探讨碳纤维布在桥梁加固工程中的应用

碳纤维布以其具有高强度、耐腐蚀、抗老化、施工简便等优异性能,目前在桥梁、隧道、混凝土结构的修复、加固、补强方面的应用得到广泛推广。讨论碳纤维布在桥梁工程中应用的问题,介绍桥梁加固中运用碳纤维布的几种方法,并以工程实例来介绍碳纤维布的应用。     

浅析碳纤维布加固砌体结构新技术

碳纤维又称碳纤维增强复合材料(Carbon Fiber Reinforced Polymer,简称CFRP)广泛应用混凝土结构加固技术,而粘贴碳纤维布对砌体结构进行加固仍处于试验研究的初始阶段。粘贴碳纤维布加固是提高砌体结构抗剪承载力和延性的非常有效的办法。本文主要介绍碳纤维布加固砌体结构的工作原理,施工步骤,总结了碳纤维布加固技术的优点,通过试验进一步探究碳纤维布在受剪构件中的力学性能。     

碳纤维材料加固钢筋混凝土梁疲劳性能分析

碳纤维材料的主要特点为耐腐蚀、施工方便、强度高、质量轻,能够在不对既有结构使用造成影响时施工,所以在桥梁加固中被广泛使用.目前研究大部分为加固梁静载性能,缺乏对碳纤维布加固混凝土梁疲劳性能的研究.以此,本文就对碳纤维材料加固钢筋混凝土梁疲劳性能进行分析.     

碳纤维布粘贴加固混凝土构件的抗爆性研究

碳纤维布增强胶粘材料在混凝土构件加固技术中的应用已是建筑及岩土工程中研究热点之一。本文就其在抗爆性能提升方面的研究,作一简要叙述。     

CFRP加固钢筋混凝土结构的技术与应用

碳纤维复合材料（CFTP）具有比强度比模量高、耐腐蚀、可设计性好且成型容易等优异特性；采用碳纤维复合材料加固钢筋混凝土结构，完全避免了传统加固方法施工周期长、难度大、费用高、不能加固曲面等形体复杂构筑物等缺点；综述了国内外有关CFRP加固钢筋混凝土结构的技术与应用的最新进展。     

碳纤维复合材料的新应用

本文介绍了国外碳纤维复合材料片及其在修补加固钢筋混凝土结构中的应用情况、碳纤维复合材料片修补加固工艺的特点和对钢筋混凝土结构物修补加固的效果及推广应用前景。     

CFRP加固含初始裂纹的RC梁的抗爆性能研究

碳纤维复合材料(CFRP)加固建筑结构是一种新兴的加固技术。国内外鲜有CFRP加固含初始裂纹的结构构件(如RC梁)的抗爆性能的研究报道。基于大型非线性动力学分析软件LS-DYNA,从加固层数和加固宽度两方面对CFRP局部全包裹加固含初始裂纹RC梁(裂纹梁)的抗爆性能进行非线性有限元数值分析。研究表明,采用CFRP对裂纹梁的裂纹处进行局部全包裹加固可提高裂纹梁的整体刚度,减小其在爆炸荷载作用下的损伤和变形程度。当CFRP的加固层数为4层、加固宽度为300mm时,可有效提高裂纹梁的抗爆性能。该研究成果对建筑结构抗爆设计和抗爆加固研究具有一定的指导意义。     

碳纤维布在水库加固工程中的应用

碳纤维布加固技术是当前比较有效和新颖的一种加固方式,碳纤维布具有非常好的力学性能,甚至能够作为钢筋的替代品在混凝土中使用。我国很多水库建设时间较为久远,运行到今天,水库的结构部分会出现各种问题,需要对其进行加固处理。研究将碳纤维布运用于水库加固工程中,其优势有加固效果好、施工简单、施工质量有所保障、防水和防腐蚀等。所以水库加固工程使用碳纤维布具有良好的效果。然后再以湖北省某水库为例,发现其闸墩和检修平台梁板不符合规范标准,通过利用碳纤维布对该结构进行加固处理,能够达到很好的施工效果,使其满足规范要求。最后提出了碳纤维布在水库加固工程中的施工注意事项,以期达到水库加固的目的。     

碳纤维布在加固工程中的应用

碳纤维布作为一种常用的复合材料,凭借着自身重量轻、强度高、施工操作高效等优势,被广泛地应用于旧桥加固工程中,为了提高旧桥加固效率和效果,本文首先以"广州港务局西基桥"为例,根据碳纤维布的主要特点,从工艺材料准备、粘贴碳纤维布典型工艺流程、关键工序施工要点等方面入手,探讨了碳纤维布粘贴施工工艺。最后,将本文所提出的碳纤维布粘贴施工工艺应用于工程实践中,结果表明:本文所提出的碳纤维布粘贴施工工艺具有非常高的可靠性和可行性,不仅可以实现对桥跨结构的科学加固,还能保证桥跨结构加固效果,其加固效果完全符合现有使用功能的需求。     

CFRP加固初始受载钢筋砼梁抗剪性能的试验研究

在一组采用CFRP进行抗剪加固的初始受载钢筋混凝土梁试验的基础上，研究了这些梁的裂纹扩展。载荷-挠度曲线，碳纤维布的应变，箍筋应变，破坏载荷和破坏特征。     

碳纤维加固材料研究新进展

阐述了结构加固用碳纤维复合材料（CFRP）在耐热性、耐候性、抗腐蚀性和抗爆炸能力方面的最新研究进展。指出防止加固构件与CFRP间发生早期层间剥离,处理好CFRP约束混凝土本构关系是今后研究核心;完善结构加固用CFRP材料标准,新研究成果的推广和实用化是今后的研究方向。     

Feather‐inspired carbon fiber reinforced polymers with nanofibrous fractal interlayer

Much work has been performed in improving carbon fiber‐reinforced polymer (CFRP) composites to prevent delamination, which is the major defect in laminated composites. Nevertheless, there is not much focus on improving conventional CFRP systems in terms of weight, especially when these are used in primary structures. This article explores whether lighter and at the same time stronger CFRP composites can be manufactured to replace conventional CFRP systems in major applications. Under this perspective, and having established the fundamentals for creating the next generation of light weight structural composites—the featherweight composites—this work introduces a feather‐inspired case which uses a controlled interlayer reinforcement in a fractal and reproducible manner at the macro‐, micro‐, and nano‐scales. By extensively describing the matrix system and the manufacturing processes and focusing on analytically and thermomechanically testing the CNT (Carbon Nanotubes) reinforced nanofiber interlayer system, it is shown that this feather‐inspired CFRP achieves significantly higher mechanical properties as well as potential weight savings. POLYM. COMPOS., 168–181, 2016. © 2014 Society of Plastics Engineers     

Ceramic molds suitable for rapid forming of CFRP composites via microwave irradiation

Carbon fiber reinforced plastic (CFRP) composites have been considered quite eminent structural materials. For more extensive applications, however, more rapid forming methods of the CFRP composites are required. As for CFRP composites with thermoplastic matrices, microwave heating and pressing with ceramic molds should be promising. In the present work, zirconia molds with varied thermal conductivity were employed to give a desired shape to the CFRP composites heated with microwave irradiation. Experimental results showed that use of the zirconia molds with smaller thermal conductivity results in shorter necessary time for the forming process. Mechanism of the notable change in the heating efficiency is discussed as well.     

Evaluation of the moulding process for production of short-fibre-reinforced C/C-SiC composites

For the production of C/C-SiC brake discs via the liquid silicon infiltration method (LSI), the hot pressing process is the state of art technique for the moulding of the CFRP composites. This technique consists of several manual steps which increase production cost. The overall cost can be reduced by implementing injection moulding process.In this paper the influence of the moulding process (hot pressing, injection moulding) on the properties of semi-finished and final products during the production of short-fibre-reinforced C/C-SiC composites by means of the LSI process are examined. The starting polymer is chemically characterised. Carbon-fibre-reinforced plastic (CFRP) composites are fabricated by hot pressing, as well as injection moulding process. The CFRP composites are converted into porous C/C composites by pyrolysis. Liquid silicon is infiltrated to form dense C/C-SiC composites, which are further investigated during the course of this paper. Significant differences in properties of the composites are discussed.     

Experimental and finite element modeling of vinyl ester nanocomposites under blast and quasi‐static flexural loading

Materials used in blast, penetration, and impact loaded structural applications require high strength and toughness under high strain rate loading. 510A‐40 brominated bisphenol‐A‐based vinyl ester resin was developed and reinforced with different loadings of nanoclay and exfoliated graphite platelet to produce composites with optimal flexural rigidity, vibration damping, and enhanced energy absorption. As these reinforced polymeric materials are viscoelastic in principle, the mechanical behavior was characterized under two extremes of strain rate loading. In this article, the macroscopic response of brominated vinyl ester reinforced with 1.25 and 2.5 wt % nanoclay and exfoliated graphite platelet is considered. Air‐blast experiment was conducted by subjecting these specimens to a high‐transient pressure in a shock‐tube with flexural loading configuration. The axial response was investigated quasi‐statically in a uniaxial tension/compression test and dynamically in a compression Split‐Hopkinson bar test. The servo‐hydraulic MTS system was used to simulate the shock‐tube testing in a flexural quasi‐static loading configuration. High strain rate properties obtained from shock‐tube experiment are compared with that of characterized under the simulated quasi‐static flexural loading. Further, a computational finite element analysis model was developed in ANSYS LSDYNA to predict with reasonable accuracy the dynamic response of shock‐loaded nanoreinforced specimens. Drop in both failure strain and energy absorption was observed with the addition of nanoparticles to pristine vinyl ester. However, an improvement in energy absorption was observed in case of shock‐tube loading at high strain rates as compared to that loaded quasi‐statically. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci., 2012     

三维针刺CFRP复合材料的制备及显微结构研究

以三维针刺碳毡作为预制体,采用树脂浸渍-热压固化工艺快速制备了碳纤维增强树脂基复合材料(CFRP)。通过光学和扫描电子显微镜观察了材料的显微结构,使用阿基米德方法测定材料的密度和气孔率,并利用压汞仪分析了材料的孔隙分布。结果表明,树脂浸渍-热压固化是一种理想的制备CFRP复合材料的方法,制备出的材料密度可达1.45 g/cm3,孔隙率仅为3%,且孔隙主要为由热应力引起的纤维束内贯穿裂纹和基体-纤维界面脱粘两类。     

复合材料单钉搭接单剪与双剪的挤压破坏试验研究

复合材料机械连接在航空结构中应用广泛,在受力过程中,挤压破坏为主要关注的破坏模式。对于复合材料单钉连接结构,单剪有面外弯曲存在,双剪可视为孔边纯挤压受力模式。采用试验的方法,研究了相同孔径、厚度及铺层的单钉单剪与单钉双剪的破坏模式、挤压变形及屈服和挤压强度,发现单剪形式的二次面外弯曲对强度及变形影响大,双剪结构大幅提高了复合材料机械连接结构的屈服强度和挤压强度。在不改变铺层比例的前提下,通过改变铺层数量,探讨了层合板厚度对单钉单剪受力及破坏的影响,发现层合板的厚度增厚对单钉单剪的屈服及挤压强度提高不显著。     

Effects of electrophoretic deposition process parameters on the mechanical properties of graphene carboxyl-grafted carbon fiber reinforced polymer composite

Carbon fiber (CF) modification by grafting of various graphene-based nanofillers (GBN) by electrophoretic deposition (EPD) technique was proven to be a successful technique to enhance the out-of-plane performance of carbon fiber reinforced polymer (CFRP) composites. Graphene carboxyl (G-COOH) grafting on carbon fiber by electrophoretic deposition (EPD) is a promising technique to improve the mechanical properties of CFRP composites. To our knowledge, there is a dearth of literature available on the effect of EPD process parameters on the mechanical behavior of modified CFRP composites. The aim of this study is to evaluate the effect of nanofiller concentration in the suspension, applied current, and the time of deposition during EPD on the mechanical behavior of nanophase CFRP composites, thus making it a novel work. With increasing concentration, interlaminar shear strength (ILSS) improved consistently and has shown a maximum enhancement of 24.7% than that of neat CFRP composite at 1.5 g/L nanofiller concentration, whereas flexural strength remained almost unaffected with varying concentration. On the contrary, variation of deposition current has affected the flexural strength but not ILSS. The maximum flexural strength was obtained at a deposition current of 5.0A with an improvement of 16.3% in comparison with neat CFRP samples. However, both flexural strength and ILSS of hybrid CFRP composites have shown improvement with increasing deposition time. At 60 min of deposition, ILSS and flexural strength have shown maximum improvements of 35.0 and 26.6%, respectively, when compared to control specimen. After evaluating the effect of process parameters future scope of the work involves the optimization of parameters for EPD of G-COOH. Fractographic analysis of the fractured samples was performed using scanning electron microscope (SEM) to apprehend prominent failure mechanisms. © 2020 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48925.     

Low‐velocity impact response and compression after impact assessment of recycled carbon fiber‐reinforced polymer composites for future applications

The influence of recycling on the impact damage resistance of recycled carbon fiber‐reinforced polymer (CFRP) composites was investigated using low‐velocity impact and compression after impact (CAI) tests. The relationships among load, force, and time were analyzed to gain insight into the damage characteristics of three types of composite laminate: virgin CF‐reinforced polymer (V‐CFRP), recycled CF‐reinforced polymer (R‐CFRP), and treated recycled CF‐reinforced polymer (TR‐CFRP). Special emphasis was placed on evaluating the extent of damage and the residual mechanical properties as affected by three different fiber surface states. Substantial differences were noted in the shape, area, and damage mode of impact using ultrasonic c‐scanning, photography, and scanning electron microscopy (SEM). V‐CFRP indicated significant improvement in impact damage resistance in the form of less damage, higher residual strength, and greater shear failure angle. Damage resistance was improved up to 80% of V‐CFRP by surface cleaning while R‐CFRP is 50% of V‐CFRP. Shear failure angle of 16° was attained from R‐CFRP and it was increased to 24° when the recycled fibers were cleaned. The result of SEM showed that there was less delamination of TR‐CFRP compared with R‐CFRP. This work proves that the low‐velocity impact response of recycled composites can rival that of virgin composites, while providing a basis for future applications of recycled carbon in many fields. POLYM. COMPOS., 35:1494–1506, 2014. © 2013 Society of Plastics Engineers     

电极布置方式对CFRP电阻-应变特性的影响

用端部四电极布置方法和中间四电极布置方法对单向和正交CFRP材料在循环加载情况下的应变敏感性系数（GF）值进行了测试；结果表明：单向CFRP的GF随着电极布置方式的不同而反向，采用端部四电极布置方法其测试值为3．06、中间四电极布置方法为-4．76；研究了机理；为保证测得的电阻应变系数尽可能真实，应采用端部四电极布置方法。