Armor Panels Research Articles

3D scanning technique for morphological analysis of behind armour blunt trauma

In this paper, a 3D scanning method was used to measure behind armour blunt trauma (BABT). Ballistic tests were performed using two different bimetallic projectiles against armour panels consisting of 36 plies of DYNEEMA® SB21, mounted on blocks of red Weible® plastilina. The deformed surfaces of the witness material were meticulously scanned to isolate the imprinted indentations, allowing a comprehensive topological analysis to estimate various BABT quantifiers. In addition, detailed examinations of the deformed projectiles and damaged armour panels were carried out, including counting of the number of perforated plies. The added value of using 3D scanning techniques to more precisely assess the performance of armour panels in mitigating BABT was demonstrated. This approach facilitates more accurate measurements compared to conventional methods. It provides not only the depth of the imprinted cavities, but also the access to a more complete set of topological information to potentially further the understanding of ballistic trauma mechanics. In addition, these records allow the information contained in the imprints to be preserved for possible additional analysis.

Analysis of the state of the problem of improving the armor-piercing properties of personal protective equipment: a review study

The object of the study is personal protective equipment such as body armour, and the subject of the work is the study of the processes of destruction of the integrity of personal protective equipment such as body armour in order to find ways to improve their strength characteristics. Protective body armour is a key element of protection for the military, law enforcement agencies and other professions involving risk to life. Modern materials and technologies make it possible to produce bulletproof vests of the highest level of protection, providing not only protection against bullets but also against other hazards such as explosions and shrapnel. However, the systems must have improved ballistic efficiency, be lightweight, flexible and comfortable for effective work. In general, the effectiveness of protective body armour is determined by various factors, including the construction technique of the vest, the type of materials and the finish of the protective panels.
 This paper provides a detailed overview of the current state of the art in body armour panel design and various materials for the manufacture of protective plates. A detailed analysis of the different types of protective body armour and their categories is provided. Next, various methods of panel construction, their problems and possible solutions will be presented. Finally, various polymeric fibre and future possible advanced materials, including carbon nanotubes (CNTs), graphene CNTs and super thickened fluids (STFs), will be discussed for the development of enhanced protection panels.

A review on current status and development possibilities of soft armour panel assembly

A review on current status and development possibilities of soft armour panel assembly

A Novel Multi-Scale Ceramic-Based Array (SiCb+B4Cp)/7075Al as Promising Materials for Armor Structure.

Ceramic panel collapse will easily lead to the failure of traditional targets. One strategy to solve this problem is to use separate ceramic units as armor panels. Based on this idea, we propose an aluminum matrix composite using pressure infiltration, containing an array of ceramic balls, the reinforcement of which consists of centimeter-scale SiC balls and micron-scale B4C particles. Three different array layouts were designed and fabricated: compact balls in the front panel (F-C), non-compact balls in the front panel (F-NC), and compact balls inside the target (I-C). The penetration resistance properties were tested using a 12.7 mm armor-piercing incendiary (API). The results show that there are no significant internal defects, and the ceramic balls are well-bonded with the matrix composite. The F-NC structure behaves the best penetration resistance with minimal overall damage; the I-C structure has a large area of spalling and the most serious damage. Finite element simulation reveals that the ceramic balls play a major role in projectile erosion; in the non-compact structure, the composite materials between the ceramic balls can effectively disperse the stress, thereby avoiding the damage caused by direct contact between ceramic balls and improving the efficiency of ceramic ball erosion projectiles. Furthermore, it is essential to have a certain thickness of supporting materials to prevent spalling failure caused by stress wave transmission during penetration. This multi-scale composite exhibits excellent ballistic performance, providing valuable insights for developing anti-penetration composite armor in future applications.

Ballistic limit evolution of field-aged flexible multi-ply UHMWPE-based composite armour inserts

The development of high-performance polymer-based fibres has given rise to new generations of ballistic protection. However, as polymers and their composites are sensitive to ageing, it is important to understand how these armours maintain their protective capabilities over time. This paper focuses on two sets of armour panels consisting of 36 plies of DYNEEMA® SB21. The 'aged' samples, were collected after ten years of regular use in the field, while the equivalent 'new' samples were manufactured specifically for this study. A large number of ballistic impacts were performed using fragment simulating projectiles to determine differences in ballistic limit. In addition, the number of perforated plies was recorded for non-perforations, while residual velocities were assessed for perforations using a high-speed camera. Overall, the ballistic performance of the samples did not appear to change significantly over time. Nevertheless, the statistics show that 'aged' specimens have slightly more dispersion at their ballistic limit and absorb slightly more kinetic energy than 'new' specimens. Apparently, the ageing of this protection was responsible for the oxidation of the composite material and a partial adhesion between the plies, which explains the small differences in the evaluated ballistic limit quantifiers.

Numerical investigation of the high-velocity impact performance of body armor panels

The body armor can effectively reduce penetration injuries and save many soldiers’ lives. However, back face deformation (BFD) accompanied by ballistic impacts on body armor can lead to fatal injuries to soldiers on the battlefield. In the study, ballistic tests and finite element models are performed to evaluate the protection of body armor panels. Both soft body armor and ceramic till are validated against the experimental data. Then, the performance of the ultra-high molecular weight polyethylene (UHMWPE) soft armor incorporating the RP #1 clay and foam pad is discussed. The simulation results show that the addition of a foam pad can effectively reduce the maximum clay BFD. At the same time, the performance of the ceramic-UHMWPE panel is studied. The ceramic tile can partly absorb the kinetic energy of the high-velocity projectile and enlarge the contact area between the UHMWPE panel and RP #1 clay, which leads to a lower BFD value. In addition, the effects of the interlaminate strength and the laminate stacking direction of the UHMWPE panel on the BFD are discussed. The current simulation can capture the damage behavior of UHMWPE laminates and ceramic tile well, which can be a guide for the design and improvement of new body armor panels.

Design of cost-effective hybrid soft armour panels by strategic replacement of backing layers with a non-ballistic material: A parametric study

Primary requirements of personal protective armour are light-weight, enhanced protection level, and low cost. This work explores the use of ultra-high molecular weight polyethylene (UHMWPE) cross-ply laminates and polycarbonate (PC) sheet to develop hybrid soft armour panels (SAP) for personal protection. Three SAP configurations were prepared and analysed both numerically and experimentally. These configurations were: (1) panel composed of only UHMWPE laminate, (2) panel consisting of UHMWPE laminate and two layers of PC, and (3) panel with UHMWPE laminate and three layers of PC. The ballistic performance of these SAPs was evaluated in terms of back face signature (BFS) and number of perforated layers against the 9 mm × 19 mm lead core bullet having a striking velocity 430 m s−1. Corresponding finite element models of SAPs were also developed using LS-DYNA and validated with experimental results. Further, a parametric study was performed to obtain the cost-effective hybrid solution of SAP and BFS as per IS-17051: 2018. Results revealed that SAPs retained their ballistic performance in terms of BFS for up to 52.5% substitution of the backing layers of UHMWPE laminate with PC sheets. Analyses confirmed that strategic replacement of backing layers with PC sheets is a cost-effective solution to design SAPs.

High- and Medium-Velocity Impact Behavior of Al5083/SiC Interpenetrating Lightweight Composites for Monocoque Armor Panels

High- and Medium-Velocity Impact Behavior of Al5083/SiC Interpenetrating Lightweight Composites for Monocoque Armor Panels

Computational modeling of composite armour and effect of CNT inclusion using orthotropic material model

We report development of indigenous Material Point Method (MPM3D) and Smoothed Particle Hydrodynamics (SPH3D) codes for modeling and design of composite body armour. Typical armour consists of a ceramic backed by a polymer matrix composite. The ceramic plate contributes to blunting of bullet nose, its erosion and reduction in speed. The polymer matrix with high tensile strength arrests the bullet. Mie-Gruneisen EOS, Johnson-Cook strength and failure models were used for projectile. Johnson-Holmquist (JH2) model was used for ceramics. An orthotropic model which accounts for different compression and tensile properties in through-thickness and in-plane directions was implemented and used for Ultrahigh Molecular Weight Polyethylene (henceforth termed as ‘PE’). The codes were validated against published results for impact onto PE targets. Then the codes were used to simulate various published experiments (of coauthors) on ceramic/PE composite targets performed according to NIJ standards. Back Face deformation (BFS) is measured. In all cases, the projectiles do not penetrate through the armour panels, consistent with experiments. Typically, the SPH and MPM codes compute BFS values which only deviate within 10–20 % of measured values. The simulation results are also compared with the commercial FEM code simulations. Experiments and simulations were carried out for PE reinforced with Carbon Nanotube (CNT) inclusions. The mechanical moduli and other strength parameters of PE are adjusted to account for the increase in flexural strength due to inclusion of CNT. The CNT inclusion greatly reduces the BFS. The simulations results qualitatively follow these trends.

Exploration of disentangled UHMWPE tape as a soft body armour material

Disentangled ultrahigh molecular weight polyethylene (UHMWPE) is a very promising material with extremely high tenacity and modulus. In this work, the effect of drawing on the morphological, physical, and mechanical properties of disentangled UHMWPE tapes was studied. The tapes were characterised by using the density gradient column method , wide-angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), polarised optical microscopy and scanning electron microscopy (SEM). The density and crystallinity of tape improved after each stage of drawing. The unoriented crystalline structure of the as-prepared UHMWPE tape gradually transformed into an oriented crystalline structure on drawing as confirmed by WAXD patterns. As the draw ratio increased, concomitant increase in birefringence, and tensile properties were also noticed. The tape obtained after the final stage of drawing had tensile properties similar to that of gel spun UHMWPE fibres. Hence, this tape was used to make prototype of soft armour panel (SAP) that stopped all the bullets fired when subjected to ballistic test and yielded very low back face signature (BFS) justifying the potential of disentangled UHMWPE tape as a ballistic material.

Review of ballistic protection materials: Properties and performances

Ballistic clothing is a crucial safety element that helps to save lives of its wearers. According to the protection level, the ballistic vest is reinforced by one or two armor panels designed to resist to attacks destinated to upper parts of the body. The resistance behavior of ballistic body armor depends on several factors. The most important factors are related to the ballistic fabric properties such as the type of fabric, its thickness, its structure, its strength and strain, and the type of the employed resin. In this review paper, the factors influencing the ballistic performances of soft armor panel and hard armor panel are presented. They are investigated based on an in-depth review of previous research studies and experimental test results. This paper also reports the various methods developed by the researchers to improve the performance of ballistic materials. Thus, ballistic material manufactures and researchers could find some guidelines on promising materials and structures that can be used to build efficient body armors.

Parametric optimisation of shear thickening fluid treatment for ultra-high molecular weight polyethylene woven fabric

The shear thickening fluid (STF) treatment enhances the low and high velocity impact resistance performances of para-aramid woven fabrics for soft armour application. This research investigates the effects of important parameters on the STF add on and impact energy absorption with the aim to develop a hybrid soft armour. The STF add-on on ultra-high molecular weight polyethylene (UHMWPE) woven fabrics was varied by altering the silica particle size, dilution ratio of STF and padding pressure. The results of the full factorial design of experiment showed that the energy absorption is independent of the add-on. Further, a soft armour panel (SAP) was made from the STF treated woven fabric. The ballistic performance of the panel was evaluated in terms of back face signature (BFS) against a 9 × 19 mm lead core bullet and was compared to that of a weight equivalent untreated panel. A hybrid SAP with unidirectional (UD) laminates of UHMWPE as strike face layers and STF treated woven fabrics as backing layers was prepared, and the BFS was found to be equivalent to that of a SAP containing 100% UD laminates (∼30 mm). The results imply that a certain number of UD laminate layers can be replaced with STF treated flexible woven fabrics without compromising on the ballistic performance of SAP.

Ballistic performance of a lightweight nacre-inspired armour panel – a numerical study

This paper provides a numerical investigation on the ballistic performance of ceramic composite armour panels with porous architectures inspired by nacre from mollusc shells. The development of such armour panels can lead to reduced weight and improve ballistic performance through projectile rotation induced by non-uniform contact stresses. The porous tablets of nacre have the potential to reduce the mass of armour panels without compromising their ballistic performance. Preliminary simulations were conducted to assess the performance of several porous bio-inspired structures that have the potential to survive projectile impact with less mass. Several bio-inspired panels composed of various porous designs were generated based on the different void architectures of nacre's tablets. Their performances were benchmarked against a monolithic panel under the same projectile impact condition and having the same 4.5 mm overall panel thickness but higher mass. It was found that for the cases considered, the biomimetic panels with porous architectures possess better ballistic performance compared to the corresponding monolithic panel by arresting the projectile having an initial impact velocity of 500 m/s, whilst reducing its mass by up to 18%. A further study was conducted on bio-inspired panels with a higher thickness but the same mass as the solid monolithic panel under the same projectile impact condition. It was found that the bio-inspired panel exhibits significantly improved ballistic performance when subjected to a fragment simulating projectile having an initial velocity chosen to be the ballistic limit velocity of the corresponding monolithic panel.

Influence of stacking sequence on the impact behaviour of UHMWPE soft armor panels

Mechanical behavior of Ultra-High Molecular Weight Polyethylene (UHMWPE) under high-velocity impact is critical for the design of soft armor vests. Several types of UHMWPE are available with different mechanical properties. However, no validated methodology has been published in literature to analyze the influence of stacking sequence combining different UHMWPE materials to maximize the ballistic limit. In this work, a combined experimental–numerical methodology is proposed to predict the change of the ballistic limit with the stacking sequence, and hence to find the optimum combination. First, the FEM model is fitted using high-velocity impact tests on single layer specimens. Then, the FEM model is validated with the comparison of impact tests on 6 stacking sequences. Once validated, the FEM model is used to analyze 17 stacking sequences with similar areal densities to find the best configuration. In the optimum stacking sequence, for the conditions studied in this work, the material with highest ultimate strain in back face, the material with lowest ultimate strain in the front face, and the intermediate material in the middle. This combination can improve the ballistic limit of the best material reducing the final cost. Conclusions obtained can be used by composite design engineers to improve ballistic performance of UHMWPE protections.

Особенности математического моделирования разрушения керамических пластин под воздействием высокоскоростных ударников

The paper examines the issues of mathematical modeling of ceramic armor panels’ penetration by high-speed cylindrical impactors. By means of the LS-DYNA software package, a corresponding numerical simulation methodology was developed by combining a chosen method, adjusted computational mesh cells size, appropriate Courant number, and values of linear and quadratic pseudo-viscosity coefficients. The results compared with experimental data show that Lagrangian and Eulerian numerical methods, unlike the SPH method (Smoothed Particle Hydrodynamics), improperly reproduce the process of the shock wave disintegration into an elastic precursor and a plastic wave. In addition, the common size of conical fractions dislodging from the ceramic plates was determined and the influence of the scale effect on the ceramics damage patterns was shown: an increase in the absolute value of the plate thickness leads to the increase in the dislodging cone semi-vertex angle.

Criticality of inter-yarn friction in high-performance fabrics for the design of soft body armour

Inter-yarn friction plays a pivotal role in determining the impact resistance of woven fabric based soft armour panels (SAPs). This study presents a comparison of ballistic performance of SAPs made from para-aramid, ultra-high molecular weight polyethylene (UHMWPE) and poly para-phenylene-2,6-benzobisoxazole (PBO) woven fabrics and demonstrates the importance of inter-yarn friction. Plain woven fabrics were prepared using para-aramid, UHMWPE and PBO yarns and SAPs of constant areal density were produced using multiple layers of these fabrics. It is found that despite lower tenacity and modulus of para-aramid fibres, in comparison to those of UHMWPE and PBO, para-aramid SAP exhibits the lowest back face signature (BFS) owing to the highest inter-yarn friction. On comparing UHMWPE based SAPs made from fabrics with yarns of different fineness, fine UHMWPE yarn based fabric exhibits higher inter-yarn friction owing to more number of crossovers per unit length, which further translates into lower BFS of respective SAP. Therefore, while selecting fibres for soft body armour applications, inter-yarn friction should be considered along with the tensile properties.

Kevlar fabric reinforced polybenzoxazine composites filled with silane treated microcrystalline cellulose in the interlayers: The next generation of multi-layered armor panels

The design of astonishing combinations of benzoxazine resins with various fillers is nowadays of great interest for high quality products, especially in ballistic armors. The objective of this study is to investigate a new hybrid material prepared as multi-layered composite plate by hand lay-up technique. Different composites were manufactured from Kevlar fabrics reinforced polybenzoxazine, which was filled with silane treated microcrystalline cellulose (MCC Si) at various amounts in the interlayers. The developed materials were tested for their flexural, dynamic mechanical and ballistic performance. The aim was to highlight the effect of adding different amounts of MCC Si on the behavior of the different plates. Compared to the baseline, the dynamic mechanical and bending tests revealed an obvious decrease of the glass transition of 21 °C and a notable increase in storage modulus and flexural strength of about 180 %and17%, respectively, upon adding 1% MMC Si as filler. Similarly, the ballistic test exhibited an enhancement in kinetic energy absorption for which the composite supplemented with 1% MCC Si had the maximal energy absorption of 166.60 J. These results indicated that the developed panels, with interesting mechanical and ballistic features, are suitable to be employed as raw materials to produce body armor.

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.

Mitigating the Blunt Trauma of Soft Armour Panels using Polycarbonate Sheets: A Cost-effective Solution

Reduction of back face signature (BFS) or blunt trauma of soft armour panel (SAP) is one of the major aspects of armour design. This research explores the use of stiff polymeric materials (polycarbonate or PC sheet) to mitigate the BFS of hybrid SAPs. Two sets of SAPs were prepared—the first set comprising of para-aramid based woven fabrics and UD laminates and the second, of ultra-high molecular weight polyethylene (UHMWPE) UD laminates. The areal density of all the panels was within the range of 4.7 ± 0.3 kg m−2. The ballistic performance of SAPs was evaluated in terms of BFS and perforation ratio against a 9 mm × 19 mm lead core bullet fired at 430 m s−1 velocity. The BFS of SAPs reduced when PC sheets were used as backing materials, with a maximum improvement of 27.5% noticed in case of the SAP made from woven para-aramid fabrics. PC sheets were able to replace up to 41% of the high-performance materials thereby reducing the materials cost of armour significantly (38%). The outcome of this research opens up possibilities to replace costly high-performance fabrics with low-cost materials while improving the ballistic performance of SAPs.

Dynamic Impact Surface Damage Analysis of 3D Woven Para-Aramid Armour Panels Using NDI Technique.

The effects of the yarn composition system inside 3D woven high-performance textiles are not well investigated and understood against their final ballistic impact behaviour. The current study aims to examine the ballistic impact performances of armour panels made of different 3D woven fabric variants through postmortem observations. Four high-performance five-layer 3D woven fabric variants were engineered based on their different warp yarn compositions but similar area density. A 50 × 50 cm2 armour system of each variant, which comprises eight nonbonded but aligned panels, namely, 3D-40-8/0 (or 8/0), 3D-40-8/4 (or 8/4), 3D-40-8/8 (or 8/8) and 3D-40-4/8 (or 4/8), were prepared and moulded to resemble female frontal morphology. The armour systems were then tested with nonperforation ballistic impacts according to the National Institute of Justice (NIJ) 0101.06 standard Level-IIIA. Two high-speed cameras were used to capture the event throughout the test. Nondestructive investigation (NDI) using optical microscopic and stereoscopic 3D digital images were employed for the analysis. The armour panels made of the 8/0 and 4/8 fabric variants were perforated, whereas the armour made of the 8/8 and 8/4 fabric variants showed no perforation. Besides, the armour made of the 8/4 fabric variant revealed higher local and global surface displacements than the other armours. The current research findings are useful for further engineering of 3D woven fabric for seamless women’s impact protective clothing.