penetration of thick section composites has been developed. The penetration model is developed by breaking down the penetration event into two major phases, that is, (i) the short-time phase I shock compression and (ii) the long-time phase II dynamic penetration. Phase I shock compression considers a one-dimensional stress wave propagation theory and the rate effects on material properties. On the other hand, the phase II dynamic penetration phase incorporates a dynamic increase factor to a semiempirical quasi-static penetration resistance curve. The combined theoretical–semiempirical penetration model is compared with finite element analyses of the same problem and good correlations are obtained. [ABSTRACT FROM AUTHOR]

Objective: This study was aimed to determine the effects of direction and path length on movement time when traversing a constrained path of width, W, in a mouse tracking task.Background: Tracking within constrained paths has been demonstrated to hold in many applications. Movement time and velocity of movement have shown very similar relationships, possibly because of the lack of extreme testing conditions. Most previous research evaluated conditions with only constant path length (A) of movement.Method: A total of 15 participants performed a mouse steering task within a constrained path at various angles. The independent variables were track width (W), path length, and path angle. Movement time was the dependent variable.Results: Analyses showed a significant effect of movement direction on movement time, and the relationship was approximately sinusoidal and symmetrical about the horizontal axis. Path length had a significant effect on speed of movement, which was not that apparent on movement time. At low A/W values, movements appeared to be ballistic.Conclusion: Tracking within constrained paths can be modeled to account for the effect of path angle.Application: Vertical hand movements, especially within constrained paths, may not be ideal from a performance and biomechanical standpoint. The performance curve gradients are a good way to evaluate and standardize the testing of input devices and to define acceptable speeds for various tolerances in computer and industrial tasks that involve angular motions. The results of this experiment will help designers to optimize products and training programs. [ABSTRACT FROM PUBLISHER]

The increasing use of suicide bombs has brought a new set of problems for the modern clinician. To competently manage these, the clinician must have an appreciation of the underlying ballistic principles of these attacks and their common manifestations as patterns of injury. There are forensic implications in managing the casualties of such an attack, as well as those of scene and resource management. The risks of intentional and unintentional incorporation of biohazardous materials are also discussed. [ABSTRACT FROM AUTHOR]

This study reports the results of an empirical investigation into the ability of textbooks to form an effective ballistic shield that can be incorporated into school safety plans. The authors examine the history of assaultive violence with firearms in schools and the evolution of school emergency plans. The most common calibres used in school shootings were tested for their ability to penetrate hardback textbooks. The results indicate that most common handgun bullets can be stopped by only one or two textbooks and that even most assault rifle rounds can be stopped by three to five books. Examples are also provided on how law enforcement officers might incorporate the ballistic resistance of textbooks concept into a school emergency plan. [ABSTRACT FROM AUTHOR]

Polycarbonate is commonly used as the material of riot shields. Firings of 83 g steel ball bearings at velocities of 23–98 ms–1 produced damage in the form of dents. Subsequent tensile testing showed a small drop in yield strength and ductility for impact velocities greater than 58 ms–1. This drop in yield strength and ductility was more marked for specimens that had been soaked in acetone for 10 min after ballistic impact. Soaking in n-heptane produced no similar effect to that seen with acetone. Measurements were taken of the velocities of projectiles likely to be thrown by rioters. These showed that the measured velocities were lower than those that caused macroscopic damage to polycarbonate when hit by a ball bearing. Thus susceptibility to brittle failure is likely to be associated with shields that have been hit by sharp objects and exposed to solvents after impact. Mechanical stressing of polycarbonate at the point of impact by the ball bearing had no effect on the subsequent mechanical properties. This is in contrast to the embrittlement seen in polycarbonate when internal strains are present produced on fast cooling from the melt. [ABSTRACT FROM AUTHOR]

In the present study, the ballistic resistance of sandwich composite structures for vehicle armor panel applications is investigated. The core material of each sandwich structure is a layer of tiled alumina ceramic, combined with a layer of two-dimensional (2D)/three-dimensional (3D) S-2 glass-based woven composite laminate, sandwiched between 2D plain weave composite skins. The 2D composite backing consists of a plain woven fiberglass, with fiber orientation predominantly in the direction of plane of the weave. The 3D contains similar in-plane fiber preform structure, with the inclusion of an integral through thickness fiber, creating a 3D structure. The ballistic performance of sandwich composite with several types of 3D woven backings is compared to the baseline 2D plain weave backed sandwiched composites. An IMACON 200 high-speed camera is used to obtain high-speed photographs of the ballistic events of penetration and damage. These images are analyzed to study the real-time damage mechanism of the strike face surface of several targets and subsequently to obtain average resistive force of target points during impact. The velocities of the projectile (M2AP armor piercing bullets) are recorded in all the experiments, and they range from 915 to 975 m/s. Postmortem analyses, which include through thickness sectioning, are performed on each sandwich structure. The results show that armor panels with 3D woven backing have a higher ballistic efficiency than the 2D baseline panels, strike face damage mechanics are predominantly axisymmetric about the impact point and the panels with 3D backing had controlled delamination and fewer complete penetrations. [ABSTRACT FROM AUTHOR]

The development of lightweight armour systems for ballistic protection is under continuing attention of the manufacturers and users. A new design of the composite armour systems has been developed and ballistically tested. A new armour system consists of a ceramic plate, an intermediate ceramic–polymer layer and a polymer fibre lining as a backing material. The proposed composite armour systems prepared with a use of specially selected compositions of the intermediate layer promoting the absorption of the kinetic energy of projectiles provide adequate ballistic protection to National Institute of Justice (NIJ) level III and level IV, and they successfully withstand multiple hits. [ABSTRACT FROM AUTHOR]

The standard bottleneck model of the psychological refractory period (PRP) assumes that the selection of the second response is postponed until the first response has been selected. Accordingly, dual-task interference is attributed to a single central-processing bottleneck involving decision and response selection, but not the execution of the response itself. In order to critically examine the assumption that response execution is not part of this bottleneck, we systematically manipulated the temporal demand for executing the first response in a classical PRP paradigm. Contrary to the assumption of the standard bottleneck model, this manipulation affected the reaction time for Task 2. Specifically, reaction time for Task 2 increased with execution time for Task 1. This carryover effect from Task 1 to Task 2 provides evidence for the notion that response execution can be part of the processing bottleneck. [ABSTRACT FROM AUTHOR]

Wound ballistics is a science which can relate to other disciplines such as law, design of weapons, forensic pathology and surgery. We present an approach to wound ballistics which should make this complex subject accessible to and understandable by surgeons. There are two major contributions made by the science of wound ballistics to the surgical management of war-wounded people. The first is the demonstration of the transfer of kinetic energy from the projectile to the tissues along the projectile's track ('down-track'); this explains the heterogeneity of war wounds. The 'down-track' deposit of energy of a projectile is determined principally by the mass and velocity of the projectile and also, in the case of a bullet, by its construction and stability in flight. The rate with which energy is transferred determines the amount of tissue damage. If surgeons recognize the heterogeneity of wounds they can adopt appropriate management strategies for each individual wounded person. However, guidelines for surgeons as to which or how much tissue should be excised from a war wound have not yet been generated from wound ballistics studies. The second contribution pertains to fractures; the transfer of energy from the projectile to the bone and its surrounding soft tissues has important implications for fracture management. A comminuted fracture may result from low energy transfer. The extent of soft tissue damage surrounding a fracture influences the excision of the wound and the choice of fracture holding. In the context of the law of war and, in particular, the Hague Declaration of 1899, we propose that 'down-track' deposit of energy as opposed to technical consideration of bullet construction should be a starting point for legal debate about weapons. [ABSTRACT FROM AUTHOR]

The article presents two cases of civilian gunshot wounds. The first case was that of a 20-year old man who was shot in the left side with a handgun. The second case was that of a 29-year old man who was shot in the left side by a .38 caliber handgun. Civilian gunshot wounds are usually caused by low velocity, relatively small caliber missiles. Ballistic specialists spend their time studying the pattern of holes created by the bullets.