The influence of carbon nanotubes on quasi-static puncture resistance and yarn pull-out behavior of shear-thickening fluids (STFs) impregnated woven fabrics

This study focuses on the puncture resistance performance of woven high modulus polypropylene (HMPP) fabric impregnated with shear-thickening fluids (STFs) composed of fumed silica nanoparticles suspended in polyethylene glycol (PEG) and those containing carbon nanotubes (CNTs). The shear-thickening characteristics and rheological features of suspensions were determined at steady and oscillatory shear stress using a stress controlled rheometer. The puncture resistance performance of STF-treated HMPP fabrics were evaluated by the quasi-static puncture test. To gain a better understanding of the effect of these two suspensions on puncture resistance mechanism of fabric, yarn pull-out test was conducted to examine internal shear strength and inter yarn frictional behavior of fabric. The results showed that both the STF-treated fabrics exhibited significant enhancement in puncture resistance performance as compared to neat fabric. However, the fabric impregnated with the suspension containing CNTs showed lower enhancement, due to its lower degree of shear-thickening as confirmed by rheological measurement. The possible improving mechanisms responsible for puncture resistance performance of STF-treated fabrics were also discussed.     

Numerical and experimental investigations into ballistic performance of hybrid fabric panels

Strong, low density fibres have been favoured materials for ballistic protection, but the choice of fibres is limited for making body armour that is both protective and lightweight. In addition to developments of improved fibres, alternative approaches are required for creating more protective and lighter body armour. This paper reports on a study on hybrid fabric panels for ballistic protection. The Finite Element (FE) method was used to predict the response of different layers of fabric in a twelve-layer fabric model upon impact. It was found that the front layers of fabric are more likely to be broken in shear, and the rear layers of fabric tend to fail in tension. This suggested that using shear resistant materials for the front layer and tensile resistant materials for the rear layer may improve the ballistic performance of fabric panels. Two types of structure, ultra-high-molecular-weight polyethylene (UHMWPE) woven and unidirectional (UD) materials, were analyzed for their failure mode and response upon ballistic impact by using both FE and experimental methods. It was found that woven structures exhibit better shear resistance and UD structures gives better tensile resistance and wider transverse deflection upon ballistic impact. Two types of hybrid ballistic panels were designed from the fabrics. The experimental results showed that placing woven fabrics close to the impact face and UD material as the rear layers led to better ballistic performance than the panel constructed in the reverse sequence. It has also been found that the optimum ratio of woven to UD materials in the hybrid ballistic panel was 1:3. The improvement in ballistic protection of the hybrid fabric panels allows less material to be used, leading to lighter weight body armour.     

仿生柔性防护装具的设计及防弹性能测试

依据仿生学原理,借鉴硬骨鱼鳞的微观结构及叠加模式,设计并制备了6套仿生柔性防护装具。使用了两种复合鳞片,分别为SiC陶瓷-超高分子量聚乙烯(UHMWPE)复合防护鳞片和Al₂O₃陶瓷-UHMWPE复合防护鳞片。对柔性防护装具进行侵彻测试,分析了复合鳞片类型、覆盖角度和子弹侵彻位置对柔性鳞片防护装具防弹性能的影响。结果表明,新型柔性鳞片状防护装具均能成功抵挡速度为(445±10) m/s的手枪弹(铅芯)侵彻,垫层材料的凹陷深度为5~20 mm。SiC-UHMWPE复合鳞片防护装具的防弹性能显著优于Al₂O₃-UHMWPE复合鳞片防护装具。此外,柔性防护装具的防弹性能均随着鳞片覆盖率的增加而提高。本研究成果为新型柔性防护装具的设计提供理论依据和科学指导。      

Influences of weaving architectures on the impact resistance of multi-layer fabrics

Fabrics constructed from different weaving architectures such as plain, basket, twill and satin provide varying flexibility and durability when applied on surfaces of complex structures for protective applications. They also affect the manufacturing processes and mechanical properties of both fabrics and composite structures in various applications such as soft armours, helmets, aircraft engine cowlings or automobile monocoques. In this work, the influences of weaving architectures on the ballistic resistance and energy absorption of both single and multi-layer Twaron® fabrics are investigated. A mesoscale yarn model is constructed, validated experimentally, and analytical. Finite element fabric models of different fabric structures are then developed and their firmness is quantified using interlacing factors. Numerical models for plain weave are validated against experimental results from single-ply ballistic tests. The evolutions of kinetic, strain, and friction energy components, normalised with areal mass, are presented to demonstrate the better ballistic protection of the plain weave compared with other weaving architectures. Further investigations on multi-ply systems illustrate the energy absorption capacities for different types of woven fabrics and the associated ballistic resistances. The research results indicate that weaving architectures and fabric firmness are less influential on the overall ballistic protection of multi-ply systems compared to the single-ply cases.     

有机包覆改性SiC粉体表面结构与性质的表征

本研究中的有机包覆改性SiC微粉通过硅烷偶联剂处理以及有机单体在其表面上的接枝聚合而获得。通过X-射线衍射分析改性前后粉体的主要物相成分;以粉体悬浮液离心清液的离子电导率和粉体胶粒的Zeta电位曲线来表征粉体表面的吸附离子浓度及表面电性;通过TEM、FTIR等测试手段表征粉体有机包覆层的形貌和化学组成结构。研究表明:以提高SiC粉体水基分散固含量为目的的有机包覆改性工艺在未改变粉体基本成分的基础上,有效降低了粉体表面吸附离子的浓度,提高了表面电荷;其完整的表面有机包覆层体现包覆物质的结构和性质,有效地掩蔽了SiC粉体原有的表面,使有机包覆改性成为SiC粉体水基分散性能提高的有效方法。     

基于犰狳外壳仿生的SiC-超高分子量聚乙烯柔性防护板的试验测试和有限元模拟

个体防护装甲的发展对提高单兵作战能力具有重要意义,基于仿生研究可以为设计高性能装甲提供新的思路。犰狳外壳由六边形鳞片紧密拼接而成,采用分层结构设计,具有很好的柔性和防护能力。本文借鉴犰狳外壳的几何排列模式,采用SiC陶瓷片模仿硬质壳层,超高分子量聚乙烯(UHMWPE)热压板模仿软质壳层,按1∶1厚度比例设计制备仿生复合鳞片,将仿生鳞片紧密排列后封装制成一种新型柔性复合防弹插板。为了验证该种防弹插板的防弹性能并研究其破坏特征,进行弹道极限V0试验测试,结合有限元模拟分析其抗7.62 mm手枪弹侵彻的能力。结果表明:该柔性防弹插板不仅满足防弹性能要求,且具备较好的柔性,可为今后新型防弹插板的设计和优化提供参考。      

Finite Element Study on the Influence of Structural Parameters on the Ballistic Performance of 3D Networked Fabrics

Networked fabrics are a type of three-dimensional multilayer fabrics having predetermined interconnections between layers by combining yarns from two adjacent sublayers into one. This paper reports the research on the influence of structural parameters on the ballistic performance of networked fabrics using finite element analysis in parallel with experiment. The widths of separate and combined sections are found to affect the energy absorption (EA) of regular networked fabrics against high-velocity impact. Separate sections of networked fabrics generally outperform combined sections. The optimal width of the separate section is around 9.5 cm for both dense and loose networked fabrics when impacted at the separate section. The optimal width of combined section decreases from 2.38 cm to 1.15 cm with the decrease of weave density in this area. For the studied structural parameters, highest EAs of dense and loose networked fabrics are around 13.3% and 17.1% higher than those of their counterpart layups of dense and loose plain-woven fabrics, respectively. These findings suggest networked fabrics could be engineered to improve the ballistic performance of flexible fabrics.     

A numerical investigation into the influence of fabric construction on ballistic performance

The use of high-performance fibres has made it possible to produce lightweight and strong personal body armour. Parallel to the creation and use of new fibres, fabric construction also plays an essential role for performance improvement. In this research, finite element (FE) models were built up and used to predict the response of woven fabrics with different structural parameters, including fabric structure, thread density of the fabric and yarn linear density. The research confirmed that the plain woven fabric exhibits superior energy absorption over other structures in a ballistic event by absorbing 34% more impact energy than the fabric made from 7-end satin weave. This could be explained that the maximum interlacing points in this fabric which help transmit stress to a larger fabric area, enabling more secondary yarns to be involved for energy dissipation. It was found that fabric energy absorption decreases as fabric is made denser, and this phenomenon becomes more pronounced in a multi-ply ballistic system than in a single-ply system. The research results also indicated that the level of yarn crimp in a woven fabric is an effective parameter in influencing the ballistic performance of the fabrics. A low level of yarn crimp would lead to the increase of the fabric tensile modulus and consequently influencing the propagation of the transverse wave. In addition, it was found that for fabrics with the same level of yarn crimp, low yarn linear density and high fabric tightness were desirable for ballistic performance improvement.     

The ballistic performance of narrow fabrics

Woven fabrics are widely used in soft body armour. The ballistic performance of a range of narrow fabrics was determined and compared to that of wider fabric panels. In contrast to conventional ballistic fabrics, it was found that the performance of narrow fabrics was highly sensitive to changes in fabric specification. Furthermore, it was shown that square weave fabrics may not necessarily be superior to unbalanced fabrics in narrow fabric form. It was also confirmed that narrow fabrics absorb more energy than wider fabric panels when undergoing direct ballistic impact, particularly when gripped in a two-sided configuration. Ways were sought of utilising these improvements in performance when the narrow fabrics are brought together to make full-width armour panels. Potentially, the observed improvements in performance could have been offset by the lines of weakness between adjacent fabric strips or by the weight of the structure required to grip on two sides. However, after investigating a number of potential solutions, significant improvements in the performance-to-weight ratios over simple fabric armour were achieved using an assembly of narrow fabrics attached to a lightweight composite frame.     

浸轧压力对STF-Kevlar织物高速冲击性能影响研究

为研究浸轧压力对剪切增稠液体(STF)增强Kevlar织物高速冲击性能的影响,分别采用50 kPa, 100kPa, 200kPa的压力浸轧STF-Kevlar织物,并使用钛合金模拟叶片弹体开展打靶试验。研究结果表明:STF表现出明显的剪切增稠现象,增稠范围为169～1 500 s^-1,增稠比为56.4;Kevlar织物浸渍STF后,二氧化硅(SiO₂)纳米粒子均匀附着在纤维表面;浸轧压力的增加使STF-Kevlar织物的质量增加率降低;STF-Kevlar织物的能量吸收较纯Kevlar织物高29.4%,但其弹道性能指数(BPI)低于纯Kevlar;浸轧后STF-Kevlar织物的能量吸收高于纯Kevlar织物,但低于未浸轧STF-Kevlar织物;在100 kPa的浸轧压力下,STF-Kevlar织物的单位面密度吸收的能量最高;STF-Kevlar织物能量吸收的变化趋势与织物极限变形高度的变化一致。     

基于A-T模型的长杆弹超高速侵彻陶瓷靶体强度分析

Alekseevskii-Tate(A-T)模型广泛应用于长杆弹超高速冲击的终点效应分析中。A-T模型对于金属弹靶强度有明确的表达式,而对于陶瓷靶体强度尤其是弹体初始冲击速度大于1 500 m/s时还没有统一的结论。基于长杆钨弹超高速(1 500~5 000 m/s)侵彻三种陶瓷(Al N,B4C,Si C)/铝复合靶体的缩比逆弹道实验数据;基于A-T模型,给出了上述陶瓷材料在不同侵彻速度范围内的靶体强度表达式。进一步通过与47发长杆钨弹超高速(1 250~2 500 m/s)侵彻陶瓷(Al N,B4C,Si C,AD85)/RHA钢复合靶体DOP实验数据对比,验证了提出的陶瓷靶体强度表达式的适用性。     

Electrodeposited composite coating of Ni-W-P with nano-sized rod- and spherical-shaped SiC particles

In this research, Ni-W-P-SiC nanocomposite coatings are electrodeposited from the plating solution containing suspension of nano-sized spherical- and rod-shaped SiC particles. The influence of SiC particle charge, applied current density, surfactant addition and the particle shape on the SiC incorporation rate has been studied. The phase structure, microhardness and wear resistance of Ni-W-P-SiC nanocomposite coatings were evaluated using X-ray diffraction (XRD), microhardness tester and wear test apparatus. The surface morphology of the produced coatings and worn surfaces has been investigated using scanning electron microscope (SEM). Additionally, the composite coating exhibited higher hardness and wear resistance than the pure Ni-W-P alloy. Regardless the particle shape, the mechanical characteristics of composite coatings are improved with increasing of SiC wt.% into the matrix. The corrosion behavior of the produced coatings was studied using anodic polarization measurements. The nanocomposite coating incorporating SiC rods exhibited higher mechanical and corrosion performance compared with deposits with spherical SiC nano-particles.     

Comparative analysis of oblique impact on ceramic composite systems

An experimental programme is presented which investigated the performance of oblique, ceramic/metal, bilayer composite armours. The ceramics, alumina and silicon carbide, were backed by either Rolled Homogeneous Armour steel (RHA) or 7000 series aluminium. Using a model scale tungsten penetrator at two velocities (representing current and future ordnance threats) the effect of configuration on ballistic limit or depth of penetration (DOP) areal densities was determined. Areal densities of the DOP targets decreased with increasing ceramic thickness, achieving a minimum at zero residual penetration in the backing. The bilayer targets, loaded at the ballistic limit needed a larger areal density to defeat the penetrator. This areal density also decreased with ceramic thickness but showed a minimum with respect to ceramic thickness, as a result of reduced support by the thinner metallic backing. At 1450ms⁻¹ the most efficient system was found to be a SiC/Al, which demonstrated a 25% weight saving over the monolithic aluminium reference target. The Al-alloy backing performs better than RHA, and SiC better than Al₂O₃.     

The ballistic impact characteristics of Kevlar® woven fabrics impregnated with a colloidal shear thickening fluid

This study reports the ballistic penetration performance of a composite material composed of woven Kevlar® fabric impregnated with a colloidal shear thickening fluid (silica particles (450 nm) dispersed in ethylene glycol). The impregnated Kevlar fabric yields a flexible, yet penetration resistant composite material. Fragment simulation projectile (FSP) ballistic penetration measurements at 244 m/s have been performed to demonstrate the efficacy of the novel composite material. The results demonstrate a significant enhancement in ballistic penetration resistance due to the addition of shear thickening fluid to the fabric, without any loss in material flexibility. Furthermore, under these ballistic test conditions, the impregnated fabric targets perform equivalently to neat fabric targets of equal areal density, while offering significantly less thickness and more material flexibility. The enhancement in ballistic performance is shown to be associated with the shear thickening response, and possible mechanisms of fabric-fluid interaction during ballistic impact are identified.     

Analysis of nanostructured coatings synthesized by ballistic impaction of nanoparticles

SiC nanostructured coatings were synthesized by ballistic impaction of nanoparticles using a process called hypersonic plasma particle deposition (HPPD). X-ray diffraction spectra of typical samples showed the presence of crystalline SiC and Si. Grain sizes obtained through transmission electron microscopy showed particles in the sub 10 nm range with primarily crystalline β-SiC and some crystalline Si particles present. These results correlate well with particle size distributions measured using an aerosol sampling probe coupled to a scanning electrical mobility spectrometer. Interestingly, particle size distributions indicated only small changes in the particle size distributions when Si deposition was compared to SiC. Examination of adhesion characteristics highlighted the importance of a chemically bound interlayer during SiC deposition on Mo and steel substrates.     

Experimental investigation on the ballistic resistance of monolithic and multi-layered plates against ogival-nosed rigid projectiles impact

In this paper, the ballistic performance of single, two-, three- and four-layered steel plates impacted by ogival-nosed projectiles were experimentally investigated. Thin multi-layered plates arranged in various combinations of the same total thicknesses were normally impacted with the help of a gas gun. Ballistic limit velocity for each configuration target was obtained and compared based on the investigation of the effect of the air gap between layers, the number, order and thickness of layers on the ballistic resistance of targets. The results show that the thin monolithic targets have greater ballistic limit velocities than multi-layered targets if the total thickness less than a special value, and also the ballistic limit velocities of multi-layered targets decrease with the increase of the number of layers. Otherwise, the moderate thickness monolithic targets give lower ballistic limit velocities than multi-layered targets. Furthermore, the ballistic limit velocities of in-contact multi-layered targets are greater than those of spaced multi-layered targets. The order of layers affects the ballistic limit velocities of multi-layered targets, the ballistic resistance of the multi-layered targets is better when the first layer is thinner than the second layer.     

弹道防护用先进复合材料弹道响应的研究进展

本文对弹道防护用先进复合材料的弹道响应研究及其在工程领域的应用现状进行了综述。首先,基于工程应用研究的试验结果,对超高分子量聚乙烯(UHMWPE)纤维、对位芳香族聚酰胺(PPTA)纤维、芳Ⅲ纤维、聚对苯撑苯并双噁唑(PBO)纤维和聚酰亚胺(PI)纤维等高性能纤维的防弹性能及其复合材料在弹道防护工程领域的应用现状进行了概述,近年来先进复合材料的防弹性能随着纤维力学性能的突破而逐渐提高;其次,讨论了先进复合材料弹道响应的影响因素及其作用机制,发现先进复合材料的塑性拉伸变形是其抵挡弹丸侵彻的主要防弹机制;最后,对弹道防护用先进复合材料的研究方向进行了展望。      

Effect of Frictions on the Ballistic Performance of a 3D Warp Interlock Fabric: Numerical Analysis

3D interlock woven fabrics are promising materials to replace the 2D structures in the field of ballistic protection. The structural complexity of this material caused many difficulties in numerical modeling. This paper presents a new tool that permits to generate a geometry model of any woven fabric, then, mesh this model in shell or solid elements, and apply the mechanical properties of yarns to them. The tool shows many advantages over existing software. It is very handy in use with an organization of the functions in menu and using a graphic interface. It can describe correctly the geometry of all textile woven fabrics. With this tool, the orientation of the local axes of finite elements following the yarn direction facilitates defining the yarn mechanical properties in a numerical model. This tool can be largely applied because it is compatible with popular finite element codes such as Abaqus, Ansys, Radioss etc. Thanks to this tool, a finite element model was carried out to describe a ballistic impact on a 3D warp interlock Kevlar KM2? fabric. This work focuses on studying the effect of friction onto the ballistic impact behavior of this textile interlock structure. Results showed that the friction among yarns affects considerably on the impact behavior of this fabric. The effect of the friction between projectile and yarn is less important. The friction plays an important role in keeping the fabric structural stability during the impact event. This phenomenon explained why the projectile is easier to penetrate this 3D warp interlock fabric in the no-friction case. This result also indicates that the ballistic performance of the interlock woven fabrics can be improved by using fibers with great friction coefficients.     

Experimental and numerical investigation of fabric impact behavior

This paper presents experimental and numerical research regarding blunt trauma resistance of ten fabrics made of high strength fibers. Fabrics of various architecture were examined, including plain woven fabrics, unidirectional laminates and multiaxial fabrics. The fabrics were compared with respect to the depth of the depression formed and the amount of energy transferred to the backing during projectile impact. Absolute values of mentioned parameters were compared, as well as their values after normalization with respect to thickness and areal density of the fabrics. A numerical method for estimating the amount of energy transferred to the backing was proposed.Normalized results, obtained experimentally and numerically, proved that most of the analyzed fabrics provide a similar level of protection, but the best blunt trauma resistance is given by multiaxial fabrics and the least by plain woven fabrics. This study has also shown that the depth of the depression in the backing material is an insufficient parameter in describing protective properties of fabric against blunt trauma. It is possible that impacts into ballistic packages composed of different fabrics with the same depth of depression may cause completely dissimilar injuries because of the amount of energy transferred to the backing material.     

Ballistic impact response of laminated hybrid materials made of 5086-H32 aluminum alloy,epoxy and Kevlar® fabrics impregnated with shear thickening fluid

The ballistic impact behavior of hybrid composite laminates synthesized for armor protection was investigated. The hybrid materials, which consist of layers of aluminum 5086-H32 alloy, Kevlar® 49 fibers impregnated with shear thickening fluid (STF) and epoxy resin were produced in different configurations using hand lay-up technique. The hybrid materials were impacted by projectiles (ammunitions of 150 g power-point) fired from a rifle Remington 7600 caliber 270 Winchester to strike the target at an average impact velocity and impact energy of 871 m/s and 3687 J, respectively. The roles of the various components of the hybrid materials in resisting projectile penetration were evaluated in order to determine their effects on the overall ballistic performance of the hybrid laminates. The effects of hybrid material configuration on energy dissipation during ballistic impacts were investigated in order to determine a configuration with high performance for application as protective armor. The energy dissipation capability of the hybrid composite targets was compared with the initial impact energy of low caliber weapons (according to NATO standards) in order to determinate the protection level achieved by the developed hybrid laminates. Deformation analysis and penetration behavior of the targets were studied in different stages; the initial (on target front faces), intermediate (cross-section), and final stages (target rear layers). The influence of target thickness on the ballistic impact response of the laminates were analyzed. Differences in ballistic behavior were observed for samples containing Kevlar® impregnated with STF and those containing no STF. Finally, mechanisms of failure were investigated using scanning electron microscopic examination of the perforations.