三维机织夹芯复合材料的制备与压缩性能研究

以玻璃纤维为原料,采用2个系统经纱(一个为上下表层经纱,另一个为夹芯层经纱)、1个系统纬纱,在SU111型全自动剑杆织机上制织经向截面为“口”字形的新型三维夹芯织物.以环氧树脂E-44与9055型固化剂为基体体系,采用手糊成型工艺将上述机织物复合制成三维机织夹芯复合材料.研究三维机织夹芯复合材料的压缩性能,分析材料结构与压缩性能之间的关系,并与“8”字形中空复合材料进行比较.结果表明,芯材间距为5mm的“8”字形中空复合材料的压缩强度高于芯材间距为25 mm的三维机织夹芯复合材料,但是后者的弹性模量高于前者.实验结果对该类结构材料的优化设计与力学性能研究具有极其重要的指导价值.     

整体夹芯中空复合材料的性能研究与开发应用

整体夹芯中空复合材料是一种新型的结构、功能材料,具有学性能优异,可设计性强的特点.本文研究了中空复合材料的成型工艺、连接方式,制作了满足测试要求的测试件,对材料的经、纬向的拉伸、平压、双层剪切和四点弯曲等性能进行了测试研究,获得了该种材料的主要力学性能参数,并与类似的蜂窝等夹层材料进行了性能对比.简单概述了该类材料的应用开发情况,并展望了在国内的开发与应用前景.     

整体夹芯中空复合材料的性能研究与开发应用EI

整体夹芯中空复合材料是一种新型的结构、功能材料,具有学性能优异,可设计性强的特点.本文研究了中空复合材料的成型工艺、连接方式,制作了满足测试要求的测试件,对材料的经、纬向的拉伸、平压、双层剪切和四点弯曲等性能进行了测试研究,获得了该种材料的主要力学性能参数,并与类似的蜂窝等夹层材料进行了性能对比.简单概述了该类材料的应用开发情况,并展望了在国内的开发与应用前景.     

嵌入式增强多层整体机织中空复合材料及其抗压性能的研究

提出一种对叠经多层间隔结构整体机织复合材料的改进方法,该结构复合材料采用增强体嵌入的方式对材料强度进行改进,增加了中空复合材料强度的可设计性。对嵌入用的增强体材料、非嵌入的多层整体机织中空复合材料和嵌入后的多层整体机织中空复合材料分别进行了抗压力学性能测试。在平压和侧压力学测试实验中,嵌入式机织复合材料的力学性能均好于非嵌入机织复合材料,而在平压测试实验中,得到了嵌入式机织复合材料预制体与树脂的共同增强系数为1.40,证明该嵌入式机织复合材料结构设计的合理性。此外得出3种材料侧压的力学性能也均好于平压。     

复合材料管状结构的能量吸收性能

复合材料结构作为防撞结构的能量吸收元件,已经逐步得到工程领域的广泛认同。复合材料结构的能量吸收能力是一种特殊要求的力学性能,它的研究目标和研究手段有其独特之处。综述了近年来复合材料管状结构能量吸收性能研究的最新进展,以及有待进一步研究的问题。     

蜂窝状三维整体机织结构型吸波复合材料的设计、制备与性能

为了解决蜂窝夹层结构材料的开裂和分层问题,以玄武岩纤维长丝纱和碳纤维长丝纱为原料,在普通织机上,经合理设计,织造了顶层为透波层、中间层为吸波层和底面为反射层的蜂窝状三维整体机织结构型吸波织物;其次,以蜂窝状三维整体机织结构型吸波织物为增强体,双酚A型环氧树脂为基体,羰基铁粉(CIP)和炭黑(CB)为吸波剂,采用真空辅助树脂传递模塑(VARTM)成型工艺,制备了不同结构参数的蜂窝状三维整体机织结构型吸波复合材料;最后,采用矢量网络分析仪和万能试验机分别对蜂窝状三维整体机织结构型吸波复合材料的吸波性能和力学性能进行研究。研究表明,其有良好的整体性能,兼具吸波和承载能力。     

树脂基体种类对三维中空夹芯织物复合材料力学性能影响的研究

以不饱和树脂和环氧树脂为基体,与三维中空织物分别复合成中空夹芯织物复合材料,利用万能材料试验机分别对2种复合材料的拉伸、压缩和弯曲性能进行测试,研究了树脂种类对复合材料力学性能的影响规律。结果表明:不饱和树脂与固化剂质量比为100∶2,固化温度为70℃时,复合材料具有最佳的拉伸、弯曲和压缩性能。环氧树脂基复合材料的弯曲和压缩性能远优于不饱和树脂基复合材料,而拉伸性能则相差不大。     

含局域共振单元复合材料格栅夹芯结构的吸声性能研究

提出了一种耐静压的复合材料格栅夹芯吸声结构.格栅格内填充聚氨酯基体,基体内嵌入软橡胶包覆的铁球作为局域共振散射体单元.采用有限元方法对结构在常压和3 MPa静压下的吸声性能进行了对比计算,结果表明静压下结构吸声性能稳定.通过建立吸声系数曲线、平均能耗曲线、位移场和能耗密度场的关系,对结构吸声机理进行了分析.最后采用遗传...     

复合材料点阵夹芯结构平压性能不确定分析与优化

考虑一体化成型工艺制备的复合材料点阵夹芯结构及其不确定性,采用区间向量实现不确定参数定量化,建立复合材料点阵夹芯结构平压性能区间分析模型.考虑结构功能状态判断的模糊性,分别在不考虑设计容差与考虑设计容差情形下,建立了不确定平压载荷作用下含区间参数模糊可靠性分析与优化模型.研究结果表明:材料参数及结构参数不确定性,特别是设计容差对复合材料点阵夹芯结构平压性能影响明显,因此在工程优化中不仅需要充分考虑材料参数与外部载荷等不确定性,而且需要充分重视传统不确定设计方法中未计及的设计容差的影响.本研究实现了理论成果与工程应用的有机结合,为工程领域复合材料点阵夹芯结构平压性能分析与优化提供有效理论方法.     

组织结构对三维整体中空复合材料压缩性能的影响

为了研究整体中空复合材料的压缩性能,制作了满足要求的测试件.选取不同面板组织的整体中空复合材料进行侧压性能对比实验,对不同芯材结构的整体中空复合材料进行平压性能对比实验.借助ORIGIN软件对上述几类材料的压缩特性进行分析,研究了组织结构对材料压缩性能的影响.结果表明:面板组织为平纹的整体中空复合材料的压缩性能比经重平结构材料好；芯材结构为“细长X型”的整体中空复合材料压缩性能比“扁平X型”结构材料好.     

Experimental Investigation on Low-Velocity Impact Performance of 3D Woven Textile Composites

Applied Composite Materials - The objectives of this experimental study are to develop impact-resistant three-dimensional (3D) woven textile-reinforced composites as well as to clarify the...     

Tensile Properties and Failure Mechanism of 3D Woven Hollow Integrated Sandwich Composites

Tensile properties and failure mechanism of 3D woven hollow integrated sandwich composites are investigated experimentally, theoretically and numerically in this paper. Firstly, the tensile properties are obtained by quasi-static tensile tests on the specimens in two principal directions of the sandwich panels, called warp and weft. The experimental results shows that the tensile performances of the warp are better than that of the weft. By observing the broken specimens, it is found that the touch parts between yarns are the main failure regions under tension. Then, a theoretical method is developed to predict the tensile properties. By comparing with the experimental data, the accuracy of the theoretical method is verified. Simultaneously, a finite element model is established to predict the tensile behavior of the composites. The numerical results agree well with the experimental data. Moreover, the simulated progressive damages show that the contact regions in the warp and weft tension are both the initial failure areas.     

Influence of Fibre Architecture on Impact Damage Tolerance in 3D Woven Composites

3D woven composites, due to the presence of through-thickness fibre-bridging, have the potential to improve damage tolerance and at the same time to reduce the manufacturing costs. However, ability to withstand damage depends on weave topology as well as geometry of individual tows. There is an extensive literature on damage tolerance of 2D prepreg laminates but limited work is reported on the damage tolerance of 3D weaves. In view of the recent interest in 3D woven composites from aerospace as well as non-aerospace sectors, this paper aims to provide an understanding of the impact damage resistance as well as damage tolerance of 3D woven composites. Four different 3D woven architectures, orthogonal, angle interlocked, layer-to-layer and modified layer-to-layer structures, have been produced under identical weaving conditions. Two additional structures, Unidirectional (UD) cross-ply and 2D plain weave, have been developed for comparison with 3D weaves. All the four 3D woven laminates have similar order of magnitude of damage area and damage width, but significantly lower than UD and 2D woven laminates. Damage Resistance, calculated as impact energy per unit damage area, has been shown to be significantly higher for 3D woven laminates. Rate of change of CAI strength with impact energy appears to be similar for all four 3D woven laminates as well as UD laminate; 2D woven laminate has higher rate of degradation with respect to impact energy. Undamaged compression strength has been shown to be a function of average tow waviness angle. Additionally, 3D weaves exhibit a critical damage size; below this size there is no appreciable reduction in compression strength. 3D woven laminates have also exhibited a degree of plasticity during compression whereas UD laminates fail instantly. The experimental work reported in this paper forms a foundation for systematic development of computational models for 3D woven architectures for damage tolerance.     

2.5维机织复合材料的强度特性

针对浅交弯联和浅交直联两种2.5维机织结构,采用VARTM工艺制备了试验件并进行了强度性能测试,通过对其拉伸后的试样进行切片和断面的SEM观察,研究了拉伸过程中复合材料内部的破坏机理。实验结果表明:在相同纱线排列密度情况下,浅交直联结构的经、纬向拉伸强度明显高于浅交弯联结构;随着纱线层数的增加,两种结构的经向拉伸强度均增大,而纬向拉伸强度则有所波动;对于不同结构的2.5维机织复合材料在单一拉伸载荷作用下,表现出不同的损伤模式,且损伤的初始位置和扩展路径具有一定的分散性。     

Shear Behavior of 3D Woven Hollow Integrated Sandwich Composites: Experimental,Theoretical and Numerical Study

An experimental, theoretical and numerical investigation on the shear behavior of 3D woven hollow integrated sandwich composites was presented in this paper. The microstructure of the composites was studied, then the shear modulus and load-deflection curves were obtained by double lap shear tests on the specimens in two principal directions of the sandwich panels, called warp and weft. The experimental results showed that the shear modulus of the warp was higher than that of the weft and the failure occurred in the roots of piles. A finite element model was established to predict the shear behavior of the composites. The simulated results agreed well with the experimental data. Simultaneously, a theoretical method was developed to predict the shear modulus. By comparing with the experimental data, the accuracy of the theoretical method was verified. The influence of structural parameters on shear modulus was also discussed. The higher yarn number, yarn density and dip angle of the piles could all improve the shear modulus of 3D woven hollow integrated sandwich composites at different levels, while the increasing height would decrease the shear modulus.     

三维织造复合材料用导向套的表面结构研究

设计并制备了5种不同表面结构的导向套,采用单根导向套压出实验、三点弯曲实验,并结合破坏界面形貌的观察,研究了不同表面结构对导向套与树脂界面结合强度及其自身抗弯性能的影响。结果表明,相对于无加工的导向套,周向粗化后的导向套与树脂结合强度提高了56%。而轴向开槽导向套、径向开孔导向套及表面带嵌合槽的导向套与基体的界面结合强度相对无加工导向套,提高了40%~46%;带凸起结构对于界面结合强度的提高不明显。同时,周向粗化处理和带凸起结构的导向套,其抗弯强度与无加工的导向套相差不大;而轴向开槽、嵌合槽结构、径向开孔处理均不同程度地降低了导向套的抗弯强度,其中径向开孔对导向套的抗弯强度的降低幅度最大。晓国种     

三维机织管状复合材料力学模型与实验验证

对管状结构的三维机织复合材料采用椭圆形纤维束截面假设,提出一种管状结构的单元体划分方式,建立力学模型预测其工程弹性常数.采用分层研究的方法.讨论了弹性模量以及纤维体积含量与圆管半径的关系.自行设计了一套RTM(Resin Transfer Molding)注射装置并研究其成型工艺,制备实验件进行轴向拉伸、压缩和扭转实验,理论预测值和实验值具有良好的一致性,证明力学模型的正确性.     

2.5维机织复合材料强度准则

2.5维机织复合材料已有较为广泛的应用,目前对该类复合材料强度理论的研究还相对较少。根据2.5维机织复合材料拉伸破坏的细观机理,基于单向复合材料的三维Hoffman准则,建立了2.5维机织结构复合材料拉伸破坏准则,通过对2.5维机织复合材料3种结构24个试件进行拉伸试验,与计算预测结果的对比表明了本文建立的强度准则的合理性。研究表明,纤维拉伸断裂是2.5维机织复合材料拉伸破坏的主要原因;相比基于最大应力准则、Hashin准则建立的强度准则,基于Hoffman准则建立的强度准则综合考虑了纤维在外载荷作用下各应力分量对纤维断裂破坏的影响,其预测结果与实际试验结果更为接近;在其他条件不变情况下,随纱线取向角增大,纱线拉伸断裂应力呈非线性降低。随纱线纤维体积含量增加,纱线拉伸断裂应力成线性增加。