不同层数的超高分子量聚乙烯纬平针织复合材料冲击损伤

研究了不同层数超高分子量聚乙烯(UHMWPE)纤维/环氧树脂纬平针织复合材料的冲击性能,并讨论了其冲击损伤模式。复合材料板分别为4、6、8层纬平针织结构,采用真空辅助树脂传递模塑(VARTM)工艺层合而成,以不同的冲击能量(10~55J)冲击复合材料板直至层合板被穿透,得到冲击能量与吸收能量关系图以及接触力-挠度曲线。分析了不同冲击能量下,复合材料中织物的损伤形式和破坏过程。研究结果表明:在3种针织结构复合材料中,8层纬平针织结构承受载荷的能力最强,6层纬平针织结构次之,4层纬平针织结构最差;随着冲击能量的增加,3种试样的冲击挠度均增大;基体开裂、纤维断裂是试样被渗透时有效的损伤模式,基体和纤维断裂是试样被穿孔时有效的损伤模式。     

GF/PCBT复合材料熔融连接接头失效分析的实验研究与数值模拟

为了解决高黏度热塑性树脂难以制备高强度、大尺寸纤维增强热塑性复合材料构件的问题,采用真空辅助树脂传递模塑(VARTM)工艺与热压工艺相结合的方法,以环状对苯二甲酸丁二醇酯(CBT)在催化剂作用下聚合成的聚环状对苯二甲酸丁二醇酯(PCBT)为基体,制备了纤维体积分数达70%的连续玻璃纤维(GF)/PCBT复合材料层合板及熔融连接件,并测得其力学参数。采用数值模拟方法对连接界面层数分别为1、2、3层的A、B、C型3种不同方案的GF/PCBT复合材料熔融连接接头的承载能力和失效模式进行了预测。结果表明:不同的结构设计方案对GF/PCBT复合材料接头性能的影响较大,当连接长度在一定范围内时,接头区域主要发生界面分层失效,接头处复合材料的翘曲为界面裂纹加速扩展的主要因素,C型连接方式的接头结构承载能力相比于A型连接方式有明显提高;增加C型接头连接长度,试件承载能力提高,直至接头处界面分层失效和纤维、基体失效同时发生;继续增加连接长度,纤维与基体失效将成为接头区域的主要失效模式,此时承载能力无明显提升。     

大丝束CF/EP汽车地板VARTM模拟与高温力学性能

汽车轻量化是全球面临的共同问题,采用更具成本优势的大丝束碳纤维（CF）增强复合材料是实现汽车轻量化结构化的重要途径。然而,大丝束碳纤维在液体成型时,单束过多的纤维丝易导致纤维束内微观浸润困难,易产生干斑、气泡等缺陷。同时,传统的汽车电泳烘干工艺对复合材料的高温性能提出了挑战。鉴于此,本文采用0°/90°双轴向缝编大丝束碳纤布和耐高温环氧树脂（EP）,开展了纤维渗透率测试和汽车地板真空辅助树脂传递成型（VARTM）模拟优化研究,设计、制造了成型模具,成功试制出汽车地板样件,超景深显微镜观测显示纤维束内和层间浸润良好,无明显缺陷。高温在线拉伸和应变测试显示,温度对材料拉伸模量影响显著而对强度影响不大,180℃高温下应变恢复能力良好,表明该材料在高温下仍具备较好的强度和抗蠕变性能,该结果对指导复合材料能否通过传统汽车的电泳烘干工艺具有重要意义。     

亚麻纤维增强热固性树脂复合材料板材的研究

本文以亚麻纤维作为原料,经过针刺工艺制得亚麻纤维针刺毡,作为复合材料的增强体.通过改变纤维、热固性树脂种类,利用真空辅助RTM方法及模压法制备复合材料板材.对板材进行了拉伸及弯曲性能测试,比较了不同纤维和树脂的结合情况,进一步阐述了板材破坏机理.     

非织造工艺对天然纤维增强体树脂流动性能的影响

纤维增强体的树脂流动性能是影响树脂传递模塑工艺设计及其复合材料质量的一个重要因素。本文利用单向法测试真空辅助传递模塑工艺中非织造工艺对亚麻纤维增强体对树脂流动性能的影响。结果表明,相同压力条件下,由平行铺网工艺制作的纤维增强体比交叉铺网工艺增强体树脂渗透率低,流动各项异性大;随着层数的增加及压力的增大,两种铺网工艺增强体的树脂渗透率降低,压力的变化对流动各向异性影响不大。     

复合材料液体模塑成型技术(LCM)的研究进展

LCM是近些年发展起来的一类复合材料成型技术。它的出现打破了长久以来高性能复合材料必然具有制造成本高的惯例,为高性能复合材料开辟了广阔的应用领域。LCM工艺技术是先进复合材料低成本制备技术的主要发展方向,是现在复合材料领域研究的重点。LCM成型技术主要包括:RTM、VARTM、SCRIMP、RFI、SRIM。主要综述了这几种常见的LCM工艺各自的发展现状、成型原理、特点、存在的问题以及解决对策。     

Comparison of the fatigue behaviors of FRP bridge decks and reinforced concrete conventional decks under extreme environmental conditions

This paper summarizes the results of the fatigue test of four composite bridge decks in extreme temperatures (-30°C and 50°C). The work was performed as part of a research program to evaluate and install multiple FRP bridge deck systems in Dayton, Ohio. A two-span continuous concrete deck was also built on three steel girders for the benchmark tests. Simulated wheel loads were applied simultaneously at two points by two servo-controlled hydraulic actuators specially designed and fabricated to perform under extreme temperatures. Each deck was initially subjected to one million wheel load cycles at low temperature and another one million cycles at high temperature. The results presented in this paper correspond to the fatigue response of each deck for four million load cycles at low temperature and another four million cycles at high temperature. Thus, the deck was subjected to a total of ten million cycles. Quasi-static load-deflection and load-strain responses were determined at predetermined fatigue cycle levels. Except for the progressive reduction in stiffness, no significant distress was observed in any of the composite deck prototypes during ten million load cycles. The effects of extreme temperatures and accumulated load cycles on the load-deflection and load-strain response of FRP composite and FRP-concrete hybrid bridge decks are discussed based on the experimental results.     

A structural supercapacitor based on activated carbon fabric and a solid electrolyte

ABSTRACT

This paper presents investigations to create a structural supercapacitor with activated carbon fabric electrodes and a solid composite electrolyte, consisting of organic liquid electrolyte 1?M TEABF₄ in propylene carbonate and an epoxy matrix where different compositions were considered of 1:2, 1:1 and 2:1 w/w epoxy:liquid electrolyte. Vacuum-assisted resin transfer moulding was used for the impregnation of the electrolyte mixture into the electrochemical double layer capacitor (EDLC) assembly. The best electrochemical performance was exhibited by the 1:2 w/w epoxy: liquid electrolyte ratio, with a cell equivalent-in-series resistance of 160?Ω?cm² and a maximum electrode-specific capacitance of 101.6?mF?g^?1 while the flexural modulus and strength were 0.3?GPa and 29.1?MPa, respectively, indicating a solid EDLC device.     

FTIR and SEM analysis of polyester‐ and epoxy‐based composites manufactured by VARTM process

Polyester‐ and epoxy‐based composites containing glass and carbon fibers were manufactured using a vacuum‐assisted resin transfer molding (VARTM) process. Fourier transform infrared (FTIR) spectroscopy analyses were conducted to determine the interaction between fibers and matrix material. The results indicate that strong interaction was observed between carbon fiber and epoxy resin. However, weak interactions between remaining fiber‐matrix occur. Scanning electron microscopy (SEM) analysis was also performed to take some information about strength of interaction between fibers and matrix material. From SEM micrographs, it is concluded that the findings in SEM analysis support to that obtained in FTIR analysis. Another aim of the present work was to investigate the influence of matrix on composite properties. Hence, the strengths of composites having same reinforcement but different matrix systems in axial tension and transverse tension were compared. Short beam shear test has been conducted to characterize the interfacial strength in the composites. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

缝合参数对缝纫平纹玻璃纤维织物复合材料弯曲性能的影响研究

本文参照美国ACT计划设计的最优缝合参数,用无捻Kevlar纤维缝合成不同缝合密度的预成型体,讨论并优化了缝合过程中重要参数的影响。采用改良的缝合机器,使缝合质量大幅提升,并发展了加固嵌板的缝合技术。本文采用VARTM工艺制备玻璃纤维织物增强复合材料,通过比较不同缝合密度下的力学性能,讨论了VARTM工艺中缝合密度对材料性能的影响。实验结果表明,在一定的缝合密度下,缝合复合材料能表现出最好的冲击韧性。随着缝合密度的提高,复合材料的弯曲性能下降,但是层间性能有所提升。