Ballistic Armor Research Articles

Experiment and Simulation Study of the Effect of Fillers on Mechanical Properties of Sustainable Composite

Abstract Natural fiber reinforced polymer matrix composites are gaining increasing attention as engineering materials for advanced applications, including high performance ballistic armor components. This requires superior mechanical properties, such as toughness. Jute fiber reinforced composites are currently being explored as possible advanced engineering materials. Therefore, the objective of this study is to investigate the mechanical characteristics of epoxy composites reinforced with jute fibers and steel fillers. In the present study, three types of the composite of two-way jute carpet and steel fillers were reinforced with epoxy, with different rates of each material.

Fabric Impregnation with Shear Thickening Fluid for Ballistic Armor Polymer Composites: An Updated Overview.

As destructive power of firearms raises over the years, ballistic armors are in continuous need of enhancement. For soft armors, this improvement is invariably related to the increase of stacked layers of high-strength fiber fabrics, which potentially restrains wearer mobility. A different solution was created in the early 2000s, when a research work proposed a new treatment of the ballistic panels with non-Newtonian colloidal shear thickening fluid (STF), in view of weight decreasing with strength reinforcement and cost-effective production. Since then, databases reveal a surge in publications generally pointing to acceptable features under ballistic impact by exploring different conditions of the materials adopted. As a result, several works have not been covered in recent reviews for a wider discussion of their methodologies and results, which could be a barrier to a deeper understanding of the behavior of STF-impregnated fabrics. Therefore, the present work aims to overview the unexplored state-of-art on the effectiveness of STF addition to high-strength fabrics for ballistic applications to compile achievements regarding the ballistic strength of this novel material through different parameters. From the screened papers, SiO, Polyethylene glycol (PEG) 200 and 400, and Aramid are extensively being incorporated into the STF/Fabric composites. Besides, parameters such as initial and residual velocity, energy absorbed, ballistic limit, and back face signature are common metrics for a comprehensive analysis of the ballistic performance of the material. The overview also points to a promising application of natural fiber fabrics and auxetic fabrics with STF fluids, as well as the demand for the adoption of new materials and more homogeneous ballistic test parameters. Finally, the work emphasizes that the ballistic application for STF-impregnated fabric based on NIJ standards is feasible for several conditions.

An Optimization Study on Material Selection for FRPCs in Multi Layered Armour System Through Hybrid MCDM Approach and Numerical Simulation

Fiber reinforced polymer composites (FRPCs) are considered as core structure in Multi layered armour systems (MAS) to take advantage of maximum energy absorption, mobility and cost criteria design. In this article, based on the problem defining attribute�s optimal material selection in FRPCs determined by Multiple criteria decisions making (MCDM) approach for considered alternative materials from polymer resin, synthetic and natural fiber. Attribute�s weightage and alternatives priority rank were determined through Fussy-Analytical hierarchy process (F-AHP) and Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) method. Obtained rank was compared with Preference selection index (PSI) an another MCDM method, for better computational conformity. Selected materials from MCDM approach, simulated for energy absorption ability and damage after impact were studied by considering Cowper-Symonds constitutive materials model using 3D macro shell analysis. Various impact velocities were considered from 3 to 50 m/s for rigid steel impactor directed towards the deformable plate. Parameter like Residual kinetic energy, Residual velocity, Energy absorption ratio after impact were studied numerically. Simulation results in terms of specific energy absorption were compared with the rank obtained in MCDM approach. Among the polymers considered epoxy, polyurethane and polyester found better choice. In fibers hemp and basalt found better materials choice for heterogenous FRPCs design in ballistic armour.

Numerical and Experimental Study of Multi-layer Armors for Personal Protection

Currently, personal armor is considered the basic requirement in combat, especially in the Middle East. The current research attempts to design and manufacture a novel body armor from cheap and available materials. When compared to traditional materials’ body armor, composite ballistic body armor has become a superior alternative for personal protection. In this study, alternative materials were proposed to develop an armor consisting of modified rubber and ebonite, as well as pieces of ceramic from alumina as hexagons shape, Kevlar and Carbon woven, and modern technologies shear thickening fluids. The armor was numerically evaluated using (ANSYS) commercial software using different bullet velocities ranging from (740 to 940) m/s and different numbers of carbon and Kevlar woven soaking shear thickening fluids to reach the best arrangement of layers with the best performance and compare them in the experimental data. The numerical results show the best performance for plate armor consisting of 23-layers, which were then experimentally tested using a weapon type (AK-47) rifle with bullet 7.62*39 mm. The experimental test showed no complete penetration, with a back deformation of 7.5 mm. When the shock of the double bullet into the plate at the same location showed no complete penetration with a back deformation of 11.3 mm, the body armor exhibited superior protective performance and was compatible with standard NIJ Standard-0101.03.

Dynamic Mechanical Analysis and Ballistic Performance of Kenaf Fiber-Reinforced Epoxy Composites.

Several industry sectors have sought to develop materials that combine lightness, strength and cost-effectiveness. Natural lignocellulosic natural fibers have demonstrated to be efficient in replacing synthetic fibers, owing to several advantages such as costs 50% lower than that of synthetic fibers and promising mechanical specific properties. Polymeric matrix composites that use kenaf fibers as reinforcement have shown strength increases of over 600%. This work aims to evaluate the performance of epoxy matrix composites reinforced with kenaf fibers, by means of dynamic-mechanical analysis (DMA) and ballistic test. Through DMA, it was possible to obtain the curves of storage modulus (E′), loss modulus (E″) and damping factor, Tan , of the composites. The variation of E′ displayed an increase from 1540 MPa for the plain epoxy to 6550 MPa for the 30 vol.% kenaf fiber composites, which evidences the increase in viscoelastic stiffness of the composite. The increase in kenaf fiber content induced greater internal friction, resulting in superior E″. The Tan was considerably reduced with increasing reinforcement fraction, indicating better interfacial adhesion between the fiber and the matrix. Ballistic tests against 0.22 caliber ammunition revealed similar performance in terms of both residual and limit velocities for plain epoxy and 30 vol.% kenaf fiber composites. These results confirm the use of kenaf fiber as a promising reinforcement of polymer composites for automotive parts and encourage its possible application as a ballistic armor component.

Ballistic Properties and Izod Impact Resistance of Novel Epoxy Composites Reinforced with Caranan Fiber (Mauritiella armata).

Natural lignocellulosic fibers (NFLs) possess several economic, technical, environmental and social advantages, making them an ideal alternative to synthetic fibers in composite materials. Caranan fiber is an NFL extract from the leafstalk of the Mauritiella armata palm tree, endemic to South America. The present work investigates the addition of 10, 20 and 30 vol% caranan fiber in epoxy resin, regarding the properties associated with Izod notch tough and ballistic performance. Following ASTM D256 standards, ten impact specimens for each fiber reinforcement condition (vol%) were investigated. For the ballistic test, a composite plate with 30 vol%, which has the best result, was tested with ten shots, using 0.22 ammunition to verify the energy absorption. The results showed that when compared to the average values obtained for the epoxy resin, the effect of incorporating 30 vol% caranan fibers as reinforcement in composites was evident in the Izod impact test, producing an increase of around 640% in absorption energy. Absorbed ballistic energy and velocity limit results provided values similar to those already reported in the literature: around 56 J and 186 J, respectively. All results obtained were ANOVA statistically analyzed based on a confidence level of 95%. Tukey’s test revealed, as expected, that the best performance among the studied impact resistance was 30 vol%, reaching the highest values of energy absorption. For ballistic performance, the Weibull analysis showed a high R2 correlation value above 0.9, confirming the reliability of the tested samples. These results illustrate the possibilities of caranan fiber to be used as a reinforcement for epoxy composites and its promising application in ballistic armor.

Dynamic and Ballistic Performance of Graphene Oxide Functionalized Curaua Fiber-Reinforced Epoxy Nanocomposites.

Graphene oxide (GO) functionalized curaua fiber (CF) has been shown to improve the mechanical properties and ballistic performance of epoxy matrix (EM) nanocomposites with 30 vol% fiber. However, the possibility of further improvement in the property and performance of nanocomposites with a greater percentage of GO functionalized CF is still a challenging endeavor. In the present work, a novel epoxy composite reinforced with 40 vol% CF coated with 0.1 wt% GO (40GOCF/EM), was subjected to Izod and ballistic impact tests as well as corresponding fractographic analysis in comparison with a GO-free composite (40CF/EM). One important achievement of this work was to determine the characteristics of the GO by means of FE-SEM and TEM. A zeta potential of −21.46 mV disclosed a relatively low stability of the applied GO, which was attributed to more multilayered structures rather than mono- or few-layer flakes. FE-SEM images revealed GO deposition, with thickness around 30 nm, onto the CF. Izod impact-absorbed energy of 813 J/m for the 40GOCF/EM was not only higher than that of 620 J/m for the 40CF/EM but also higher than other values reported for fiber composites in the literature. The GO-functionalized nanocomposite was more optimized for ballistic application against a 7.62 mm projectile, with a lower depth of penetration (24.80 mm) as compared with the 30 vol% GO-functionalized CF/epoxy nanocomposite previously reported (27.43 mm). Fractographic analysis identified five main events in the ballistic-tested 40GOCF/EM composed of multilayered armor: CF rupture, epoxy matrix rupture, CF/matrix delamination, CF fibril split, and capture of ceramic fragments by the CF. Microcracks were associated with the morphological aspects of the CF surface. A brief cost-effective analysis confirmed that 40GOCF/EM may be one of the most promising materials for personal multilayered ballistic armor.

Numerical investigation on hybridization of woven fabric armour to enhance ballistic protection

The soft ballistic armour design requirement involves maximum ballistic energy absorption with lower backface deformation at minimum possible weight. Yarn mechanical properties play a primary role in influencing the above armour characteristics. The study reported to date has analysed the yarn properties, which will yield maximum ballistic energy absorption. However, finding the optimal combination of yarn mechanical properties that will simultaneously satisfy all the above objectives is still a matter of investigation. In view of this, the study first introduces a new parameter, “Inertial Work” (product of armour mass and backface deformation) which enables categorization of armour backface deformation in a mass normalized manner. Further, Specific Ballistic Energy Absorption (SBEA) parameter is introduced for comparison across the fabrics of different densities. The woven fabrics widely used in the ballistic protection domain Kevlar 29, Zylon AS and Spectra 1000 were extensively analysed numerically to study their ballistic response. FE simulation results showed that a single material armour would prove insufficient to simultaneously attain the above design characteristics. Hence a concept of hybridized multilayer-multimaterial armour was established to address this lacuna. It was found that hybridization significantly influenced the ballistic performance of armour. The arrangement of maximum layers of high toughness, low modulus – high failure strain material (Kevlar 29) in front, followed by a material with similar toughness but higher strength (Zylon AS) and then minimum layers of low toughness and low failure strain material (Spectra 1000) at the back resulted in higher SBEA and lower Inertial work.

Effects of Thermal Aging on Molar Mass of Ultra-High Molar Mass Polyethylene Fibers.

Ultra-high molar mass polyethylene (UHMMPE) is commonly used for ballistic-resistant body armor applications due to the superior strength of the fibers fabricated from this material combined with its low density. However, polymeric materials are susceptible to thermally induced degradation during storage and use, which can reduce the high strength of these fibers, and, thus, negatively impact their ballistic resistance. The objective of this work is to advance the field of lightweight and soft UHMMPE inserts used in various types of ballistic resistant-body armor via elucidating the mechanisms of chemical degradation and evaluating this chemical degradation, as well as the corresponding physical changes, of the UHMMPE fibers upon thermal aging. This is the first comprehensive study on thermally aged UHMMPE fibers that measures their decrease in the average molar mass via high-temperature size exclusion chromatography (HT-SEC) analysis. The decrease in the molar mass was further supported by the presence of carbon-centered free radicals in the polyethylene that was detected using electron paramagnetic resonance (EPR) spectroscopy. These carbon-centered radicals result from a cascade of thermo-oxidative reactions that ultimately induce C–C ruptures along the backbone of the polymer. Changes in the crystalline morphology of the UHMMPE fibers were also observed through wide-angle X-ray diffraction (WAXS), showing an increase in the amorphous regions, which promotes oxygen diffusion into the material, specifically through these areas. This increase in the amorphous fraction of the highly oriented polyethylene fibers has a synergistic effect with the thermo-oxidative degradation processes and contributes significantly to the decrease in their molar mass.

Codesigning a ballistic body armour with an industry partner and local police officers: focused on improving ergonomic fit and comfort

ABSTRACT We aimed to identify fit and comfort issues associated with the case company’s body armour and suggest recommendations to mitigate the issues, guided by the integrated three-stage process model for codesign. Thirteen collaborators participated in the codesign practice, including eight company employees (ICs) and five local police officers (ECs). This study adopted one-on-one interviews, focus groups, 3D body scanning and occupational task assessment. In Stage 1, we identified the problems with the existing body armour and areas of improvement based on the inputs from the ICs and ECs. The design solutions for the defined needs were sought in Stage 2. In Stage 3, the final outcomes were validated and approved by the collaborators. The results from this study provided the case company practical guidance to improve the body armour design, and further offer a new means of involving diverse stakeholders’ voices and perspectives in the product design and development process.

Machinability of Non-Conductive Ceramic by EDM: A Review

AdvancedCeramics are gaining a foothold in the lightweight aerospace, electronics, and structural engineering component markets. These ceramics could be extensively used in modern industry, such as ballistic body armour, ceramic carbon fibre composite automoti ve brakes, diesel particulate filters, prosthetic limbs, piezoelectric sensors, and computer memory products, due to their higher compressive strength, resistance to abrasion, lower thermal expansion coefficient, higher density, and chemical stability. Ceramics are notori ously difficult to handle due to the increased hardness and brittleness. Low electric-conductive ceramics, on the other hand, can be machined using the EDM technique, in which plasma energy is used to accurately remove the material by continuous sparking between the surface and the electrode submerged in dielectric. It is observed that EDM can be applied to the material having electrical resistivity below 100 ?.cm. Most recently it has been observed that EDM could be applied to insulating ceramics too. An attempt has been made in this paper to critically review the machining of ceramics by the EDM process.

Multimaterial ballistic solutions for UAVs

One of the main challenges for UAVs (Unmanned Aerial Vehicles) used in defence and military operations is to effectively conclude a flight mission in a harsh environment. The platform survivability is critical, therefore it is imperative that the vehicle is able to withstand ballistic impacts in flight and still be able to reach its destination. In the present work, the authors discuss the development of a lightweight ballistic armour to protect critical areas of the vehicle, such as the control systems and/or the payload. The structure response during and after a 9 mm bullet impact, shows that the proposed hybrid composite panels will be able to withstand high-energy ballistic impacts after optimization. The FEA (Finite Element Analysis) method is implemented to study the performance of ceramic protective plates attached to the CFRP (Carbon Fibre Reinforced Polymer) structural platform. An Eurelian-Lagrangian modelling technique is implemented with different damage models for the various materials involved in the impact event in order to properly capture each material response in this complex load scenario. Numerical studies are validated experimentally. The base structural CFRP is cured in autoclave followed by a post-cure to integrate the remaining components. Experimental tests were conducted at a shooting range where 9 mm projectiles are fired at a distance of 10 m of the target plates. Data is collected recurring to a chronograph/high speed camera combination apparatus to measure the impact and residual velocity and the projectile deformation/damage. Numerical models show good correlation with the experimentally measured data.

Mechanical properties of Ti-6Al-4V three-layer material

The paper presents the results of studies on the mechanical behavior under impact and tensile loading of a Ti-6Al-4V three-layer material obtained by diffusion bonding at 800°C. Diffusion bonding is the process that integrates one material with another by pressure at a temperature below the melting points of materials. Diffusion bonding of Ti-6Al-4V alloy is particularly interesting for aerospace structures, ballistic armor and sports equipment manufacturing. Predominantly single spherical pores are present in the joint zone; chains of pores are extremely rare. The static mechanical properties of the laminate are at the level of properties of monolithic material. The laminate is characterized by a different fracture resistance depending on the layer orientation relative to the direction of impact load action. The impact strength value of the laminate is minimum in the crack short-transverse orientation due to the lower energy of crack propagation. The energy of crack nucleation in the studied laminate is the same for all studied orientations of crack propagation. The results of the evaluation of the relative value of the impact strength showed that the laminate has the highest fracture resistance for the crack divider orientation. The studied layer orientations relative to the direction of impact load action are characteristic for the real diffusion-bonded structures.

Perforation mechanics of UHMWPE soft ballistic sub-laminate and soft ballistic armor pack: A finite element study

Soft-ballistic sub-laminate (SBSL) made from ultra-high molecular weight polyethylene (UHMWPE) fibers in [0/90] stacking sequence are the building block of a multi-layer soft-ballistic armor pack (SBAP, aka Soft Armor). A systematic study of the perforation dynamics of a single layer SBSL and several multi-layer SBAPs (2, 3, 4, 8, 16, 24, 32 layers) is presented for the first time in the literature. A previously validated finite element model of transverse impact on a single layer is used to study the perforation mechanics of multi-layer SBAPs with friction between individual layers. Following the classical definition of ballistic limit velocity, a minimum perforation velocity has been determined for free-standing single layer SBSL and multi-layer SBAPs. For the multi-layer SBAPs, complete perforations have been identified as progressive perforation of individual layers through the thickness. The minimum perforation velocities of multi-layer SBAPS is linear with the areal density for the eight (8) layer target and thicker. Large deformation behavior and perforation mechanics of the SBAPs is discussed in detail.

Energy Absorption and Limit Velocity of Epoxy Composites Incorporated with Fique Fabric as Ballistic Armor-A Brief Report.

Polymer composites reinforced with natural fabric have recently been investigated as possible ballistic armor for personal protection against different levels of ammunition. In particular, fabric made of fique fibers, which is extracted from the leaves of the Furcraea andina, was applied as reinforcement for polymer composites used in a multilayered armor system (MAS). The superior performance of the fique fabric composites as a second MAS layer motivated this brief report on the determination of the absorbed energy and capability to limit velocity in the stand-alone ballistic tests. The single plates of epoxy composites, which were reinforced with up to 50 vol% of fique fabric, were ballistic tested as targets against 7.62 mm high-speed, ~840 m/s, impact ammunition for the first time. The results were statistically analyzed by the Weibull method and ANOVA. The absorbed energies of the 200–219 J and limit velocities of 202–211 m/s were found statistically similar to the epoxy composites reinforced with the fique fabric from 15 to 50 vol%. Predominantly, these findings are better than those reported for the plain epoxy and aramid fabric (KevlarTM) used as stand-alone plates with the same thickness. Macrocracks in the 15 and 30 vol% fique fabric composites compromise their application as armor plates. The delamination rupture mechanism was revealed by scanning electron microscopy. By contrast, the integrity was maintained in the 40 and 50 vol% composites, ensuring superior ballistic protection compared to the use of KevlarTM.

The Effect of Austenization Temperature in Surface Hardening Process on Steel Plate as Ballistic Plate

Ballistic resistant plate is a plate that is able to withstand the rate of projectiles. Ballistic resistant plates or armor plates are applied to military vehicles. It requires a combination of hardness, strength and toughness. Surface hardening with heat treatment is carried out to obtain ballistic resistant properties. The article is aimed at increasing the hardness of one of the surface in commercial medium carbon steel. The variation of austenization is done at the temperatures of 700, 800 and 900 °C with induction heating and holding time for 3 seconds. The quenching media used 15 litters of oil. Several tests are conducted: The results of surface hardening are observed in microstructure, distribution of hardness is tested by micro vickers, tensile testing and impact testing. Tensile testing in accordance with ASTM E8 standards and impact testing with E 23 standards. The transformation of ferrite and perlite to marten site is obtained on the surface of the plate in the temperature of 900 °C. At that temperature, hardness increases on the surface and tenacity can be maintained. In addition, the value of hardness, tensile strength and impact energy were significantly increased. Impact energy as a material requirement for ballistic resistance had been achieved, but hardness and tensile strength still need to be increased.

Synergistic effect of hybrid ballistic soft armour panels

This study aims to identify synergistic effect of hybrid ballistic soft armour panel. According to Finite Element Simulation results and ballistic test results, a front sensitive region was identified including front one or two layers in an Ultra High Molecular Weight Polyethylene Uni-directional (UHMWPE UD) panel. These front layers displayed lower energy absorption due to thermal damage and high compressive stress concentration. While back layers possessed higher energy absorption due to significant tensile failure. When different materials were placed in the front sensitive region (such as UD laminates, woven fabric and non-woven felt), ballistic responses of whole panels was influenced including transverse deflection during impact, failure modes and ballistic energy absorption. Only when the proper materials were placed in the front sensitive region, synergistic hybrid effect can be displayed with improvement of energy absorption of the hybrid panel for a given areal weight.

Research Progress of Armor Protection Materials

With higher requirements of ballistic performance put forward by the new generation of armored vehicles, the development of new armored materials at home and abroad has made great progress. In this paper, the development status of composite ballistic armor used in armored vehicles at home and abroad is reviewed, the future development demand of composite ballistic armor used in armored vehicles is summarized, and the application prospect of new materials such as gradient functional materials, micro-laminated materials, graphene modified ceramics in armored vehicles is prospected. In order to meet the independent development needs of armored vehicles in China, it is urgent to develop new advanced lightweight protective materials with excellent performance. Only by developing new armor materials can we improve the survivability of our armored vehicles, meet the operational requirements of our weapons and equipment, and realize the synchronous development with advanced armor protection technology in the world.

Preparation and Impact Resistance Properties of Hybrid Silicone-Ceramics Composites

This article presents the method of preparation a new type of ballistic armor based on hybrid silicone-ceramic (HSC) composites with considerable flexibility. An experimental study on the ballistic behavior of HSC composites connected with soft body armor is presented against FSP.22 fragments. The effect of Al2O3 ceramics on the ballistic performance of HSC composite was investigated, and the fragmentation resistance process of the composite armor combining the HSC composite and soft aramid insert is clarified. Furthermore, impact resistance tests made with a drop tower which allows for a gravity drop of a mass along vertical guides onto a sample placed with an energy of 5 J were performed. The results presented in this paper show that the HSC composites can be successfully used as a hard body armor. However, they do not exhibit the properties of absorbing the impact energy generated during the drop tower tests. The test results show that the ballistic performance of composite armors is influenced by the hardness and Young modulus of ceramics and soft body armor panel. Additionally, in the article, the results of mechanical properties of silicones used for preparation of composites were presented and compiled to determine their role in the performance of impact protection.

Transparent glass-ceramic waveguides made by femtosecond laser writing

Transparent glass-ceramics (TGC) have been investigated to replace hard, mechanically strong, scratch resistant materials in ballistic armor applications and smart phone displays. Certain types of TGC have superior performance than borosilicate and soda-lime glasses, and are much easier to produce, especially large parts, than transparent mono or polycrystalline ceramics. Thereupon, transparent glass-ceramics could be feasible in other applications, such as stronger photonic devices. In this work, we used femtosecond laser pulses to inscribe optical waveguides inside a magnesium aluminum silicate (MAS) precursor glass and glass-ceramic, which has shown satisfactory mechanical properties to be applied as ballistic armor. Single mode waveguides for the precursor glass and ring mode for MAS-TGC were obtained and characterized (total insertion loss, mode profile, and threshold energy for heat diffusion at different fabrication depths). Micro-Raman measurements on the microfabricated waveguide core and on the pristine material surface show some difference for the TGC, but none for the glass. Particularly, we found that the threshold energy for heat diffusion is higher in the MAS glass-ceramic than in its parent glass. Its good optical waveguiding and mechanical properties indicate that this new TGC might be adequate for photonic devices that require mechanically competent materials.