Ballistic Materials Research Articles

Vacuum metal deposition enhancement of friction ridge detail on ballistic materials

The efficacy of Gold/Zinc and Silver/Zinc vacuum metal deposition (VMD) protocols were assessed as stand-alone methods of fingermark enhancement on ballistic brass materials. The results demonstrate the effectiveness of VMD enhancement on a large pool of donors (n = 20), with potentially identifiable marks recovered for the majority of donors, including samples aged up to two months. Of the 20 donors a subset of six donors were selected to assess the capability of VMD enhancement on brass fired cartridge cases, from which some friction ridge detail (FRD) was recovered. Lastly, an attempt to understand which fingermark components are facilitators of VMD enhancement was made. Fingermark residue was extracted from brass tiles and fired cartridge cases before analysing chromatographically (GC–MS). Although some key components were indicated, further evaluation of all fingermark components is needed to draw firm conclusions as to the role each plays in VMD enhancement.

Ballistic performance and failure modes of woven and unidirectional fabric based soft armour panels

This study presents the ballistic protection performance and failure modes of soft armour panels (SAPs) made from different structures, including woven fabrics and unidirectional (UD) laminates. SAPs made from para-aramid woven fabrics and UD laminates, and ultra-high molecular weight polyethylene (UHMWPE) UD laminates were developed and subjected to ballistic impact against 9 mm lead core bullets at an average velocity of 430 m s−1. Ballistic performance of SAPs was evaluated in terms of back face signature (BFS), perforation ratio (PR) and expansion of bullet. UD laminate-based SAPs outperformed their counterparts based on para-aramid woven fabric. While among the UD laminates, UHMWPE variants surpassed their para-aramid counterparts. Microscopic images and scanning electron micrographs showed extensive thermal degradation and melting in first few layers of SAP made from UHMWPE UD laminates, whereas para-aramid panels failed mainly due to fibre rupture, fibrillation along with debonding and delamination in their UD variants. Therefore, an ideal SAP design should incorporate a heat resistant material in the front layers followed by high-modulus ballistic materials in subsequent layers. Use of spacer fabric as backing material can partially replace high-cost ballistic materials without compromising ballistic performance.

Modeling micro-particles impacts into ballistic gelatine using smoothed particles hydrodynamics method

Investigating high-speed microparticle impact responses into soft tissue is essential to several fields such as medicine and biology with technological applications like transdermal delivery of pharmaceuticals. The understanding of the physical process involved in such a phenomenon is complex and few experimental tools are available to study high-velocity microparticle penetration in soft tissues, generally substituted by simulants like gels in the literature. One way to overcome these issues is to use numerical simulation as an efficient way of investigation, but also include difficulties such as accurate models for materials properties, microscale computation, and mathematical formulations. As the earliest meshless method, Smoothed Particles Hydrodynamics (SPH) has been applied in solid dynamics because of its great potentials in simulating extremely large deformation and perforation of targets by various projectiles. This paper develops an original numerical model based on SPH to study the dynamical phenomena during microscale impact of spheres into ballistic gelatin (BG), a common human tissue surrogate. By simulating a series of particle penetrations into 10 wt% BG initial velocities, the projectile trajectories and penetration depths in gelatin are investigated. The effects of the gelatin’s elastic modulus in ballistic impact are also studied. The numerical results show that this numerical model appears to be an promising approach to simulate high-velocity microparticle penetrating ballistic gelatine materials.

MR imaging in the presence of ballistic debris of unknown composition: a review of the literature and practical approach.

Due to a combination of increasing indications for MR imaging, increased MRI accessibility, and extensive global armed conflict over the last few decades, an increasing number of patients now and in the future will present with retained metallic ballistic debris of unknown composition. To date, there are no guidelines on how to safely image these patients which may result in patients who would benefit from MRI not receiving it. In this article, we review the current literature pertaining to the MRI safety of retained ballistic materials and present the process we use to safely image these patients.

Effect of Accelerated Ageing on the Ballistic Resistance of Hybrid Composite Armour with Advanced Ceramics and UHMWPE Fibers

The main objective of this complex study was to evaluate the durability of newly developed ballistic inserts designed using ultra-high-molecular-weight polyethylene (UHMWPE) fibres and advanced ceramics (Al2O3 or SiC). The forecasting of changes in the properties of the newly developed ballistic system is related to safe use and reliable construction, and requires ageing tests to be carried out in natural conditions. Due to the length of this process, a program of tests was developed for simulated use of the composite ballistic inserts under conditions of accelerated ageing, taking into account the 6-year lifespan of these products, which is in accordance with the PN-V-87000:2011 standard. As part of the research work, the new ballistic inserts were tested, and also ones subjected to laboratory ageing for 50, 100, 150 days, which corresponded to 2.2, 4.3 & 6.5 years of ageing in real conditions. The samples selected were verified in terms of ballistic and mechanical behaviour as well as changes in their chemical structure. Changes in the microstructure of the ballistic materials were evaluated using DSC analysis as well as infrared spectroscopy (FTIR-ATR).

Evaluation of recycled Al–LDPE–Al sandwich panels as ballistic protection material

Metal–polymer–metal hybrid sandwich panels are gaining importance in civil, automotive and aerospace applications due to their light weight and damping properties. Compared with composite materials, hybrid materials consisting of separate metal and thermoplastic parts can be recycled much more easily. Besides their applications as covering material on buildings as well as general insulation material, recycled aluminum (Al)–low-density polyethylene (LDPE)–aluminum hybrid panels yield a potential usage of light ballistic protection. In this study, a standard hybrid panel of 3·2 mm polyethylene filling and two 0·4 mm aluminum metal sheets was experimentally tested under ballistic impact. A finite-element model was used with a commercial software program and validated against the experimental results. The finite-element results show that stacking of multiple layers of panels absorbs more energy than an equivalent single-layer panel. Six layers of stacked hybrid aluminum–LDPE–aluminum panels are capable of absorbing the impact energy of a 9 mm pistol projectile, and they can be utilized as recyclable inexpensive ballistic protection materials.

Standardization in testing ballistic protection systems

Even more than in other field of activities, standardization in ballistic protection is in trends of CEN/CENELEC declaration that “standards build trust”, promoting innovation and introduction of new, performant solutions based on test procedures and protocols that are able to point out quality and safety for such systems. Ballistic testing standards have particular specifications for ballistic materials, differentiation of tests being made especially on the purpose of the ballistic protection product. In the last decades, test methods have been refined and measurement devices have become more complex. The main set of standards is developed by military organizations (as NATO), highly industrialized countries, where the military and research in the field are priorities (USA, European Community, Asian countries, South Africa). Some states refer to American standards by using them as guides. Depending on the destination of the ballistic product, specifications in standards are different. The authors give examples of how standards requirements are implemented in testing ballistic protection systems, in order to point out the particularities of introducing and verifying new and classical products in this domain. Generally, the results of the ballistic tests are evaluated by acceptance or rejecting the tested product, based on specific criteria, included in standards.

Investigation of Ballistic Behavior of Agricultural Waste Doped Hybrid Composite Plates in Vacuum Infusion Method

The vacuum infusion method is used in the production of ballistic composite materials, in the repair of aircraft parts and in the production of layered hybrid composite materials. In this study, production of hybrid composite materials including apricot kernel shell powder, hazelnut shell powder, walnut shell powder and graphene nanopowder added layer were made by vacuum infusion method. Layered hybrid composite samples with pure graphene nanopowder added and different shell powder added were produced. Then the produced hybrid composite samples were subjected to ballistic experiments. Due to the security, only the photographs of the ballistic test results were allowed to be shared.

Development of composites of UHMWPE with low amounts of jute fiber

The aim of the present study was to prepare and characterize composites of ultra-high-molar mass polyethylene reinforced with varied amounts of jute fibers, comparing the preparation methods to obtain the composites, either using a twin-screw contra-rotating laboratory extruder or by traditional compression molding technique. The efficiency of the preparation methods was verified by X-ray diffraction, thermogravimetric analysis and differential scanning calorimetry, and ballistic tests were also carried out for performance evaluation. The results showed that the extrusion of UHMMPE with jute fibers increased the degree of crystallinity of this polymer, as observed by both XRD and DSC analyses. Moreover, the thermal stability of the extruded composites was higher than that of the pressing molded samples. The ballistic tests confirm that the extruded samples underwent lower depth of penetration, and therefore, this set of composites presented higher impact resistance. This work highlights the merit of processing UHMMPE containing natural fiber without lubricating agents in the development of efficient ballistic shielding materials.

Study of mechanical and protective characteristics of composite materials based on aramid fabrics modified in a microwave electromagnetic field

The studies of the protective characteristics of samples of armor packages, which are compositions of aramid fabric TSVM-J and glue 88, after influenced by the microwave electromagnetic field, have been carried out. A reduction in the number of maximum punctured layers to 7, and an armor effect to 10 mm was stated. In this case, compared with the control sample, a significant change in the mechanical characteristics of the composite armor package was found. Density increased by more than 10%. At the same time, the tensile ductility decreased by (40-47)%, and the elastic deformation with indentation increased almost 5 times. The results obtained after their refinement and substantiation of the physical mechanism can be used as the basis for the development of technologies for enhancing the characteristics of armor protection elements made of composite ballistic materials and structural organoplastics for aircraft.

Enhanced thermal and mechanical properties of natural silkworm cocoon composites constructed by multi-silkworm larvae simultaneously

In this study, we developed a simple route to fabricate natural silkworm cocoon composites with dense fiber networks and low porosities. The thermal and mechanical properties of these modified cocoons are significantly improved. Especially, the tensile strength, elongation, toughness and the average peeling force of the cocoon constructed by three silkworm larvae simultaneously are found to be 1.7, 1.5, 2.1 and 2.1 times higher than those of the normal cocoon, respectively. These special cocoons with good mechanical properties could be applied to produce high-performance artificial cocoon composites, biomimetic and ballistic materials.

Rheological Characterization of Next-Generation Ballistic Witness Materials for Body Armor Testing.

Roma Plastilina No. 1 (RP1), an artist modeling clay that has been used as a ballistic clay, is essential for evaluation and certification in standards-based ballistic resistance testing of body armor. It serves as a ballistic witness material (BWM) behind the armor, where the magnitude of the plastic deformation in the clay after a ballistic impact is the figure of merit (known as “backface signature”). RP1 is known to exhibit complex thermomechanical behavior that requires temperature conditioning and frequent performance-based evaluations to verify that its deformation response satisfies requirements. A less complex BWM formulation that allows for room-temperature storage and use as well as a more consistent thermomechanical behavior than RP1 is desired, but a validation based only on ballistic performance would be extensive and expensive to accommodate the different ballistic threats. A framework of lab-scale metrologies for measuring the effects of strain, strain rate, and temperature dependence on mechanical properties are needed to guide BWM development. The current work deals with rheological characterization of a candidate BWM, i.e., silicone composite backing material (SCBM), to understand the fundamental structure–property relationships in comparison to those of RP1. Small-amplitude oscillatory shear frequency sweep experiments were performed at temperatures that ranged from 20 °C to 50 °C to map elastic and damping contributions in the linear elastic regime. Large amplitude oscillatory shear (LAOS) experiments were conducted in the non-linear region and the material response was analyzed in the form of Lissajous curve representations with the values of perfect plastic dissipation ratio reported to identify the degree of plasticity. The results show that the SCBM exhibits dynamic properties that are similar in magnitude to those of temperature-conditioned RP1, but with minimal temperature sensitivity and weaker frequency dependence than RP1. Both SCBM and RP1 are identified as elastoviscoplastic materials, which is particularly important for accurate determination of backface signature in body armor evaluation. The mechanical properties of SCBM show some degree of aging and work history effects. The results from this work demonstrate that the rheological properties of SCBM, at small and large strains, are similar to RP1 with substantial improvements in BWM performance requirements in terms of temperature sensitivity and thixotropy.

SPECIAL CERAMICS IN MULTILAYER BALLISTIC PROTECTION SYSTEMS

The paper presents some questions of designing and testing for modern ballistic protecting screens and applied materials especially such as ceramics. Continuous development of present ballistic composite materials enforces the optimisation of existing solutions for ballistic protections in respect to the mass, thickness and costs of material. In times of technological arm race a reduction of armour weight by 5% is a success. It may be achieved by development of new solutions of armour systems applying the newest materials. Ballistic ceramics both enhances the resistance of the armour against armour piercing projectiles and reduces its areal dencity in relation to traditional steel armours due to high mechanical properties, low density, high hardness and dissipation of energy at the mechanism of breaking. The paper illustrates the development of ceramic based armours and the structure of a multilayer ballistic protection, and finally the meaning of its particular layers in fighting the projectile. Moreover the impact of mechanical properties of some ceramic materials used for designing a protection system into its ballistic resistance is discussed.

Finite Element Simulation of Armor Steel used for Blast Protection

Safety of defense and paramilitary operators in hostile environments can be ensured by using ballistic materials. Various destructive and non-destructive techniques are available for characterizing ballistic materials and performance of respective products but they can be expensive and protracted. Finite Element method (FEM) is useful in these situations as it can be used during design phase to determine critical design sections and material performance in products. This study focuses on FE simulation of ARMOX armor steel used for blast protection in anti-land mine vehicles using CONWEP method to simulate blast. Plate is modeled as deformable solid with Johnson-Cook plasticity. Parametric study is performed to determine appropriate element size. Results of numerical simulation were validated from results of experiments published earlier by various researchers. Layered and laminated steel plates of varying thicknesses were tested to assess blast protection as against monolithic armor plate using developed numerical model. Results showed that layered steel plates performed worse and laminated plates performed better than monolithic armor steel plates.

Unraveling the Effect of Material Properties and Geometrical Factors on Ballistic Penetration Energy of Nanoscale Thin Films

It is crucial to investigate the dynamic mechanical behavior of materials at the nanoscale to create nanostructured protective systems that have superior ballistic impact resistance. Inspired from recent experimental advances that enable ballistic materials testing at small scales, here we report a comparative analysis of the dynamic behavior of nanoscale thin films made from multilayer graphene (MLG), polymer, gold, and aluminum under high-speed projectile impact. We employ atomistic and coarse-grained (CG) molecular dynamics (MD) simulations to measure the ballistic limit velocity (V50) and penetration energy (Ep) of these nanoscale films and investigate their distinctive failure mechanisms over a wide range of impact velocities (Vi). For the local penetration failure mechanism observed in polymer and metal films, we find that the intrinsic mechanical properties influence Ep at low Vi, while material density tends to govern Ep at high Vi. MLG films uniquely show a large impact propagation zone (IPZ), which transfers the highly localized impact energy into elastic deformation energy in a much larger area through cone wave propagation. We present theoretical analyses that corroborate that the size of IPZ should depend not only on material properties but also on a geometrical factor, specifically, the ratio between the projectile radius and film thickness. This study clearly illustrates how material properties and geometrical factors relate to the ballistic penetration energy, thereby allowing a quantitative comparison of the nanoscale ballistic response of different materials.

Scale Effects on the Ballistic Penetration of Graphene Sheets

Carbon nanostructures are promising ballistic protection materials, due to their low density and excellent mechanical properties. Recent experimental and computational investigations on the behavior of graphene under impact conditions revealed exceptional energy absorption properties as well. However, the reported numerical and experimental values differ by an order of magnitude. In this work, we combined numerical and analytical modeling to address this issue. In the numerical part, we employed reactive molecular dynamics to carry out ballistic tests on single, double, and triple-layered graphene sheets. We used velocity values within the range tested in experiments. Our numerical and the experimental results were used to determine parameters for a scaling law. We find that the specific penetration energy decreases as the number of layers (N) increases, from ∼15 MJ/kg for N = 1 to ∼0.9 MJ/kg for N = 350, for an impact velocity of 900 m/s. These values are in good agreement with simulations and experiments, within the entire range of N values for which data is presently available. Scale effects explain the apparent discrepancy between simulations and experiments.

Ballistic Impact Performance Study on Thermoset and Thermoplastic Composites

Ballistic impact-resistant materials are of interest for the past few decades. Ballistic impact is a high-velocity impact where the target material is perforated by the projectile, such as a bullet hitting on a surface. In this study, the effect of ballistic impact on thermoset composites, Kevlar–Epoxy, Carbon–Epoxy, Glass–Epoxy, and thermoplastic composite, Carbon–Polyetheretherketone, was done. Projectile residual velocity and projectile penetration depth were used to quantify the effectiveness of the composite material to resist perforation. The simulation study was done on ABAQUS-6.13. The study included preliminary fiber orientation studies and selection of the best performing composite with the most effective fiber orientation. Further, the selection of the best performing target material was done by varying target thickness and projectile velocity. In this study, high-performance Carbon–Polyetheretherketone composite showed the most impact resistance.

Nanostructural evidence of mechanical aging and performance loss in ballistic fibers

ABSTRACTIt is understood that the ballistic resistance of aromatic polyamide fibers is related to the fiber's ultimate tensile strength, strain‐to‐failure, and Young's modulus. Ideal high‐performance ballistic materials maximize these properties while minimizing material density. Equally important is long‐term mechanical and chemical stability: the fibers should not exhibit performance loss over their lifetime. However, less is known quantitatively about their modes of degradation, and experimental methods to quantify the aging and degradation in these fibers are critical. Multiple variations of next generation high‐performance fibers have been investigated under chemical and mechanical accelerated aging conditions. Performance losses have been empirically correlated to chemical degradation of the polymer chain and nanostructural changes in the fiber morphology through X‐ray photoelectron spectroscopy (XPS). Here, we introduce positron annihilation lifetime spectroscopy measurements as a sensitive method to quantify the early onset of damage in the flexed fibers as quantified through changes in the nanoscale void structure in the material. Published 2017.† J. Polym. Sci., Part B: Polym. Phys. 2017, 55, 1711–1717

Ballistic impact response of Kevlar Composites with filled epoxy matrix

Impact resistance and weight are important features for ballistic materials. Kevlar fibres are the most widely reinforcement for military and civil systems due to its excellent impact resistance and high strength-to-weight ratio. Kevlar fibres or spectra fiber composites are used for designing personal body armour to avoid perforation. In this study, the ballistic impact behaviour of Kevlar/filled epoxy matrix is investigated. Three different fillers, nanoclay, nanocalcite and nanocarbon, were used in order to increase the ballistic impact performance of Kevlar-epoxy composite at lower weight. The filler, nanoclay and nanocalcite, content employed was 1 wt.% and 2 of the epoxy resin–hardener mixture while the nanocarbon were dispersed into the epoxy system in a 0.5%, 1% and 2% ratio in weight relating to the epoxy matrix. Specimens were produced by a hand lay-up process. The results obtained from ballistic impact experiments were discussed in terms of damage and perforation. The experimental tests revealed a number of damage mechanisms for composite laminated plates. In the ballistic impact test, it was observed whether the target was perforated completely penetrated at the back or not. The presence of small amounts of nanoclay and nanocalcite dispersed into the epoxy system improved the impact properties of the Kevlar/epoxy composites. The laminates manufactured with epoxy resin filled by 1 wt.% of nanoclay and 2 wt% nanocalcite showed the best performance in terms of ballistic performance. The addition of nanocarbon reduced ballistic performance of Kevlar-epoxy composites when compared the results obtained for laminates with 0% nanoparticles concentration.

Stabbing resistance of body armour panels impregnated with shear thickening fluid

This paper presents an investigation on the use of shear thickening fluid (STF) to improve stabbing resistance of soft ballistic body armour. STFs were produced from polyethylene glycol and silica nanoparticles. The effects of silica nanoparticle sizes and silica nanoparticle weight fraction were studied and STFs made with the different compositions were used to impregnate the Twaron® woven fabrics. Systemic investigations into rheological behaviour of STF were carried out experimentally on STFs with different compositions. STF impregnated woven fabric panels were created and tested for stabbing resistance. Stabbing impact tests were conducted on 6 different types of STF impregnated fabric panels against 2 untreated fabric panels, and the results were studied against the benchmark fabrics without STF impregnation. Based on the same number of layers of fabric, the STF impregnation improves the stabbing resistance notably. For same panel areal density, the STF impregnated panels outperform the untreated fabric panel. The results of this research indicate the possibility of lighter ballistic panel materials for higher stabbing protection. It was also found that higher nanoparticle weight fraction and larger nanoparticle size of silica leads to better stabbing resistance performance among the STF impregnated panels.