Ballistic Materials Research Articles

Effects of Dephasing on Spin Lifetime in Ballistic Spin-Orbit Materials.

We theoretically investigate spin dynamics in spin-orbit-coupled materials. In the ballistic limit, the spin lifetime is dictated by dephasing that arises from energy broadening plus a nonuniform spin precession. For the case of clean graphene, we find a strong anisotropy with spin lifetimes that can be short even for modest energy scales, on the order of a few ns. These results offer deeper insight into the nature of spin dynamics in graphene, and are also applicable to the investigation of other systems where spin-orbit coupling plays an important role.

Effect of Accelerated Ageing on Ballistic Textiles Modified By Plasma-Assisted Chemical Vapour Deposition (PACVD)

The functionalisation of textile products and materials using the low temperature plasma technique is increasingly used in industrial practice, mainly because of the many benefits, often unattainable with the use of other techniques. The study focused on the modification of the composite textile materials - sheets of Ultra High Molecular Weight Polyethylene (UHMWPE) fibres (Dyneema ® SB51) by applying the surface deposition of silicone-like polymer in an environment of low temperature plasma. The aim of this study was to evaluate changes in the mechanical and physical properties of modified ballistic textiles un der simulated storage conditions in accelerated time. Based on experiences in planning the research on accelerated aging, a test programme was developed for the assessment of changes during the aging process in ballistic fibrous materials under various environmen tal conditions. The process of low temperature plasma modification affected the mechani cal properties of the ballistic composite textile materials during the accelerated ageing using temperature or temperature and humidity. The effect of the modification varied with the mechanical properties investigated.

Structural Changes in Fibrous Ballistic Materials During PACVD Modification

Structural Changes in Fibrous Ballistic Materials During PACVD Modification

Numerical Simulation on Effect of Impact Velocity and Target Thickness in Magnesium Alloy AZ31B

Recent research works indicate that magnesium alloy can be used for constructing light weight armor because of its density, which is 35% lower than aluminium and 77% lower than steel and also it exhibits superior vibration damping and better failure mechanisms than the contemporary ballistic materials. In this study, numerical simulations were carried out in a monolithic magnesium AZ31B plate using AUTODYN software to understand the effect of Impact velocity and plate thickness on the deformation of target plates. The projectiles are normally impacted on target plates of varying thickness plates at different velocities. Lagrangian solver was used for meshing, in which the grid developed by the solver distorts with the material helps in eliminating the inaccuracies caused by the cell growth due to the shear force of the bullet impact. The simulation results are verified with the experimental data available in the literature.

Characterization of clay composite ballistic witness materials

Mechanical and thermal properties of Roma Plastilina Clay #1 (RP1) were studied through small-amplitude oscillatory shear (SAOS), large-amplitude oscillatory shear (LAOS), and differential scanning calorimetry (DSC), supplemented with thermogravimetric analysis, X-ray diffraction, and X-ray florescence. Rheological characterizations of RP1 through SAOS indicate that the clay composite softens as it is worked and slowly stiffens as it rests. Upon heating, the clay composite softens, prior work history is erased, and the composite undergoes a melting transition, although melted clay is significantly stiffer when returned to the usage temperature. Continuing mechanical characterizations into the LAOS or nonlinear region, RP1 transitions from a transient network to a viscous shear-thinning material as the temperature is increased. Using the MITlaos framework, RP1 exhibits intra-cycle strain stiffening and intra-cycle shear thinning at all temperatures.

Small Scale Test Method To Determine The Capacity Of The Ballistic Protection Materials To Mitigate The Blast Overpressure

Abstract In order to design and implement ballistic protective equipment, several common stages in developing any product must be taken (technical studies, technological demonstrators, prototypes, etc.). The final stage should be the testing-assessing of development phase, followed by the homologation of the product obtained, which is a compulsory stage. In order to characterize the properties of shock waves passing through various materials and media (air, water, materials for ballistic protection), certain techniques and working procedures were established. The most common method is testing in the shooting range where the real conditions of a detonation can be faithfully reproduced. Such tests, however, despite being the most accurate and reliable way to check the shock waves mitigation properties of materials, in addition to being extremely dangerous activities, most often require expensive materials and full-scale structures. In the first stage of development, the new materials have to be selected through the small scale tests performed in laboratory. This paper presents one test procedure that could be used to determine the capacity of the ballistic protection materials to mitigate the effects of the shock wave in laboratory conditions and at low cost.

Numerical Studies Regarding Underwater Detonation

Abstract The article presents the results of a numerical study regarding a primary explosive detonation in aquatic medium. The main purpose of this study is the evaluation of underwater explosion effects in order to conceive an effective attenuation method. Since the development of mass destructive guns, explosive materials have been the most effective means to threat live. However, the most recent researches have proved that these instant pressure generators could be used also in positive purposes. In this way, controlled demolition, development of new ballistic materials, simulation of meteorite impact on earth, lithotripsy, mining and blasting wouldn’t have been possible without the aid of explosions. The theme of this article is born from the idea of utilizing controlled underwater explosions as antifouling means. The protection of sea fauna and flora is a priority so the actual antifouling method are either toxic or complicated and costly inefficient. Numerical simulations performed in order to achieve the purpose of this work consist in utilizing ANSYS AUTODYN soft to evaluate the effects of 10 mg detonation of a primary explosive. Numerical researches are based on experimental data from laboratory tries and have the main purpose validation of the results with the practical ones.

Thermal Effects of Design and Materials on QuadGard™ Body Armor Systems

QuadGard™ arm and leg protection systems were developed to better protect key areas of arms and legs from blast fragments. The purpose of this investigation was to use sweating thermal manikin Walter™ and examine the intrinsic clothing insulation (Rcl), intrinsic clothing evaporative resistance (Recl), micro-climate temperature, and moisture retention of three QuadGard™ systems (QG II, QG IV Ventilated, and QG IV Not Ventilated) constructed with two ballistic materials, Dyneema® and Kevlar®. With similar protection level, the ballistic material Dyneema®, consistently measured lower in Rcl and Recl than the ballistic material Kevlar®, indicating body armor made with ballistic material Dyneema® is more comfortable. There was no significant difference between QG II and QG IV Ventilated in Rcl and there was no significant difference between the three armor systems in Recl. This indicated that design features have the potential to reduce thermal stress on the human body when protective clothing is necessary.

Production and Mechanical Characterization of Ballistic Thermoplastic Composite Materials

Production and Mechanical Characterization of Ballistic Thermoplastic Composite Materials

The Effects of Stacking Sequence Layers of Hybrid Composite Materials in Energy Absorption under the High Velocity Ballistic Impact Conditions – An Experimental Investigation

In the current study, the effects of stacking sequence layers of hybrid composite materials on ballistic energy absorption, which were fabricated from Kevlar, carbon, glass fibres and resin have been experimentally investigated at the high velocity ballistic impact conditions. All the samples have equal mass, shape and density, but they have different stacking sequence layers. After running the ballistic test in the same conditions, the final velocities of the bullets showed that how much energy absorbed by the samples. The energy absorption of each sample through the ballistic impact has been calculated, accordingly , the decent ballistic impact resistance materials could be found by conducting the test. This paper can be further studied in order to characterise the material properties.

A Novel Barrier Controlled Tunnel FET

A novel structure of tunnel field-effect transistor (FET) is introduced with the gate composed of three segments of different work functions. The tunnel current is controlled by an in channel potential barrier as well as the source-channel tunnel junction bandgap, which combines the merits of both bandgap-controlled tunnel FET and barrier-controlled traditional MOSFET. Intuitive explanation is provided for this novel device structure. The performance enhancement is confirmed by numerical simulation with carbon nanotube as the channel material. This structure is especially suitable for bandgap tunable ballistic transport materials (e.g., carbon nanotube and graphene nanoribbon).

The surface modification of ballistic textiles using plasma-assisted chemical vapor deposition (PACVD)

This paper describes studies on the surface modification of so-called ballistic materials (materials commonly used to protect the human body against firearms, i.e. fragments or bullets). Two materials, an ultra-high molecular weight polyethylene (UHMWPE) composite and aramid fabric, were investigated. The surfaces of these fibrous materials were modified using plasma-assisted chemical vapor deposition (PACVD) to examine the effects of the modification on the material properties, which are important for designing ballistic protections. Accordingly, both the mechanical strength and water resistance of the modified materials were tested. The results clearly show the impact of the modification on both parameters.

Helmet liner evaluation to mitigate head response from primary blast exposure

Head injury resulting from blast loading, including mild traumatic brain injury, has been identified as an important blast-related injury in modern conflict zones. A study was undertaken to investigate potential protective ballistic helmet liner materials to mitigate primary blast injury using a detailed sagittal plane head finite element model, developed and validated against previous studies of head kinematics resulting from blast exposure. Five measures reflecting the potential for brain injury that were investigated included intracranial pressure, brain tissue strain, head acceleration (linear and rotational) and the head injury criterion. In simulations, these measures provided consistent predictions for typical blast loading scenarios. Considering mitigation, various characteristics of foam material response were investigated and a factor analysis was performed which showed that the four most significant were the interaction effects between modulus and hysteretic response, stress–strain response, damping factor and density. Candidate materials were then identified using the predicted optimal material values. Polymeric foam was found to meet the density and modulus requirements; however, for all significant parameters, higher strength foams, such as aluminum foam, were found to provide the highest reduction in the potential for injury when compared against the unprotected head.

Ballistic characteristics improving and maintenance of protective ballistic vests

The work presents research of the materials necessary for the maintenance of protective ballistic vests. In this paper is proposed a new construction design with modern materials for ballistic inserts producing. This paper also presents the results of laboratory tests of ballistic cartridges with new materials. Based on the test results, it can be concluded, the proposed technical solution for making ballistic inserts adequately meets current standards. Introduction The introduction explains the purpose of the armor and the history of models of protective vests for us. The aim of this study is to improve the structure of existing protective ballistic vests, to propose a new mechanism construction ballistic cartridge, and to examine the validity of the proposed design based on the results of laboratory tests. Existing structural solution In the above is explained existing model of protective ballistic vests that are in use in our army. Structural solution, composition of these models and used materials for ballistic inserts are shown. It is explained reactions (resistance) of the ballistic inserts materials, when bullets pass through them. Time resource of the materials for current models of body armor is expired. According to this fact, it is started research work, with intention to extend the current time resource. Standards of ballistic protection It is shown requirements for standards of ballistic protection level III and III A. Also are explained standards requirements and under what circumstances is performed laboratory testing of protective ballistic vests. Modern ballistic materials The characteristics and description of the currently most advanced materials for ballistic inserts that meet the requirements of the protection level III A are explained. The comparison of material characteristics Dyneema producer of the first models to contemporaneously under the symbol SB 51 is performed. Based on the characteristics of the analyzed material, in the research is used material Dyneema SB 51. Proposal of a new structural solutions In papaer is proposed a new construction solution from the cartridge ballistic material Dyneema SB 51, which should satisfy the protection level III A. In addition, we prepare two new samples of material combinations SB 21 and old material and material SB 21. With such samples the ballistic protective inserts started with laboratory tests. Analysis of test results In tables we show results of testing the samples of ballistic inserts. The conclusion from the performed tests is all samples meet the requirements of the current standards. With observing other aspects of the samples, we give the proposal for maintain ballistic inserts with implementation of material Dyneema SB 51. The reason for this proposal is given in conclusion. Conclusion The aim of the research conducted was to get results that will explicitly show the best material for making ballistic inserts in the technological process of maintenance of protective ballistic vests. Conducted research in the economics analysis and the laboratory tests showed that the ballistic inserts made of a material Dyneema SB 51 to the proposed construction solutions to meet the requirements of Figure 3 standard NIJ 0101. 04 and allow: - better ballistic properties of the protection level IIIA, - the long time resource, up to 10 years, - reduce the number of layers of sheets of ballistic materials for making cartridges, - a small amount of material for making ballistic inserts for the required level of protection, - easier to cut sheets of ballistic material during cutting and making ballistic inserts, - less time developing new ballistic inserts, - less money for making balcistickih cartridges for the required level of protection.

Recent Trends in Ballistic Protection

There has been a tremendous improvement in the design of ballistic protective materials, which have been in use from time immemorial. Developments in the technology of manufacturing high performance fibres and production processes have enabled the production of light weight body armour with improved protection levels. In this article we summarise different types of body armour used for ballistic protection and different materials and structures used for body armour. In addition, the test methods used for the evaluation of ballistic performance are also outlined. Government regulations related to the manufacturing and use of protective clothing and the methods of testing in several countries of the world have also been described. The future scope focuses on important materials, their selection criteria and parameters are to be considered when designing ballistic protective materials.

Hybrid Composite Laminates Reinforced with Kevlar/Carbon/Glass Woven Fabrics for Ballistic Impact Testing

Current study reported a facile method to investigate the effects of stacking sequence layers of hybrid composite materials on ballistic energy absorption by running the ballistic test at the high velocity ballistic impact conditions. The velocity and absorbed energy were accordingly calculated as well. The specimens were fabricated from Kevlar, carbon, and glass woven fabrics and resin and were experimentally investigated under impact conditions. All the specimens possessed equal mass, shape, and density; nevertheless, the layers were ordered in different stacking sequence. After running the ballistic test at the same conditions, the final velocities of the cylindrical AISI 4340 Steel pellet showed how much energy was absorbed by the samples. The energy absorption of each sample through the ballistic impact was calculated; accordingly, the proper ballistic impact resistance materials could be found by conducting the test. This paper can be further studied in order to characterise the material properties for the different layers.

The Charge Transport in (2, 2) Armchair Carbon Nanotube: A Theoretical Modeling

Carbon nanotubes are excellent charge transports due to the relationship between the length–diameter in the order of microns to nanometers, respectively, thus being characterized as ballistic conductors and excellent materials for field emission applications in electronic devices. We study the Fowler-Nordheim formalism and first-principles calculations of metallic (2, 2) singlewall carbon nanotube with a diameter of 0.24 nm. Our results are consistent for field emission devices nanostructured with these specifications. Summarize the following results: (i) for the both methods used the same trend I–V; (ii) exponential behavior and quasi-ballistic, indicating the proportionality between I and V characteristic of (2, 2) carbon nanotube armchair, (iii) tendency of inelastic tunneling under intense field electric, which is consistent with studies on inelastic electron tunneling spectroscopy (IETS); (iv) matching number Mulliken charge for using the formalism of the Fowler-Nordheim equation to reduce the computational first-principles calculations for this (2, 2) carbon nanotube.

Characterisation of explosive fragments injuring the neck

Penetrating explosive fragments are the most common cause of neck injuries sustained by UK service personnel deployed to Afghanistan. Analysis of these fragments will enable future ballistic protective materials to be tested with appropriate projectiles. However, only a small number of fragments excised from the neck have been available for analysis and they are potentially unrepresentative. We analysed computed tomograms (CTs) of 110 consecutive UK soldiers whose necks were wounded by explosive fragments. Fragments were classified according to shape, and their dimensions used to estimate volume and mass. These calculations were then compared with the actual measurements of the excised fragments using a general linear model. The 2 most common shapes were cylinders (52%) and spheres (21%). Known and estimated masses were not significantly different (p=0.64). A fragment-simulating projectile of 0.49g represented 85% of fragments retained in the neck. CT can accurately delineate the shape and mass of fragments, which increases the number from which the most appropriate simulated projectile can be designed. We think that this methodology should be applied to fragments retained in other parts of the body to enable broader recommendations to be made regarding the testing of ballistic materials used to protect service personnel.

Characterisation of explosively propelled fragments injuring the neck

Introduction: Penetrating explosive fragments are the most common cause of neck injury sustained by UK service personnel deployed to Afghanistan. Characterisation of these fragments enables testing of future ballistic protective materials with appropriate Fragment Simulating Projectiles (FSPs). However due to its relatively small surface area, the numbers of fragments excised from the neck is small and potentially unrepresentative.

Computed Tomography Can Improve the Selection of Fragment Simulating Projectiles From Which to Test Future Body Armor Materials

Ballistic protective materials used in body armor are tested with fragment simulating projectiles (FSPs). The type of FSP used has historically been made by choosing fragments representative of those produced by controlled explosions, which may not be representative of those fragments actually injuring soldiers. 75 cylindrical FSPs of three different sizes were fired into six euthanized pigs, imaged using computed tomography (CT) and the wound tracks dissected. Skin entry wound locations, as determined by surface-shaded CT, were compared to clinical photographs. FSP dimensions and depth of penetration derived from CT were compared to surgical dissection using a Mann-Whitney U test. Skin entry wound locations derived from CT were identical to that seen clinically. FSP dimensions were consistently 15% to 19% larger than the true measurements, reflecting the magnifying effect associated with metallic artifact. No statistical difference (p = 0.26) was found between depth of penetration measured radiologically compared to dissection when a projectile did not hit bone but there was a statistical difference when bone was hit (p < 0.05). CT has the potential to accurately ascertain values required to improve the selection of representative FSPs from which future ballistic protective materials are tested.