平面三向织物增强橡胶复合材料的偏轴拉伸性能研究

研究了平面三向织物增强橡胶复合材料的偏轴拉伸性能,并与平纹织物增强橡胶复合材料的偏轴拉伸性能进行了对比,同时分析了试样形状（长方形和哑铃形）对织物增强橡胶复合材料的偏轴拉伸的影响。结果表明,平面三向织物增强橡胶复合材料在各个方向的拉伸断裂强度及断裂伸长率变化较小,表现出准各向同性,而平纹织物增强橡胶复合材料则表现为明显的各向异性;哑铃形试样更适合织物增强橡胶复合材料的偏轴拉伸性能测试。     

三维机织热塑性复合材料的拉伸性能测试与分析

本研究对三维机织热塑性复合材料的拉伸力学性能进行了测试,分析了三维机织热塑性复合材料预型件的结构(纱线的直径、三维机织物的结构)、预型件的预拉伸工艺(经纱和接结经的伸直程度)、复合成型工艺(成型压力)对复合材料的力学性能的影响.     

超薄高模量织物研制及其在星载反射器上的应用

为了满足天线反射器轻量化以及高精度要求,通过多级展纱工艺制备超薄碳纤维织物并应用于反射器结构。通过对机械展纱原理进行分析,采用多级展纱辊设备展纱,展纱后纱片宽度为4 mm,织物的面密度为106 g/m2。对展纱后丝束与原丝束进行复丝拉伸试验,实验结果表明,展纱后丝束拉伸强度和模量分别下降了1.26%和1.29%。通过工艺试验制备单层厚度的蒙皮试样,试样表观形貌明显提高。同时结合天线反射器结构,采用有限元仿真手段针对超薄高模量碳纤维织物进行复合材料设计,计算得到天线反射器基频为138.53 Hz,蒙皮减重达到16.1%;将超薄高模量碳纤维织物蒙皮与蜂窝夹芯胶接制造反射器,并通过正弦振动试验验证了超薄高模量碳纤维织物可以应用于星载天线反射器结构。     

单向导湿三维机织物的开发

以不同细度的丙纶长丝作为原料,运用差动毛细效应原理,设计开发了具有单向导湿性能的正交、角联锁和多层接结三种结构的15层三维机织物,通过对三种结构织物导湿性能的测试分析,优选出正交结构为导湿性能最佳的三维机织物结构。     

玻纤捆绑纱双轴向经编碳纤维增强复合材料拉伸性能的研究

为了探讨玻璃纤维捆绑纱对复合材料拉伸性能的影响,对使用高性能玻璃纤维作为捆绑纱的双轴向碳纤维织物以及复合材料进行了拉伸性能测试,分析了材料的破坏模式以及影响因素。结果表明,使用玻纤捆绑纱并未提高增强织物的经向和45°的拉伸强度;玻纤捆绑纱可改善树脂浸渍,减少捆绑纱附近的应力集中,增强碳纤维层间的结合,大大提高碳纤维断裂同时性,从而提高其拉伸性能。捆绑纱相同时,经平组织试样经向强度优于编链组织,凸显了玻纤纱的优势,材料的拉伸性能更好。     

三维织物碳／碳复合材料中层间剪切强度的改进

碳纤维增强碳(C/C)复合材料是由沥青基碳纤维粗纱纺织的多层织物和煤沥青基体构成的,本次实验研究了两种C/C多层织物复合材料和一种平纹编织C/C布复合材料,测试了弯曲、剪切和压缩强度。根据不同跨距--高度比下的三点弯曲试验结果,表明C/C1多层织物复合材料具有高的剪切性能,多层织物复合材料的分层断裂比平纹编织C/C布复合材料具有更高的层间断裂韧性。     

组织结构对三维机织物的吸水导湿性能影响

以差动毛细效应为基础,细旦丙纶和黏胶长丝为原料,设计织造了正交结构、角联锁结构和多层接结结构的三维机织物,并对各织物的吸水导湿性能进行测试分析。结果表明:正交结构三维机织物的吸水导湿性能最优。     

碳纤维织物在室内空间中的设计与性能研究

为了将现代碳纤维织物应用于室内空间设计,对比分析了编织角度和纤维含量对单向编织对称铺层复合材料和二维编织对称铺层复合材料拉伸强度、拉伸模量和破坏模式的影响。结果表明,单2试样的最内层和最外层角度的差值高于单1和单3试样,造成纤维体积分数明显减小,拉伸强度明显降低;二维2试样的最内层编织角相较于二维1和二维3分别增加5o和3o,最内层编织角都相比增加了3o,纤维体积分数分别减小3.02%和2.87%,拉伸强度分别减小30.22MPa和7.7MPa;编织角和纤维含量都会对单向编织对称铺层复合材料和二维编织对称铺层复合材料的拉伸强度和拉伸模量造成显著影响。相较于单向编织对称铺层复合材料,二维编织对称铺层复合材料中的裂纹或者裂缝变得杂乱无章,但破坏最严重的区域都出现在外侧,而1/2宽度处的破坏相对较轻。     

竹/麻复合材料的性能研究

采用不同的铺层比例以及化学试剂,考察了苎麻/竹纤维复合材料的拉伸强度。试验结果表明:与未处理试样相比,经过KH-570和NaOH处理以后,复合材料试样的拉伸强度有所提高。随着竹纤维含量的增加,经KH-570处理的试样的拉伸强度逐渐增大,而经NaOH处理的试样的结果与之相反。     

双罗纹衬纬纬编针织物增强复合材料的拉伸性能

在电脑横机上使用玻璃纤维编织了三种双罗纹衬纬纬编针织物,以玻璃纤维针织物作为增强体,采用手糊工艺与环氧树脂复合制备了复合材料板材,在万能强力机上测试了复合材料试样的拉伸性能。结果表明,双罗纹衬纬纬编针织物增强复合材料在横向拉伸时的应力应变曲线呈现近似线性,纵向拉伸具有明显的屈服现象,横向拉伸断裂强度和模量最高,斜向次之,纵向最低;拉伸应变沿横列方向最小,拉伸性能各向异性明显;复合材料拉伸性能与增强织物结构、密度和纤维体积分数有关。     

Drape behavior of 3D woven glass‐epoxy composites

This article deals with the drapability of 3D woven glass fabrics for composite applications. The study focuses on forming a 3D fabric over the mold, the result is a preform, which generally is then injected with a polymer matrix by so called Liquid Composite Molding (LCM) technique. When draping pre–impregnated composites, the fabric is embedded in the epoxy resin as matrix material. Various drape models for dry and pre‐impregnated fabrics have been proposed in the work. Solidworks and ANSYS are the software used for modeling and simulation of 3D woven fabric composites. Given the linear density (tex) and density of E‐glass fiber, the radius of the yarn was calculated. So far the cross section of yarn is assumed to be perfectly circular in shape, keeping the perimeter of yarn constant the circular cross section was deformed into a race track shape which is a much more practical and realistic shape of a yarn cross section. After calculating all the required dimensions, all the three 3D woven structures namely angle interlock, warp interlock and orthogonal were developed in solidworks. All the parameters like total number of warp and weft yarn per unit distance and thickness of the fabric were kept constant in all three structures. The analysis is based on first principles and the parameters of yarn and fabric construction. Results obtained through simulation are reported. These are validated with experimental composite samples. The model used to predict drapability of 3D woven glass‐epoxy composite gives good results. Orthogonal structure proves to be the best as far as resistance to deformation is concerned. However, if a relatively more flexible and formable prepreg is desired, it is advisable to use angle interlock or warp interlock structures. Warp interlock 3D structure proves most beneficial for draping on a mold. POLYM. COMPOS., 37:472–480, 2016. © 2014 Society of Plastics Engineers     

制备工艺对亚麻增强聚丙烯复合材料拉伸性能的影响

以亚麻纤维为增强体,与聚丙烯（PP）长丝进行丝束级共混,形成PP包覆亚麻的纱线结构,利用机织工艺织成二维机织布,作为复合材料的预制件。采用层合热压方法制备PP／亚麻复合材料板材。通过对板材拉伸性能测试及扫描电镜（SEM）拉伸断口形貌分析,研究了不同纤维体积分数、织造密度及织造组织等因素对复合材料拉伸性能的影响。结果表明,在选取最优热压温度与压力的条件下,纤维体积分数为50％的板材性能最优;经向密度相同时,拉伸性能随着纬向密度的增加而提高;经、纬向密度均相同时,斜纹3／1组织的板材性能最优,纬向最大拉伸强度可达92．42 MPa。     

New constitutive model for anisotropic hyperelastic biased woven fibre reinforced composite

Abstract

This paper presents an improved constitutive model having application in finite element analysis of composites made of hyperelastic matrix with biased woven fabric reinforcement and is based on a pragmatic approach and the continuum mechanics theory. A generalised strain energy function is developed via a series of uniaxial tests in fibre warp and weft directions and via shear tests of representative samples of composite fabric. The proposed material characterisation approach is demonstrated on composites made of neoprene rubber matrix with nylon biased woven reinforcements having volume fraction composition 0·74 vol.-% neoprene and 0·26 vol.-% nylon. The material parameters in the anisotropic hyperelastic model are obtained by minimisation of least square residuals of uniaxial and pure shear energy densities against the respective strain invariants. Numerical simulations of uniaxial and bulge tests of the composites using the material model presented in this paper are shown to correspond well with results obtained from laboratory experiment.     

三维正交机织物组织结构的几何表征和数学表征

切取三维正交机织物沿经向和纬向的连续横截面,在三维视频显微镜下拍摄和分析织物横截面中经纱、纬纱和Z纱的横截面形态、纱线空间构型,用参数方程表征理想状态下织物中经纱、纬纱和Z纱截面尺寸及屈曲形态。基于三维绘图软件Pro/E,重构三维正交机织物单胞模型及大尺寸织物模型,使其能更准确、更真实地反映三维正交机织物真实细观结构。     

Establishment of a color tolerance for yarn-dyed fabrics from different color-depth yarns

Yarn-dyed fabric is often woven from warp and weft yarns in the same color depth to ensure a uniform color appearance. The difference in color depth between warp and weft tends to result in the uneven color of the yarn-dyed fabric. This article aims to establish a color tolerance for yarn-dyed fabric that can be woven with a qualified color appearance but from the warp and weft yarns in different color depths. A total of 27 yarn-dyed fabric samples in three color series (red, yellow, and blue) were evaluated by using the yarn-dyed fabric from warp and weft yarns in the same color depth of 2% (on weight of fabric, owf) as the standard. Visual assessment and instrumental measurement of color were carried out to establish the color tolerance ellipse that was defined as CMC (Color Measurement Committee) color differences (2:1) of no more than 1.00. It was found that the color strengths (K/S) and color differences (ΔE_CMC(2:1)) of these fabric samples for each color series had linear relationships with the color depths of warp and weft yarns. The color tolerance ellipses indicated that, even though the warp and weft yarns had an apparent color difference, they could be woven in fabrics with relatively uniform color appearance and meet the requirements for yarn-dyed fabric. This work provided valuable insight into the production of qualified yarn-dyed fabrics from unqualified dyed yarns.     

Creep and relaxation behavior of woven glass/epoxy substrates for multilayer circuit board applications

The creep behavior of a common woven glass/epoxy composite substrate for multilayer circuit board applications was characterized using dynamic mechanical analysis (DMA). The creep compliance was measured in both the warp and fill directions of the composite over a temperature range of 30°C to 155°C. The creep compliance of the neat FR-4 epoxy matrix was also characterized for comparison with the composite response. Master creep curves were obtained for the neat resin and the composite in the warp and fill directions assuming thermorheologically simple behavior and applying the time-temperature superposition principle. The creep data was fit to a Prony series and then converted to relaxation data in the Laplace domain. Micromechanical models were developed to predict the relaxation behavior of the woven glass/epoxy composite from the elastic properties and the geometry of the glass fabric and relaxation behavior of the neat resin. Model predictions were compared with experimental data.     

An experimental and theoretical study of creep of a graphite/epoxy woven composite

The creep behavior of woven fiber polymer composites has been investigated through both an experimental study and analytical modeling. In the modeling, the matrix is assumed to be a 4-parameter model (a Maxwell-Voigt combination) and the fibers to be elastic. The fiber undulation model developed by Ishikawa and Chou for elastic behavior of woven fiber composites has been extended to the viscoelastic system by the correspondence principle. This considers the longitudinal and transverse fibers separately. The weave geometry and dimensions are accounted for, thus bringing the model closer to the actual composite. While this model has been used previously to predict the composites elastic behavior, this is the first time it is considered as a viscoelastic solid, which helps determine its time dependent behavior. The resultant model takes into account the different parameters associated with the weave (the density of the fibers in the weave, the radius of the fibers and the profile of the fill and warp fibers), volume concentration of the fiber and matrix in the composite, and the elastic moduli of the fill and warp fibers and the viscoelastic properties of the polymer matrix. We have conducted creep tests on graphite fiber/epoxy composites to evaluate our model. Experiments have been conducted from room temperature (22°C) to 200°F (93°C). The results from experiments have been analyzed and an inverse simulation has been performed to obtain the unknown parameters of the matrix and fibers in the composite. The model is then used to predict the creep behavior of the woven fiber composite under other loading conditions and temperature levels, showing satisfactory agreement with the data.     

Use of a predictive colour model for managing the colour appearance of two‐colour woven fabrics

The aim of this study was to implement a two‐dimensional colour appearance model for prediction of the colour values of weft threads when the optical mixing of a two‐colour woven structure had to match the colour appearance of a single‐colour reference woven fabric. Five single‐colour woven fabrics were woven from five threads of similar hue. One of the samples was chosen as a reference, for which the colour appearance was the goal to be achieved in the two‐colour woven fabrics prepared with the other available warp threads and newly dyed weft threads. The colour values of dyed weft threads were predicted by a two‐dimensional colour appearance model. With dyed weft threads, managing the colour appearance of the two‐colour woven fabric was enabled to achieve the colour values of the reference. In the results, colour deviations between the predicted and measured colour values of weft threads revealed some limitations to the colour appearance model and performance of the dyeing process. After the production of the two‐colour woven fabric, the colour appearance matched the appearance of the reference, resulting in deviations of ΔE_CMC(2:1) = 1.2‐7.8. Moreover, the differences between theoretically predicted and measured colour values of the two‐colour woven fabric were evaluated as small, ranging from ΔE_CMC(2:1) = 1.5‐1.9. The results demonstrated the efficiency of implementing the colour appearance model and the dyeing process of weft threads as an approach to achieve the defined colour appearance of two‐colour woven fabrics, which with small colour deviations matches the colour of a single‐colour reference.     

GA747织机生产新型玻璃纤维纱罗网布的实践

新型玻璃纤维纱罗网布的地经和纬纱采用玻璃纤维无捻直接纱,绞经采用涤纶丝生产,取代传统网布使用的有捻纱线,并去除传统纺织中的整经工序,在GA747织机上安装绞综综框且采用合理的织造工艺,有效降低原料成本,提高产品品质。     

The large deformation elastic response of woven kevlar fabric

The large deformation elastic response of a plane woven Kevlar fabric is investigated analytically and experimentally. The analysis assumes the undeformed geometry to be a sequence of interlaced arcs of circles that reverse at each yarn midpoint, and each yarn is modeled as an extensible elastica subject to certain compatibility conditions. Deflection-force relations for the fabric are determined in terms of the initial weave geometry and the elastic properties of the individual yarns. The theoretical results agree well with the results of experiments performed on a fabric woven from 400 denier Kevlar yarns under conditions of uniaxial loading in both warp and fill directions.