Search Results (122)

Gunshot injuries are challenging conditions because of the unique characteristics of the wounding agents producing soft tissue damage that may be compounded by the formation of an expanding temporary cavity (cavitation). Variations in ballistic performance leading to higher energy transfer by the projectile, including bullet tumbling, deformation, and fragmentation, cause increased soft tissue injury and may also lead to more extensive bone comminution compromising local blood supply. Once life-threatening injuries have been excluded or properly addressed, the emergency management of localized trauma from bullets and shotgun pellets may be complicated due to progressive tissue necrosis within the zone of injury. Additionally, the risk of infection should be tackled, especially in high energy bone injuries. War experience suggests a baseline separation between wounds with limited tissue destruction which can routinely be managed as simple penetrating injuries and those resulting from high energy transfer to the tissues involving a substantial amount of necrotic elements surrounding the wound channel which call for a more aggressive surgical approach. A further justification for such a distinction is the need for antibiotic therapy, which varies according to most studies depending on the wounding mechanism, the nature of the wound, and the extent of tissue injury. The emergency physician should also be aware of the possibility of “bizarre” bullet paths resulting in occult injuries of important anatomic structures. Full article

This study evaluates the structural safety of composite RC wall systems, which consist of outer and inner RC walls with either an empty or a filled gap, against projectile impacts. The system is considered to have failed if its ballistic limit falls below the projectile’s striking velocity. To determine this limit, the wall system is transformed into an equivalent monolithic wall of the same total reinforcement and perforation energy. A modified UKAEA formula was employed to estimate this limit. To perform the reliability assessment, as the experiments were limited, over one million composite walls were simulated, and the probability of failure and reliability were estimated. Results show that, by leaving the gap unfilled between equally thick inner and outer walls, safety improves by 49.2% compared to a monolithic wall; the safety increases further to 68.2% and 68.9% by filling the gap with sand and recycled concrete aggregate, respectively. Greater gains occur with unequal wall thicknesses: 62% (no fill), 95% (sand), and 96% (recycled aggregate). Parametric analysis demonstrated the influence of filling density, gap thickness, and wall thickness ratios on system reliability. Overall, the findings confirm the superior protective performance and higher safety of composite wall systems compared to monolithic walls. Full article

The paper presents experimental results for a modified pulsed plasma thruster (PPT) with solid propellant, using a coaxial anode–cathode design. Graphite from pencil leads served as propellant, and a tungsten trigger electrode was tested to reduce carbonization effects. Experiments were performed in a vacuum chamber at 0.001 Pa, employing diagnostics such as discharge current/voltage recording, power measurement, ballistic pendulum, time-of-flight (TOF) method, and a Faraday cup. Current and voltage waveforms matched an oscillatory RLC circuit with variable plasma channel resistance. Key discharge parameters were measured, including current pulse duration/amplitude and plasma channel formation/decay dynamics. Impulse bit values, obtained with a ballistic pendulum, reached up to 8.5 μN·s. Increasing trigger capacitor capacitance reduced thrust due to unstable “pre-plasma” formation and partial pre-discharge energy loss. Using TOF and Faraday cup diagnostics, plasma front velocity, ion current amplitude, current density, and ion concentration were determined. Tungsten electrodes produced lower charged particle concentrations than graphite but offered better adhesion resistance, minimal carbonization, and stable long-term performance. The findings support optimizing trigger electrode materials and PPT operating modes to extend lifetime and stabilize thrust output. Full article

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

Aramid fibre has become a critical material for individual soft body armour due to its lightweight nature and exceptional impact resistance. To investigate its energy absorption mechanism, quasi-static and dynamic tensile experiments were conducted on Kevlar^® 29 plain-woven fabric using a universal material testing machine and a Split Hopkinson Tensile Bar (SHTB) apparatus. Tensile mechanical responses were obtained under various strain rates. Fracture morphology was characterised using scanning electron microscopy (SEM) and ultra-depth three-dimensional microscopy, followed by an analysis of microstructural damage patterns. Considering the strain rate effect, a viscoelastic constitutive model was developed. The results indicate that the tensile mechanical properties of Kevlar^® 29 plain-woven fabric are strain-rate dependent. Tensile strength, elastic modulus, and toughness increase with strain rate, whereas fracture strain decreases. Under quasi-static loading, the fracture surface exhibits plastic flow, with slight axial splitting and tapered fibre ends, indicating ductile failure. In contrast, dynamic loading leads to pronounced axial splitting with reduced split depth, simultaneous rupture of fibre skin and core layers, and fibrillation phenomena, suggesting brittle fracture characteristics. The modified three-element viscoelastic constitutive model effectively captures the strain-rate effect and accurately describes the tensile behaviour of the plain-woven fabric across different strain rates. These findings provide valuable data support for research on ballistic mechanisms and the performance optimisation of protective materials. Full article

Wildlife–vehicle collisions (WVCs) remain a significant cause of animal mortality worldwide, particularly in regions experiencing rapid road network expansion. During the COVID-19 pandemic, a number of studies reported decreased WVC rates, attributing this trend to reduced traffic volumes. However, the validity of the simplified assumption that “fewer vehicles means fewer collisions” remains underexplored from a mechanistic perspective. This study aims to reevaluate that assumption using two simulation-based models that incorporate both the physics of vehicle movement and behavioral parameters of road-crossing animals. Employing an inverse modeling approach with quasi-realistic traffic scenarios, we quantify how vehicle speed, spacing, and animal hesitation affect collision likelihood. The results indicate that approximately 10% of modeled cases contradict the prevailing assumption, with collision risk peaking at intermediate traffic densities. These findings challenge common interpretations of WVC dynamics and underscore the need for more refined, behaviorally informed mitigation strategies. We suggest that integrating such approaches into road planning and conservation policy—particularly under the European Union’s ‘Vision Zero’ framework—could help reduce wildlife mortality more effectively in future scenarios, including potential pandemics or mobility disruptions. Full article

The Anderson localization of phonons in disordered superlattices has been proposed as a route to suppress thermal conductivity beyond the limits imposed by conventional scattering mechanisms. A commonly used signature of phonon localization is the emergence of the nonmonotonic dependence of thermal conductivity $\kappa$ on system length L, i.e., a $\kappa$-L maximum. However, such behavior has rarely been observed. In this work, we conduct extensive non-equilibrium molecular dynamics (NEMD) simulations, using the LAMMPS package, on both periodic superlattices (SLs) and aperiodic random multilayers (RMLs) constructed from Si/Ge and Lennard-Jones materials. By systematically varying acoustic contrast, interatomic bond strength, and average layer thickness, we examine the interplay between coherent and incoherent phonon transport in these systems. Our two-phonon model decomposition reveals that coherent phonons alone consistently exhibit a strong nonmonotonic $\kappa$-L. This localization signature is often masked by the diffusive, monotonically increasing contribution from incoherent phonons. We further extract the ballistic-limit mean free paths for both phonon types, and demonstrate that incoherent transport often dominates, thereby concealing localization effects. Our findings highlight the importance of decoupling coherent and incoherent phonon contributions in both simulations and experiments. This work provides new insights and design principles for achieving phonon Anderson localization in superlattice structures. Full article

Parameters of EPFM are used as relevant parameters in structural integrity assessments. In this research, the fracture toughness of armoured steel was determined. The resulting resistance curves and K_JIC obtained according to the ASTM E1820 standard with normalization, compliance and multi-specimen methods were compared. Also, the K_IC was verified according to the ASTM E399 standard as the most precise method for obtaining the K_IC, which also requires a lot of knowledge. For the experiment, the multi-specimen method was used, which is the most expensive and most accurate method, where the least assumption and crack size is measured on the specimen. A fractographic analysis was also presented, and this heat-treated high-strength steel, which is used for anti-ballistic protection, was fully characterized. Full article

Elastoplastic and tribological characteristics of polystyrene are investigated as a model glassy polymer at the ultrahigh-strain rate (>10⁶ s ⁻¹) through the temperature-controlled laser-induced particle impact testing (LIPIT) technique. Polystyrene (PS) microparticles with a diameter of 44 µm are subjected to collisions on a rigid surface at speeds ranging from 200 to 600 m s⁻¹, while the temperature is systematically varied between room temperature and 140 °C. Utilizing the flight path and rebound motion measured from 45-degree angled LIPIT experiments, the coefficients of restitution and dynamic friction are quantified with vectorial analysis. The onset of inelasticity can be possible at a temperature substantially lower than T_g due to the early onset of crazing dominance. While temperature- and velocity-dependent coefficients of friction suggest that the activated surface of PS can facilitate the consolidation of PS microparticles, the enhancement effect is expected more profoundly when the temperature exceeds the glass transition temperature. The microscopic ballistic approach with controlled temperature demonstrates its capability of systematically evaluating the temperature effects on various inelastic deformation mechanisms of polymers at the ultrahigh-strain-rate regime. Full article

To investigate the size effect on fragmentation phenomena during hypervelocity impact, scaled experiments were conducted using a 30 mm smooth-bore ballistic range (DBR30) driven by a detonation-driven two-stage launching system. Unique stripping of sandstone target was observed, revealing that free-surface unloading waves govern peak pressure attenuation and fragmentation patterns. By establishing a shock wave attenuation model, the typical failure characteristics of different regions were distinguished, including jetting, crushing, and cracking. Parameter λ was defined to distinguish two forms of destruction, Class I (stripping-dominated) and Class II (cratering-dominated). Given the significant difference between the compressive and tensile strength of sandstone, the influence of the size effect on its failure characteristics was notable. This research also provides a valuable reference for understanding the evolution and formation mechanisms of binary asteroids. Full article

This study explores the damage behavior of typical titanium alloy aircraft panel structures under high-speed fragment impacts via ballistic experiments and FEM-SPH simulations. Using a ballistic gun and two-stage light gas gun, tests were conducted with spherical, rhombic, and rod-shaped fragments at 1100–2100 m/s to analyze damage morphology. The FEM-SPH method effectively modeled dynamic impacts, capturing primary penetration and debris cloud-induced secondary damage. Residual strength under tension was evaluated via multiple restart analysis, linking impact dynamics to post-damage mechanics. Experimental results revealed fragment-dependent damage modes: spherical fragments caused circular shear holes with conical/jet-like debris clouds; rhombic fragments induced irregular tearing and triangular perforations due to unstable flight; rod-shaped fragments produced elongated breaches with extensive plastic deformation in stringers. Numerical simulations accurately reproduced debris cloud diffusion and secondary effects like spallation. Residual strength analysis showed tensile capacity was governed by breach geometry and location: rhombic breaches (34.6 kN) had lower strength than circular/square ones (38.1–38.3 kN) due to tip stress concentration, while stringer-located damage increased ultimate load by 8–12% via structural redundancy. In conclusion, high-speed fragment impacts dominate shear/tensile tearing, with morphology dependent on fragment characteristics and impact conditions. Debris cloud-induced secondary damage must be considered in structural assessments. The FEM-SPH method is effective for complex damage simulation, while breach geometry and damage location are critical for residual strength. Stringer involvement enhances load-bearing capacity, highlighting component-level design importance for aircraft survivability. The study results and methodologies presented herein can serve as references for aircraft structural damage analysis, residual strength evaluation of battle-damaged structures, and survivability design. Full article

Thermoplastic fiber–metal hybrid composite laminates exhibit superior high-temperature resistance, fatigue resistance, and impact resistance, leading to their increasingly widespread application in the defense, military, aerospace, and marine engineering sectors. In this paper, the impact resistance of laminates with different layup sequences was compared and analyzed through high-speed impact experiments, the dynamic response and failure mechanisms of laminates were explored, and the influence rules of different factors on the impact resistance of laminates were revealed. The findings indicate that distinct laminate configurations possess varying ballistic limits and failure modes. As the number of aluminum alloy layers increases along the thickness direction of laminates, the ballistic limit decreases progressively. When the aluminum alloy layer is distributed on the back of the laminate, the deformation and delamination degree of the laminate will be reduced, and the ballistic limit of the laminate will be improved. The aluminum alloy sandwich will cause more fiber damage, which is not conducive to the energy dissipation of the laminate. These research outcomes are anticipated to provide a technical foundation for the broader application of thermoplastic fiber–metal hybrid composite laminates. Full article

The cross-media water entry problem widely exists in fields such as ocean engineering and aerospace. The highly non-stationary characteristics of the cross-media water entry process significantly influence the structural strength and ballistic stability of vehicles. This paper selects air-dropped torpedoes, supercavitating vehicles, and high-speed projectiles as three typical types of cross-media vehicles for study. Based on their unique structural characteristics and typical water entry conditions, this paper focuses on the current status of their respective impact load and load reduction challenges, as well as water entry ballistic stability issues. At the research methodological level, this paper systematically reviews the progress of current research in three directions: theory, experiments, and numerical simulations, and introduces the application of artificial intelligence in solving cross-media problems. Finally, this paper looks forward to future development trends in cross-media water entry research, aiming to provide a reference for structural optimization design, motion stability control, and other related studies of cross-media vehicles. Full article

The ballistic performance of fiber-reinforced polymer composites (FRPC) is influenced by the adhesive’s mechanical properties, such as stiffness, toughness, and energy dissipation. However, the specific contributions of these properties remain unclear. This study explores how varying the hard segment (HS) content in water-based polyurethane (WPU) impacts the thermal, mechanical, and ballistic performance of FRPCs. By increasing HS content, the storage modulus and tensile strength of WPU improved, while elongation at break decreased, transitioning the adhesive from soft and ductile to rigid and brittle. Quasi-static tests, ballistic experiments, and SEM analysis were conducted on UHMWPE fiber-reinforced WPU-HS% composites. Results reveal that adhesives with high hardness and modulus hinder fiber deformation, reducing energy dissipation and causing severe delamination, which diminishes ballistic performance. Conversely, soft and ductile adhesives allow deformation alongside fibers during bullet impact, suppress delamination, and absorb more kinetic energy while transferring load. Among the tested formulations, WPU with 45% HS content exhibited the best balance of mechanical properties, achieving the most significant improvement in ballistic performance by enhancing energy absorption and minimizing damage. This study establishes a clear relationship between WPU properties and composite protective behavior, providing insights for designing high-performance ballistic materials. 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