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Methods used nowadays in forensic laboratories allow to stop some kinds of projectiles with degree of deformation which lets to use them for comparing traces to projectiles found on the crime scene. However they are not useful for every type of projectiles. Comparative physical tests are enough to indicate the best method for soft catching projectiles. For this aim point of view no modeling needed. The paper presents the results of ballistic tests of impact of chosen types of soft point projectiles into water. The behavior of projectiles of various shapes, with different kinetic energy, was analyzed. On the basis of the obtained results, the projectiles with the highest susceptibility to deformation were identified. Research works described in the paper were performed within the framework of the project Laboratory stand for stopping high-energy projectiles financed from the National Centre for Research and Development (Agreement no. DOB-BIO10/04/02/ 2019). The project is implemented in cooperation with Warsaw University of Technology, Military Institute of Armament Technology and Tebbex 2 since 2019 to 2022. [ABSTRACT FROM AUTHOR]

Aramid fiber/epoxy resin (AF/EP) composite has been heavily used as an impact protection material due to its excellent mechanical properties and lightweight merits. Meanwhile, it is also necessary to concern the flammability of matrix resin and the wick effect of aramid fiber, which would constitute a fire risk in harsh environments. In this work, a multifunctional flame-retardant modifier (EAD) was incorporated into the AF/EP system to improve the flame retardation. The addition of 5 wt% EAD made the AF/EP composite exhibit a high limiting oxygen index (LOI) value of 37.5%, self-extinguishment, as well as decreased total heat release and total smoke release. The results from thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA) demonstrated that the treated composites maintained good thermal stability. Due to the combined action of covalent and noncovalent bonds in the matrix-rich region, the interfacial bonding improved, which endowed AF/EP composite with strengthening and toughening effects. Compared with the control sample AF/EP, the tensile strength and ballistic parameter (V50) of the sample with 5 wt% EAD increased by 17% and 10%, accompanied with ductile failure mode. Furthermore, the flame-retardant mechanism was obtained by analyzing the actions in condensed and gaseous phases. Thanks to good compatibility and interfacial adhesion, the incorporation of EAD solved the inconsistent issue between flame retardancy and mechanical properties, which further expanded the application of AF/EP composite in the protection field. [ABSTRACT FROM AUTHOR]

The ballistic and flexural behaviors of basalt (natural fabric), carbon, glass fiber, and their hybrid composites, were investigated in this study. The main objective of the paper was the addition of natural basalt fiber to the carbon and glass fibers with inter‐ply hybrid sequences to search for possible usage to the ballistic loads carrying structures. The composite and hybrid composite plates produced nine layers with cross‐ply stacking sequences ([0/90]9). The ballistic impact tests were conducted using a specially designed ballistic test setup and the flexural tests were performed through the standard three‐point bending test. The results showed that basalt/epoxy absorbed the most energy under ballistic loading among all models. It was observed that the basalt‐glass‐basalt/epoxy (BGB) hybrid composite had an energy absorption capacity very close to the basalt/epoxy composite. When BGB and carbon‐glass‐carbon/epoxy (CGC) hybrid models were compared, the energy absorption capacity of CGC was 62.7% less than BGB. Unlike the ballistic test result, basalt/epoxy had the lowest flexural strength, while carbon/epoxy had the highest flexural strength. Among the hybrid models, it was seen that BGB had the lowest flexural strength, while CGC had the highest flexural strength. The flexural strength of the CGC is 38% higher than BGB. The study found that basalt fiber has high ballistic resistance, whether alone or when combined with commonly used fibers. It also suggests that basalt fiber is a promising candidate for future research and development in the field of protective materials. Highlights: Basalt (natural fabric) composite materials behavior.Hybridization of basalt with carbon and glass.Target plates damage resistance according to applied ballistic loads.Target plates damage resistance according to applied flexural loads.Non‐hybrid and hybrid composites plates comparisons. [ABSTRACT FROM AUTHOR]

Polymer matrix types of fiber hybrid composites are key factors to improve ballistic impact damage tolerances. Here we report ballistic penetration damages of Kevlar/ultra-high molecular weight polyethylene (UHMWPE) hybrid composites with thermoplastic polyurethane (PU) matrix. The hybrid composites were penetrated by fragment-simulating projectiles (FSPs) using an air gun impact system. The effects of stacking sequences on the ballistic performance of hybrid composites were analyzed. Two types of specific energy absorption (the energy absorption per unit area density and the energy absorption per unit thickness) were investigated. It was found that the main damage modes of PU hybrid composites were fiber breakage, matrix damage, fiber pullout and interlayer delamination. The instantaneous deformation could not be used as a reference index for evaluating the ballistic performance of the target plate. The energy absorption process of the PU hybrid composites showed a nonlinear pattern. The hybrid structure affected the specific energy absorption of the materials. [ABSTRACT FROM AUTHOR]

Copyright of Light Industry Machinery is the property of Light Industry Machinery Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The TPMS lattice structure is widely utilized in the military UAV, and effectively striking the TPMS structure holds significant reference value in bullet design. This paper conducts a numerical simulation to study the penetration performance of exponential curve bullets with varying power exponents on the TPMS structures of Gyroid and Diamond. MATLAB is employed to design the TPMS lattice structure, and ABAQUS is used for numerical simulation. The results indicate that the velocity reduction rate of the bullet initially increases and then decreases with an increase in power exponent. Moreover, a larger power exponent leads to a smaller residual velocity and kinetic energy of the bullet. Different cell structures have a substantial impact on residual kinetic energy, with the Gyroid structure exhibiting significantly greater residual kinetic energy compared to the Diamond structure, resulting in an average kinetic energy difference of 15.429J. The research shows that the curve of the arc part of the warhead has a great influence on the penetration performance. When designing the bullet used to hit the military UAV, the warhead with a large curvature change within a certain range can be considered. [ABSTRACT FROM AUTHOR]

AbstractDue to the constant updates in armor materials and structures, as well as the continuously increasing ballistic threats, higher requirements have been put forward for the ballistic performance of lightweight ceramic armor. In this paper, we first studied the types of ballistic threats faced by lightweight armor and determined the range of main materials and various combinations used in common ceramic composite armor, while comparing their performance with other constituent materials. Next, we reviewed the coupling mechanism of the projectile and target during the ballistic penetration process and the energy dissipation mechanism, and discussed the structural parameters that affect the ballistic performance of the ceramic composite armor. Finally, we pointed out the future direction of development for ceramic composite armor, reviewed the coupling mechanism of the projectile and target during the ballistic penetration process and the energy dissipation mechanism, and discussed the structural parameters that affect the ballistic performance of the ceramic composite armor. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Ordnance Equipment Engineering is the property of Chongqing University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this investigation, simulations are conducted to assess the ballistic resistance of an armor system composed of 95% alumina–Kevlar 29/epoxy composite subjected to normal and oblique impact. The oblique angles are varied from 0° to 70° in the step of 10-degree increments, and the projectile's impact velocities range between 220 and 1200 m/s. The present simulation results are aligned with existing numerical and experimental data available in the literature, demonstrating the consistency and reliability of the approach. Special attention is provided to obtain the critical oblique angle at which the projectile's penetration mode switches from perforation to embedment or ricochet. The simulation results also include the projectile's residual velocities, ballistic limit velocities, and the armor system's performance in terms of penetration or damage for normal and oblique impact. It is established that the oblique angle of the projectile significantly alters the effectiveness of the ceramic–composite armor against ballistic impact. When dealing with oblique angles below 30° (< 30°), the reduction in the projectile's residual velocity, as the obliquity angle increases, is limited to a maximum of 15%. This implies that the target's perforation resistance exhibits less sensitivity to the applied load of the projectile in this range. However, when incident angles exceed 45° (> 45°), the ballistic limit velocity has a significant and abrupt rise due to the augmented effective target thickness under oblique impact conditions. [ABSTRACT FROM AUTHOR]

The study explores the ballistic impact performance of shear thickening fluid (STF) impregnated sisal fabric panels with varying nano silica loadings (10 wt%, 20 wt%, and 30 wt%). Rheological analysis indicated improved shear thickening behavior with increased nano-silica. FESEM, XRD, and FTIR analyses were conducted to assess changes in morphology, phase structure, and functional groups. The yarn pull-out test showed a higher pull-out force for STF-impregnated fabrics, with 30 wt% STF demonstrating the highest pull-out speed. Ballistic impact tests revealed significant improvements in energy absorption for STF-impregnated fabrics compared to neat fabrics, with energy absorption enhancements of 4.40% for 10 wt%, 45.09% for 20 wt%, and 50.17% for 30 wt%. The increased nano-silica loading resulted in greater energy absorption, attributed to enhanced inter-yarn friction and improved fabric integrity.

Hybrid composite sandwich structures, known for remarkable energy absorption, rigidity, and strength, are emerging as a preferred choice for fortifying structures against a diverse range of firearms and artillery. Despite their higher density, these panels demonstrate commendable qualities, making them optimal for armored vehicles and body armor. Numerous structural options compete for recognition as effective ballistic shields in today's context. In this study, three sample configurations were rigorously tested for ballistic impact using a 7.62×39 mm bullet. The first sample (S1) comprised silicon carbide ceramic tiles (SiC), Kevlar fiber, and carbon fiber in the face sheet, with an unfilled aluminum honeycomb core and a carbon fiber rear sheet. Subsequent samples, S2 and S3, maintained the S1 composition but varied in the core. S2 had a honeycomb core injected with polyurethane foam, while S3 utilized a silicone rubber-filled honeycomb core. Ballistic tests revealed a notable difference: S1 and S2 failed to prevent bullet penetration, whereas S3 successfully met this crucial objective. After penetration, the bullets' velocities were S1 -45.9 m/s, S2-22.9 m/s, and S3 -0m/s. Remarkably, S3 exhibited an optimal 0mm back face signature (BFS) and a penetration depth (DOP) of 13.74 mm, well within limits. Cumulative energy absorption (EA) was as follows: S1-2577.23 J, S2-2583.57 J, and S3-2617.92 J. The armors demonstrated specific energy absorptions (SEA) of 2386.33, 2389.97, and 2015.32 J/kg, respectively. Their areal densities were 48, 48.1, and 57 kg/m2, respectively. The ballistic limit velocities (BLV), derived from initial (IV) and residual velocities (RV), measured 802.68, 803.673, and 804 m/s for S1, S2, and S3.

This research delves into the design, modeling, and finite element impact analysis of the segmented sandwich composite armor system subjected to impact loading, considering different parameters such as materials to be used, armor height, and armor design configuration. Initial studies were performed to select the ideal model that will provide the best impact resistance at the least weight and with minimal fabrication requirements. Material type, thickness, and overall model configuration were defined during the initial model development period. Once the final design was defined, finite element analysis was performed using 2017 ABAQUS software to observe the performance of the model and to validate the efficiency of the chosen armor. Based on the results from the material selection and thickness validation, the optimal design with the best impact resistance was noted as 1.2 mm thick rectangular segmented silicon carbide tiles, serving as the top layer that covers the three-level gradient core composed of a titanium metal honeycomb frame filled with silicon carbide inserts, and finally a 2 mm thick glass epoxy composite layer made from four laminas in a 0/45/90/-45-degree configuration serving as the last layer of the armor.

This study discusses the experimental results of the ballistic impact on thick-layered carbon fibre-reinforced polymer (CFRP), glass-based FRP (GFRP), and Kevlar-based FRP (KFRP) composite plates. Ten 10 mm plates of each type were manufactured via the hand lay-up and vacuum bagging techniques to produce plates with a thickness of 2 mm each, which were bonded together using epoxy adhesive and hot pressed at 75°C to obtain thick layered plates with a total thickness of 20 mm each. The specimen plates were tested according to the NIJ 0108.01 standard in a special firing room using a 9 mm G2 Elite handgun with a full metal jacketed round nose 9 mm × 19 mm Mu1-TJ bullets moving at a velocity of approximately 358 m/s. The results indicated that no total penetration occurred on any of the plates. The bullets were destroyed by impact, and the penetration depths of the CFRP, GFRP, and KFRP plates were 11.10, 9.95, and 22.22%, respectively. The layered structures in these plates appear to have changed the penetration behaviour compared with previous studies. In this study, delamination was the primary failure mode.

In this study, aramid fiber (AF)/phenolic resin prepreg was fabricated by impregnating low content carbon nanotube (CNT)‐reinforced phenolic resin with aramid fabric through a two‐roll pressing process. Both non‐functionalized and carboxylic‐functionalized CNTs (CNTs and CNTs‐COOH) were used for comparison study. For each of the formulations, composite laminate was made by a hot‐pressing process with a number of the prepregs stacked together. Mechanical properties and ballistic performance of the laminates and material failure mechanisms were evaluated and analyzed. Both non‐functionalized and CNTs‐COOH can effectively improve the mechanical and ballistic performance of the laminates. With CNTs‐COOH reinforcement, better results were achieved. As compared with the laminate without CNT reinforcement, 1.0 wt% CNTs‐COOH‐reinforced laminate showed 19.41%, 22.29%, and 45.83% improvement in tensile, flexural, and adhesion shear strength, respectively. The ballistic test results showed that the V50 and the specific energy absorption (SEA) were increased by 5.77% and 13.44%, respectively. The correlation between mechanical and ballistic performance of the composites was analyzed and conducted. [ABSTRACT FROM AUTHOR]

This study analyzes the behavior of CFRP tape laminates under high-velocity impact when they are subjected to in-plane tensile preload. Experimental tests were carried out using a gas-gun setup in non-loaded and preloaded laminates. Impact and residual velocities were measured, the ballistic limit and damage area were estimated, and it was observed that the ballistic limit was lower in preloaded specimens. An analytical model was developed and validated. Some differences were observed in terms of energy absorption mechanism distribution between preloaded and non-loaded laminates for impact velocities close to the ballistic limit. The influence on the ballistic limit with the preload level was studied. [ABSTRACT FROM AUTHOR]

For understanding characteristics of polymethylmetacrylate (PMMA) under impact, the damage behavior of PMMA plates with various thicknesses (1.5 to 6.0 mm) subjected to ballistic impacts with various velocities (63 to 180 m/s) is experimentally investigated using a specialized testing apparatus. Moreover, numerical simulations using FEM are conducted for the corresponding experimentally studied cases. Ductile response and brittle tensile failure behavior are considered in the FEM to describe the nonlinear response and the failure mode of the PMMA plates. The numerical simulations effectively describe the shape of cracks and perforations of the PMMA plates for all studied 25 cases, verifying the validity of the numerical model. Although the PMMA plates are generally brittle in the selected range of impact velocity, it was found that these plates exhibit ductile behavior under low-velocity impacts. Moreover, the numerical simulations imply that the kinetic energy loss of the projectile is linearly dependent on the plate thickness, whereas the impact velocity hardly affects this loss. This behavior obtained experimentally and numerically illustrates the usefulness of the PMMA material for the use as a protective layer in many applications involving ballistic (high-velocity) impacts. This study delves into the impact behavior of PMMA plates, offering insights with a range of practical implications. This research positions PMMA as a promising protective material for applications exposed to high-velocity impacts. The comprehensive understanding of failure modes aids in designing resilient PMMA structures. By subjecting PMMA plates of varying thicknesses (1.5 to 6.0 mm) to ballistic impacts at different velocities (63 to 180 m/s), this research reveals a nuanced interplay between ductile and brittle behavior within the material. The study uncovers a ductile response of the PMMA plates under low-velocity impacts, expanding the material's potential use in scenarios with lower impact velocities. Moreover, the linear relationship established between plate thickness and kinetic energy loss of the projectile, independent of the impact velocity, provides a practical basis for designing impact-resistant PMMA structures. The practical applications of the study extend to fields such as architectural glazing, automotive safety, and aerospace engineering, where protective materials play a crucial role in safeguarding against unexpected impacts. In summary, this study empowers practical decision-making by uncovering the PMMA's impact response, thereby contributing to optimized protective solutions across various domains. [ABSTRACT FROM AUTHOR]

The increasing demand for advanced personal protection systems has motivated a considerable interest in hybrid woven fabrics and textile composites. However, the effectiveness of the combination method of fibers on ballistic performance remains uncertain, leaving the selection of an appropriate hybridization strategy unresolved. This study conducted a thorough comparison of the ballistic responses of hybrid aramid/ultra-high molecular weight polyethylene (UHMWPE) woven fabrics, aiming to provide a comprehensive understanding of the hybridization effects. Specimens with inter-layer, intra-layer, and intra-yarn hybrid configurations were manufactured, and ballistic impact tests were performed via a light-gas gun. The residual velocity, energy absorption, dynamic penetration process, and perforation modes of the hybrid specimens were recorded at two selected impact velocities and then compared with those of non-hybrid specimens. The results demonstrated that the enhancement effect of hybridization varied with hybrid configuration and impact velocity. The interlacing of aramid yarns and UHMWPE yarns in intra-layer hybrid specimens did not promote the breakage of UHMWPE fibers, which was responsible for the inferior ballistic performance. In contrast, inter-layer hybridization and intra-yarn hybridization could overcome the insufficient friction of UHMWPE and the low mechanical properties of aramid, resulting in superior ballistic performance. [ABSTRACT FROM AUTHOR]

This research delves into the design, modeling, and finite element impact analysis of the segmented sandwich composite armor system subjected to impact loading, considering different parameters such as materials to be used, armor height, and armor design configuration. Initial studies were performed to select the ideal model that will provide the best impact resistance at the least weight and with minimal fabrication requirements. Material type, thickness, and overall model configuration were defined during the initial model development period. Once the final design was defined, finite element analysis was performed using 2017 ABAQUS software to observe the performance of the model and to validate the efficiency of the chosen armor. Based on the results from the material selection and thickness validation, the optimal design with the best impact resistance was noted as 1.2 mm thick rectangular segmented silicon carbide tiles, serving as the top layer that covers the three-level gradient core composed of a titanium metal honeycomb frame filled with silicon carbide inserts, and finally a 2 mm thick glass epoxy composite layer made from four laminas in a 0/45/90/-45-degree configuration serving as the last layer of the armor. [ABSTRACT FROM AUTHOR]

In this study, the behavior of composite material produced using basalt, a natural fabric, under ballistic and Charpy impact loads was investigated. The damage resistance of target plates under ballistic loads is an important design parameter in the structures that will be exposed to these loads. Cross‐ply fiber‐reinforced composite plates were produced with different numbers of layers. The composite specimens are produced using the vacuum infusion method, cross‐ply laminated with 3, 6, 9, and 12 layers ([0/90]3, [0/90]6, [0/90]9, and [0/90]12). Carbon/Epoxy specimens were also produced in identical sequences to be used as comparison material. The study aimed to understand the absorbed energy under ballistic loads and the required energy level under the Charpy impact loads of Basalt/Epoxy composite specimens with different thicknesses. Ballistic loads are applied to the specimens using a test set‐up including the sample holder mechanism and a firing system. Charpy impact tests were conducted using a standard test machine. According to the results, for 12‐layer specimens, the residual velocity difference between Basalt/Epoxy and Carbon/Epoxy is approximately 1.5 times. For the Basalt/Epoxy plate, increasing number of layers from 3 to 12 increases the amount of energy absorbed approximately 13 times. Although this increase is approximately 19 times for the Carbon/epoxy plate, when Basalt/Epoxy and Carbon/Epoxy plates are compared, Basalt/Epoxy absorbs more energy for all layer numbers. For the Charpy impact cases, it has been observed that Basalt/Epoxy absorbs approximately 34% more energy for flat wise impact and approximately 24% more energy for edgewise impact. Highlights: The behavior of composite material produced using basalt, a natural fabric.Cross‐ply fiber‐reinforced composite plates.Effect of different number of layers considered.The damage resistance of target plates under ballistic loads.Comparison of basalt and carbon‐reinforced composites. [ABSTRACT FROM AUTHOR]

In the present study, the behavior of plain, fiber, and reinforced concrete (PC, FC, and RC) targets against long rod rigid projectile had been investigated. Two different thickness, 55 and 80 mm of PC and FC targets were cast along with 80 mm thick RC targets with 6 different reinforcement configurations. A total of 34 different square targets were manufactured wherein, the aerial dimension measures 400 × 400 mm. The projectiles were made of hardened steel having ogive‐nose with a shank diameter of 18 mm and a mass of 450 g where the caliber‐radius‐head of the ogival nose was kept standard as 3. The ballistic response of all the targets were analyzed in terms of front and rear surface damage, mass loss rate, perforation thickness, and residual velocities against various impact velocities. Explanation regarding the behavior of three different concrete targets against long rod projectile impact loading has been well addressed through the basic laws and relevant theories associated with ballistic impact loading in order to provide guidance for subsequent research in the field of protective structures design. Additionally, perforation thickness and residual velocities corresponding to various impact velocities obtained from experimental study were also found to be in good agreement with the existing empirical model predictions. [ABSTRACT FROM AUTHOR]

Ceramics are widely employed in armor because of their toughness, but their susceptibility to fractures under high-speed impact poses a challenge. To address this gap, a comprehensive investigation using finite element analysis is undertaken. This study aims to understand the combined behaviour of ceramics and backing plates during ballistic impact. Using ABAQUS software, a range of simulations are conducted involving circular ceramics paired with different types of backing plate, considering varying impact energies. The results revealed that the integrity of the ceramic-metal laminate structure is highly dependent on the laminate configurations. From four combinations of hybrid laminates, the combination of boron carbide with Armox 500T as the backing plate produced an outstanding result based on the structural response analysed in this work. The key results obtained provide valuable insights into the response of ceramic-armored configurations, filling a critical knowledge gap. [ABSTRACT FROM AUTHOR]

Defense mechanisms remain important and indispensable due to the different types of pistols and ordnance besides many guns. Hybrid composite sandwich panels are an attractive focus because of their ingrained characteristics, such as high stuffiness and high energy absorption. Hybrid composite sandwich panels are among the most important in armoring various structures. Despite the high density of these panels, they have significant qualities that qualify them to be the first selection for use in armored vehicles or body armor. Recently, there have been several types of structures, and selecting the appropriate structure as armor against the projectiles is very important. The study subjected three samples to the ballistic impact test using a 7.62 × 39 mm bullet. The first sample, S1, consists of ultra high molecular weight polyethylene (UHMWPE)/epoxy, unfilled honeycomb core, Kevlar/epoxy, unfilled honeycomb core, Kevlar/epoxy, and UHMWPE/epoxy; the second sample, S2, comprises Kevlar/epoxy, unfilled honeycomb core, Kevlar/epoxy, unfilled honeycomb core, and UHMWPE/epoxy, and the third sample, S3, comprises Al2O3, Kevlar/epoxy, unfilled honeycomb core, carbon/epoxy, unfilled honeycomb core, and carbon/epoxy. ABAQUS software was used to evaluate the ballistic impact numerically, and after that, the study examined the same armor samples experimentally. The results manifested that only the armor S3 succeeded in stopping the bullet. This is attributed to the structure of the cores, which helps compress and accumulate the cells under the projectile. The speeds of the bullet after penetration (residual velocity; VR) were 748.5 and 715.3 m/s for S1 and S2 armors, respectively, where the back face signature for S3 was 1.5 mm, which is optimum and within the allowed range. The total energy absorption of these armors S1, S2, and S3 is 344.65, 539.04, and 2585.66 J. Furthermore, the highest deviation between numerical and experimental approaches is about 2.04% in the VR.

A terminal ballistic analysis of the effects of 7.62 mm × 51 AP P80 rounds on inclined high-strength armor steel plates is the focus of the presented study. The findings of an instrumented ballistic testing combined with 3D advanced numerical simulations performed using the IMPETUS Afea® software yielded the conclusions. The experimental verification proved that slight differences in the pitch-and-yaw angles of a projectile upon an impact caused different damage types to the projectile’s core. The residual velocities predicted numerically were close to the experimental values and the calculated core deviations were in satisfactory agreement with the experimental results. An extended matrix of the core deviation angles with combinations of pitch-and-yaw upon impact angles was subsequently built on the basis of the numerical study. The presented experimental and numerical investigation examined thoroughly the influence of the initial pitch and yaw angles on the after-perforation projectile’s performance.

Towards higher impact velocities, ballistic events are increasingly determined by the material temperatures. Related effects might range from moderate thermal softening to full phase transition. In particular, it is of great interest to quantify the conditions for incipient or full melting of metals during impact interactions, which result in a transition from still strength-affected to hydrodynamic material behavior. In this work, we investigate to which extent the respective melting thresholds are also dependent on the initial, and generally elevated, temperatures of projectiles and targets before impact. This is studied through the application of a model developed recently by the authors to characterize the transition regime between high-velocity and hypervelocity impact, for which the melting thresholds of materials were used as the defining quantities. The obtained results are expected to be of general interest for ballistic application cases where projectiles or targets are preheated. Such conditions might result, for example, from aerodynamic forces acting onto a projectile during atmospheric flight, explosive shaped-charge-jet formation or armor exposure to environmental conditions. The performed analyses also broaden the scientific understanding of the relevance of temperature in penetration events, generally known since the 1960s, but often not considered thoroughly in impact studies.

In the present study, finite element analysis were carried out to investigate the ballistic performance of Al2O3-Kevlar 29/epoxy armour system impacted by a 4340 steel projectile. The perforation capacity of a 10 mm thick target was studied against a blunt, ogive, and conical shaped projectile with a fixed diameter and mass of 7.56 mm and 10.7 gm, respectively. The simulations were carried out in Ansys/Autodyn by considering the projectile as a deformable body. The variation of the ballistic limit velocity (BLV) and energy, progressive damage of the target, and projectile deformation were studied comprehensively. It was found that the nose configuration of the projectile significantly influence the target's ballistic performance. The perforation capacity of the blunt projectile was lower than the ogive and conical shape in all the velocity regimes. At higher impact velocity (Vi >600 m/s), the target's resistance was better against the ogive projectile than that of the sharp conical projectile. Interestingly, this phenomenon got reversed when the incident velocity nears the ballistic limit. Also, from the simulation results, it has been possible to obtain the optimum thicknesses of the components for a given total thickness of the armour. [ABSTRACT FROM AUTHOR]

AbstractArmor steel is widely used for ballistic resistance in military infrastructures and vehicles. However, the high areal density of monolithic steel plates presents challenges in balancing protection and maneuverability. This study focuses on a novel armor design, invented by the authors: An N-shaped perforated armor plate (NPAP). The NPAP consists of a perforated plate, an inclined plate, and a back plate. A validated finite element (FE) model was used to analyze the dynamic damage behavior of the NPAP target and projectile under ballistic impact. Numerical simulation revealed that the NPAP target combined the edge and obliquity effects, resulting in asymmetric interaction and causing yaw and fracture of the projectile. The kinetic energy of the steel core after penetrating the NPAP target decreased by 84.7–88.0% compared to the initial kinetic energy. The NPAP target showed a 20.7–43.9% lower residual depth of penetration (RDOP) compared to the monolithic target. Furthermore, the effects of the dip angle of the inclined plate and plate thickness configurations on the ballistic performance of NPAP were examined. The results indicated that the NPAP target’s ballistic performance is more susceptible to the impact location on the perforated plate with a larger dip angle of the inclined plate. Additionally, the NPAP target with a thin perforated plate and a thick back plate configuration exhibited better ballistic performance, given the constant thickness of the inclined plate. [ABSTRACT FROM AUTHOR]

In some countries, airguns capable of inflicting injuries are legally regulated and considered to be controlled firearms. In this study, the deformation of witness plates was utilized to assess the wounding potential of airguns. A series of firing tests was conducted using four airguns and two lead ball-type projectiles. The impact velocity (V) and energy density (ED) of the projectiles fired at the witness plates were determined based on a ballistic chronograph. The deformation depths (H) of the uncracked and unperforated witness-plates were measured. Correlation analysis revealed that H was linearly correlated with V. The coefficient of determination between H and V was greater than 0.99. Two-variable linear equations were employed to calculate the evaluated impact velocity (VE) and energy density (EDE). Validation firing tests were conducted using four real-case airguns seized and submitted by local police departments. To calculate VE and EDE, we employed H and linear equations, respectively. The percentage difference between ED and EDE was less than or equal to 12%. These results demonstrate that the witness-plate deformation method is an efficient presumptive test for reducing backlogs of muzzle energy examinations of airguns in forensic laboratories. [ABSTRACT FROM AUTHOR]

Natural protective materials offer unparalleled solutions for impact-resistant material designs that are simultaneously lightweight, strong, and tough. Particularly, the Bouligand structure found in the dactyl club of mantis shrimp and the staggered structure in nacre achieve excellent mechanical strength, toughness, and impact resistance. Previous studies have shown that hybrid designs by combining different bioinspired microstructures can lead to enhanced mechanical strength and energy dissipation. Nevertheless, it remains unknown whether combining Bouligand and staggered structures in nanofibrillar cellulose (NFC) films, forming a discontinuous fibrous Bouligand (DFB) architecture, can achieve enhanced impact resistance against projectile penetration. Additionally, the failure mechanisms under such dynamic loading conditions have been minimally understood. In our study, we systematically investigate the dynamic failure mechanisms and quantify the impact resistance of NFC thin films with DFB architecture by leveraging previously developed coarse-grained models and ballistic impact molecular dynamics simulations. We find that when nanofibrils achieve a critical length and form DFB architecture, the impact resistance of NFC films outperforms the counterpart films with continuous fibrils by comparing their specific ballistic limit velocities and penetration energies. We also find that the underlying mechanisms contributing to this improvement include enhanced fibril sliding, intralayer and interlayer crack bridging, and crack twisting in the thickness direction enabled by the DFB architecture. Our results show that by combining Bouligand and staggered structures in NFC films, their potential for protective applications can be further improved. Our findings can provide practical guidelines for the design of protective films made of nanofibrils. [ABSTRACT FROM AUTHOR]

AbstractThere is no native support for the modeling of woven fabric composites within Abaqus. A new approach has been implemented within Abaqus, which is shown to be robust and capable of modeling woven composites across a range of loading conditions. This approach predicted the bending modulus and displacement at failure of woven carbon-fiber composites under three-point bending within the standard deviation of experimental results. Under high-velocity impact loading, the critical perforation velocity of woven aramid panels was predicted to within 3% of the experimental results, while the back face deformation to within the experimental error. [ABSTRACT FROM AUTHOR]

This study investigated the high‐velocity impact behavior of composite plates with different hybrid ratios and structural configurations through experimental and numerical simulation studies. The results showed that the critical penetration velocity of the composite plate generally increases with an increase in the volume fraction of aramid fibers. The high‐velocity impact finite element model developed in this study accurately simulated the high‐velocity impact behavior of laminated fiber composite plates with various hybrid ratios and different structures. The impact failure patterns of the plates were analyzed, and it was observed that the carbon fibers on the back face were prone to tensile fracture, followed by the gradual fracture of aramid fibers. The numerical simulation results show significant differences in residual impact velocity and energy absorption when impacted from different sides and the impact from the aramid side resulted in better energy absorption, which is contrary to the findings in many existing research papers. These findings provide valuable insights into the impact resistance of composite materials and can guide the design and development of high‐performance composite structures for aero‐engine case designing. Highlights: The high‐velocity impact behavior of C/K fiber epoxy resin matrix composite laminates are studied.The critical penetration velocity increases with the increase of aramid fiber volume fraction.The laminate absorbs most of the impact energy during the instantaneous impact time.Energy absorption ability is better when the impact surface is aramid fibers.Carbon fibers on the back side of the laminate are more prone to tensile fracture. [ABSTRACT FROM AUTHOR]

A terminal ballistic analysis of the effects of 7.62 mm X 51 AP P80 rounds on inclined high-strength armor steel plates is the focus of the presented study. The findings of an instrumented ballistic testing combined with 3D advanced numerical simulations performed using the IMPETUS Afea® software yielded the conclusions. The experimental verification proved that slight differences in the pitch-andyaw angles of a projectile upon an impact caused different damage types to the projectile's core. The residual velocities predicted numerically were close to the experimental values and the calculated core deviations were in satisfactory agreement with the experimental results. An extended matrix of the core deviation angles with combinations of pitch-and-yaw upon impact angles was subsequently built on the basis of the numerical study. The presented experimental and numerical investigation examined thoroughly the influence of the initial pitch and yaw angles on the after-perforation projectile's performance. [ABSTRACT FROM AUTHOR]

Towards higher impact velocities, ballistic events are increasingly determined by the material temperatures. Related effects might range from moderate thermal softening to full phase transition. In particular, it is of great interest to quantify the conditions for incipient or full melting of metals during impact interactions, which result in a transition from still strength-affected to hydrodynamic material behavior. In this work, we investigate to which extent the respective melting thresholds are also dependent on the initial, and generally elevated, temperatures of projectiles and targets before impact. This is studied through the application of a model developed recently by the authors to characterize the transition regime between high-velocity and hypervelocity impact, for which the melting thresholds of materials were used as the defining quantities. The obtained results are expected to be of general interest for ballistic application cases where projectiles or targets are preheated. Such conditions might result, for example, from aerodynamic forces acting onto a projectile during atmospheric flight, explosive shapedcharge-jet formation or armor exposure to environmental conditions. The performed analyses also broaden the scientific understanding of the relevance of temperature in penetration events, generally known since the 1960s, but often not considered thoroughly in impact studies. [ABSTRACT FROM AUTHOR]

Aramid fiber/epoxy resin (AF/EP) composite has been heavily used as an impact protection material due to its excellent mechanical properties and lightweight merits. Meanwhile, it is also necessary to concern the flammability of matrix resin and the wick effect of aramid fiber, which would constitute a fire risk in harsh environments. In this work, a multifunctional flame-retardant modifier (EAD) was incorporated into the AF/EP system to improve the flame retardation. The addition of 5 wt% EAD made the AF/EP composite exhibit a high limiting oxygen index (LOI) value of 37.5%, self-extinguishment, as well as decreased total heat release and total smoke release. The results from thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA) demonstrated that the treated composites maintained good thermal stability. Due to the combined action of covalent and noncovalent bonds in the matrix-rich region, the interfacial bonding improved, which endowed AF/EP composite with strengthening and toughening effects. Compared with the control sample AF/EP, the tensile strength and ballistic parameter (V50) of the sample with 5 wt% EAD increased by 17% and 10%, accompanied with ductile failure mode. Furthermore, the flame-retardant mechanism was obtained by analyzing the actions in condensed and gaseous phases. Thanks to good compatibility and interfacial adhesion, the incorporation of EAD solved the inconsistent issue between flame retardancy and mechanical properties, which further expanded the application of AF/EP composite in the protection field.

The aim of this study is to analyze the ballistic impact behavior of a panel made of Twaron CT736 fabric with a 9 mm Full Metal Jacket (FMJ) projectile. Three shots are fired at different velocities at this panel. The ballistic impact test procedure was carried out in accordance with NIJ 010106. The NIJ-010106 standard is a document that specifies the minimum performance requirements that protection systems must meet to ensure performance. The 9 mm FMJ projectile is, according to NIJ 010106, in threat level II, but the impact velocity is in threat level IIIA. Analysis of macro-photographs of the impact of the Twaron CT736 laminated fabric panel with a 9 mm FMJ projectile involves a detailed examination of the images to gather information about the material performance and failure mechanisms at the macro- or even meso-level (fabric/layer, thread). In this paper, we analyze numerically and experimentally a panel consisting of 32 layers, made of a single material, on impact with a 9 mm FMJ projectile. The experimental results show that following impact of the panel with three projectiles, with velocities between 414 m/s and 428 m/s, partial penetration occurs, with a different number of layers destroyed, i.e., 15 layers in the case of the projectile velocity of 414 m/s, 20 layers of material in the case of the panel velocity of 422 m/s and 22 layers destroyed in the case of the projectile velocity of 428 m/s. Validation of the simulated model is achieved by two important criteria: the number of broken layers and the qualitative appearance. Four numerical models were simulated, of which three models validated the impact results of the three projectiles that impacted the panel. Partial penetration occurs in all four models, breaking the panel in the impact area, with only one exception, i.e., the number of layers destroyed, in which case the simulation did not validate the validation criterion. The performance of Twaron CT736 fabric is also given by the indentation depth values by two methods: according to NIJ 0101.06 and by 3D scanning. The NIJ 010106 standard specifies that a panel provides protection when the indentation depth values are less than 0.44 mm.

In order to investigate the influence of the backspace on the ballistic performance of the bullet-proof fabric, Twaron® ballistic impact models with different backspaces were established by using the finite element method, and the models were verified. The deformation degree and strain energy absorption of clay for different models were analyzed and compared, and the evolutions of strain energy absorption of fabric layers were analyzed to explore the mechanism. The finite element results show that the clay with the largest backspace has the least deformation and the least energy absorption, while the fabric has the most energy absorption. It is found that the bullet-proof fabric with a backspace has the better performance. In the range of 0-8 mm, the larger the backspace, the better the bullet-proof performance. That is attributed to the fact that the fabric with the backspace has less reaction force and smaller fabric tension, thus it is not easier to be damaged. [ABSTRACT FROM AUTHOR]

To increase safety and enhance the armor plate's ballistic performance, an advanced hybrid ceramic composite plate design is being investigated. The ballistic limits and safety levels were significantly improved by the hybridization of ceramic materials. In this present study, three different types of ceramic plates were modeled using the finite element (FE) software with a subroutine to define user material model (VUMAT) code and determine the ballistic behavior of the body armors for défense industries. The significant improvement of the ballistic limit velocities of the B8K8 panel and SB2K2 panel are investigated that the 416 m/s and 606 m/s, respectively. [ABSTRACT FROM AUTHOR]

This research investigated the ballistic response of homogenous and hybrid multi-ply fabrics toward developing a full-scale hybridized soft armor system. Fabrics with varying yarn and thread counts were manufactured from para-aramid and ultra-high molecular weight polyethylene yarns through a plain-woven architecture. Homogeneous fabrics used the same yarn and thread count for two- and three-ply systems. For hybrid systems, two- and three-ply stacks were assembled in various sequences including increasing and decreasing cover factor (Cfab) and varying yarn types as the strike face and rear face. Ballistic impact testing was performed on all fabrics at low (340 m s−1) and high velocity (620 m s−1). Observations and measurements were performed to determine failure mechanisms, energy absorption, transverse wave propagation, and system effects of multi-ply systems. Hybrid systems showed significant differences in specific energy absorbed (SEA), dependent on the layer order. The para-aramid hybrid systems impacted at 340 m·s−1 showed a significantly greater SEA when the fabrics were ordered with an increasing rather than a decreasing cover factor. At 620 m·s−1 the difference in SEA was less pronounced or absent entirely. It was concluded that hybridization would enhance the performance of a soft armor system and was likely to be most effective for the rear layers of the system where fabrics with a progressively increasing cover factor that were manufactured of fine (550 dTex) para-aramid yarns would offer an advantage. The front layers of the system, subjected to higher strain loading, would benefit from low cover factor fabrics (0.76), which maximize the dissipation of strain from the point of impact. [ABSTRACT FROM AUTHOR]

The importance of inter-yarn friction to ballistic fabric has been widely investigated. However, the couple effects of inter-yarn friction, fabric structure and number of layers have not been explored. Therefore, this paper put forward to investigate the ballistic performance of multi-layer fabric panels with different weave structure and inter-yarn friction. Three different structures (plain, sateen and UD-like), various number of layer (1-layer, 4-layer, 8-layer and 12-layer) and three levels of coefficients of friction were considered and their effects on the ballistic performance will be discussed through finite element (FE) method. The impact velocity is set as 475 m/s and the projectile is a 1 g steel flat cylinder with both the diameter and height of 5.5 mm. It has been found that the sateen fabric structure with 12-layer and higher coefficients of friction firstly reduces the projectile velocity to zero, while the corresponding plain structure and the UD-like structure reduce the projectile velocity to 125 m/s and 200 m/s individually, which indicates that when the number of layer and coefficients of friction are both much larger, the sateen fabric shows the best ballistic performance among the three structures. The reasons behind are as following. As far as the structure concerned, sateen structure has more interlacements than UD-like fabric and more straight sections than plain fabric. In addition, at higher coefficients of friction, this structure enables higher stress distribute in more layers and in larger areas than plain fabric and UD-like fabric and give rise to a layer-by-layer fracture but not fracture simultaneously. [ABSTRACT FROM AUTHOR]

This study investigates the ballistic performance of a ceramic composite target plate consisting of Alumina with the Dyneema fiber. The objective is to achieve a lightweight structure. Different thickness combinations of alumina/Dyneema targets were studied based on the areal density of the targets. Energy absorption criteria were used to determine the ballistic performance of the target. The ANSYS/LS-DYNA® code was used to conduct the finite-element numerical simulations. 12.7 mm projectile core and 7.62 mm projectile core was used to normally impact the target plate. The projectile impact velocities were in the range–500–887 m/s. First, the model is verified by comparing it with existing experimental studies. Subsequently, various thickness combinations of alumina with different numbers of layers of Dyneema were studied numerically to determine the effective thickness combination of the entire target. The initial kinetic energy of the target dissipated into the ceramic fracture, and the remaining energy in the deformation of the composite plate. Projectile erosion and the target's energy absorption are the determining factors of the study. [ABSTRACT FROM AUTHOR]