具有三维编织结构碳纤维复合材料管件的能量吸收机理

以碳纤维与环氧树脂通过真空辅助树脂传递成型技术制备得到具有三维四向编织结构的管件物为研究对象,探究了编织角(30°、45°、60°)和编织结构中排纱层数(3、4、5层)对碳纤维复合材料管件在轴向压缩条件下吸能性能的影响.试验结果表明:采用三维编织结构可以阻止在厚度方向上裂纹的扩展;编织角的变化所引起的碳纤维复合材料管件的压缩模式以及能量吸收特性的变化较明显,而编织层数则无明显影响.     

PTT“形状记忆”织物回复原始形状的机制

为探究PTT（聚对苯二甲酸丙二醇酯）“形状记忆”织物回复原始形状的机制,设计试验,分别应用悬臂梁装置和模仿人熨烫服装的熨烫力作用,研究了外力、温度、外力与人体温度联合3种外界条件对该类织物折皱回复性能的影响。实验结果表明：温度对织物经纬向的回复性能均无明显影响,当温度升至PTT聚合物玻璃化转变温度以上时,织物的折皱回复角没有显著提高;模仿人熨烫服装的作用力对该织物回复原始形状非常有效,当施加很小的力（5 N/cm²）,折皱回复率就超出81%,当温度低于和高出聚合物的玻璃化转变温度时,施加同样的力,PTT织物的折皱回复率却没有显著提高,故认为力是影响PTT“形状记忆”织物回复其原始形状的主要因素。     

温敏形状记忆织物的开发及其起拱回复性研究

探讨棉温敏形状记忆聚氨酯包芯纱织物的加工方法及其起拱回复性能。通过分析形状记忆聚氨酯纤维的性能及其作用原理,设计了棉温敏形状记忆聚氨酯包芯纱织物,并将其与纯棉织物和棉氨纶包芯纱织物进行了起拱回复性能的对比试验。试验结果表明,温敏形状记忆聚氨酯包芯纱织物经过热处理后,热回复率高于其他织物,具有良好的形状记忆功能。     

棉/形状记忆氨纶纬编免烫衬衫面料制备及其性能评价

为改善纬编衬衫面料的折皱回复性能，利用温敏型形状记忆氨纶与棉纱设计了平纹、单珠地、双珠地3款面料，并对面料进行3种不同预定形温度处理。分别对形状记忆氨纶的转变温度、形状记忆性进行表征，同时对面料的折皱回复性、形状记忆性、弹性回复性、缩水性进行评价。结果表明，当环境温度达到32.45℃及以上时，即人体体温就可触发形状记忆氨纶的形状记忆功能；形状记忆氨纶的使用可改善纬编衬衫面料的折皱回复角与弹性回复率，当形状记忆氨纶含量为8.4%时，折皱回复角与弹性回复率可分别提高20.5%、14.35%。     

形状记忆聚氨酯材料的进展

国内外形状记忆聚氨酯材料在性能改进上的最新进展,包括链段上的优化设计,与各种无机纳米材料的掺杂复合,交联和超分子网络化改性等.各种改性方法皆在获得更佳形状固定率、形变回复率、精确的形状记忆温度、材料的耐热性和力学强度以及生物适应性等性能.近几年,形状记忆聚氨酯在医学领域、纺织领域以及其它相关领域均获得新的应用和进展.     

编织结构周围神经再生导管的径向压缩性能研究

研究了几种用于修复周围神经缺损的编织结构聚乙丙交酯(PGLA)神经再生导管及其径向压缩性能。为了获得更佳的径向压缩性能,对编织结构和编织角等工艺参数对导管50%变形时的径向压缩力、压缩力保持率和弹性回复率等径向压缩力学性能的影响进行了实验和讨论。     

形状记忆整理织物的折皱回复角与温度的关系

探讨形状记忆整理织物在热环境下的折皱回复角随温度变化的规律。结果表明,形状记忆整理织物在热水和热空气介质中,在激发温度60℃附近具有温度响应,折皱回复角显著增大。说明形状记忆整理织物对定型时的平整形状具有记忆,并在激发温度附近回复形状。由于导热系数不同,相同温度下,热空气中的折皱回复时间比热水中的回复时间长得多。采用非线性回归方法进行计算发现,形状记忆整理织物在热环境下的折皱回复角与温度存在指数关系。热水介质中温度与折皱回复角函数为y=3.446 7x0.557 9;热空气介质中温度与折皱回复角函数为y=3.282 0x0.591 0。     

形状记忆聚氨酯在非织造织物中的应用

应用涂层工艺,将不同浓度的形状记忆聚氨酯涂覆到非织造织物上,制得具有不同聚氨酯含量的形状记忆聚氨酯非织造织物材料,并对处理前后非织造织物的表面结构、形状回复性、折皱回复性、透气透湿性、强伸力等性能进行了测试。实验结果表明:经形状记忆聚氨酯处理后的非织造织物具有很好的形状记忆功能,提高了非织造织物的抗皱性能;当聚氨酯含量较少时,对形状记忆聚氨酯非织造织物的透湿性没有显著影响,但透气性有明显下降。     

碳纤维增强编织复合材料圆管的扭转力学性能及其损伤机制

为研究编织层数对编织复合材料圆管的扭转力学性能和失效模式的影响,采用二维编织铺层(Over-Braiding)工艺及真空辅助树脂灌注成型工艺分别制备了2、3和4层的碳纤维/树脂编织复合材料圆管.通过搭建扭转试验-非接触全场应变测试平台,研究了3种编织层数的复合材料圆管的扭转力学响应.基于扫描电子显微镜与微计算机断层扫描...     

压烫工艺对SMF/棉机织物的折痕保持性能研究

为研究压烫工艺对聚氨酯形状记忆纤维(SMF)/棉机织物的折痕保持性能,采用不同的压烫温度和压烫时间制备了25个试样,并进行折痕保持性(CR值)的测试。结果表明,在压烫时间不变的情况下,随着压烫温度的提高,织物的CR值呈上升态势;只有当外界作用温度高于形状记忆纤维定型温度一定幅度时,织物的CR值才达到最高值(5级);最佳压烫工艺为温度190℃,时间50 s。对6个CR值达到5级的试样进行形变固定率、形状回复率、缩水率和平整度的测试,结果显示经过压烫定型整理后的SMF/棉机织物具有较高的形变固定率和形状回复率,以及优于纯棉织物的布面平整度和尺寸稳定性。     

Quasi-static compression and compression–compression fatigue characteristics of 3D braided carbon/epoxy tube

This study presents an experimental study of the quasi-static axial compression and compression–compression fatigue behavior of a three-dimensional braided carbon/epoxy composite tube. Three kinds of tubes with different braiding angles, i.e. 25º, 35º, and 45º were used to examine the dependence of fatigue behavior on the braiding parameters. Quasi-static compression and compression–compression cyclic loadings were carried out on the braided composite samples. The S–N [stress and number of cycles to failure] curves, strain–N (number) curves, and damage observation were used to evaluate the behavior of the braided tubes under fatigue loading. The test results showed that braiding angle had significant effect on the ultimate compression strength (UCS) and the number of cycles per stress level that the sample could withstand. The tube with 25º braiding angle had the highest UCS while the tube with 45º braiding angle accumulates high number of cycles for the same stress level as compared to other samples. Damage occurred along the braid angle for 25º tubes while matrix crack plus bulging occurred in the tubes with 35º and 45º braiding angles.     

Axial compressive deformation and damage of four-step 3-D circular braided composite tubes under various strain rates

This paper reports the axial compressive deformation and damage of three-dimensional (3-D) braided carbon/epoxy composite circular tubes under quasi-static and high strain rate loadings. Three kinds of 3-D circular braided composite tubes with different braiding angles of 25°, 35°, and 45° were tested under strain rates of 0.001/s, 330/s, 500/s, and 650/s. The stress–strain curves, deformation and damage of the braided tubes under axial compressions were obtained to analyze the compressive failure mechanisms and the influences of the braiding angles on the compressive behaviors. A finite element model based on the meso-structure of the braided preform and the braided composite was established to reveal the axial compressive deformation and damage mechanisms. The axial compressive behaviors were compared both in the finite element analyses (FEA) results and the tested data, and good agreements were found. From the FEA and experimental results, it was concluded that the compressions deformation, damage, and stress–strain curves are sensitive to the strain rate and the braided angles. The strain rate and braided angle are the key parameters for the design of the braided composite tubes with high compression strength.     

碳纤维二维编织管状织物的编织工艺

针对碳纤维在二维编织过程中不耐扭折、易受损断纱的问题,通过拉伸性能实验和导纱瓷眼折角磨损实验分析了碳纤维复丝的可编织性能,探讨了纱管在缠绕过程中应注意的问题。在24 锭二维编织机上编织了8 种不同工艺参数的碳纤维管状编织物,研究了编织工艺对织物外观起毛情况及力学性能的影响。结果表明：碳纤维复丝的断裂强度为86.39 cN/tex,断裂伸长率为1.12%,断裂强度远高于其他纤维,但延伸性差;影响碳纤维复丝在导纱瓷眼处折角磨损程度的因素依次为牵引力、折角、编织速度;在编织纱线根数不变的情况下,随编织节距的减小,管状编织物的面密度逐渐增加,起毛现象严重,编织物的拉伸断裂强力降低。     

光纤布拉格光栅在复合材料连续状态健康监测中的应用

为实现三维编织复合材料状态健康连续监测,根据三维编织复合材料的编织工艺,将光纤布拉格光栅(FBG)传感器嵌入到复合材料制件中,分析拉伸承载下的制件内部应变与FBG传感器信号变化的关系.实验结果表明,FBG传感器信号与制件应变具有较好的线性关系,复合材料的表面编织角对FBG的信号具有一定影响,嵌入FBG传感器对复合材料的...     

碳纤维增强编织复合材料圆管制备及其压缩性能

为进一步探究编织结构与长度对复合材料圆管压缩性能的影响,采用树脂传递模塑成型工艺复合二维编织铺层与三维四向编织圆管,通过轴向准静态压缩试验获取了4种复合材料圆管试样的压缩力学行为。结合高速摄影记录,分析了编织复合材料圆管的破坏过程及失效模式,探索其压缩失效机制。结果显示:试样均表现出弹塑性特征,但三维编织圆管呈现出更好的压缩承载特性,其压缩模量与载荷峰值分别达到5.91 GPa与14.23 kN;试样呈现出纤维断裂、基体开裂脱黏、瓣状破坏、剪切以及挤压屈曲等破坏模式中的几种或全部的组合;二维编织复合材料圆管的渐进失效特征更为明显,具有较好的吸能特性,且其压缩模量随管件长度的增加而有所提升,但是吸能效果与试样长度呈非线性关系。     

二维二轴编织铺层复合材料压缩性能的研究

利用二维编织机,设计编织用芯模尺寸,编织成不同层数的编织铺层复合材料。讨论多层碳纤维/环氧树脂编织铺层复合材料的压缩性能,并分析不同层数、不同编织角的编织铺层复合材料的平均压缩模量的变化规律及压缩破坏模式。结果表明,随着层数的增加,编织铺层复合材料的平均压缩模量呈下降趋势;在同一块编织铺层复合材料板内,编织角影响编织铺层复合材料的平均压缩模量,其随编织角增大而减小;编织铺层复合材料的压缩破坏模式主要是分层现象较明显,其次是树脂剥离、碳纤维脆断。     

Finite element analyses on longitudinal compressive behaviors of 3D braided carbon /epoxy composite with different braided angles at low temperatures

This paper presents a numerical study on the effect of temperature and braided angle on quasi-static longitudinal compression of 3D braided carbon fiber/epoxy composites. The 3D braided composites with different braided angles, i.e. 26°, 35° and 48° were analyzed to examine the temperature-dependent longitudinal compressive behaviors with finite element method (FEM) based on the full-scale meso-structure model. Three temperatures (20, ?50 and ?100 °C) were used to investigate the influence of temperature on the longitudinal compression behaviors. In addition, the imperfect interface and the fiber waviness were combined into the FEM model. Both interfacial properties and fiber waviness were closely associated with compression modulus of 3D braided composites. The FEM results revealed thermal stress distribution and its influence on stress evolution in braided composites with different braided angles. The influence of temperature on stress distribution manifested the temperature-dependent damage of 3D braided composite.     

Surface parameters measurement of braided preform based on local edge extreme

This paper proposes a local edge extreme-based method to automatically measure the pitch length and surface braiding angle of braided preforms. The Lab space transform and an artistic edge and corner enhancing filter are used first to pre-process the original acquired images. An algorithm based on local edge extreme is then used to detect corners. Finally, the pitch lengths and surface braiding angles are measured based on the detected corner maps. Experimental results show that the proposed method achieves automatic measurements of pitch lengths and surface braiding angles of biaxial braided carbon-fiber preforms with good accuracy.     

编织管增强型聚乳酸中空纤维膜结构及其性能

为制备兼具高强度、高分离精度的聚乳酸(PLA)中空纤维膜,采用同心圆复合纺丝技术,分别制备了PLA同质编织管与聚对苯二甲酸乙二醇酯(PET)异质编织管增强型PLA中空纤维膜。考察聚乙二醇(PEG)相对分子质量对PLA增强膜结构和性能的影响,并通过物理反冲洗、超声水浴振荡实验研究了同质、异质编织管表面分离层与增强体界面结合性能。结果表明:随PEG相对分子质量的增大,纤维膜的表面孔径逐渐减小,渗透通量先增大后减小,牛血清蛋白截留率先增大后保持稳定,添加PEG相对分子质量为10 000的增强膜的渗透通量最大且分离效果最佳;增强膜与同质编织管的界面结合性能明显优于异质的。