Lightweight Armor Research Articles

Review of the penetration resistance performance of lightweight ceramic composite armor under high-speed impact

Due 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.

Simulation of the Performance of Kevlar Impregnated Shear Thickening Fluid Ballistic Test Results (STF) Ballistic Test Results

This study explores the enhancement of Kevlar fabric’s ballistic performance through impregnation with Shear Thickening Fluid (STF) for potential application in soft body armor. The experimental approach often fails to elucidate mechanical phenomena critical for the development of lightweight and high-strength body armor designs. To address this limitation, the finite element method, specifically using ANSYS/LS-DYNA R.13, was employed for a comprehensive analysis. The simulation aimed to evaluate the impact of STF on Kevlar fabric by assessing projectile velocity, force exerted by the projectile onto the fabric, displacement, stress distribution, and fabric failure mechanisms. Kevlar yarn was modeled as a shell element formed into fabric with a sine wave profile, investigating two types of STF: SiO2-PEG200 (S0) and SiO2-PEG200-B4C (S1), differing in maximum viscosities. The addition of STF resulted in increased coefficients of friction on Kevlar, with the highest values observed for the SiO2-PEG200-B4C impregnated fabric ( =0.87 and =0.82). The incorporation of the second STF type (S1) significantly reduced the projectile’s velocity from an initial 200 m/s to 153.2 m/s upon impact. Additionally, the force on the S1 fabric surged to 121,556 N, a threefold increase compared to neat Kevlar. STF's influence was further evidenced by enhanced fabric displacement and more uniform stress distribution upon ballistic impact. The fabric's thickening upon failure indicated STF's ability to enlarge the deformation area, facilitating uniform distribution of ballistic kinetic energy across the impact zone. Notably, the fabric impregnated with the second type of STF, featuring boron carbide (S1), demonstrated superior ballistic performance. This study concludes that STF-impregnated Kevlar fabric, particularly the SiO2-PEG200-B4C variant, not only surpasses the ballistic performance of neat Kevlar but also meets the criteria for NIJ Level IIIA standards, highlighting its potential as a highly effective material for advanced soft body armor designs.

A design model of multi-layer modified aramid fabrics against fragment simulating projectiles and full metal jacketed bullets

Soft body armor is required to meet threats of both bullets and explosion fragments in battlefield. However, designing body armor that can protect against these two types of projectiles considering both critical velocity and back face deformation (BFD) is often based on experience and extensive ballistic experiments. This paper proposes a quick design model for determining the layers of aramid fabrics modified by polyethylene (PE) to protect against fragment simulating projectiles (FSP) and full metal jacketed bullets (FMJ). Firstly, ballistic experiments are conducted discovering the optimal concentration of PE modification against the sphere and FSP is 10 %. Secondly, finite element model is adapted to explore the protection capabilities of modified aramid fabrics against FSP and FMJ and a linear relationship between the BFD and the critical velocity has been observed. Thirdly, an analytical model is established to uncover the reason of this relationship. Finally, a design model is proposed to configure the improved outer tactical vest (IOTV) generation III based on the derived formulae of critical velocity and BFD for different layers of modified aramid fabrics against FSP and FMJ. The model indicates that the objectives of intercepting FSP or FMJ and reducing blunt trauma are usually not simultaneously attainable. 38 layers of modified aramid fabrics are sufficient to meet the protection requirements for both FSP and FMJ, regardless of critical velocity and BFD. Besides, 498 m/s is the threshold of FMJ impact velocity to determine the priority of intercepting bullets or reducing blunt trauma. The design model can serve for the development of lightweight and effective body armor.

DETERMINATION OF PROSPECTIVE DIRECTIONS FOR THE IMPROVEMENT OF MATERIALS FOR INDIVIDUAL ARMOR PROTECTION

An analysis of world experience in the direction of modern developments of high-strength aluminosilicate glass-crystalline materials, in particular, in the creation of lightweight armor, was carried out. The trends and current state of the glass-ceramics market from 2019 to 2023 have been determined, and an increase in demand for glass-crystalline materials for technical purposes has been established. It was determined that the orientation of the global glass-ceramic market towards fragmentation will allow domestic manufacturers to reduce import dependence and increase the competitiveness of domestic glass-ceramic materials on the world market. The prospect of using high-strength aluminosilicate glass-crystalline materials as a basis for the production of armor protection elements has been established. The criteria for the synthesis of high-strength armored steels have been selected. The choice of oxide systems for the production of protective glass-crystalline materials is substantiated, model glasses are synthesized and the technological parameters of production of impact-resistant sitals, which include cooking, forming, annealing and heat treatment, are determined. Model glasses were synthesized and their structure under thermal treatment conditions was investigated in relation to the physical and chemical properties of the materials based on them. It was established that the developed glass-crystalline materials based on lithium disilicate are characterized by high operational properties and can be used in the creation of modern armor. It was established that the developed high-strength spodumene glass-crystalline materials under the conditions of low-temperature two-stage heat treatment are characterized by high operational properties and can be used as a basis for the development of a composite element of individual armor protection. A comparative assessment of the operational properties and technical and economic indicators of known ceramic and glass-ceramic materials for armor protection made it possible to establish the competitiveness of the developed domestic spodumene-containing materials as elements of individual protection.

The Influences of Nb Microalloying and Grain Refinement Thermal Cycling on Microstructure and Tribological Properties of Armox 500T

This study aims to investigate the combined effect of niobium (Nb) microalloying and austenite grain refinement, using a specific heat treatment cycle, on the microstructure and tribological properties of Armox 500T steel. In this work, Nb addition and thermal cycling were utilized for grain refinement and enhancement of the mechanical properties of Armox 500T alloy, to provide improved protection via lightweight armor steel components with a high strength-to-weight ratio. The kinetics of transformation of the developed Armox alloys were studied using JMATPro version 13.2. The samples were subjected to two austenitizing temperatures, 1000 °C and 1100 °C, followed by 4 min of holding time and three consecutive thermal and rapid-quenching processes from 900 °C to room temperature. Scanning electron microscopy with energy dispersive X-ray analysis (SEM-EDX) was employed to analyze the microstructure, which primarily consists of four types of martensite: short and long lath martensite, blocky martensite, and equiaxed martensite. Additionally, a small percentage (not exceeding 3%) of carbide precipitates was observed. The wear characteristics of the investigated alloys were evaluated using a pin-on-disc tribometer. The results demonstrate that alloying with Nb and grain refinement using a thermal cycle significantly reduce the wear rate.

Investigations on compression behavior of fused filament fabricated hybrid biomimetic structures

The objective of this study is to design a biomimetic hybrid structure inspired by nacre, and conch shells and compare how the compressive characteristics change when key geometric design parameters are varied. Nacre, also known as mother of pearl, has a host of traits, suitable for survival, like its stiffness and strength. Conch, which is a common name for a number of sea snails, possesses a unique cross-lamellar structure which has a tough outer layer to resist penetration from the sharp-toothed attacks of predators, and a nacreous inner layer which can dissipate energy. A novel nacre–conch–nacre inspired sandwich core structure is designed and fabricated with fuse filament fabrication using acrylonitrile styrene acrylate filament according to the ASTM C365 standard for the flatwise compression test of sandwich core structures. Three key design parameters, namely the wall thickness, the thickness between two nacre walls, and the angle of conch were selected and varied to form nine different iterations of this design. An Abaqus finite element analysis was validated by experimental testing using an Instron 8801 servo-hydraulic universal testing machine. The results showed that conch-inspired structures’ compression properties depend on wall thickness and angle. The sample with 2 mm wall thickness and 45° conch angle had the highest compressive strength of 3.62 MPa, while the sample with 1 mm wall thickness and 50° conch angle had the lowest at 2.09 MPa. These findings suggest this structure could be used in lightweight armor, car, and aerospace parts.

A comparative study on dynamic deformation and ballistic impact response of Ti–4Al–2.5V–1.5Fe–0.25O and Ti–6Al–4V alloys

Titanium alloys are most suitable for lightweight armour applications due to their superior strength to weight ratio, and α+β Ti alloy Ti–6Al–4V is widely used in armour applications. One of the critical factors limiting the widespread use of Ti alloys in armour application is their high cost. Recently, Allegheny Technologies Incorporated introduced ATI-425® Ti alloy with the chemical composition of Ti–4Al-2.5V-1.5Fe-0.25O as a low-cost alternative to Ti–6Al–4V. Though ATI-425 Ti alloy is primarily intended for armour applications, only limited ballistic results are available in the open literature. In the present work, we compare the quasi-static, dynamic deformation, ballistic impact response and post-deformation microstructure of a low-cost α+β Ti alloy ATI-425 with that of Ti–6Al–4V alloy. Analysis of the results showed that both alloys showed similar yield strength values during quasi-static tension and compression tests, while ATI-425 Ti alloy showed higher tensile ductility, Charpy-V notch impact energy and dynamic flow stress than Ti-6Al-4V. The ATI-425 Ti alloy also exhibited slightly better ballistic performance measured in terms of V50 ballistic limit velocity. Detailed microstructural analysis on quasi-static and dynamic compression-tested samples showed mainly {101–2} tensile twins, whereas {101–2} and {112–1} tensile twins are observed in ballistic-tested samples of both the alloys. Activation of deformation twinning in ATI-425 Ti alloy with higher oxygen is attributed to lower Al content which enhances the twinning activity. Adiabatic shear band (ASB)-induced plugging mechanism is ascertained as the perforation mode in both alloys during the ballistic impact. Analysis of propensity to ASB formation indicated that Ti-6Al-4V has a slightly better resistance to ASB formation than ATI-425 Ti alloy. The improved ballistic performance of ATI-425 Ti alloy in comparison to Ti-6Al-4V is attributed to the higher dynamic flow stress, Charpy-V notch impact energy absorption, and moderate resistance to adiabatic shear band formation.

Ballistic response and failure mechanisms of gradient structured Mg alloy

Due to their low density, high specific damping capacity and high shock absorbency, magnesium (Mg) alloys have great potential for development as high-performance lightweight armor materials in industrial applications. However, their applications are still limited owing to low strength, ductility and formability. Gradient structure design has been shown to be a good method for improving the mechanical properties and ballistic resistance of Mg alloy plate. This work aims to thoroughly reveal the root causes of ballistic performance enhancement of gradient structured (GS) Mg alloy armor material through ballistic tests and finite element simulations. Compared with homogeneous Mg alloy plate of the same dimensions, the impact energy absorption of GS plate is increased by about 40%. The enhanced strength and plasticity from the gradient structure design certainly contribute in part to the ballistic resistance. More importantly, the gradient structure results in a transition of failure modes from the typical petal-shaped dehiscence to delamination and shear fracture. Based on detailed finite element analysis, we deeply understand the deformation process and the effect of the gradient structure on the propagation of stress wave during ballistic impacting. The energy absorption by each defeat mechanism is also theoretically calculated to quantitatively interpret their intrinsic effects. Meanwhile, microstructural observations and fracture morphology have demonstrated the appearance of adiabatic shear bands along the boundary of the cylindrical plunger after ballistic perforation of GS plate. Therefore, the failure mode transition caused by gradient structure design must also play a major role in improving the ballistic resistance.

Effect of Z-binding depths on the ballistic performance of 3D woven through-the-thickness angle-interlock fabrics in a multiply system

Lightweight armor with excellent protection against ballistic impacts are pursued by researchers worldwide. This paper systematically investigates the effect of the Z-binding depths on the ballistic performance and failure mechanisms of para-aramid 3D fabrics. Two types of 3D woven through-the-thickness angle-interlock fabrics were designed and fabricated in comparison to the 2D plain weave fabric. The ballistic tests and finite element simulation analyses were carried out based on a similar areal density of 5.2 kg/m2 by layering up the fabrics. According to the experimental results, the variability and cumulative probability of penetration of the 20-P are higher than that of the 3D fabric systems, resulting in a 2.5% higher ballistic limit V50 of 8-5 TA than 20-P. Fabric plies failed abruptly in the 2D system, while the 3D system showed a progressive failure mode. The Z-warps, configure through the thickness of the fabric, result in the projectile tumbling and deviating from its original direction. A larger binding depth can help to prolong the defending process, which will mobilize more yarns to resist the projectile impact. The back-face deformation is well constrained by the 3D fabrics. Due to the fact that the designed 3D woven fabrics are more moldable than the plain weave, it could be potential candidates for the engineering design of female bullet-proof vest interlining.

Ballistic performance of optimised light weight composite armour

This research paper presents a comprehensive investigation into the response of a 3D finite element model when subjected to 7.62 AP projectiles. The study utilises Hetherington's armour composite equation and incorporates the Johnson-Holmquist material model to analyse the strength and failure criteria of the ceramic and Kevlar/epoxy components, respectively. The results highlight the remarkable resilience of the composite armour, demonstrating its ability to withstand projectile velocities up to 1500 m/s. However, as the ballistic velocity limit increases, the armour experiences significant damage, including projectile erosion and panel delamination. Through numerical simulations and advanced modelling techniques, the paper thoroughly explores the failure modes and energy absorption characteristics of composite armour systems under projectile impact. It investigates key parameters such as velocity, acceleration, kinetic energy, internal energy, pressure distribution, displacement, and damage progression. The analysis reveals a progressive decrease in kinetic energy as the projectile interacts with the armour, underscoring the crucial role of energy absorption in preventing projectile penetration. Moreover, the impact velocity influences the distribution of internal energy within the composite armour, with higher velocities leading to greater energy absorption up to a threshold limit. The study also determines the ballistic limit velocity (V50) using the velocity history approach and validates the findings with existing literature. Overall, the research provides valuable insights into the limitations of composite armour and offers important recommendations for designing and improving materials to achieve superior ballistic protection. It emphasises the significance of reaching the maximum ballistic limit while maintaining a lightweight armour structure by optimising the total armour thickness. This study contributes to the advancement of armour technology and enhances our understanding of the behaviour of composite materials under high-velocity impacts. It offers valuable guidance for the development of more robust armour systems suitable for various defence and protection applications.

Ballistic performance of functionally graded B4C/Al composites without abrupt interfaces: experiments and simulations

Functionally graded materials (FGMs) are promising protective structures for lightweight armor plates because of their features and designability. However, traditional discretely layered FGMs with macroscopic interfaces can generate unfavorable interlaminar stresses under ballistic attacks, eventually leading to delamination or interlayer tearing. Herein, we constructed new B4C/2024Al FGMs without sharp interfaces between layers. The FGM armor systems with varying through-the-thickness distributions were tested against 7.62 mm armor-piercing incendiary projectiles. The effects of compositional gradient exponent on the damage characteristics, stress distribution and energy evolution were numerically and experimentally investigated. The results indicated that the smooth transition within through-the-thickness microstructures effectively avoided the occurrence of interlayer delamination or tearing. The compositional gradient exponent played an essential role in the impact response of the FGM targets. The FGM having a linear composition gradient outperformed other nonlinear types with respect to energy absorption and ballistic properties due to the reduced tensile wave strength and prolonged projectile-target interaction time. Furthermore, the structural optimization problem with the objective of maximizing ballistic efficiency was solved using the conjugate gradient method, and the optimal design of the FGM targets was achieved. The current research provides a promising design guideline for developing and optimizing new advanced lightweight composite armor.

Experimental and simulation investigations on perforation of titanium alloy plates against armor-piercing projectile at oblique impacts

Titanium alloy is an advanced lightweight armor material, widely used in armored vehicles. Experimental and simulation investigations on perforation of titanium alloy plates impacted by armor-piercing projectiles were performed in this study. The critical ricochet angle and failure morphology of 6 mm, 8 mm, 10 mm and 12 mm titanium alloy plates subjected to projectiles were obtained. Simultaneously, Numerical simulations of the oblique perforation of titanium alloy plates were then performed on the high-performance computer using the explicit finite element code LS-DYNA, and the validity of the numerical model was verified by comparing with the experimental results. Furthermore, typical process of projectile oblique penetration into titanium alloy target plate was analyzed and the influence of factors such as inclination angle and thickness on the ballistic performance of titanium alloy plates were discussed. It is found that the residual velocity of the projectiles decreases with the increase of inclination angle of target, indicating that increasing the inclination angle of the target plate can significantly reduce the perforation performance of armor-piercing projectile. In addition, the critical ricochet angle of titanium alloy plate is sensitive to its thickness, and larger thickness can reduce the critical ricochet angle of the titanium alloy plate.

Institutional and technical history of requirements‐based strategic armor ceramics basic research leading up to the multiscale material by design materials in extreme dynamic environments (MEDE) program. Part II: Dynamic effects on the physics and mechanisms of advanced ceramics such as boron carbide

AbstractThis paper follows a historical background on requirements‐based strategic armor research, leading to the materials in extreme dynamic environments program presented in Part I, now focusing on the developed technical aspects and state‐of‐the‐art. It starts with some background on dynamic testing techniques and a structural ceramics review. Then, selected armor ceramics research results and relevant single‐grain anisotropic crystal physics, microstructure, and defect mechanics mechanisms: Including pivotal armor ceramics research results prior to the adoption of the strategic research objective (SRO). Next, multiscale characteristics, crystal physics, planar features, anisotropy, and relevant mechanisms will be described. The historic progression/evolution of multiscale lightweight armor ceramics research results will be summarized, including multiscale dynamic deformation and damage characteristics. The focus of the following sections will be on the role of defects, quasi‐plasticity, and anisotropic crystal physics properties, including preexisting single grain synthesis and process‐induced planar features (aka twins) and planar deformation features (PDF); for example, nano‐amorphization in boron carbide. A new model for boron carbide processing planar features will be discussed. A schematic diagram illustrating the hypothetical formation of PDFs in a dynamic event is also presented. An expended canonical equation is introduced, suggesting possible strategies for boron carbide research using the canonical figures of merit approach. Finally, we highlight the efficacy of the materials by design process and approach in a multiscale framework for the simultaneous experimental and theoretical research trajectories guided by the accepted canonical equation.

Improved ballistic performance of a continuous-gradient B4C/Al composite inspired by nacre

Functionally gradient materials (FGMs) primarily composed of a discretely layered structure with relatively sharp macroscopic interfaces are highly susceptible to interlayer failure under impact loading. Nacre is regarded as a model system for lightweight armor with high impact-resistant performance owing to its multiple length-scale and gradient structures. However, the simultaneous translation of both structural features into artificial assemblies remains challenging. Herein, we constructed new B4C/2024Al FGMs with eliminated sharp interfaces, which reproduced the hierarchical and gradient architectures of nacre. A combined experimental and numerical approach was employed to investigate the protective mechanisms of nacre-like FGMs subjected to 7.62 mm armor-piercing incendiary bullet, and two homogeneous composites were also tested under the same conditions for comparison purposes. The FGMs exhibited improved performance to resist ballistic attacks and maintain integrity compared with the uniform structures. As the ceramic contents decreased along the thickness, the energy dissipation mechanisms transitioned from eroding projectile to plastic deformation. The toughness gradient and varying energy dissipation modes prevented the formation of crushed cones at the ceramic-rich layers. The nacre-like structure created several extrinsic toughening mechanisms, which led to the increased energy-absorbing capability of the target. Meanwhile, the eliminated abrupt interfaces avoided the occurrence of interlayer tearing by diminishing the tensile wave strength and the sudden change of wave impedance, which prolonged the projectile-target interaction period and strengthened the eroding effect on the projectile. The present study opens new opportunities to design advanced lightweight FGMs armors with high impact-resistant protective performance.

Diamond-TiC composite with an ultrahigh Hugoniot elastic limit

The Hugoniot elastic limit (HEL) is widely adopted as an important criterion for assessing the dynamic strength of materials, representing the transition stress from elastic to plastic response prior to failure under shock compression. Nano-polycrystalline diamond currently holds the highest HEL of 208 (±14) GPa. Here, we report a diamond-TiC composite (∼11.5 wt. % TiC) showing an ultrahigh HEL of at least 195 (±3.5) GPa, which is comparable to that of nano-polycrystalline diamond. All measured velocity profiles on the diamond-TiC free surface exhibited a single-wave structure at shock pressures of 48–195 GPa. Moreover, the measured Us–Up (shock wave velocity–particle velocity) relation can be linearly fitted, indicating no elastic–plastic transition or solid–solid phase transition up to a shock pressure of 195 GPa. The diamond-TiC composite's compression ratio was similar to that of TiC but significantly higher than that of diamond. These extraordinary dynamic responses are intrinsically attributed to the unique microstructure in which diamond polycrystals are encased in a TiC matrix, providing protection against yielding. Our findings not only developed a mechanically reliable, lightweight, and high-performance armor material at low synthesis costs, but also provided new insights into the shock compression behavior of diamond composites.

Investigation of Impact Performance of STF Impragnated Composites

It is important to achieve high strength, high modulus of elasticity, good energy damping for lightweight armor materials. For this purpose, two or more similar or different materials are combined at the macro level. In this way, a new structure emerges that we call composite material. A composite is a new structure in which the good properties of the components in its structure become evident in the material. Research on the production and mechanical properties of composites that meet the needs of the developing technology continues. Military personnel, armored vehicles and many security elements are tested in the field with a lot of threats (such as mines, armor piercing ammunition, explosives etc.). Therefore, the armor used by security elements should be strengthened without compromising features such as lightness, cost and long-term use. This study covers the development of Kevlar's ballistic properties by impregnating Shear Thickening Fluid (STF). STF is composed of silica (AEROSIL 200) and polyethylene glycol (PEG 400). STF-impregnated Kevlar fibers have been subjected to impact testing at low and high speeds. Low-speed tests were carried out with a drop tower. High-speed tests were carried out according to NIJ 0101.06 Level II standards. The mass fraction of silica in the STF was determined as the research parameter. The change in the behavior of the materials with the change of silica ratio was investigated; Although improvements were observed in energy dissipation in low-speed impacts, it was noted that ballistic behavior improved up to a certain point, and then the improvement in behavior decreased.

Dynamic response of the TiB2–SiC/B4C composite ceramic under dynamic loading

AbstractTiB2–SiC/B4C composite ceramics have application as lightweight armor ceramic material, and therefore, it is particularly important to research their dynamic mechanical properties and fracture behavior under high strain rates. In the present research, the dynamic compression strength and Hugoniot elastic limit (HEL) of these composite ceramics were determined by split Hopkinson pressure bar technology and plate impact equipment, respectively. The experimental investigation results illustrated that the composite ceramic exhibited outstanding dynamic compression strength (2750 MPa) and displayed a remarkable strain‐rate strengthening effect. The HEL was calculated as 18.49 GPa, and the commonly used P–μ form of the Hugoniot curve was derived from the calculated data of the shock velocity and particle velocity. The dynamic fracture morphologies of the TiB2–SiC/B4C composite ceramic and monolithic B4C ceramic (correlation data) at macro and micro scales were observed and analyzed in detail. The dynamic fracture mechanisms were summarized in‐depth into the following three points. First, the strengthening mechanism offered by the in situ second phases could significantly improve the comprehensive property. Second, the mixed‐inter/transgranular fracture mode was conducive to energy absorption. Third, the anchoring effect and thermal expansion coefficient mismatch contributed to the energy dissipation and fracture toughness improvement. This work provides the foundation for the application and development of lightweight armor ceramic materials.

Optimization of sandwiched armour plate using energy conversion principle via dynamic analysis

Defence can play a paramount role in military organization thus designing light weight armour capable of protecting target from lethal damage is important. While the traditional armour plated use high hardness steel but in recent development of advanced ceramics with low density and high strength properties have opened new door of possibilities in the field. The presented paper bring outs a study regarding protection efficiency of superposed sandwiched panel with metal matrix interface and honeycomb structures against ballistic impacts is performed. The authors have developed a composite armour plate with non-ricochet properties capable of taking resisting multiple projectiles, using ceramics Honey-comb structure tile glued together encased within metal matrix. Paper discusses experimental data, geometry of the experimental setup, modelling (meshing and initial conditions). Numerical analysis has been done on different metals, ceramics and polymers and the best among them are selected. The stacking sequence of the selected materials is developed using crashworthy design concepts. Design parameters for optimized sandwiched panel are provided and superposed sandwiched panel responses with metal matrix interface and honeycomb structures are assessed.

Ballistic performance and protection mechanism of aramid fabric modified with polyethylene and graphene

Aramid fabric has been widely used as a bulletproof material due to its lightness and comfort. However, multiple fabric layers must be used in one body armour, inevitably reducing its flexibility. To improve the ballistic performance of single-layer aramid fabric, we innovatively modify the fabric with polyethylene (LDPE) and graphene/polyethylene (GR/LDPE). Based on mechanical property tests, ballistic impact test and finite element analysis (FEA), the ballistic behaviours and key mechanism of modified fabrics are revealed. Experimental results show that LDPE or GR/LDPE modification does not change the tensile strength and Young's modulus much, but it greatly improves the interyarn friction of fabric. This improvement in the interyarn friction leads to twice ballistic limit velocities of pure aramid fabric; the ballistic limit velocities of pure, LDPE and GR/LDPE aramid fabrics are 105 m/s, 223 m/s and 216 m/s, respectively. However, excessive friction causes negative effects, which is why GR/LDPE/aramid fabric is weaker than LDPE/aramid fabric. The FEA results show that fabric motion and deformation are the main ways to resist impact as they absorb over 85% of the dissipated kinetic energy of the projectile. The novel modification method could be applied to the manufacturing of lightweight and effective body armour.

Lightweight but strong wood armor can fend off bullets

Lightweight but strong wood armor can fend off bullets