双轴向纬编针织复合材料准静态侵彻性能及有限元模拟

本文使用双轴向纬编针织复合材料，利用MIS得出材料准静态侵彻实验的载荷-位移曲线，并计算得出侵彻功-位移曲线。运用有限元方法，模拟整个破坏过程，通过计算得出理论上的载荷-位移曲线和侵彻功-位移曲线。将模拟结果与实验结果进行比较，表明两种分析结果具有较好的一致性，并揭示双轴向纬编针织复合材料准静态侵彻机理。     

三维正交机织复合材料准静态侵彻实验和有限元模拟

用钢制侵彻体对三维正交机织复合材料在MTS材料试验机上作准静态侵彻测试，得到的准静态侵彻位移一载荷曲线用来研究材料的能量吸收和破坏模式。根据三维机织复合材料的细观结构建立单胞模型，结合应力更新原理编写用户子程序（VUMAT）。利用ABAQUS有限元软件及用户子程序模拟实验过程，得到的位移一载荷曲线与实验对比，可以看出有限元计算得到的结果与真实实验比较吻合，表明单胞的建立和用户子程序的编写是正确的。     

纬编双轴向多层衬纱织物增强复合材料的弯曲性能研究

本文主要对高性能纤维的纬编双轴向多层衬纱织物增强复合材料的弯曲性能进行研究分析.本文所用的增强纤维为玻璃纤维和高强聚乙烯纤维两种,增强织物包括玻璃纤维织物、高强聚乙烯纤维织物及玻璃纤维/聚乙烯纤维层间混合织物三种,基体为乙烯基酯树脂,文中着重对几种复合材料的弯曲性能进行测试和分析比较.分析结果表明,该类复合材料有很好的弯曲性能,含有玻璃纤维的横向弯曲破坏有其特点,玻璃纤维为脆性破坏,而聚乙烯纤维表现为屈曲破坏.     

双轴向经编针织复合材料的冲击压缩性能

利用分离式霍普金森压杆(SHPB)装置对双轴向经编针织(BWK)复合材料在面外、面内共三个方向进行了高应变率压缩试验,并在MTS材料试验机上进行了准静态压缩试验。计算并提取各应变率下的应力-应变曲线,观察各应变率下材料的破坏形态特征。结果表明,双轴向经编针织(BWK)复合材料具有应变率敏感性和各向异性,在面外压缩中其破坏形态主要是剪切破坏,在面内压缩中准静态下为剪切破坏,在高应变率下为分层破坏。     

缝合混杂针织结构复合材料准静态弯曲试验及有限元模拟

利用MTS-810材料试验机,研究缝合层合板复合材料的准静态三点弯曲实验,分析准静态下材料的破坏机制,即上表面的压缩破坏和下表面的拉伸破坏。根据缝合层合板的细观结构建立单胞模型,连接用户子程序,进行有限元模拟,深入分析材料破坏机理和最终破坏模式,两者均说明经向材料和纬向材料的破坏无显著区别,并且两者的载荷-位移曲线和能量吸收曲线具有良好的一致性,证明有限元模拟的正确性,为进一步研究纺织复合材料的力学性能奠定良好的基础。     

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。     

三维纺织预型件织物

在现有的制备工艺中,具有一定厚度的复合材料通常由若干层单层织物经铺设而成。由于织物层间缺乏有效的增强,在动载荷作用下,层间剥离是这种结构复合材料的主要失效形式之一。提高复合材料层间断裂韧性有多种方法,如采用高性能热塑性树脂、优化复合材料界面微结构以及利用具有三维结构的纺织预型件加工复合材料制品等,其中后面一种方法由于具有仿型加工和结构整体性的特点,而被认为是顺应当前复合材料制造发展趋势的新方法,此外,这种方法容易实现工艺自动化,有成本低的潜在优势,对于制件的加工重复性,提高韧性及损伤容限,这种方法也有着十分重要的意义。目前,用于复合材料领域的三维纺织预型件主要有：正交织物、多层机织物、多层针织物、编织物和缝合织物等。近期国内外对上述产品的盛开开发证明,这是提高复合材料层间抗剪切强度和降低生产成本的有效前途。     

双轴向经编针织复合材料的弹道侵彻破坏

通过真空辅助树脂传递模压法（VARTM）制造双轴向经编针织复合材料。在350～750m/s冲击速度范围内对复合材料作弹道冲击测试,得到弹体的入射速度、剩余速度及动能损失,弹体的剩余速度与入射速发近似满足线性关系,动能损失随弹速的增加呈现先上升后下降的状态。考察复合材料靶体的弹道侵彻破坏损伤形态,发现复合材料受弹面的破坏区域较子弹出射面的破坏区域小且破坏形态不同,由此揭示双轴向经编针织复合材料的弹道侵彻破坏模式与机理。     

新型起圈织物增强蜂窝夹层板力学性能研究

复合材料夹层结构由于其优越的力学性能被广泛应用于当今航空工业,但是传统编织二维复合材料夹层板在厚度方向抗分层与抗剥离能力较差,起圈织物作为一种新型三维机织复合材料,可通过z方向预织的毛圈有效改善复合材料夹层板在厚度方向的力学性能。但目前国内对起圈织物增强夹层结构的力学性能研究较少。对起圈织物蜂窝夹层板的平拉力学性能进行研究,通过真空袋成型工艺制作了玻璃纤维起圈织物增强夹层板与传统玻璃纤维夹层板并完成平拉试验,获得了平拉载荷作用下的力-位移曲线与拉伸强度。试验结果表明起圈织物增强蜂窝夹层板具有更高的平拉模量与平拉强度。主要原因是固化时,起圈织物夹层板的蜂窝夹层中形成了环氧树脂胶柱体。胶柱体参与了芯材受力,增大了拉伸模量,同时嵌入胶柱体的毛圈也提高了起圈织物夹层板的平拉强度。由此可以得出结论:起圈织物可以有效提高蜂窝夹层板的平拉性能。最后就研究中出现的一些问题提出相应的改进方法与思路。     

热塑性摩擦纺包芯纱纺织预型件的织造

纺织结构在纤维增强复合材料中占有重要地位.对于连续纤维增强热塑性复合材料,预混料具备良好的纺织加工性能是顺利加工纺织预型件的前提.由于热塑性摩擦纺包芯纱的特殊结构,采用机织和纬编针织两种方法进行预型件的加工,结果表明:热塑性摩擦纺包芯纱有较好的纺织加工性,其经纬密度等技术参数和纺织结构均可根据热塑性复合材料成型物的要求进行选择.     

柔性复合材料及其增强体顶破形态和机理的研究

本文研究了柔性机织复合材料及其增强体顶破的破坏形态和失效机理。在MTS-810材料试验机上分别对两种材料进行准静态顶破实验测试,通过观察顶破过程中两种材料变形,指出它们形变的异同点。并对实验得到的载荷—位移曲线进行分析讨论,说明材料在顶破载荷作用下的失效机理以及涂层对织物顶破性能的影响。     

An acoustic emission study on the fracture behavior of continuous glass fiber/polypropylene composites based on commingled yarn

The fracture behavior of continuous glass fiber reinforced polypropylene composites made of commingled yarn in the form of biaxial (±±45°) noncrimp warp‐knitted fabric, twill woven fabric, and swirl mat, respectively, was investigated by virtue of single edge notched tensile (SEN‐T) specimens. These composite laminates were manufactured by compression molding and cooled at two different rates (1°C/min and 10°C/min) during the last processing phase of the laminates. The failure mechanisms were studied by acoustic emission (AE) analysis. AE amplitude ranges corresponding to the individual failure modes have been identified. For biaxial noncrimp fabric reinforced materials, the failure mechanisms involved in the fracture procedure are governed by the interface related failure events. Higher cooling rate, which is accompanied by better fiber/matrix adhesion, results in not only the increase in the relative proportion of high‐amplitude failure events, but also the occurrence of a large quantity of fiber fracture events. For woven fabric and mat reinforced composites, fiber‐dominated failure mechanisms result in the higher fracture toughness when compared with biaxial noncrimp fabric composites. Under this circumstance, the change in cooling rate only results in the difference in the relative frequency of the individual failure modes. In addition, it is found out that the initiation fracture toughness of SEN‐T specimens can be easily assessed by marking the load value which corresponds to the first point of AE signals emitted stably in AE events‐displacement curves. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers     

机织/针织混合铺层对复合材料力学性能的影响

为使纺织复合材料同时具有机织结构复合材料和针织结构复合材料的综合力学性能,通过混合铺层方式制备机织/针织混合结构复合材料。以芳纶机织平纹织物和针织罗纹织物为增强体,以环氧树脂为基体,调整复合材料中增强体的铺层顺序,利用真空辅助成型技术制备四层层压机织/针织混合结构复合材料。通过对复合材料拉伸性能、弯曲性能和冲击性能的测试,分析混合铺层和铺层顺序对芳纶环氧树脂复合材料力学性能的影响。结果表明,混合铺层和铺层顺序对芳纶环氧树脂复合材料的弯曲强度和冲击强度有较大影响,特别是对罗纹结构复合材料纬向弯曲强度和冲击强度的改善。当采用相同铺层方式,罗纹织物为受力面时,机织/针织混合结构复合材料具有较大弯曲强度和冲击强度。     

Energy absorptions and failure modes of 3D orthogonal hybrid woven composite struck by flat‐ended rod

Three‐dimensional (3D) orthogonal woven composite has high stiffness, strength, and energy absorption capacity along X, Y, and Z directions because there are no crimps in yarn. This paper presents mechanical behaviors and energy absorptions of the 3D orthogonal hybrid woven composite under transverse impact and quasi‐static loading by flat‐ended rod. The failure load and energy absorption of the composite increase with the increase in loading rate. The damage morphology of the composite coupon manifests the compression failure in the front side and tension failure in rear side. There are no delaminations in the composite coupons for both quasi‐static and impact loading for the existence of Z‐yarn in fabric structure. This phenomenon manifests the potential application of the 3D orthogonal woven composite to impact resistance areas. POLYM. COMPOS., 27: 410–416, 2006. © 2006 Society of Plastics Engineers     

三维角联锁机织复合材料低速冲击破坏的有限元计算

测试三维角联锁机织复合材料低速冲击性能,得到复合材料在低速冲击过程中的载荷－位移曲线等。结合采用冲击接触定律、单元失效准则和材料刚度退化技术,建立复合材料低速冲击的三维有限元单胞模型。运用商业有限元软件ABAQus／Explicit,联合用户子程序（VUMAT）计算复合材料低速冲击破坏过程。比较有限元计算结果和实验结果,发现二者在载荷一位移变化规律和复合材料破坏形态上较为吻合。     

Mechanical performance of tubular composites reinforced by innovative 3D integrated knitted spacer fabrics

This article aimed to investigate the mechanical performance of 3D integrated knitted spacer composites with a tubular shape, in term of internal hydrostatic and external static pressures (ESP). All the tubular‐knitted fabrics were produced on a modern flat knitting machine using untwisted glass and HT‐nylon yarns. Then, the epoxy resin was transferred through the whole fabric structure via vacuum infusion molding process. Produced tubular composites were subjected to internal hydrostatic and ESP. Accordingly, force–displacement curves were obtained and experimental results were discussed. The results revealed that the tubular composite samples containing non‐knitting yarns show 27.33 and 37.50% improvement in internal hydrostatic and ESP, respectively, compared with the plain knitted fabric reinforced composite. Also, the finding demonstrated that mechanical performance of the tubular‐knitted spacer composites is highly affected by aspect ratio and the number of connecting layers. Knitted spacer reinforced composite containing 5 and 10 connecting layers can improve the resistance against internal hydrostatic pressure 35.08 and 51.29%, respectively, compared with the plain knitted reinforced composites. In this case, 84.20 and 89.86% improvement can be achieved in term of the resistance against ESP. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46074.     

编织复合材料的横向冲击力学行为研究

本文利用冲击加载实验装置对碳纤维编织复合材料梁的横向冲击损伤与断裂行为进行了实验研究,确定了不同冲击速度下冲击载荷响应、梁的动态位移变化以及梁的动态应变演化历史等动态力学行为,给出复合材料梁的冲击吸收能量及其Mises有效应力。同时,利用扫描电镜对编织复合材料的损伤断裂机理进行微观分析。     

Fracture evolution in thick composites under compression

This study reports the evolution of fracture in thick woven fabric composites under static compression loading. The materials examined were carbon/epoxy composites laminated with up to 180 plies of the woven prepreg. A pressure rolling setup was designed and employed in the present materials in order to compact the laminate and to remove air possibly trapped in between plies. To apply the compressive load, an end‐supported, end‐loaded fixture was used. The growth of cracks was monitored and recorded in real‐time by picture and video cameras. The continuous monitoring of the failure progression provides detailed information about the onset and growth of cracks in various specimens under different support conditions. The modulus, strength, and the loss of stiffness in the post‐failure portion have been examined. The loading curves have several sudden drops and regains in the post‐failure portion. The causes of the sudden load drop can be identified by correlating with the corresponding fracture image. The influence of the support in the fixture has been examined. Two major modes of failure are fiber kink‐band and longitudinal splitting. The branching and coalescence of cracks of these two modes of failure have been observed and examined. Thickness effects exist in the present composites. The processing–property relationships are discussed. How these modes evolve with the applied strain in specimens of different thicknesses and how they affect the load‐carrying capability of the material are examined. POLYM. COMPOS., 28:425–436, 2007. © 2007 Society of Plastics Engineers     

三维多重结构增强玄武岩复合材料的力学性能研究

根据机织和针织复合材料各自的特点，以玄武岩纤维为材料，设计出一种新型的三维玄武岩纤维增强复合材料。对这种复合材料进行了拉伸、弯曲和重锤冲击测试，并对三种破坏机理进行了分析。     

Bending properties of the multilayer‐connected biaxial weft knitted fabrics‐reinforced composites made with carbon fibers

This article presents an experimental study of bending properties of multilayer‐connected biaxial weft knitted (MBWK) fabrics‐reinforced composites made with carbon fibers. Three types of composites are used in bending test, which are three‐layer‐connected biaxial weft knitted fabric‐reinforced composite, four‐layer‐connected biaxial weft knitted fabric‐reinforced composite and five‐layer‐connected biaxial weft knitted fabric‐reinforced composite. Two‐way ANOVA analyzing method was used to deal with whether the carbon fiber volume fraction and the cutting direction have significant effect on the bending strength of the MBWK fabrics‐reinforced composites. Failure analysis is also available by means of samples debris examination to identify the failure mode. POLYM. COMPOS., 36:2291–2302, 2015. © 2014 Society of Plastics Engineers