Bulletproof Vests Research Articles

Modeling the Effect of Non-Penetrating Ballistic Impact As a Means of Detecting Behind Armor Blunt Trauma

According to the National Institute of Justice (NIJ) Standard 0101.04, the maximum deformation a soft armor vest can undergo without penetration is 44 mm. However, this does not take into account the effect of the pressure wave or energy transferred to the organs within the torso due to behind armor blunt trauma (BABT). Therefore, a study was undertaken to develop a finite element model (FEM) to study these effects. A finite element model (FEM) of the human thorax; complete with musculoskeletal structure and internal organs (heart, liver, lungs and stomach), intercostal muscle and skin, has been developed in LS-DYNA. A Kevlar vest was modeled on the chest to simulate non-penetrating ballistic impact. Using a projectile modeled with a size and mass equivalent to a 9 mm (124 grain) bullet at 360 and 425 m/s, four impacts were simulated against NIJ Level II and Level IIIa Kevlar vests at the midsternum and right thorax. At the same velocity, the pressures decreased by a factor of 3 and the energy absorbed by the organs decreased by a factor of 6 for the NIJ Level II and Level IIIa vests, respectively. As the projectile velocity increased, the peak pressures increased by a factor of 3 while the energy absorbed by the organs increased by a factor of 4. The resulting pressure profiles and kinetic energy exhibited by the respective organs indicate this model may be useful in identifying mechanisms of injury as well as organs at an elevated injury risk as a result of BABT.

Analysis of 3D woven structure as a device for improving thermal comfort of ballistic vests

PurposeThis study presents the design, manufacture and evaluation of a type of 3D hollow woven structure, as a mean for improving ventilation underneath ballistic body armour and thus, thermal comfort.Design/methodology/approachBy means of a computational fluid dynamic package, fluid flows through different cross‐sectional tubular geometries were simulated in order to predict, which structural parameters of the 3D hollow fabrics are optimal to support ventilation.FindingsAs the result of the computational analysis four optimised 3D hollow woven structures were selected and generated on a standard weaving loom.Originality/valueInvestigation of thermal comfort of 3D ballistic vests.

Influence of Personal Armor on Distribution of Entry Wounds: Lessons Learned from Urban-Setting Warfare Fatalities

This study was undertaken to examine the distribution of entry wounds resulting from firearms and shrapnel in soldiers wearing military personal armor systems (MPAS) in low-intensity urban combat conditions. Data were collected for a retrospective analysis on all combat fatalities sustained by the Israeli Defense Force (IDF) between March 30, 2002, and April 22, 2002, during Defensive Shield Operation in the West Bank. Twenty-six of the 30 fatalities were evaluated in the Israeli National Center of Forensic Medicine. A total of 149 entrance wounds were divided into shrapnel and bullet groups. The "face-neck" region had the highest density rate compared with other body regions in both shrapnel and bullet groups (2.97 and 2.41, respectively; p < 0.0001). In both groups, the overall prevalence of anterior injuries was significantly higher than posterior ones (78.9% vs. 21.1% in the shrapnel group and 68.5% vs. 31.5% in the bullet group, p < 0.001). However, anterior and posterior chest injuries had a reverse yet more even distribution (43.8% and 56.2% in the bullet group and 40% and 60% in the shrapnel group, respectively; p < 0.001). The difference in the average diameters of entry wounds in the covered versus uncovered regions (0.79 +/- 0.42 cm vs. 0.73 +/- 0.29 cm, respectively) was not statistically significant (p = 0.11). The use of MPAS turned the face-neck region into the most vulnerable body part, as shown by its prominent density rate, especially in the shrapnel group. MPAS designed for urban setting warfare should provide maximal shielding both to the anterior and posterior chest regions. The diameter of entrance wounds in the covered versus the uncovered areas was not statistically significant, suggesting that only a minor deformation of the bullet takes place while traversing the Kevlar vest.

Novel Compound Cushion Layer for Reinforcement of Ballistic Resistance

Energy transmission and dissipation are the basic functions of cushion materials. In this investigation, spread polyester filament was laid on the pre-punching polyamide web with low-melted polyester staple fibers to create a sandwich structure by covering another web. Bonding by needle punching and thermal calender then, produced compound nonwoven fabrics, and these were then used to replace the original cushion material of a bulletproof vest. The buffer effect of the compound nonwoven fabrics in the bulletproof complex fabrics was assessed based on the deformation of the backing material in a bullet-shooting test. The content of low-melting-temperature polyester staple fibers, needle punching density and the polyester filament content were adjuster to determine the influences of these parameters on the buffer effect of the compound nonwoven fabrics in bulletproof complex fabrics. The compound nonwoven fabrics were demonstrated to be superior to the original cushion material of a bulletproof vest in terms of buffer effect. Additionally, this work hoped to reduce the production cost of bulletproof vests. The analytical results show that the maximum deformation of the backing material changes from 3.29 to 1.85 cm under adaptable processing conditions. Compound nonwoven fabrics with improved buffer effect thus can be used to replace the original cushion material of a bulletproof vest.

Multifunctional Carbon Nanotube Yarns by Downsizing an Ancient Technology

By introducing twist during spinning of multiwalled carbon nanotubes from nanotube forests to make multi-ply, torque-stabilized yarns, we achieve yarn strengths greater than 460 megapascals. These yarns deform hysteretically over large strain ranges, reversibly providing up to 48% energy damping, and are nearly as tough as fibers used for bulletproof vests. Unlike ordinary fibers and yarns, these nanotube yarns are not degraded in strength by overhand knotting. They also retain their strength and flexibility after heating in air at 450 degrees C for an hour or when immersed in liquid nitrogen. High creep resistance and high electrical conductivity are observed and are retained after polymer infiltration, which substantially increases yarn strength.

Death and injury on duty--a study of South African police officers.

Sections of contemporary South African society are characterised by high levels of crime and interpersonal conflict. The South African Police Service (SAPS) is in the front line, with many deaths and injuries occuring among serving officers in recent years. The circumstances and nature of the injuries sustained by these officers have received little attention in the medical literature. A retrospective review of all injured SAPS members was undertaken at a single level one trauma centre in Johannesburg between June 1993 and June 2002. The following factors were recorded: demographics, mechanism and anatomical site of injury, mode of transportation to hospital, whether personal protection had been used, mortality, and return to work. One hundred and thirty-four SAPS personnel were admitted over a 9-year period. The majority (95%) were male and the median age was 31 years. One hundred and thirty-two were on duty and two were in transit to a place of duty when injured. Ninety-two (69%) were injured by gunshot, (including 3 attempted suicides and 9 injuries due to negligent discharge), 2 members were stabbed, 31 were involved in motor vehicle accidents, 2 in motorbike accidents, 1 member was struck by a car while directing traffic, 3 officers were injured by falls from a height, 2 members were injured in helicopter crashes, and 1 member required treatment for gas inhalation. Documentation on whether some form of personal protection was worn at the time of injury was only available for 43 of the 92 cases of gunshot wounds (47%); of these, only 15 (35%) were wearing a bulletproof vest. Use or non-use of a seat belt was documented by hospital staff for only 6 of the 31 officers (19%) injured in motor vehicle accidents. None of the 6 officers had been restrained by a seatbelt. Nineteen SAPS personnel (14%) died of their injuries, but the majority of surviving members returned to duty. There is an unacceptably high level of violence in South African society today and SAPS members regularly have to deal with dangerous or violent situations. There is a clear need to introduce a reporting system within the SAPS to record the use of personal protection by officers. Education needs to target SAPS members in order to enhance their use of personal protection. There is a further need to design and implement personal protection that will be universally acceptable by SAPS members.

Ergonomics and safety in law enforcement

In law enforcement, ergonomics and safety issues are approached with threepriorities that are essential for that occupation and sometimes are oppositional:public safety, officer survival, and avoidance of litigation. Police officers serveand protect the public, insure their own safety, and make sure that their actions donot create litigation against themselves or their agencies.The equipment used by law enforcement to support these priorities has to beeffective, safe, and reliable. The reliability sometimes is overlooked. During aperiodof12months,alargemunicipalpolicedepartmentexperiencedfailureofitsammunition, handguns, ballistic vests and automated external defibrillators. Onceequipment is selected and issued, it has to be evaluated constantly for its efficacy,reliability, risks for acute or chronic injuries, and associated risk for litigation.Training safetyTraining causes significant mortality and morbidity among law enforcementofficers. Proper equipment and safety procedures should be used to preventtraining injuries. Between 1992 and 2001, nine officers died in training fromaccidental shootings in the United States [1]. Several officers died from falls,overexertion, and other causes during training sessions.Between 1990 and 1997, 612 incidents with casualties during tacticaloperations were reported to a database operated by the Casualty Care ResearchCenter at the Uniformed Services University of the Health Sciences. There were

Assessment of New High-Performance Fibers for Advanced Applications

AbstractHigh-performance fibers, used in fabric applications ranging from bulletproof vests to trampolines, must have a sufficient number of chemical and physical bonds for transferring the stress along the fiber. To limit their deformation, the fibers should possess high stiffness and strength. Stiffness is brought about by the degree to which the chemical bonds are aligned along the fiber axis. In fiber-reinforced composites, the fibers are the load-bearing element in the structure, and they must adhere well to the matrix material. An ideal reinforcing fiber must have high tensile and compressive moduli, high tensile and compressive strength, high damage tolerance, low specific weight, good adhesion to the matrix materials, and good temperature resistance. This article reviews and compares the properties and behavior of novel high-performance fiber materials including polyethylene, aramid, polybenzobisoxazole, M5, and carbon fibers.

A one-dimensional model for the propagation of transient pressure waves through the lung

The propagation of pressure waves in the lung has been investigated by many authors concerned with respiratory physiology, ultrasound medical techniques or thoracic impact injuries. In most of the theoretical studies, the lung has been modeled as an isotropic and homogeneous medium, and by using Hooke's constitutive law (see e.g. Ganesan et al. Respir. Physiol. 110 (1997) 19; Jahed et al. J. Appl. Physiol. 66 (1989) 2675; Grimal et al. C.R. Acad. Sci., Paris 329 (IIb) (2001) 655–662), or more elaborated material laws (see, e.g. Bush and Challener (Proceedings of the International Research Council on Biokinetics Impacts (IRCOBI), Bergish-gladbach, 1988); Stuhmiller et al. J. Trauma 28 (1988) S132; Yang and Wang, Finite element modeling of the human thorax. Web page: http://wwwils.nlm.nih.gov/research/visible/vhpconf98/AUTHORS/YANG/YANG.HTM.). The hypothesis of homogeneous medium may be inappropriate for certain problems. Because of its foam-like structure, the behavior of the lung—even if the air and the soft tissue are assumed to behave like linearly elastic materials—is susceptible to be frequency dependent. In the present study, the lung is viewed as a one-dimensional stack of air and soft tissue layers; wave propagation in such a stack can be investigated in an equivalent mass–spring chain (El-Raheb (J. Acoust. Soc. Am. 94 (1993) 172; Int. J. Solids Struct. 34 (1997) 2969), where the masses and springs, respectively, represent the alveolar walls and alveolar gas. Results are presented in the time and frequency domains. The frequency dependence (cutoff frequency, variations in phase velocity) of the lung model is found to be highly dependent on the mean alveolar size. We found that short pulses induced by high velocity impacts (bullet stopped by a bulletproof jacket) can be highly distorted during the propagation. The pressure differential between two alveoli is discussed as a possible injury criterion.

Impact non-pénétrant sur le thorax : influence de la courbure sur la propagation des ondes

Theoretical studies of the propagation of impact waves through the thorax are needed to improve the design of bulletproof jackets and blast protections (Fung in ‘Biomechanics Motions, Flow, Stress, and Growth’, Springer-Verlag, 1990; Cooper et al., J. Trauma 40 (1996) S38–S41). The influence of the weak acoustic coupling at the interface between the thoracic wall and the lung were described in (Grimal et al., C. R. Acad. Sci. IIB 329 (2001) 655–662); in this work, we study, within the frame of elastodynamics and with an approximate analytical method, the effects of the curvature of this interface. Results are given in terms of strain energy for the pressure wave, transmitted or converted. Focalisation of energy in the medium representing the lung is important for curvatures measured in humans. To cite this article: Q. Grimal et al., C. R. Mecanique 330 (2002) 569–574.

Ballistic protection mechanisms in personal armour

High strength and high modulus fibres have revolutionised the design of lightweight armour, main fibre reinforced ballistic products are: ballistic helmets, vests, blankets and add-on car armour. Modelling of the ballistic properties of multi-layer fibre reinforced armour is still in the development stage, structural models that can be used to describe the penetration of such armour by deformable projectiles, and to design new armour, are not yet available. A simple model has been developed that can be used to calculated the performance of Dyneema armour against deformable bullets and FSPs. Most important in this model is that the number of input values is very small. For calculating the performance of Dyneema UD-based armour only two materials related parameters are required. Four projectile related parameters are needed. For non-deformable projectiles the number reduces to a single material related and two projectile related parameters.

The Real Military Revolution

military implications of new organizational sciences that examine internetted, nonhierarchical versus hierarchical management models are yet to be fully understood. TRADOC Pam 525-5, Force XXI Operations [1] Digitization of the battlefield is producing a in military affairs, but not the one the architects of the military future have in mind. It is occurring because the American military, more than any other, has seized on the digital information and is adapting it for combat as rapidly as possible. Using a carefully networked array of sensors, shooters, and automated information systems, the US armed forces expect to dominate 21st-century battlefields. Farther down the road, beyond 2010, the Army expects to marry these knowledge-rich attributes to new speed and agility, and to the increased range and lethality of new weapons. [2] These innovations are to become not merely part of, but the basis for, day-to-day military operations. What is likely to happen, however, is more than just a new way to conduct old business. The work of complexity theorists (notably Andrew Ilachinski, Margaret Wheatley, and J. M. Epstein) suggests that something wholly new is going on. [3] In this case, revolution is not just a metaphor for rapid change. It really is a in the basic sense, a new order of things that is sweeping away the old order whether we want it to or not. The implications of these new electronic networks for the structure of human institutions, including armies, are far more profound and far-reaching than most commentators seem to recognize. Dr. Wheatley, a behavioral theorist, put it this way: They [the US Army] have the technology to move information down to the lowest level so that it is possible for the men inside tanks to have as much information as their commanders have.... But once you give that information to tank crews, and they start working for their own safety, their own victory, how are they going to respond to commands from above? And what happens to battle strategy? Is it in the head of the commander, or do you just train the crews and let them figure it out for themselves as the situation demands? [4] Dr. Wheatley focuses on the decisionmaking questions posed by widespread use of automated information systems on the battlefield. This is a serious question, but it becomes urgent when the expected speed, agility, and lethality of the 21st-century Army is added to the equation. The urgency is generated not only by the ongoing digitizing of headquarters or large crewed vehicles such as tanks, but also by the effort to ensure that even individual soldiers are wired into the digital battlefield. [5] One important outcome of this may be the destruction of the long-standing, traditional military hierarchy. If so, one of the important instruments of this destruction could be the Land Warrior system, a set of personal information components designed to make individual soldiers an integral part of the digital battlefield by connecting them with Force XXI Battle Command Brigade and Below--the computer system and software at the heart of the Army's digitization effort. [6] The Land Warrior system in its test and evaluation version includes a helmet eyepiece that folds down, presenting a computer screen or the display from a combination sighting system and video camera on the soldier's rifle. A personal computer and two radio systems are worn underneath the rucksack. On the chest strap of the soldier's ballistic protection vest is a folding handgrip that acts as a computer mouse, allowing him to operate the radios and manipulate his computer. Land Warrior's capabilities are impressive, but they are directed toward traditional battlefield functions such as quicker response times, better reconnaissance, faster communications, more accurate artillery, and so forth. [7] All this will undoubtedly happen, but it won't happen in isolation. …

Thermotropic Liquid Crystalline Polymer Fibers

Super-strength, lightweight materials used in bullet-proof vests, high-performance cables and tires, and stealth airplanes are built from liquid crystalline polymer (LCP) fibers. The remarkable strength properties are dominated by molecular alignment achieved as a result of the complex interactions at play in fiber processes. The fiber manufacturing process begins with a high temperature liquid phase of rigid rod macromolecules, whose orientation couples to the strong elongational free surface flow. The flow exits at a prescribed radius and velocity ($v_0$), tapers and cools as it evolves downstream, and solidifies along some free boundary, below which a take-up velocity ($v_1 > v_0$) is imposed at a fixed location. Our goal in this paper is a model for this process which realistically couples the hydrodynamics, the LCP dynamics, and the temperature field, along with the free surface and boundary conditions. Moreover, we aim for a model, by necessity complex, that provides nontrivial fiber process predict...

A Chest Wall Restrictor to Study Effects on Pulmonary Function and Exercise

Chest wall-restrictive loading reduces a person’s ability to expand the chest wall during inhalation and results in decrements in lung capacities, resting pulmonary function, and ultimately, exercise performance. Chest wall restriction is observed in some forms of skeletal and pulmonary diseases (e.g., scoliosis) as well as in occupational situations (e.g., bulletproof vests). We have designed a constant-pressure chest wall-restrictive device that provides a quantifiable and reproducible load on the chest. This paper describes the device and the initial pulmonary function tests conducted. Ten subjects participated in this study. Subjects wore the restrictive device while performing pulmonary function tests at four externally added restrictive loads on three separate occasions. A two-way repeated-measures multivariate analysis of variance revealed significant decreases in forced expiratory vital capacity (FVC) and forced expiratory volume in 1 s (FEV_1.0) at each load while the ratio of FEV_1.0 to FVC (FEV_1.0%) was maintained. No significant differences in any variable were found across time or between the seated and standing position. These results indicate that this chest wall-restrictive device provides a quantifiable added inspiratory load in the breathing cycle that results in reproducible decrements in pulmonary function representative of those seen in some restrictive pulmonary disease and occupational situations.

Injuries to emergency medicine residents on ems rotations

Objectives. To study the incidence and nature of injuries sustained by emergency medicine (EM) residents during EMS rotations, and steps taken at EM residency programs to increase resident safety during field activities. Methods. An eight-question survey form was mailed to all 114 U.S. EM residency directors, with a second mailing to nonresponders eight weeks after the initial mailing. Results. A total of 105 surveys were returned (92%). Six surveys were from new programs whose residents have not yet rotated on EMS. These were excluded from further analysis, leaving 99 programs. Of these, 91 (92%) reported no injuries. One EM resident died in a helicopter crash in 1985. Seven other injury events were reported: 1) facial lacerations, rib fractures, and a shoulder injury in an ambulance accident; 2) an open finger fracture (crushed by a backboard); 3) contusions and a concussion when an ambulance was struck by a fire engine; 4) a groin pull sustained while entering a helicopter; 5) bilateral metatarsal fractures in a fall; 6) rib fractures, a pneumothorax, and a concussion in an ambulance accident; and 7) “minor injuries” sustained in a crash while responding to a scene in a program-owned response vehicle. Actions taken at residency programs to reduce the risk of injury include the use of ballistic vests (four programs), requiring helmets on flights (five programs), and changing flight experience from mandatory to optional (two programs). Ten programs (10%) reported using ground scene safety lectures, and nine programs (15% of those offering flights) reported various types of flight safety instruction. Sixty-nine programs (70%) reported no formal field safety training or other active steps to increase resident safety on EMS rotations. Conclusions. Injuries sustained by EM residents during EMS rotations are uncommon but nontrivial, with several serious injuries and one fatality reported. The majority of EM residency programs have no formal safety training programs for EMS rotations.

Structural and mechanical characteristics of aramid fibres for bullet-proof vests

The following conclusions can be drawn from an analysis of the data reported in the present article: SVM and Armos fibres are now the most promising for use in bulletproof materials; increasing the elongation to 5–6% while preserving the strength at the level of 400–450 kgf/mm 2 allows increasing the efficiency of use of fibres for bulletproofing; the method proposed here allows rapidly and efficiently conducting comparative tests and initial selection of materials and the pack structure of the energy-absorbing polymer support; new types of bulletproof fabrics must be developed to increase the efficiency of manifestation of the energy-absorbing properties of fibres.

U.S. announces medals in science, technology

President Clinton last week announced the 1996 recipients of the U.S/s highest awards for research and for technological achievement. Among the eight winners of the National Medal of Science and five winners of the National Medal of Technology, several are cited for chemically related work. recipients of these prestigious medals are the nation's champions of research and innovation, said Clinton. For their leadership and originality, we honor them with America's version of the Nobel Prize. The science medal has been awarded since 1962 and the technology medal since 1985. Clinton will present them at a White House ceremony this summer. Polymer chemist Stephanie Louise Kwolek, a DuPont consultant since retiring as a research associate in 1986, will receive a technology medal for her contributions to the discovery and development of high-performance aramid fibers. These tough fibers, sold by DuPont as Kevlar, are used in products as diverse as lightweight bulletproof vests and fiber-optic cables. ...

TV Miniseries Explores Impact of New Materials on Daily Life

Ever since police officer Joseph Somma's life was saved by a bulletproof vest, he's been indebted to the materials scientists and engineers who developed that high-tech piece of apparel. creators of the miracle fabric that absorbed the deadly energy of the bullets meant for him are the true unsung heroes, Somma says at the beginning of a three-part miniseries on materials science that premieres next week on Public Broadcasting Service television stations. program, called The Stuff of Dreams, explores the impact that new materials have on our daily lives and our world. And it gives viewers a taste of the even greater wonders that materials scientists and engineers hope to unveil in the future. Made possible by funding from Dow Corning Corp. in celebration of the company's 50th anniversary, the series surveys developments in materials science in terms that are relevant to the average viewer. For example, we are introduced to a new ...

Unspecified injuries on death certificates: a source of bias in injury research.

Protective gear (for example, helmets and bulletproof vests) shields certain body regions from damaging energy. Failure to specify on death certificates the body region and nature of fatal injuries compromises the utility of mortality data for epidemiologic or prevention research. Of fatally injured California motorcyclists, 41% had no specific injuries listed on their death certificates in 1988. To examine the implications of this problem, the authors abstracted 186 coroner's or medical examiner's reports from four California counties with over 60% nonspecific injuries and one county with few such injuries. These data were merged with computerized death certificate files and with the Fatal Accident Reporting System. Among the 99 cases with nonspecific injury codes, 68% had head injuries, 63% had chest injuries, 58% had abdominal injuries, and 58% had extremity injuries. Reporting sensitivity in the four problem counties varied from 36% for head injury to less than 5% for abdominal, spinal, and extremity injury. The association between head injury and failure to wear a helmet was statistically significant using the coroner's diagnoses (p = 0.02), but not using death certificate diagnoses (p = 0.17). The value of mortality data to injury researchers would be enhanced by better reporting of the nature of injury on death certificates.

Spider silk gene route to high-tensile fiber

The more sophisticated man-made fibers may face competition from an unexpected source—spiders. The physical properties of spider silk are such that it may prove ideal for use in bullet-proof vests, flack jackets, and similar protective garments, as well as for adding strength to structural plastic components employed by the aerospace and automobile industries. That's the thinking behind work now getting under way at PA Technology's research center in Melbourn, near Cambridge, England. Studies to date are very much at the lab stage, remarks Nick V. Ashley, who heads the program. But if we could interest a partner in joining us, the project should move ahead fairly rapidly. Employing a technique Ashley and his team have previously used for producing a silkwormlike silk, the researchers will synthesize a gene analogous to the gene that codes for spider silk and insert it into Eschenchia coli . Following growth in a fermentation bath, the bacteria will be harvested, and ...