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。     

二维二轴编织铺层复合材料细观几何模型及拉伸模量的一种计算方法

建立了一套工程实用的二维二轴2×2编织结构的单层和多层的细观几何模型及拉伸模量的计算方法,分析复合材料的细观结构特征,考虑了编织纱束的实际横截面形态和屈曲起伏,还有实际编织工艺和成型固化,提出了单层和多层结构复合材料的细观几何模型,基于细观分析,建立了单层和多层二维二轴编织铺层复合材料等效力学模型和拉伸模量的计算方法,最终计算数值结果趋势上与实际情况一致,在具体数值上吻合度很好,表明该方法实际有效可行。结论表明,建立的细观几何模型能很好地表达单层和多层二维二轴2×2编织复合材料的结构特征,等效力学模型能够很好地反映复合材料的拉伸行为,建立的拉伸模量预测方法能够很好地导出拉伸模量。     

三维编织结构参数对复合材料拉伸性能的影响

通过7组实验比较和分析研究,评价了编织结构参数(如编织角,纤维体积分数,轴向纱数与编织纱数之比,三维四向/五向,厚度)对复合材料拉伸性能的影响,且对复合材料的破坏模式进行了研究。实验结果表明,三维编织复合材料具有良好的力学性能,编织角、复合材料尺寸、纤维体积含量、轴向纱数与编织纱数之比等对复合材料的性能有较大的影响;复合材料有两种破坏模式,一种是裂纹沿纤维束扩展,另一种是纤维束拉断,后者为主要破坏模式。这些结果为三维编织复合材料的设计提供了依据。     

三维全五向编织复合材料的弯曲性能研究

以无碱玻璃纤维为原料,采用四步法1×1编织工艺在全自动模块组合式编织平台上制备三维五向及全五向编织物;以E51环氧树脂、70#固化剂(四氢邻苯二甲酸酐)为树脂基体,与编织物复合制备三维五向及全五向编织复合材料;利用Instron万能材料试验机对比测试上述编织复合材料的弯曲性能,研究轴纱、编织角、纤维体积分数等结构参数对材料弯曲性能的影响。结果表明,编织复合材料的弯曲性能随着编织角的增加而减少,随着轴纱、纤维体积分数的增大而增加;三维全五向编织复合材料的弯曲性能明显好于三维五向编织复合材料。     

二维三轴编织复合材料的开孔静力学性能及失效行为

为考察典型二维三轴编织复合材料(2DTBC)在开孔条件下的静力学性能及失效机理，采用机器人辅助二维三轴编织及真空树脂灌注工艺成型制备了2DTBC试样，并分别考察了其在开孔拉伸(OHT)、开孔压缩(OHC)、单钉单剪(SBS)及单钉双剪(SBD)四种典型开孔静力测试下的力学响应及失效行为。结果表明：较传统层合板而言，2DTBC的开孔性能保持率显著提高，轴向及横向开孔拉伸强度保持率分别达到94.77%和96.88%，轴向及横向开孔压缩强度保持率分别达到93.25%和82.74%。OHT试样的失效模式表现为纤维束断裂、纤维束拉拔损伤、基体破坏和界面分层损伤。OHC试样的失效模式表现为纤维束屈曲失效、分层损伤和基体破坏。SBS及SBD试样的失效模式主要表现为螺钉连接处的分层、纤维束开裂及基体破坏，且试样在达到载荷峰值后没有立即失效，表现出了较好的能量吸收能力。     

二维编织复合材料管件轴向压缩性能研究

通过优化二维编织复合材料管件复合工艺,制作了碳纤维含量较高的碳纤维复合材料管件,同时对管件进行了轴向压缩性能测试,分析并探讨了编织参数对复合材料管件纤维体积含量及轴向压缩性能的影响。结果表明:优化后的复合工艺可保持复合材料管件纤维体积含量在20%~40%之间,同时使得复合后管件的内径达到一致;在编织速度不变的情况下,随着编织节距的减小,编织角逐渐增加,纤维体积含量逐渐增加,当编织节距减小到一定程度后,纤维体积含量的增加变缓,而轴向压缩强度先升高后降低,当达到最大值时,编织角为46°。     

二维两轴编织铺层复合材料压缩弹性性能的一种计算方法

通过在体式显微镜下,观测编织铺层复合材料纱线走向,考虑纱线在交织处屈曲起伏,纤维轴向模量会有部分损失,提出纤维轴向模量损失系数ξ。通过测量编织复合材料中的基本参数,结合复合材料细观结构、弹性力学、迭层理论和多层等效弹性力学模型,利用推导出一套比较简单而实用的二维两轴编织铺层复合材料平均压缩模量的计算方法。实验结果表明:理论计算值与实测值吻合度较高,为编织复合材料的工业应用提供了一种简单而实用的弹性性能计算方法。     

二维编织复合材料管件力学性能研究进展

综述了近年来国内外对二维编织复合材料管件力学性能的研究成果及研究进展,主要包括力学性能实验研究、结构几何模型和数值仿真研究。在实验研究中介绍了二维编织复合材料管件的能量吸收性能及弹性性能,同时重点介绍了编织角及编织结构的变化对复合材料各种性能的影响的最新研究进展;在结构几何模型研究中,以细观结构、宏-细观结构模型研究为主,详细介绍了当前流行的建模方法;在数值仿真研究方面,介绍了研究人员根据二维编织成型原理以及纤维在复合材料中的取向建立的实体模型仿真分析。最后,总结当下研究中存在的问题,并对未来研究趋势进行展望。     

2．5维编织复合材料的细观结构与弹性性能

介绍2．5维编织工艺的概念,归纳3种较有代表性的细观结构几何模型并对比各结构模型的优缺点,从理论计算与数值模拟两方面总结2．5维编织复合材料弹性性能预测的研究成果,最后分析了几何结构及经、纬密等工艺参数对纤维体积分数（体积含量）与复合材料弹性性能的影响。     

二维编织复合材料在正交切削中的切削力和加工表面质量研究

二维编织碳纤维复合材料因其具有优异的力学性能和耐疲劳、耐冲击等特点被广泛用于制造各类复合材料结构件中。但是由于二维编织碳纤维复合材料的多相性和特殊的纤维结构,其机械加工性能与传统金属材料和单向纤维复合材料差异较大。为了研究二维编织碳纤维复合材料的切削性能,提高加工效率和加工后的表面质量,基于正交切削实验对二维编织碳纤维复合材料在切削过程中的切削力进行测试,并利用金相显微镜和粗糙度轮廓仪来表征加工表面质量。实验结果显示,正交切削过程中纤维方向角度对切削力的大小影响巨大,当切削速度提高和切削深度降低时,复合材料展现了更好的切削性能,并且加工后的表面质量更高。     

In-situ observation of damage in unidirectional CMC laminates under tension

We observe microscopic damage progression in un-notched unidirectional SiC–SiC ceramic matrix composite laminates loaded monotonically in tension. In situ tensile testing was conducted in air at room temperature and combined with X-ray tomography imaging. The unidirectional specimens tested were novel double-reduced dogbones designed to develop matrix cracks in the synchrotron field of view. Multiple matrix cracks that rapidly traversed the section of each specimen were observed through the volume until the specimens broke into two pieces. The details of each matrix crack were tracked at each stress increment to better understand how the cracks evolve under load. One of the unidirectional specimens contains a matrix crack that displays a sharp 90° turn along the fiber direction in its final crack path. Fiber breaks were observed and several fibers in the unidirectional specimen showed multiple breaks. Fiber break opening was measured for each fiber break and the average fiber break opening for each stress increment is reported. The location and pullout distance of fiber breaks surrounding a matrix crack, as well as matrix crack spacing, are of modeling interest and are reported.     

单向芳纶/玻璃纤维混杂复合材料板材拉伸性能研究

本文对单向芳纶/玻璃纤维复合材料进行制作,对其纵向拉伸强度、拉伸模量和弹性伸长进行实验分析。实验结果表明,单向混杂复合材料的拉伸断裂大多为多次性,界面数越多,一次性断裂的可能性越大。界面数为1的混杂纤维复合材料的芳纶纤维体积含量在对拉伸强度影响上的存在临界值,表现出明显的混杂效应。界面数大于1的混杂复合材料在芳纶纤维铺层数一定的情况下,界面数的多少不影响混杂复合材料拉伸强度和拉伸弹性模量的大小。界面数大于1比界面数为1的复合材料的拉伸强度和拉伸模量明显偏高。同时对不同制作条件下纯玻璃纤维单向复合材料的拉伸性能进行剖析。     

Micromechanical analysis of long fiber‐reinforced composites with nanoparticle incorporation into the interphase region

The influence of the distribution type, Young's modulus, and volume fraction of the nanoparticles within the interphase region on the mechanical behavior of long fiber‐reinforced composites with epoxy resin matrix under transverse tensile loading is investigated in this article. An infinite material containing unidirectional long fiber and periodic distribution of elastic, spherical nanoparticles was modeled using a unit cell approach. A stiffness degradation technique has been used to simulate the damage and crack progress of the matrix subjected to mechanical loading. A series of computational experiments performed to study the influence of the nanoparticle indicate that the mechanical properties, nanoparticle‐fiber distance, and volume fraction of nanoparticle have a significant effect on both the stiffness and strength properties of these composite materials. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41573.     

Mechanical characterization of triaxially braided hybrid composites

The use of advanced composites has been expanded to the oil and gas industry. One of the newly developed technologies is in composite coiled tubing that offers the potential of exceeding the performance of metallic tubings. The high strains due to bending and the complex state of stress in these tubes necessitate the better understanding of the correlation between fiber architecture and tube performance. Braided composites can withstand high bending deformation without severe degradation of properties. In this study, braided hybrid composites are presented as an option for achieving high performance coiled tubing under tensile and flexural loads. The effects of material and fabric microstructural parameters on the mechanical behavior of braided hybrid composites are studied. The mechanical characterization of triaxially braided composites has identified the influence of the mechanical properties of the axial yarn, the axial yarn volume fraction, and the braid angle. Overall, this study provides a sound knowledge base for the design, fabrication, and characterization of triaxially braided composites for coiled tubing applications in the petroleum industry.     

Hysteresis loops of carbon fiber-reinforced ceramic-matrix composites with different fiber preforms

The hysteresis loops of C/SiC ceramic-matrix composites (CMCs) with different fiber preforms, i.e., unidirectional, cross-ply, 2D and 2.5D woven, 3D braided, and 3D needled at room temperature have been investigated. Based on fiber slipping mechanisms, the hysteresis loops models considering different interface slip cases have been developed. The effects of fiber volume fraction, matrix cracking density, interface shear stress, interface debonded energy, and fibers failure on hysteresis loops, hysteresis dissipated energy, hysteresis width, and hysteresis modulus have been analyzed. An effective coefficient of fiber volume fraction along the loading direction (ECFL) was introduced to describe fiber preforms. The hysteresis loops, hysteresis dissipated energy and hysteresis modulus of unidirectional, cross-ply, 2D and 2.5D woven, 3D braided and 3D needled C/SiC composites have been predicted.     

Mechanical properties of unidirectional continuous fiber self‐reinforced polyethylene graded laminates

The aim of this study is to prepare of self‐reinforced polyethylene graded composite laminates (SrPEGCL) by adopting both concepts of “graded” and “self‐reinforced” and analyze their mechanical properties under tensile loading. Three different kinds of fiber volume fractions were employed to prepare continuous fiber unidirectional symmetry SrPEGCL with two graded directions. Tensile experiments were carried out to investigate tensile properties of SrPE composites in longitudinal, transverse, and 45‐bias direction. The microscopic failure mechanism of SrPEGCL were studied and observed by Scanning Electron Microscope (SEM). Laminate stress analysis with ply‐by‐ply discount method was adopted to investigate the damage mechanism using failure criteria and parallel spring model. Observations and conclusions about the effect of graded structure and graded direction on mechanical properties of SrPEGCL under tensile loading were discussed. Compared to common self‐reinforced polyethylene composites, SrPEGCL with the same or even less overall fiber volume fraction exhibited 10–20% higher tensile strength under longitudinal, transverse and 45‐bias loading direction, while graded direction had an effect on the mechanical strength of SrPEGCL as well. POLYM. COMPOS., 36:128–137, 2015. © 2014 Society of Plastics Engineers     

Electromechanical characteristics of unidirectional glass fiber epoxy composites

Because crack detection for laminated composites in‐service is an effective method for improving structural reliability, various nondestructive methods have been studied to detect cracks in laminated composites. A recent study on the damage monitoring of composite materials using the piezoelectric method, which uses the piezoelectric characteristics of polymeric materials for the matrix of composite materials, concluded that the piezoelectric method can be a useful, nondestructive method for the damage monitoring of glass fiber epoxy composites. The dielectric and piezoelectric properties of composites are the basic properties used for the analysis of electromechanical coupling systems, along with the mechanical properties. In this research, therefore, the electromechanical characteristics of unidirectional glass fiber epoxy composites as well as their electric and mechanical characteristics were investigated. The dielectric, piezoelectric, and mechanical properties of unidirectional glass fiber epoxy composites were measured experimentally with respect to the fiber orientation, and the relationship between the piezoelectric and mechanical characteristics of unidirectional glass fiber epoxy composites was analyzed. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

正交各向异性易碎复合材料层合板的设计与试验研究

提出一种新型正交各向异性易碎复合材料结构,利用单向连续纤维板具有纵向拉伸强度高而横向易于被撕裂的特点,在制备好的单向板上垂直于纤维方向预制刻槽,然后将单向板正交复合而制备成正交各向异性易碎复合材料层合板,并对这种层合板作了承压试验与冲击试验.结果表明,所设计并制备的正交各向异性易碎复合材料层合板试样可承受一定的均布载荷...     

Determination of mechanical properties of glass‐epoxy composites in high temperatures

The objective of this study is to determine the tensile, compressive, and shear properties of unidirectional glass/epoxy composite plates under room (∼20°C) and high (40, 60, 80, and 100°C) temperatures. Mechanical properties were determined according to the ASTM standards. A hot lamination press was used for fabrication of composite plates. For curing process, laminated plates were retained at a constant pressure (250 kPa) and 120°C during 2 h. And then, composite plate is cooled to room temperature at the same pressure. The fiber volume fraction of laminated composite plate is measured as 65%. Experimental results show that the mechanical properties (except for the transverse tensile strength) of glass/epoxy composites are reduced by increasing temperature. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Investigation of mechanical properties of unidirectional steel fiber/polyester composites: Experiments and micromechanical predictions

The article introduces steel fiber reinforced polymer composites, which is considered new for composite product developments. These composites consist of steel fibers or filaments of 0.21 mm diameter embedded in a polyester resin. The goal of this investigation is to characterize the mechanical performance of steel fiber reinforced polyester composites at room temperature. The mechanical properties of unidirectional steel fiber reinforced polyester composites (SFRP) are evaluated experimentally and compared with the predicted values by micro‐mechanical models. These predictions help to understand the role of material and process parameters on material properties. Two types of SFRP were studied: polyester resin reinforced by both steel fabric containing unidirectional fibers and steel fibers wound on a metal frame with 0° orientations. The effects of the fiber volume fraction and the role of polymer yarns (weft) on mechanical properties were analyzed through tensile, compressive, and shear tests. These tests were performed as per the standard test procedures. In particular, issues related to processing difficulties, polymer yarns effect on properties, standardized testing, and properties under various loading conditions were addressed. Microscopic observations were analyzed to assess the laminate quality and the macroscopic fracture surfaces of shear test specimens were studied by standard techniques. POLYM. COMPOS., 37:627–644, 2016. © 2014 Society of Plastics Engineers