Search Results (110)

The aim of this research was to develop a lightweight armor that could be used in bulletproof vests or vehicle protection, offering an alternative to the disadvantageous properties of high-strength steel plates. Specifically, the study focused on investigating the properties of different binders to identify the most suitable one for further development. The bulletproof characteristics of Kevlar (aramid) fiber fabric (200 g/m², plain weave, CT709) were examined using both the Ansys simulation environment and ballistic laboratory testing. In the experiments, three different layer configurations were tested on 300 × 300 mm specimens, each consisting of 20 layers of Kevlar. The layers were arranged as follows: dry lamination for the first specimen, epoxy binder for the second, and polyurethane binder for the third. Laboratory tests were conducted using 9 mm Parabellum bullets, in accordance with the parameters defined in the MSZ K 1114-1:1999 standard. Both the ballistic and simulation tests indicated that the Kevlar laminated with polyurethane resin demonstrated the most promising performance and is suitable for further development. Full article

Soft body armor (SBA) remains an essential component of first responder protection. However, most SBA design concepts do not adequately address the unique performance, morphological, and psychological needs of women as first responders. In this review, female-specific designs of ballistic-resistant panels, material systems, and SBA performance testing are critically examined. The paper also explores innovations in shaping and design techniques, including darting, dartless shape construction, modular assembly, and body scanning with CAD integration to create contoured and structurally stable panels with improved coverage, reduced bulk, and greater mobility. In addition, the review addresses broadly used and emerging dry textile fabrics and fiber-reinforced polymers, considering various innovations, such as 3D warp interlock weave, shear thickening fluid (STF) coating, nanomaterials, and smart composites that improve energy dissipation and impact tolerance without sacrificing flexibility. In addition, the paper also examines various emerging ballistic performance testing standards and their revisions to incorporate gender-specific standards and measures their ability to decrease trauma effects and maintain flexibility and practical protection. Finally, it identifies existing challenges and areas of future research, such as optimizing multi-layer systems, addressing fatigue behavior, and improving multi-angle and low-velocity impact performance while providing avenues for future sustainable, adaptive, and performance-optimized body armor. Full article

Aluminum alloy laminates have extensive applications in protective armor systems. A simulation-based approach was employed to investigate the anti-penetration performance of aluminum alloy laminates with different configurations. Experiments were carried out to study the mechanical properties of 7055 and 7075 aluminum alloys, and a J-C constitutive model was established for the 7055/7075 aluminum alloy laminate. Based on the J-C constitutive model, numerical simulation was performed to assess the anti-penetration performance of an aluminum alloy laminate with various configurations. Velocity curves during the projectile penetration process were obtained. The simulation results show that the four-layer laminate exhibits superior anti-penetration performance compared to the two-layer laminate. The four-layer laminate with the 7055/7075/7075/7055 configuration demonstrates optimal anti-penetration performance. Full article

Electrothermal superhydrophobic surfaces are regarded as possessing significant potential in anti-icing applications. However, their limited mechanical durability has constrained practical implementation. Herein, this work fabricated a robust electrothermal superhydrophobic surface by femtosecond laser texturing combined with the filling of functional coatings of Ti₃C₂ MXene and hydrophobic SiO₂ nanoparticles (modified with dimethyldichlorosilane), which shows great superhydrophobic anti-icing and electrothermal deicing properties, as well as outstanding mechanical durability. The as-prepared electrothermal superhydrophobic surface exhibited a water contact angle of 160.3° and achieved temperature elevation to 104.2 °C within 180 s under an applied voltage of 5 V. Furthermore, the as-prepared electrothermal superhydrophobic surface demonstrated exceptional anti-icing/deicing performance: ice formation time was prolonged to 75.2 s at −35 °C, ice adhesion strength was reduced to 14.65 kPa, and the frozen droplet on the surface melted rapidly within 10.12 s upon electrifying. Moreover, benefiting from the protection of the designed bionic armor structure (honeycomb-like structure), the as-prepared electrothermal superhydrophobic surface maintained outstanding electrothermal and anti-/deicing properties even after 200 times of blade abrasion. This work paves the way for designing robust electrothermal superhydrophobic surfaces in anti-/deicing applications. Full article

AppArmor is a mandatory access control (MAC) system for Linux based on profiles. It focuses on protecting processes, without differentiating profiles based on the users running the processes themselves. Moreover, it does not implement inheritance mechanisms to simplify the management of profiles and avoid the duplication of rules. This work introduces UserArmor, an extension of AppArmor that overcomes the aforementioned limitations by allowing specific profiles to be associated with users and implementing an inheritance system to reduce complexity, improve reusability, and ensure consistency in security rules. An application to Answer Set Programming is discussed. Full article

Dynamic stab resistance is a critical property for protective textiles and fibrous composites used in body armor and protective gear applications. This is also a very complex property that depends on various factors, including material properties, structural design, and external impact conditions. This review paper presents an in-depth investigation into the dynamic stab impact response and performance of textile and composite materials, focusing on the influences of various endogenous and exogenous parameters. Material-level factors, including material type and properties, fiber orientation, yarn density, textile architecture, chemical treatments, and coatings, are reviewed. In addition, the influence of external conditions, including impact velocity and energy, blade shape and type, impact condition, and impact angles on the stab resistance of the protective materials are discussed. The interplay of these factors significantly affects penetration resistance, energy absorption, and trauma mitigation. This paper further discusses different stab resistance testing methods and standards on various kinds of protective materials and relatively compared the efficiencies of each. Current challenges on flexibility versus protection and future research directions necessary to realize advances in protective textiles with dynamic stab resistance are debated. The present comprehensive analysis gives useful insights to engineers, manufacturers, researchers, and standard makers for selecting, developing, and testing protective textiles and fibrous composite materials with improved stab protection applications. Full article

With elevations mostly less than 2 m, the Florida Keys, an island chain stretching nearly two hundred kilometers from Biscayne Bay to Key West, Florida, is among the most vulnerable coastal regions globally. As the threats from tropical cyclones, storm surges, and sea level rise intensify, urbanized areas increasingly rely on shoreline armoring, disregarding the negative effects on coastal habitats. Living shorelines, which integrate coastal vegetation to stabilize erodible shoreline segments or enhance existing grey infrastructure, have successfully addressed some of these challenges. We present a decision framework for evaluating the suitability of different stabilization methods for existing shoreline conditions. The framework incorporates a Shoreline Relative Exposure Index (SREI) based on shoreline orientation, wind and wave exposure, shoreline slope, bathymetry, nearshore habitat, and storm surge. To refine this framework, we conducted an expert opinion survey to determine parameter weights. The results will inform decisions on using vegetated shorelines alone or with structural elements to reduce wave action, control erosion, and protect Florida Keys communities from storm damage. Implementing innovative shoreline stabilization methods is crucial as climate change and population growth are expected to exacerbate flood management challenges. Full article

The development of efficient and sustainable armor systems is crucial for protecting bodies and vehicles. In this study, epoxy composites reinforced with natural lignocellulosic fibers (NLFs) from carnauba (Copernicia prunifera) were produced with 0, 10, 20, 30, and 40% fiber volume fractions. Their ballistic performance was evaluated by measuring residual velocity and absorbed energy after impact with 7.62 mm ammunition, as well as their application in a multilayer armor system (MAS). Scanning electron microscopy (SEM) was used to analyze fracture regions, and explicit dynamic simulations were performed for comparison with experimental tests. Residual velocity tests indicated a limit velocity (V_L) between 213 and 233 m/s and absorbed energy (E_abs) between 221 and 264 J, surpassing values reported for aramid fabric. All formulations showed indentation depths below the National Institute of Justice (NIJ) limit, with the 40% fiber sample achieving the lowest depth (31.2 mm). The simulation results correlated well with the experimental data, providing insight into deformation mechanisms during a level III ballistic event. These findings demonstrate the high potential of carnauba fibers in epoxy-based polymer composites, particularly as an intermediate layer in MAS, offering a sustainable alternative for ballistic protection. Full article

The biomimetic structures in nature, such as shells, turtles, and other scaly organisms, inspire the design of transparent protective composites for enhancing their anti-penetration performance. Here, we designed the borosilicate glass composites with nacreous and tortoiseshell structures and examined their mechanical properties and damage mechanisms under high-speed impact using ballistics experiments. The effects of arrangements and tablet size on the dynamic performance of borosilicate glass composites were also investigated. The results suggest that the biomimetic structure exhibits better impact performance than traditional composites with whole plate structure. Using the biomimetic structure, the average damage area is decreased by 57.6–66.5% and the average energy dissipation is increased around 5% for the transparent composites. Compared to the aligned arrangements, the staggered arrangement of tablets is more beneficial to the anti-penetration when the staggered point is positioned symmetrically. In addition, the tablet size also plays a significant role, where a small tablet can decrease the average damage area around 15.4–24.1% and increase the average energy dissipation up to 4.2%. Therefore, the tortoiseshell structure with the staggered arrangement of small tablets is an optimal combination of the design parameters, which exhibits the best ballistic performance among other configurations due to the substantial enhancement of the locking effect at the tablet interface. This study provides valuable insights into the impact performance and fracture mode of the biomimetic structural composites, especially for the transparent armors of glass materials. Full article

Natural armors found in animals like fish and armadillos offer inspiration for designing protective systems that balance puncture resistance and flexibility. Although segmented armors have been used historically, modern applications are hindered by a limited understanding of their mechanics. This study addresses these challenges by presenting two novel bio-inspired scale structures with overlapping and staggered configurations, modeled after the elasmoid designs found in fish. Their shapes differ significantly from other artificial scales commonly described in the literature, which are typically flat. Instead, these scales feature a support that extends vertically from the substrate, transitioning into an inclined surface that serves as the protective component. Finite element method tests evaluated their performance in puncture resistance and flexibility. The results showed that one type of scale provided better puncture resistance, while the other type offered greater flexibility. These findings highlight how small geometric variations can significantly influence the balance between protection and flexibility. The results offer new insights into the mechanisms of natural armor and propose innovative designs for personal protective equipment, such as bulletproof vests, protective gloves, and fireproof systems. The finite element simulations employed to test the protective systems can also serve as valuable tools for the scientific community to assess and refine designs. Full article

The aim of this work is to comparatively analyze, using numerical simulation, the impact behavior of aramid fabric. A layered panel was impacted by two projectiles specific to the NIJ protection level HG1. The protection level in this study is based on NIJ Standard 0123.00. This standard is used to establish protection levels. The two projectiles specific to the NIJ HG1 protection level are 9 mm Luger and .357 Mag FMJ. Law enforcement personnel use body armor designed to protect the torso. With the help of numerical simulation, the mechanisms of destruction of the aramid fabric on impact are identified. The protection performance is analyzed as a function of the influence of the number of layers and the projectile velocity variation. The fabric is modeled at the yarn level, with each yarn consisting of hundreds or even thousands of fibers. Simulations are performed at the yarn level, since fiber-level modeling is difficult to implement due to high computational resource requirements. The material properties for the yarn, as well as for the projectiles, are selected from the literature. The results show that only the 20-layer fabric panel impacted by the 9 mm Luger FMJ RN 9 mm FMJ RN projectile at 398 m/s meets the protection requirements of the NIJ standard (NIJ HG1 protection level). In contrast, panels impacted at 436 m/s, or those with fewer layers, show rapid stress wave propagation, severe deformation, and complete perforation, indicating insufficient energy dissipation. This study highlights the critical role of impact velocity, projectile geometry, and number of layers in determining ballistic resistance. These findings contribute to the development of more effective ballistic protective equipment, highlighting the need for optimized layer configurations and improved material properties to meet NIJ standards under different impact conditions. Full article

Ceramic armor protection with complex shapes is limited by the difficult molding or machining processing, and 3D printing technology provides a feasible method for complex-shaped ceramics. In this study, ZrO₂ ceramics were manufactured by 3D printing accompanied with microwave sintering. In 3D printing, the formula of photosensitive resin was optimized by controlling the content of polyurethane acrylic (PUA) as oligomer, and the photosensitive resin with 50% PUA showed excellent curing performance with a small volume shrinkage of 4.05%, media viscosity of 550 mPa·s, and low critical exposure of 20 mJ/cm². Compared to conventional sintering, microwave sintering was beneficial to dense microstructures with fine grain size, and microwave sintering at 1500 °C was confirmed as an optimized sintering process for the 3D-printed ZrO₂ ceramics, and the obtained ceramics showed a relative density of 98.2% and mean grain size of 2.1 μm. The PUA content further affected the microstructure and mechanical property of the ZrO₂ ceramics. The sample with 10%~40% PUA showed some pores due to the low viscosity and large volume shrinkage of photosensitive resins, and the sample with 60% PUA exhibited an inhomogeneous microstructure with agglomeration, attributed to the high viscosity of photosensitive resins. Finally, the ZrO₂ ceramics via 3D printing with 50% PUA showed superior mechanical properties, whose Vickers hardness was 3.4 GPa, fracture toughness was 7.4 MPa·m^1/2, flexure strength was 1038 MPa, and dynamic strength at 1200 s⁻¹ was 4.9 GPa, conducive to the material’s employment as armor protection ceramics. Full article

The design and multi-objective optimization of auxetic sandwich panels (ASPs) are performed to enhance the blastworthiness of armored fighting vehicles (AFVs). Various metastructures in the form of four auxetic geometries are proposed as the sandwich core: re-entrant honeycomb (REH), double-arrow honeycomb (DAH), star honeycomb (SH), and tetra-chiral honeycomb (CH). This paper employs a combination of finite element and machine learning methodologies to evaluate blastworthiness performance. Optimization is carried out using the nondominated sorting genetic algorithm II (NSGA-II) method. The optimization results show significant improvements in blastworthiness performance, with notable reductions in permanent displacement and enhancements in specific energy absorption (SEA). Global sensitivity analysis using SHapley Additive exPlanations (SHAP) reveals that cell thickness is the most critical factor affecting blastworthiness performance, followed by the number of cells and corner angle or radius for CH. The application of optimized ASP on AFVs shows promising results, with no failure occurring in the occupant floor. Furthermore, AFVs equipped with the optimized ASP DAH significantly reduce maximum displacement and acceleration by 39.00% and 43.56%, respectively, and enhance SEA by 48.30% compared to optimized aluminum foam sandwich panels. This study concludes that ASPs have potential applications in broader engineering fields. Full article

The development of ballistic materials has improved very rapidly in the last few years. Body armor plays an important role in protecting individuals during military threats. Body armor can be divided into hard and soft variants depending on the trade-offs between protection levels and wearer agility. Current research aims to optimize strength-to-weight ratios by using different combinations of synthetic or natural fibers or their combinations to achieve increasingly demanding requirements for ballistic materials. Moreover, it examines the various types of fibers utilized in the construction of body armor, ranging from traditional materials like metal and ceramic to synthetic and natural fibers. This paper discusses ongoing research efforts aimed at further enhancing the performance of these materials, such as the incorporation of modified natural fibers into advanced composite systems. The review provides a comprehensive analysis of the current state of the materials utilized in ballistic protection. Full article

Ballistic helmets are individual pieces of armor equipment designed to protect a soldier’s head from projectiles and fragments. Although very common, these helmets are responsible for several casualties due to their significant back face deformation and low ballistic resistance to projectiles. Therefore, to enhance helmet performance, studies have focused on the development of new materials and new ballistic protection solutions. The purpose of this study was to develop and evaluate a new ballistic solution using thermoplastic-based matrices. The first matrix was based on high-density polyethylene (HDPE). The second matrix was based on HDPE modified with exfoliated montmorillonite (MMT). The main manufacturing processes of a thermoplastic-based ballistic helmet are presented, along with its ballistic performance, according to the National Institute of Justice (NIJ) standard 0106.01 and an investigation of its failure mechanisms via a non-destructive technique. All the helmets resulted in level III-A ballistic protection. The postimpact helmets were scanned to evaluate the back face deformation dimensions, which revealed that the global cone deformation was deeper in the HDPE than in the HDPE/MMT helmet. The failure analysis revealed an overall larger deformation area in the HDPE and HDPE/MMT helmet delamination zones in the regions with a large radius of curvature than in the zones with the lowest radius, which is in accordance with previous simulations reported in the literature. Full article