Strain coordination of quasi-plane-hypothesis for reinforced concrete beam strengthened by epoxy-bonded glass fiber reinforced plastic plate

The testing of thirteen reinforeed concrete （RC） beams strengthened by epoxy-bonded glass fiber reinforced plastic plate （GFRP） shows that the RC beam and the GFRP plate with epoxy bonding on it can work fairly well in coordination to eaeh other. But there is relative slipping between RC beam and GFRP plate. And the strain of GFRP and steel rebar of RC beam satisfies the quasi-plane-hypothesis, that is, the strain of longitudinal fiher that parallels to the neutral axis of plated beam within the scope of effective height （ h0 ） of the cross section is in direct proportion to the distance from the fiber to the neutral axis. The strain of GFRP and steel rebar satisfies the equation： εGFRP=Kεsteel.

Development and Properties of Glass Fiber Reinforced Plastics Geogrid

Glass fiber reinforced plastics geogrid has a wide application in the field of soil reinforcement because of its high strength, good toughness, and resistance to environmental stress, creep resistance and strong stability. In order to get high-powered glass fiber reinforced plastics geogrid and its mechanical characteristics, the properties and physical mechanical index of geogrid have been got through the study of its raw material, production process and important quality index. The analysis and study have been made to the geogrid＇s mechanical properties with loading speed, three-axial compression, temperature tensile test and FLAC3D numerical simulation, thus obtain the mechanical parameters of its displacement time curve, breaking strength and elongation at break. Some conclusions can be drawn as follows： （a） Using glass fiber materials, knurling and coated projection process, the f^acture strength and corrosion resistance of geogrid are greatly improved and the interlocking bite capability of soil is enhanced. （b） The fracture strength of geogrid is related to temperature and loading rate. When the surrounding rock pressure is fixed, the strength and anti-deformation ability of reinforced soil are significantly enhanced with increasing reinforced layers. （c） The pullout test shows the positive correlation between geogrid displacement and action time. （d） As a new reinforced material, the glass fiber reinforced plastics geogrid is not mature enough in theoretical research and practical experience, so it has become an urgent problem both in theoretical study and practical innovation.

Behaviour of Multiscale Progressive Damage for Different Matrix Glass Fiber Reinforced Plastics Bars

The damage formation and evolution of glass fiber reinforced plastics( GFRP) bar on mechanical properties were mainly evaluated by theoretical analysis and numerical calculations which lack of test basis of damage process. The two different matrices of unsaturated polyester and vinylester GFRP bars were selected to carry out a series of macro-mesoscopic physical and mechanical tests to analyze the tensile progressive damage process on a multiscale. The formation of apparent crack,the bonding of internal components as well as the strain change were all reflected damage evolution of GFRP bar,and a certain correlation existed between them. Wherein the matrix has an obvious impact on the damage of bar,the component stress transfer effect of vinylester bar is better than unsaturated polyester from crack propagation observation and scanning electron microscopy( SEM). The cyclic loading tests quantitatively reflect the difference of damage accumulation between different matrix bars,and the failure load of bars decreases nearly 10%.

Predicting the Fatigue Life in Steel and Glass Fiber Reinforced Plastics Using Damage Models

Three cumulative damage models are examined for the case of cyclic loading of AISI 6150 steel, S2 glass fibre/epoxy and E glass fibre/epoxy composites. The Palmgren-Miner, Broutman-Sahu and Hashin-Rotem models are compared to determine which of the three gives the most accurate estimation of the fatigue life of the materials tested. In addition, comparison of the fatigue life of the materials shows the superiority of AISI 6150 steel and S2 glass fibre/epoxy at lower mean stresses, and that of steel to the composites at higher mean stresses.

Application of Glass Fiber Reinforced Polymer Composite (GFRPC) Escape Pipeline in Tunnel

During the tunnel construction process,unfavorable geological conditionsare often encountered.Geological disasters such as collapse,roof fall,water inrush,gas explosion,etc.occur frequently,causing different degrees of property damage and casualties to the construction of the tunnel,seriously affecting harmony during construction.The domestic emergency hedging is mainly the use of 8-10mm steel coils,but the steel is heavy and not suitable for the frequent movement of tunnels.This paper introduces the new Glass Fiber Reinforced Polymer Composite(GFRPC)escape pipeline used in Chongqing Jiuyongyi Jinyunshan Tunnel,and compares the traditional steel coil parameters to provide reference for subsequent tunnel hedging measures.

Thermal Structure of Glass Fiber Reinforce Plastic Support Structure

The assembled form of thick-wall glass fiber reinforced plastics (GFRP) tube and 0Cr18Ni9 austenitic stainless steel pipes was designed as the radius thermal-insulating and load-supporting structure in cryogenic vessels. In order to study the thermal leakage and gap changes on the support structure, as well as radius temperature and stress distribution on GFRP tube, an experimental investigation has been taken. The results indicate that the support structure is proved to fit well as thermal-insulating and load-supporting part in cryo-genic vessels, furthermore has high security during cryogenic applications.

Experimental Analysis on Local Buckling of GFRP?Foam Sandwich Pipe Under Axial Compressive Loading

To find out the local buckling behaviors of glass fiber reinforced plastic(GFRP)-foam sandwich pipe suffering axial loading,a series of quasi-static axial compression tests are carried out in the laboratory.Comparing with the test data,systematic numerical analysis on the local buckling behavior of this sandwich pipe is also conducted,and the buckling failure mechanism is revealed.The influences of the key parameters on bearing capacity of the sandwich structure are discussed.Test and numerical results show that the local buckling failure of the GFRPfoam sandwich pipe is dominated basically by two typical modes,i.e.,the conjoint buckling and the layered buckling.Local buckling at the end,shear failure at the end and interface peeling failure are less efficient than the local buckling failure at the middle height,and ought to be restrained by appropriate structural measures.The local buckling bearing capacity increases linearly with the core density of the sandwich pipe structure.When the core density is relatively high(higher than 0.05 g/cm3),the effect of increasing the core density on improving the bearing efficiency is less on the specimens with a large ratio of the wall thickness to the radius than on those with a small one.Local layered buckling is another failure mode with lower bearing efficiency than the local conjoint buckling,and it can be restrained by increasing the core density to ensure the cooperation of the inner and the outer GFRP surface layer.The bearing capacity of the GFRP-foam sandwich pipe increases with the height-diameter ratio;however,the bearing efficiency decreases with this parameter.

Experimental Investigation of Defects Inspection for FRP Pipeline based on Single-side NMR

The fiberglass reinforced plastic （FRP） pipelines have been used widely in oil-gas gathering and transportation. The defects of FRP pipelines would increase with the extension of service time. However, it is very difficult to detect the defects of FRP pipelines on-spot quickly. In this paper, a new method detecting defects for FRP pipes has been provided based on the NMR. The proton density distributions have been obtained at different depth of FRP components using single-side NMR. The experimental results show that there is a significant change of proton density distribution at the location of defects. And, these results would be useful for defects inspection of composite material component.

考虑注射成型特性影响的汽车前端模块结构性能仿真

利用Autodesk Helius PFA软件,将注射成型纤维取向张量和残余应力及应变分布等历史映射至前端模块的结构性能评价仿真。结果表明,注射成型纤维取向张量和残余应力及应变分布等成形历史影响前端模块的服役性能评价。与试验测试结果相比,映射和未映射注射成形历史的仿真最大位移均偏小。相比之下,映射注射成型纤维取向张量和残余应力及应变分布等成形历史的最大位移较大,且这种趋势随变形位移的增大而增大。当试验测试位移很小时,两种仿真方法的结果都与试验有较大的误差。当试验测试位移大于0.65 mm时,映射注射成型历史的百分误差Er、极差R和方差s2均较小,有利于指导玻璃纤维增强塑料车身结构的精准设计。

玻璃纤维增强聚合物管约束高强混凝土柱轴压试验研究

为研究玻璃纤维增强聚合物管约束高强混凝土柱的轴压性能,设计了6个不同长细比的试件并对其进行了轴心受压试验,分析了其破坏过程及破坏形态、承载力、位移、荷载-位移曲线、骨架曲线、荷载-应变曲线。研究表明:玻璃纤维增强聚合物管约束混凝土柱轴压承载性能优异,随着长细比的减小,试件的轴压承载力提升显著;加载后期,该组合结构的破坏模式为玻璃纤维增强聚合物管发生环向破坏,内部混凝土被压溃;玻璃纤维增强聚合物空管轴压承载力相对较低,破坏时脆性特征明显;随着长细比的减小,玻璃纤维增强聚合物管约束高强混凝土柱的承载力和刚度逐步增加,长细比对结构的承载能力影响显著。研究结果对玻璃纤维增强聚合物管约束高强混凝土柱的理论研究和工程应用具有一定的指导意义。

长距离输调水工程大口径FRPM管道研发与工程安全保障技术

长距离输调水工程是中国新疆地区重要的基础生命线,其长久稳定运行对于促进经济平稳增长和保障居民供水安全至关重要。新疆位居大陆中心,属温带极端大陆性气候,其长距离输调水工程面临严峻的环境挑战。玻璃纤维增强塑料夹砂管(glass fiber reinforced plastic mortar pipes,FRPM)作为长距离输调水工程中重要的水工地下结构用材,凭借其优异的耐化学腐蚀、轻质高强、无二次污染、安装方便、综合造价低等诸多优良特性而被广泛应用于新疆地区。然而,传统FRPM管生成工艺在铺层设计与生产自动化程度方面存在一定局限,导致工程施工过程效率低下;同时,缺少统一的技术标准和设计规范也间接制约了其应用范围。此外,管道工程自动巡检技术与缺陷定量评价标准尚未统一,无法合理量化和准确评价整体工程质量。为此,依托北疆小洼槽供水工程,围绕长距离大口径FRPM管的管材铺层设计与制造工艺、工程设计、质量评定、自动巡检、运行监测与安全保障等关键技术,通过产学研用相结合,持续15年攻关,取得突破性创新成果:①引进吸收并创新了适合于长距离、高工作压力、以连续缠绕工艺为首选的FRPM管生产工艺,优化了大口径FRPM管材铺层设计方法,实现了供料—缠绕—固化—切割—检测全自动化控制,与国外同类产品标准相比,管道挠曲性能和轴向拉伸强度等提高了20%~50%;②提出了安全防护的工程和非工程措施,建立了长距离FRPM管不同缺陷类型危害性等级划分原则,创建了复杂地质条件下长距离FRPM管道工程安全评价理论与方法;③系统揭示了FRPM管质量缺陷产生机理,开发了FRPM管光固化片材局部修复工艺以及内衬聚乙烯(PE)的整体非开挖修复技术,提出了修复效果后评价方法,实现了对长距离FRPM管道工程运行安全的有效掌控。

GFRP/铝合金叠层结构钻削力和分层研究

玻璃纤维增强复合材料(Glass Fiber Reinforced Plastics,GFRP)具有质量轻、比强度高和耐腐蚀等优异性能,广泛应用于航空航天制造领域。为了研究GFRP/铝合金叠层结构制孔时的轴向力和分层特征,开展GFRP/铝合金叠层结构钻削试验,分析主轴转速和进给速度对GFRP/铝合金叠层结构钻削力和分层特征的影响。研究结果表明,钻削力随着主轴转速的增大而减小,随着进给速度的增大而增大,建立了钻削力经验模型,实测值与理论值误差控制在3%以内,对预测钻削力提供了理论依据。主轴转速越低,进给速度越高,分层特征越明显,高转速低进给有利于减少分层并改善加工质量。

纤维复合材料在调水工程长输管道中的应用

调水工程长距离输水管道的材料选择,对工程成本和输水线路的安全有着重要影响。纤维复合材料具有轻质高强、内壁光滑、耐腐蚀性好等特点,正逐步应用在输水管道中。文章分析了影响长距离输水管道材料选择的主要因素,介绍了钢管、球墨铸铁管、混凝土管等传统输水管道的材料特性,阐述了纤维复合材料在输水管道中的应用,重点分析了玻璃钢夹砂管的发展和特点,最后对纤维复合材料输水管道在产品升级、施工技术、安全防护和质量管理四个方面的发展进行了展望。

刀具类型及工艺方法对纤维增强复合材料制孔加工质量影响的研究进展

概括总结了刀具类型及工艺方法对纤维增强复合材料(FRC)制孔加工质量影响的最新研究进展。首先介绍了FRC的分类、特性及其在航空航天领域中的应用,以及传统麻花钻制孔刀具及工艺存在的加工缺陷及问题;其次,概述了FRC制孔的分层缺陷形成及评价;再次,从制孔刀具类型及工艺方法两方面,分别概述了FRC制孔加工质量的研究进展,并总结了改善制孔加工质量的新刀具、新工艺和新方法;最后,分析总结了刀具类型及工艺方法对FRC制孔加工质量效果的影响,同时对未来发展趋势和未来工作研究可能方向进行了展望。

压铆力对Φ4mm 2A10铆钉连接GFRP/铝合金叠层的铆接干涉量影响研究

为了精确控制玻璃纤维增强塑料(Glass Fiber Reinforced Plastic,GFRP)/铝合金叠层的铆接干涉量,降低GFRP材料因铆接产生的损伤,需要对压铆力对干涉量的影响趋势进行研究。对2A10材料Φ4mm铆钉在连接GFRP/2A12铝合金叠层的电动伺服压铆过程及不同压铆力和预制孔下的铆接干涉量进行了有限元仿真分析,根据仿真结果开展了不同压铆力的压铆试验,对钉杆不同位置的干涉量进行了测量并做了微观检测分析。结果表明,同一预制孔下同测量位置的干涉量随着压铆力的增加而增大,同压铆力下干涉量沿叠层厚度方向(铆钉头向镦头方向)呈现递减趋势;选择Φ4.2mm预制孔、18.3~18.7kN压铆力能够获得理想干涉量且GFRP复合材料无明显损伤。

纤维增强塑料在体育运动器材中的应用

体育运动器材设计制备融合了材料学、机械设计学、力学原理等多门学科知识,其中材料是体育运动器材的主要影响元素。纤维材料拥有绝缘性好、耐高温、质轻、高强度、高弹等优点。本文介绍了玻璃纤维、碳纤维、硼纤维、高强高模合成纤维、碳化硅纤维五种不同类型纤维增强塑料,并对这五种纤维在体育运动器材中的应用研究进行了综述。

GFRP材料螺旋铣孔时的制孔质量研究

采用传统钻孔方法对GFRP(玻璃纤维增强材料)进行加工时易产生毛刺、撕裂和分层等缺陷,而螺旋铣孔方法可以有效避免这些缺陷产生。运用螺旋铣孔方法对GFRP进行制孔试验,得到切削速度、刀具公转转速、轴向进给螺距对孔壁表面粗糙度以及孔径尺寸误差的影响规律,对比分析了螺旋铣孔和钻孔的孔口缺陷。试验结果表明:影响孔壁表面粗糙度的切削参数由大至小依次为切削速度>刀具公转转速>轴向进给螺距;切削速度、刀具公转转速、轴向进给螺距与孔壁表面粗糙度均呈正比关系;影响孔径尺寸误差的切削参数依次为刀具公转转速>轴向进给螺距>切削速度;螺旋铣孔的入口侧缺陷较多,钻孔时的孔口缺陷更多出现在出口侧。

基于玻璃纤维复合筋结构的光栅连续应变传感研究

为解决光纤光栅(FBG)无法实现连续应变传感的问题,提出了采用玻璃纤维复合筋(GFRP)结构的连续应变传感及信号解调方案。建立了在模拟支梁条件下5个测点(其中2个为FBG测点)的GFRP-FBG应变有限元模型,分析了各测点应变与FBG应变的关系,仿真证明该结构可实现连续应变传感。设计了与模型结构一致的GFRP-FBG传感器,并对可调谐扫描信号进行了卡尔曼滤波和最小二乘法二次拟合以保证测量精度。对GFRP-FBG进行应变测量实验,实验选取的3个模拟测点应变值与有限元模型分析基本一致,误差在6.74%以内。研究表明GFRP-FBG为实现光栅连续应变传感提供了可行的解决方案。

响应面法在玻纤增强PA66注塑工艺中的应用

采用CAE方法对某公司开发的新型蟹笼挂钩产品进行注塑成型分析,设置了合理的工艺参数及质量目标,然后,采用响应面法对玻纤增强PA66工程塑料产品的注塑成型工艺进行多目标回归分析。结果表明,在注塑成型过程中,产品的翘曲及收缩受到多种因素的影响。其中,熔体温度、保压时间及熔体温度与保压时间的交互项3个因素对产品体积收缩率的影响较显著;而熔体温度、注塑时间、熔体温度的平方及注塑时间的平方4个因素对产品翘曲变形量的影响较显著。当模具温度为115℃、熔体温度为310℃、保压时间为12 s、注塑时间为0.98 s时,产品具有最佳目标值,优化后产品的体积收缩率及翘曲量分别为14.34%、0.1925 mm。

双螺旋自由曲面混凝土厚壳模板体系设计研究

在建的上海大歌剧院B区双螺旋自由曲面混凝土厚壳的结构形式极端复杂,是几乎毫无参考规律的1.5m厚的自由曲面混凝土厚壳。舞台深坑底板顶面标高较常规区域大底板面标高的深度为16 m,且施工过程中基坑的水平支撑和立柱等基坑支护结构布置十分复杂。为了保证曲面结构的钢筋定位、模板定位、混凝土施工质量,设计双螺旋自由曲面混凝土厚壳模板体系。首先分析了施工难点,然后根据工况将双螺旋自由曲面混凝土厚壳模板体系分为底模、面模、侧模、核心柱模板四部分,最后对该双螺旋自由曲面混凝土厚壳模板体系施工工艺进行了总结。实践表明,所述模板体系可保质、保量、高精度地完成上海大歌剧院双螺旋自由曲面混凝土厚壳施工。