三维正交机织复合材料的冲后压缩性能

为揭示纱线张力对三维机织复合材料抗冲击及冲后压缩性能的影响规律,基于多剑杆织造工艺,配置不同接结纱张力(25、50、100 cN)织造三维正交机织物,通过真空辅助树脂传递模塑成型工艺制备复合材料,并在室温下进行低速冲击及冲后压缩性能测试。结果表明：当接结纱张力为100 cN时,试样在冲击载荷下发生表层树脂大面积破裂和剥离并使纬纱失去支撑,同时,试样表层纬纱发生较大卷曲,促使压缩载荷发生屈曲失效;接结纱张力为100 cN试样的压缩性能相比接结纱张力为25 cN试样下降约50%;接结纱张力较高时易导致纬纱卷曲增大和树脂富集,并由此降低试样的弯曲刚度和冲后压缩性能。     

The effect of the through-thickness yarn component on the in- and out-of-plane properties of composites from 3D orthogonal woven preforms

Development of three-dimensional (3D) weaving technology introduced new and enhanced features to the 2D weaving technology. 3D Orthogonal Woven (3DOW) preforms have a through-thickness yarn component that significantly enhances the out-of-plane properties and delamination resistance. In this study, a range of 3DOW E-glass preforms were woven using 3D weaving technology and then converted into composites, using vacuum assisted resin transfer molding technology. The composite samples had varying Z to Y-yarn/ layer ratio, the objective is to study the effect of changing the Z to Y-yarn/ layer ratio on the in-plane and out-of-plane mechanical properties. The study concludes that changing the amount of Z-yarn in the structure has negligible effect on the tensile (in-plane), yet, it has a significant effect on the drop weight impact properties (out-of-plane). Moreover, it had a strong effect on the failure mechanisms, and as the amount of Z-yarn is reduced, delamination became more significant.     

Flexural stability analysis of composite panels reinforced with stiffener integral woven preforms

3D weaving exhibits to be a guaranteeing innovation in delivering integrated near net shaped structures that might overcome the current issue of delamination and assembly cost. This paper highlights one such technique of producing preforms with integrally woven stiffener sections that can be used as a reinforcement material for composite panels. The woven performs were fabricated using high performance polyester yarns as a raw material and further consolidated to composite structures using epoxy resin. The flexural analysis of the composite panels developed from these performs revealed that the structures have better bending rigidity and structural integrity without any possibility of delamination prone failures. Investigations on fracture morphology were conducted to understand the composite failure mechanism and the structural deformation of the structures during loading. From the findings, it was evident that the polyester-epoxy material combination exhibited substantial residual strength and toughness properties.     

Large-scale finite element analysis of a 3D angle-interlock woven composite undergoing low-cyclic three-point bending fatigue

This paper reports the large-scale finite element analysis (FEA) of a 3D angle-interlock layer-to-layer woven composite material undergoing low-cyclic three-point bending fatigue at microstructure level. A microstructure geometrical model of the 3D woven composite material was established to model the real structure of the woven composite. The fatigue behaviors of the 3D woven composite undergoing three-point bending with sinusoidal wave-form were investigated from experimental and FEA approaches. Based on displacement-controlled bending and inelastic hysteresis energy fatigue damage criterion, the interior deformation, energy absorption, and stress distribution characteristics during the fatigue process were analyzed. The different failure mechanisms and damage patterns of yarns and resin were discussed. The influence of the 3D woven structure on the fatigue behaviors was discussed. The fatigue damage morphologies and stiffness degradation were obtained to compare with the experimental results. The results show that the most of energy was absorbed by warp yarns. Stress concentration was emerged on the inclined part of warp yarns and the interface between yarns and resin. The damage morphologies from experimental and FEA results are in good agreement. The stiffness degradation curves also show the same tendency.     

Mechanical properties improvement of silane addition epoxy/3D orthogonal woven composite material

In this study, the influence of silane addition on mechanical properties of epoxy/3D orthogonal glass fiber woven composite was studied. The KH560 silane modification composite specimen reinforced with 3D orthogonal woven fabric/epoxy was manufactured by means of Resin Infusion under Flexible Tooling. The mechanical properties of the epoxy/3D glass fiber woven composites were characterized by tensile and bending tests. The tensile and bending properties of silane-modified 3D orthogonal woven glass composite in warp and weft directions were compared with the pristine or epoxy/glass composite material not coupled using silane. The results show that the tensile and bending properties in warp and weft directions have been improved due to the silane addition. The bonding strength between the fiber and matrix was improved and the delamination and debonding between fiber and matrix was retarded and shifted to cohesive failure of the matrix due to the silane modification. Electron microscopy of the fracture and failure modes of the test specimens were used to support the results and conclusions.     

不同结构厚截面三维机织碳纤维复合材料的弯曲性能对比

为准确分析不同结构厚截面复合材料不同方向上的弯曲性能差异,通过设计织造三向正交、浅交直联、浅交弯联3种典型机织结构的厚截面碳纤维三维机织物,并采用真空辅助树脂成型工艺制备了近似纤维体积含量的碳纤维复合材料板,对其进行了XYZ方向的弯曲实验。结果表明:三向正交结构由于内部纤维束近似平直,碳纤维束自身性能得到最大利用,对应复合材料经向弯曲强度最好;浅交直联结构复合材料的Z经和Z纬弯曲强度累加值最大,其厚度截面上的综合弯曲性能最好,且其他各方向的弯曲强度较为均衡;浅交弯联结构内部纱线交织摩擦损伤严重,且经纱屈曲程度最大,对应复合材料经纬向弯曲性能均为最差。     

对组合式3D机织复合材料纵向拉伸性能的研究

设计并在一般剑杆织机上试织7种不同结构的组合式3D预制件,采用真空辅助成型工艺分别制作这7种复合材料,同时测试各种试样的拉伸性能.在增强体经向截面上经纱总根数（包括垂纱）相同的情况下,研究了试样的结构、结构单元及纬纱层数对材料纵向拉伸性能的影响.     

Mechanical Response of Novel 3D Woven Flax Composites with Variation in Z Yarn Binding

ABSTRACT

This paper is focused on the development of novel 3D woven flax composites for improved mechanical performance. The 3D woven interlock fabrics were produced on dobby loom using novel weaving patterns, with variation in binding point density (four different levels). These fabric structures were then used to fabricate composites with green epoxy resin as a matrix. Tensile, flexural, short beam shear, impact (pendulum and drop weight) and compression after impact properties were characterized. It was found that 3D woven composites having higher binding point density showed overall improved mechanical behavior, i.e. the out-of-plane properties were enhanced whereas in-plane properties are either reduced or unaffected.     

二维与三维机织复合材料力学性能的实验研究

对超厚三维正交机织复合材料及二维要织层合板人别进行了拉伸和压缩实验,研究比较了两种复合材料刚度和强度特性的差异研究发现无论是三维机织材料的拉压还是二维层合板的拉压应力应变曲线都近似为直线,而且具有脆性破坏的特点;三维复合材料的拉压强度要高于二维层合板.这主要是由于材料不同的增强相结构及纤维含量造成;不同的破坏模式对材料强度影响很大.     

开孔三维编织复合材料的压缩性能

为研究机械开孔对三维编织复合材料压缩性能的影响,测试了2种三维编织复合材料试验件的压缩性能。1种为基本编织(100%编织纱)结构,另1种为含有编织纱/轴向纱(58/42)的结构,试验件编织角约为±12°。根据相关标准要求,分别进行有开孔和无开孔的复合材料试验件准静态压缩试验,并与层合板的压缩性能进行对比。研究结果表明:2种三维编织结构无缺陷材料的压缩强度较为接近,但引入开孔后,无增强纱结构可保留更高比列的压缩强度;引入开孔后,2种三维编织复合材料保留的压缩强度均高于层合板;在失效形式上,2种三维编织复合材料的宏观失效形式较为相似,均为剪切失效,表现出横向断裂且无分层现象。     

Warp and weft directional tensile properties of multistitched biaxial woven E-glass/polyester composites

The objective of this research work was to understand the warp and weft directional tensile properties of the two-dimensional multistitched multilayer E-glass/polyester woven composites. The warp and weft directional specific tensile strength and modulus of unstitched structure were higher than those of multistitched structures as stitching caused minor warp and weft yarn filament breakages. Contrarily, the specific tensile strains of unstitched structure were slightly lower than those of all multistitched structures. The stitching yarn type, the number of stitching directions, and the stitching density generally influenced the warp and weft directional tensile properties of multistitched E-glass/polyester woven composites. The failure of warp and weft directional multistitched woven E-glass/polyester composite structures was matrix breakages, and partial and complete yarn breakages in their surfaces. They had a local delamination in their cross-sections and the delamination did not propagate to the large areas due to multidirectional stitching. Also, the failure was confined at a narrow area and resulted in the catastrophic fiber breakages. The warp and weft directional specific damaged areas of multistitched structures, in particular four-directional stitching, were significantly lower than those of the unstitched structures. This indicated that the multistitching made the structures better damage-tolerance materials.     

三维机织正交结构复合材料的参数化设计

为给三维机织正交结构复合材料的力学模拟分析提供一种模型,通过观察3层机织正交结构复合材料预制件的细观几何结构,分析其最小重复单元中纱线间的几何位置关系,探讨细观结构中的几何参数与宏观设计参数的关系。在此基础上,利用Pro/Engineer软件对复合材料预制件进行参数化设计,建立三维机织正交结构预制件的通用几何模型。通过对比制得的三维机织复合材料的实际结构与模型结构以及纤维体积分数,验证了该模型的合理性。     

基于气缸的三维机织增强体织造系统设计

为在经纱方向引入贯穿织物厚度的接结纱从而提升机织增强复合材料层间性能,以三维正交无卷曲机织增强体为对象,设计了一种窄幅三维机织织造系统。采用气缸作为开口、引纬和打纬的主要驱动部件,实现多重综框的独立开口运动与管状多剑杆机构的多层梭口同时引纬运动,并在可编程控制器上实现各机构协调运作,使经纬纱垂直平铺,接结纱与纬纱交织并贯穿织物起到层间约束作用。通过显微镜观察三维机织增强复合材料各个切面(分别沿经纱、纬纱和接结纱),并测量纱线卷曲度、横截面积、组织单元尺寸等关键几何参数。测量结果表明,这种三维机织系统可实现三维正交无卷曲机织增强体的织造。     

锯齿形三维机织间隔复合材料的弯曲性能

为解决层合间隔复合材料易开裂和整体性差的问题,采用绿色环保的玄武岩低捻长丝作为经、纬纱,合理设计经向截面图和组织图,并在普通织机上织造3种不同间隔高度的锯齿形三维机织间隔织物。以所织得的锯齿形三维机织间隔织物作为增强材料,环氧乙烯基树脂作为基体,利用真空辅助成型工艺,制备锯齿形三维机织间隔复合材料,同时对三维机织间隔复合材料进行三点弯曲性能测试,得到弯曲载荷-位移曲线、能量吸收图和破坏模式。结果表明:复合材料的纬向是主要承力方向;组织循环个数越多的材料表现出更好的弯曲性能;在一定间隔高度范围内,间隔高度越高的锯齿形三维机织间隔织物承受的弯曲载荷和吸收的能量也越高;锯齿形三维机织间隔复合材料的破坏模式是材料上表层受压,下表层受拉,而连接层受压;在作用力下材料只是出现明显的变形,但并未出现材料整体的破坏。     

三维机织预型件的织造技术

纺织复合材料预型件的生产工艺有多种,其生产路径主要由最终用途决定。三维机织物是通过对传统织造原理改进加工而成的。二维机织复合材料是一种由二维织物构成的层合材料,而三维机织复合材料是复杂几何结构的整体构件。三维机织复合材料预型件有许多优点,最重要的优点是它避免了二维层合材料的分层现象。介绍了三维机织预型件的织造方法,为纺织复合材料的开发提供了有益的借鉴。     

Generalized geometric modeling of three-dimensional orthogonal woven preforms from spun yarns

Through the thickness mechanical properties of composites have been improved with the advance of 3D woven preforms incorporating through-thickness reinforcement element compared to 3D woven composites from stack of 2D fabrics. In this study, a generalized geometric model considering non-jammed and jammed constructions of 3D orthogonal woven preforms from spun yarns was developed to predict fiber volume fraction (FVF) of structure constituents, preform thickness, preform areal density, and minimum thread spacing (x-, y-, and z-yarn spacing) to achieve jammed construction in terms of weave factor, number of layers, and constituents’ variables (y- and z-yarn sequence, linear densities, packing factor, and fiber volumetric density). Numerical results are presented to demonstrate the generalized model potential as a design tool to achieve broad range of constituents FVF that controls composite performance.     

组合式3D机织物复合材料的拉伸性能

采用正交和角联锁结构进行组合设计,并使用玻璃纤维试织了2种不同结构的组合式3D立体机织物,经与树脂复合制成增强复合材料,对其拉伸性能进行了测试。结果表明,组合式3D机织物增强复合材料具有接近正交3D机织物增强复合材料的弹性模量和抗拉强度。     

An experimental investigation into structure and properties of 3D-woven aramid and PBO fabrics

Three-dimensional (3D) fabrics are the focus of recent developments due to their versatile physical, structural attributes, and application scopes. These fabrics can be manufactured in various architectures which offer a great deal of opportunity to modify the weight, physical and mechanical properties, and cost of the various products. The potential usage of 3D woven fabrics in the ballistic protection applications was the main motivating factor of this research work. Thus, interest has been focused to investigate the structure and properties of 3D woven orthogonal fabrics with aramid fiber and PBO fiber in comparison with 2D fabrics. The investigation of ballistic properties of these fabrics showed that 3D woven fabrics are superior in terms of breaking load and energy absorption as compared to those of 2D woven fabrics. The specific ultimate tensile strength of 3D woven fabric was observed to be lower than 2D fabrics, which may be due to less number of load bearing yarns in the loading direction. The crimp percentages of the load bearing tows in 3D fabric are very less than that of 2D fabrics. Owing to the higher values of work at peak and load at peak, in knife penetration test, it is revealed that 3D fabrics offer better protection than 2D fabrics.     

Impact performance of two bamboo-based laminated composites

The present work aims to determine the impact performance of two bamboo-based laminated composites [bamboo/poplar laminated composite (BPLC) and bamboo/glass fiber laminated composite (BGFLC)] using low-velocity impact tests by a drop tower. In addition, fracture characteristics were evaluated using computed tomography (CT). Results showed that BPLC presented better impact properties in both directions than BGFLC. Three stages are noted in impact load–deflection curves. The load–deflection curve characteristics of two composites are different in different stages. Matrix cracking, fiber-matrix interface debonding and delamination, and fiber breakage are the three main fracture mechanisms of two composites. Structural characteristics of the components and bonding strength are the important factors for impact properties and fracture mechanism of both bamboo-based laminated composites.     

基于超声相控阵的机织层合复合薄板试件内部缺陷检测方法

针对机织层合薄板复合材料试件的内部缺陷,采用超声相控阵检测法对其进行超声100%扫查,并对得到的超声定位的缺陷区域进行分析;建立了超声回波A扫描波形图、B扫描图像以及C扫描图像和机织层合板复合材料内部区域缺陷分布的对应关系,分析比较了复合材料试件分别在同时激发4、8、16个晶片(阵元)的条件下得到的超声检测结果图,并在相控阵设置最优条件下对复合材料进行横纵方向超声扫描得到检测图,针对C扫描得到的缺陷扫查图进行定量分析。研究结果表明:扫描得到的超声A扫描波形图、B扫描图像以及C扫描图像在复合材料缺陷的位置上有一一对应的关系,超声相控阵检测法可用于机织层合板复合材料的无损检测及其缺陷的初步评价。