纤维增强树脂基复合材料防弹性能影响因素及破坏机制

以超高分子量聚乙烯(Ultra High Molecular Weight Polyethylene,UHMWPE)纤维、S-玻璃纤维、芳纶1414纤维和杂环芳纶纤维增强聚烯烃(Polyolefin,PO)和水性聚氨酯(Waterborne Polyurethane,WPU)树脂,采用热压工艺制备正交单向无纬(UD)结构复合材料装甲板;通过装甲板弹道极限速度测试,研究了纤维增强树脂基复合材料装甲板防弹性能的影响因素;通过体视显微镜观察装甲板侵彻破坏形貌,分析了纤维增强树脂基复合材料的破坏机制。结果表明:UHMWPE纤维增强PO树脂基复合材料的防弹性能与UHMWPE纤维的强度和模量呈正相关,但纤维模量对复合材料防弹性能的影响随着纤维模量的增大而逐渐变弱;在WPU树脂体系下,四种纤维的防弹性能由高到低依次是UHMWPE纤维、杂环芳纶纤维、芳纶1414纤维、S-玻璃纤维;纤维增强树脂基复合材料装甲板中纤维破坏方式有迎弹面纤维被剪切冲塞、中部被纤维拉伸变形后剪切、背弹面纤维被拉伸断裂,中部纤维拉伸变形是消耗子弹动能的主要方式。     

热塑性树脂基体对超高分子量聚乙烯纤维复合材料力学性能和抗弹道侵彻性能的影响

选用热塑性的水性橡胶、水性聚酯、水性聚氨酯作为基体树脂,超高分子量聚乙烯(UHMWPE)纤维作为增强纤维,采用热压工艺制备单向正交结构的防弹先进复合材料层压板。基于弹道侵彻试验和力学试验研究热塑性树脂基体对防弹先进复合材料弹道响应及力学行为的影响。研究结果显示：相比单一的热塑性树脂体系,以热塑性树脂混合体系作为基体制备的UHMWPE复合材料具有更优异的抗弹道侵彻性能、更高的拉伸破坏强度和层间剪切破坏强度,这是由于混合树脂体系中的UHMWPE纤维具有更高的可利用效率;此外,基于横向压缩诱导的间接张力机制和弹道侵彻下的大变形行为诱导的膜力效应,UHMWPE纤维复合材料的抗弹道侵彻性能与其准静态下的拉伸断裂强度、层间剪切强度呈现正相关的关联机制。     

破片着靶点位置对拼接的UHMWPE板抗侵彻性能影响数值研究

UHMWPE板抗侵彻性能优异但在实际使用过程中需切割成一定尺寸后再拼接安装,半穿甲导弹内爆后形成的高速破片侵彻UHMWPE板时弹着点位置具有随机性。利用数值仿真方法研究破片着靶点位置、破片速度、破片长径比对拼接的UHMWPE板抗侵彻性能的影响。结果表明:破片开始侵彻UHMWPE板时,UHMWPE板在弯矩和剪应力共同作用下出现纤维剪切破坏;随着破片继续侵彻,UHMWPE板主要受到弯矩作用发生纤维拉伸断裂破坏并伴随有严重的分层现象;当破片侵彻两块拼接的UHMWPE板速度较低(小于1 000 m/s)时,拼接的UHMWPE板存在明显的抗弹薄弱区,薄弱区域的范围大约为3倍的弹径;当破片侵彻四块拼接板时,可将靶板划分为薄弱,次薄弱及正常区域。考虑到半穿甲导弹产生破片的大小和安装工艺的方便性,认为UHMWPE板拼接安装时,拼接缝两侧10 cm范围内作为抗弹薄弱区域,需要加固。     

层间混杂复合材料装甲板防弹性能及其防弹机制

为研究层间混杂复合材料装甲板的防弹性能及其防弹机制,采用钢芯弹侵彻层间混杂复合材料装甲板。以超高分子量聚乙烯（Ultra high molecular weight polyethylene,UHMWPE）纤维、对位芳香族聚酰胺纤维作增强纤维,水性聚氨酯（Waterborne Polyurethane,WPU）树脂和环氧树脂（Epoxy resin,EP）作基体,采用热压工艺制备单向（Unidirectional,UD）结构的层间混杂复合材料装甲板。研究混杂比例、防弹面和树脂基体对混杂复合材料装甲板防弹性能的影响以及弹击后混杂复合材料装甲板的破坏形貌,分析混杂复合材料装甲板的防弹机制,并对复合材料装甲板的破坏机制进行了分析。结果表明:混杂复合材料装甲板的防弹性能优于其任一单一纤维复合材料装甲板;WPU的防弹性能要优于环氧树脂;以UHMWPE纤维复合材料充当防弹面时,混杂复合材料装甲板具有更好的防弹性能;纤维拉伸变形和装甲板分层是纤维复合材料装甲板主要的吸能方式。      

超高分子量聚乙烯纤维复合材料的应用及其抗侵彻性能研究

超高分子量聚乙烯(UHMWPE)纤维因在比强度上的巨大优势引起科研技术人员的广泛关注(其密度约为0.97g/cm3,而抗拉强度可达GPa量级)。研究表明,以UHMWPE纤维作为主要组分的复合板在侵彻防护领域具有极大的应用潜能,其防护效率明显优于现有陶瓷、轻金属等抗侵彻材料。介绍了UHMWPE纤维的基本性质、发展现状及其抗侵彻机理,概述了以UHMWPE纤维为主要组分的复合材料在抗侵彻领域中的应用,指出了UHMWPE纤维复合材料发展中有待解决的问题。     

超高分子量聚乙烯纤维的液相氧化改性及其环氧树脂基复合材料的力学和摩擦性能

为增强超高分子量聚乙烯(UHMWPE)纤维与环氧树脂(EP)基体之间的界面粘结强度,采用重铬酸钾溶液对UHMWPE纤维进行表面改性并制备UHMWPE纤维/EP复合材料。结果表明,UHMWPE纤维经液相氧化后表面刻蚀痕迹明显,表面粗糙度明显增加,结晶度增加了11.3%,与乙二醇的接触角减小了14.12°。与纯环氧树脂相比,纤维含量为0.4%的未改性UHMWPE纤维/EP复合材料的拉伸强度降低18.04%,纤维含量为0.6%的液相氧化改性UHMWPE纤维/EP复合材料的拉伸强度降低51.55%,未改性UHMWPE(纤维含量0.5%)和液相氧化改性UHMWPE(纤维含量0.4%)纤维/EP复合材料的冲击强度分别提升了3.29%和4.39%。当纤维含量为0.3%时,液相氧化改性UHMWPE纤维/EP复合材料的弯曲强度比纯环氧树脂增加6.55%,比未改性UHMWPE纤维/EP复合材料增加19%。当纤维含量由0增大到0.5%时,改性和未改性UHMWPE纤维/EP复合材料的摩擦系数先增加后减小。     

弹道防护用超高分子量聚乙烯纤维增强热塑性树脂基复合材料的拉伸力学行为

以弹道防护用超高分子量聚乙烯(Ultra-high molecular weight polyethylene,UHMWPE)纤维增强热塑性树脂基复合材料作为研究对象,通过热压工艺制备单向正交结构的复合材料层压板。基于自主设计的拉伸试验装置,开展UHMWPE纤维增强热塑性树脂基复合材料在宏观尺度和准细观尺度上的面内拉伸试验,研究其面内拉伸力学性能及失效模式。研究结果显示：弹道防护用UHMWPE纤维增强热塑性树脂基复合材料在准细观尺度上的面内拉伸力学性能是其本征性能;随着偏轴角度的增加,拉伸断裂强度呈现指数型下降,这是由于失效模式由纤维的拉伸断裂破坏转变为纤维-树脂基体的界面破坏;此外,其在宏观尺度上的拉伸破坏强度比在准细观尺度上的拉伸断裂强度降低了50.52%,这是由于宏观尺度上的面内拉伸力学响应是其面内拉伸变形和层间分层破坏的耦合结果,即层压板的叠层效应。     

FRC 层合板抗高速冲击机理研究

基于纤维增强复合材料( FRC) 层合板高速冲击下横向变形及破坏模式的分析, 根据冲击动力学理论和应力波传播特性, 建立了FRC 层合板柱形弹高速冲击下的两阶段(剪切侵彻和连续侵彻) 侵彻动力学分析模型。采用瞬态梯度变形锥理论分析了连续侵彻阶段的弹、靶相互作用, 并编制相应计算程序, 通过计算结果与实验测试结果的综合比较, 弹体初速在300～900 m/ s 范围内, 剩余速度误差小于50 m/ s , 验证了两阶段侵彻模型的适用性和稳定性, 分析了实验现象, 如梯度变形锥、背层花瓣开裂和面背层破坏模式差异等的产生及形成机理, 提出了提高现有层板结构抗弹性能的新途径, 如降低层间粘结强度、提高面层纤维的抗剪能力等。      

织物-树脂复合材料层压板的准静态侵彻机理

本文利用MTS得到了芳纶和高强维纶织物复合材料层压板受尖头侵彻体穿孔的准静态侵彻曲线 ,比较和分析了不同类型纤维集合体与热固性树脂和热塑性树脂复合材料的破坏模式 ,并考察了芳纶织物复合材料层压板侵彻的逐步破坏过程 ,揭示了复合材料层压板的准静态侵彻机理。     

三种纤维改性超高分子量聚乙烯复合材料的力学性能

以未处理和偶联剂KH550处理的C纤维、SiC纤维和Al2O3纤维为填充材料,以超高分子量聚乙烯(UHMWPE)为基体,用模压成型法制备了三种纤维改性UHMWPE复合材料,对复合材料的硬度、弯曲强度、拉伸强度和断裂伸长率进行了实验研究,用光学显微镜观察分析了拉伸断面形貌。结果表明,未处理的C纤维、SiC纤维和Al2O3纤维改性UHMWPE复合材料硬度较纯UHMWPE分别提高了11.76%、21%和6%。经KH550处理的三种纤维改性UHMWPE复合材料弯曲强度和拉伸强度均优于未处理纤维的复合材料,已处理的SiC纤维/UHMWPE复合材料弯曲强度和拉伸强度提高较大。KH550处理的三种纤维与UHMWPE基体界面粘接紧密,未处理纤维与UHMWPE基体粘接较差。     

Influence of different back laminate layers on ballistic performance of ceramic composite armor

This paper mainly reported a new type of ceramic composite armor with a back laminate of Ti6Al4V/UHMWPE/Ti6Al4V against the 12.7 mm armor piercing projectile at a velocity of 818 m/s. The mechanism of the whole ceramic composite armor against the projectile, and the function of each layer in the back laminates were systematically investigated around the experiments and numerical simulations. The results indicated that the outermost Ti6Al4V layer provided support for the UHMWPE layer, leading to the UHMWPE layer displaying the extremely high buffer performance during the impact process. Meanwhile, the middle UHMWPE layer also had an energy balance function between the first and outermost Ti6Al4V layers to cause small damage in the back laminate layers. Thus, this configuration contributed to absorb or dissipate the more energy of the impact projectile, successfully preventing the perforation of the projectile.     

Micromechanical Modeling of Impact Damage Mechanisms in Unidirectional Composite Laminates

Composite laminates are susceptible to the transverse impact loads resulting in significant damage such as matrix cracking, fiber breakage and delamination. In this paper, a micromechanical model is developed to predict the impact damage of composite laminates based on microstructure and various failure models of laminates. The fiber and matrix are represented by the isotropic and elastic-plastic solid, and their impact failure behaviors are modeled based on shear damage model. The delaminaton failure is modeling by the interface element controlled by cohesive damage model. Impact damage mechanisms of laminate are analyzed by using the micromechanical model proposed. In addition, the effects of impact energy and laminated type on impact damage behavior of laminates are investigated. Due to the damage of the surrounding matrix near the impact point caused by the fiber deformation, the surface damage area of laminate is larger than the area of ??impact projectile. The shape of the damage area is roughly rectangle or elliptical with the major axis extending parallel to the fiber direction in the surface layer of laminate. The alternating laminated type with two fiber directions is more propitious to improve the impact resistance of laminates.     

Influence of fabric structure and thickness on the ballistic impact behavior of Ultrahigh molecular weight polyethylene composite laminate

This paper presents the influence of fabric structure and thickness on the ballistic impact behavior of Ultrahigh molecular weight polyethylene (UHMWPE) composite laminate. UHMWPE composite laminates, reinforced by three kinds of fabric structures, unidirectional prepreg, 2D plain-woven and 3D single-ply orthogonal woven fabrics, were fabricated via hot pressing curing process. Through a series of standard ballistic tests, we demonstrated that unidirectional composite laminates exhibit higher ballistic impact velocity and absorbed energy capacity compared to others. A bi-linear relationship was found between the ballistic limit velocity and specimen thickness. Furthermore, the dominant failure mechanisms of unidirectional composite laminates were identified to be plugging and hole friction for thin laminates, whereas delamination, fiber tension and bulging for thick ones.     

玻璃纤维-不锈钢网混杂增强环氧树脂层合板对球形弹斜冲击响应特性实验研究

为了研究玻璃纤维-不锈钢网混杂增强环氧树脂层合板在球形弹高速斜冲击下的损伤特性,利用一级气炮对2 mm厚度的玻璃纤维增强环氧树脂复合材料层合板和含一层、三层304不锈钢网的玻璃纤维-不锈钢网混杂增强环氧树脂层合板进行倾角为30°的冲击实验,以揭示304不锈钢网对层合板弹道极限和能量吸收的影响规律,并分析层合板损伤特征及其机理。通过实验发现,含有三层不锈钢网层合板的弹道极限最高,而不含不锈钢网层合板和含一层不锈钢网层合板的弹道极限速度接近。层合板吸收的能量随着弹体速度增加呈现出先增加后趋于平稳,然后急剧上升的趋势。层合板损伤模式为基体开裂和破碎、分层、不锈钢丝拉伸断裂、纤维拉伸断裂和剪切断裂。层合板分层损伤面积随弹体速度增大先增大后减小,最后趋于稳定。当弹体速度较低时,层合板主要发生纤维拉伸断裂、基体开裂、层间有分层损伤产生。随着弹体速度的增大,层合板正面纤维逐渐发生压剪断裂、基体破碎,背面纤维发生严重的拉伸撕裂。      

Ballistic Penetration of Dyneema Fiber Laminate

UHMWPE fiber (Dyneema) reinforced composites are an important class of materials for armors.These materials provide superior ballistic performance to the armor, such as the military armor systems requiring a reduction in back-armor effects or a substrate for hardened facings of steet or ceramic. The reported work characterized the ballistic impact and mechanical performance of Dyneema fiber in composite laminates. The capability of the laminate to absorb ballistic impact energy was influenced by the impact velocity and the laminate areal density. Two kinds of penetration were compared and a two-step model for the penetration was proposed.     

复合材料层合板缺口强度的CDM三维数值模型

针对复合材料层合结构缺口强度问题,基于连续损伤力学（CDM）提出了一种三维损伤数值模型。模型区分了层内损伤（纤维失效、纤维间失效）和层间分层损伤的不同失效模式。采用三维Puck准则与Aymerich准则对上述2类损伤进行判定,材料失效后基于CDM中线性软化模型对材料损伤进行演化。模型考虑了复合材料层合板子层的就位效应和剪切非线性行为。对Carlsson的AS4/3501-6缺口拉伸强度试验进行数值模拟。结果表明:分析结果与试验结果吻合良好,证明了该模型能够准确地预测含缺口复合材料层合板面内拉伸强度。      

Damping characteristics of nanoclay filled hybrid laminates during medium velocity impact

The objective of this paper is to study the vibrational damping characteristics during medium velocity impact of nanoclay filled glass fiber reinforced epoxy hybrid laminates. A series of laminates with varying degree of nanoclay concentration (0–5 wt.%) and fiber weight fraction (25–75 wt.%) were prepared by vacuum assisted resin infusion molding (VARIM) method. The laminates were subjected to medium velocity projectile impact using in-house built gas gun set-up and the ballistic limit of laminates series was determined. The result indicated that during impact, the laminate undergoes vibrational damping. This damping property is a function of fiber weight fraction and orientation, nanoclay concentration and nanocomposite structure. A 42% increase of ballistic limit was observed for 5 wt.% nanoclay filled hybrid (50 wt.% fiber) when compared with unfilled composite. Structural and modal analysis of hybrids showed that the increased ballistic limit of nanoclay filled hybrids is due to the nanocomposite structure and improved damping and fracture properties.     

Effect of Reactive Graphitic Nanofibers (r-GNFs) on Tensile Behavior of UHMWPE Fiber/Nano-Epoxy Bundle Composites

Ultra-high molecular weight polyethylene (UHMWPE) fibers have good mechanical and physical properties and effective radiation shielding functions, which are significant for aerospace structures. In our previous work, nano-epoxy matrices were developed based on addition of reactive graphitic nanofibers (r-GNFs) in a diluent to form a blend. It is found that improved wettability and enhanced adhesion of the matrices to UHMWPE fibers can be obtained. In this study, a series of nano-epoxy matrices with different concentrations of r-GNFs (up to 0.8 wt%) and different weight ratios of r-GNFs to a reactive diluent (1:4, 1:6, 1:7, and 1:9) were prepared. Composite bundle specimens of UHMWPE fiber/nano-epoxy were fabricated and their tensile behavior was investigated. All load-displacement curves of the UHMWPE/nano-matrix bundle composites under tensile loading showed three regions corresponding to the three deformation and failure stages of the materials: 1) elastic deformation stage, 2) plateau stage, and 3) UHMWPE fiber failure stage. The nano-epoxy with 0.3 wt% of r-GNFs and with 1:6 ratio of r-GNFs to the diluent proved to be the best matrix for UHMWPE fiber composites with enhanced tensile properties. For the resulting composite, the load level and consumed energy in the plateau stage were increased by 8% and 30% over the UHMWPE fiber/pure-epoxy specimens, respectively. This UHMWPE fiber composite with the optimized nano-epoxy matrix also possesses the highest initial stiffness and ultimate tensile strength among all the resulting UHMWPE fiber composites. These results laid a foundation for us to fabricate UHMWPE fiber reinforced composite laminates in the near future.     

Ku/Ka双频段防弹天线罩复合材料性能

为解决Ku/Ka双频段天线罩的防弹和透波问题,本文通过波导法研究材料的介电性能,并利用HFSS软件对双频工作的复合材料进行透波性能仿真设计,并采用试验与理论计算验证了超高分子量聚乙烯（UHMWPE）防弹和透波性能。研究表明：UHMWPE的介电性能优异,适用于Ku/Ka双频段天线罩。HFSS仿真设计表明,7 mm UHMWPE的Ku频段损耗为0.2 dB,Ka频段损耗为0.6 dB,仿真结果与实际测试结果吻合。防弹打靶试验表明,面密度为5.6 kg/m²的UHMWPE防弹等级优于1级,实测V₅₀值为546 m/s。