Determination of Water Diffusion Coefficients and Dynamics in Adhesive/Carbon Fiber Reinforced Epoxy Resin Composite Joints

To determinate the water diffusion coefficients and dynamics in adhesive/carben fiber reinforced epoxy resin composite joints, energy dispersive X-ray spectroscopy analysis（EDX） is used to establish the content change of oxy- gen in the adhesive in adhesive/carbon fther reinforced epoxy resin composite joints. As water is made up of oxygen and hydrogen, the water diffusion coefficients and dynamics in adhesive/carben fiber reinforced epoxy resin composite joints can be obtained from the change in the content of oxygen in the adhesive during humidity aging, via EDX analy-sis. The authors have calculated the water diffusion coefficients and dynamics in the adhesive/carbon fiber reinforced epoxy resin composite joints with the aid of beth energy dispersive X-ray spectroscopy and elemental analysis. The de- termined results with EDX analysis are almost the same as those determined with elemental analysis and the results al- so show that the durability of the adhesive/carbon fther reinforced epoxy resin composite joints subjected to silane cou- pling agent treatment is better than those subjected to sand paper burnishing treatment and chemical oxidation treat- ment.

Experimental Study on Influence of Dimples on Lubrication Performance of Glass Fiber-epoxy Resin Composite under Natural Seawater Lubrication

Bionic non-smooth surface is widely applied in metal and ceramics materials. In order to introduce this technology to high pressure seawater pump, the influence of bionic non-smooth surface on the engineering plastics used in pump should be investigated. The comparative tests are carried out with a ring-on-disc configuration under 800, 1000, 1200 and 1400 r/min in order to research the influence of the bionic non-smooth surface on glass fiber-epoxy resin composite（GF/EPR） under natural seawater lubrication. The disc surfaces are textured with five kinds of pits, which are semi-spherical, conical, cone-cylinder combined, cylindrical pits and through holes, respectively. A smooth surface is tested as reference. The results show that the lubrication performance of dimpled GF/EPR sample is much better than that of the smooth sample under all rotational speeds. The semi-spherical pits surface has more obvious friction reduction than the others, which shows that the least reduction is approximately 43.29% of smooth surface under 1200 r/rain. However, the wear level is only marginally influenced by dimples. The surface morphology investigations disclose severe modifications caused by abrasive wear primarily. The results are helpful to vary friction properties of GF/EPR by non-smooth surface, or provide references to the design of non-smooth surfaces under certain condition.

Influence of Non-smooth Surface on Tribological Properties of Glass Fiber-epoxy Resin Composite Sliding against Stainless Steel under Natural Seawater Lubrication

With the development of bionics, the bionic non-smooth surfaces are introduced to the field of tribology. Although non-smooth surface has been studied widely, the studies of non-smooth surface under the natural seawater lubrication are still very fewer, especially experimental research. The influences of smooth and non-smooth surface on the frictional properties of the glass fiber-epoxy resin composite（GF/EPR） coupled with stainless steel 316 L are investigated under natural seawater lubrication in this paper. The tested non-smooth surfaces include the surfaces with semi-spherical pits, the conical pits, the cone-cylinder combined pits, the cylindrical pits and through holes. The friction and wear tests are performed using a ring-on-disc test rig under 60 N load and 1000 r/min rotational speed. The tests results show that GF/EPR with bionic non-smooth surface has quite lower friction coefficient and better wear resistance than GF/EPR with smooth surface without pits. The average friction coefficient of GF/EPR with semi-spherical pits is 0.088, which shows the largest reduction is approximately 63.18% of GF/EPR with smooth surface. In addition, the wear debris on the worn surfaces of GF/EPR are observed by a confocal scanning laser microscope. It is shown that the primary wear mechanism is the abrasive wear. The research results provide some design parameters for non-smooth surface, and the experiment results can serve as a beneficial supplement to non-smooth surface study.

Fabrication and Characterization of Glass Fiber with SiC Reinforced Polymer Composites

Glass Fiber Reinforced Polymeric (GFRP) Composites are most commonly used as bumpers for vehicles, electrical equipment panels, and medical devices enclosures. These materials are also widely used for structural applications in aerospace, automotive, and in providing alternatives to traditional metallic materials. The paper fabricated epoxy and polyester resin composites by using silicon carbide in various proportions along with GFRP. The hand lay-up technique was used to fabricate the laminates. To determine the properties of fabricated composites, the tensile, impact, and flexural tests were conducted. This method of fabrication was very simple and cost-effective. Their mechanical properties like yield strength, yield strain, Young’s modulus, flexural modulus, and impact energy were investigated. The mechanical properties of the GFRP composites were also compared with the fiber volume fraction. The fiber volume fraction plays a major role in the mechanical properties of GFRP composites. Young’s modulus and tensile strength of fabricated composites were modelled and compared with measured values. The results show that composites with epoxy resin demonstrate higher strength and modulus compared to composites with polyester resin.

交变载荷下绝缘拉杆用GFRP电树枝劣化特性

气体绝缘组合电器(gas insulated switchgear,GIS)现场调试或运行过程多次发生绝缘拉杆内部击穿问题,影响工程投运与设备可靠性,迫切需要探明故障机理。该文选取GIS断路器绝缘拉杆用玻璃纤维增强环氧树脂复合材料(glass fiber reinforced epoxy resin composite,GFRP)为研究对象,通过计算分、合闸下绝缘拉杆主应力分布特性,设置交变载荷下电树枝劣化实验条件,研究不同交变载荷对GFRP内电树枝生长特性影响规律。结果表明,相较于单一载荷,交变载荷条件下GFRP中电树枝生长速度加快,平均击穿时间降低,击穿概率增大。基于复合材料力学仿真发现交变载荷下GFRP内树脂-纤维界面处会出现较大的应力集中,局部应力损伤已达到失效的临界值。综上,交变载荷下绝缘拉杆纤维-树脂界面机械损伤与绝缘劣化交互演进是造成绝缘击穿的主要原因,也可作为试验考核与结构设计的改进依据。

Compressive Behaviour and Failure Mechanisms of GFRP Composite at High Strain Rates

Experimental investigations into the compressive behavior of glass fiber reinforced polymer(GFRP)composite at high strain rates were carried out using a split Hopkinson pressure bar(SHPB)setup.The GFRP laminates were made from E-glass fibers and epoxy resins by vacuum assisted compression molding machine.The results of the compressive tests indicated that the mechanical behavior of the GFRP composite depends highly on the strain rate.The compressive peak stress,toughness and Young's modulus of the GFRP composite increased with the increase of strain rate,while the strain level at the initial stages of damage was shortened with the increase of strain rate.In addition,the dynamic deformation behavior and failure process of the specimens were observed directly by using a high-speed camera.Following the experiments,the fracture morphologies and damage modes were examined by scanning electron microscopy(SEM)to explore the possible failure mechanisms of the specimens.The results showed that multiple failure mechanisms appeared,such as matrix crack,fiber-matrix debonding,fiber failure and shear fracture.

Studies on interacting Blends of Acrylated Epoxy resin based Poly(Ester-Amide)s and Vinyl EsterResin

Epoxy resin based Unsaturated poly(ester-amide) resins (UPEAs) can be prepared by many methods but here these were prepared by reported method [1]. These UPEAs were then treated with acrylotl chloride to afford acrylated UPEAs resin (i.e. AUPEAs). Interacting blends of equal proportional AUPEAs and vinyl ester epoxy (VE) resin were prepared. APEAs and AUPEAs were characterized by elemental analysis, molecular weight determined by vapour pressure osmometer and by IR spectral study and by thermogravimetry. The curing of interacting blends was monitored on differential scanning calorimeter (DSC). Based on DSC data in situ glass reinforced composites of the resultant blends have been prepared and characterized for mechanical, electrical and chemical properties. Unreinforced blends were characterized by thermogravimetry (TGA).

硬质合金刀具铣削GFRP材料加工特性的研究

为了获得硬质合金刀具加工玻璃纤维增强复合材料(GFRP)的理想铣削参数,为实际生产提供参考,使用硬质合金柄铣刀对GFRP进行开料铣削加工,以进给速度及主轴转速为铣削因素,以铣削力、铣削温度、表面粗糙度及表面损伤形貌为评价指标,对硬质合金铣刀开料铣削加工GFRP材料的加工特性进行探究。结果表明,随着进给速度的增加,铣削力F((x))与F((y))均呈上升趋势,铣削温度呈下降趋势,表面粗糙度随着温度的下降也呈下降趋势;随着刀具转速的增加,铣削力F((x))与F((y))呈先下降后上升的趋势,并在14000 r/min时达到谷值。同时,GFRP开料加工时顺铣端的表面损伤程度要低于逆铣端,即顺铣可以得到更好的表面质量。因此,在选择GFRP材料的开料加工参数时,应根据刀具参数,在计算出合适的每齿进给量的基础上,尽可能选用较大的进给速度与主轴转速,从而提高加工效率,并在一定程度上减小刀具磨损,提高表面质量,降低成本。

纳米颗粒填充玻璃纤维增强环氧树脂复合材料的力学性能

为探究纳米颗粒[纳米氧化铁(NFe)、纳米二氧化硅(NS)、多壁碳纳米管(MWCNT)]填充玻璃纤维增强环氧树脂复合材料(GFRP)的力学性能,对纳米颗粒质量分数分别为0.1%、0.2%、0.5%、1.0%的纳米颗粒/GFRP材料开展了拉伸、压缩、弯曲及冲击力学性能试验,并结合扫描电镜(SEM)分析了纳米颗粒的种类及质量分数对试件力学性能的影响规律。结果表明,随着纳米颗粒质量分数的增加,试件拉伸强度均先增大后降低,纳米颗粒的良好分散性及与树脂间的黏聚力能够提升试件的拉伸强度,但过量纳米颗粒的掺入会形成积聚现象,使得试件拉伸强度降低。相较于GFRP试件,掺入纳米颗粒的质量分数为0.1%、0.2%、0.5%和1.0%时,MWCNT/GFRP抗压强度的增幅分别为25.31%、36.04%、26.84%和27.25%,弯曲强度的增幅分别为58.74%、63.21%、40.89%及43.11%,纳米颗粒的掺入使得试件抗压强度、弯曲强度、冲击强度均得到改善,颗粒种类及质量分数的不同使得试件力学性能提升效果存在差异。SEM试验结果表明,外荷载作用下纤维出现断裂、分层现象,纤维与纳米颗粒间存在的摩擦效应增强其力学性能,颗粒的积聚使得试件力学性能降低。

双跨连续GFRP-混凝土组合板的试验研究

为研究GFRP-混凝土组合板的受力性能,对3块GFRP-混凝土组合连续板进行了静载试验.3块组合板分别通过环氧树脂胶或剪力栓钉与下部型钢支座连接.试验结果表明:所有组合板的最终破坏形态均表现为加载垫块处局部冲剪破坏;中支座处和边支座处没有出现荷载重分布现象,组合板表现出良好的空间受力性能及变形协调能力.然后,基于塑性极限理论,提出了一种GFRP-混凝土组合板极限承载力计算方法.预测值与试验值的比较结果表明,所提方法可以有效地预测GFRP-混凝土组合板的极限承载力.

含GFRP筋预应力混凝土管桩抗剪性能试验研究

文章介绍了含玻璃纤维增强复合材料(glass fiber reinforced polymer,GFRP)配筋预应力混凝土管桩(以下简称"PRC-G桩"),并进行了抗剪性能的对比试验研究。试验结果表明:GFRP筋与混凝土(C80)可以共同作用,能有效发挥材料的高强性能,GFRP筋的配置较大幅度地改善了普通管桩的抗剪性能,其开裂剪力有显著的提高,是规范值的1.12倍;2种类型桩破坏过程相似,均是从支座处首先出现裂缝,沿桩长方向大致20°~30°夹角方向开展延伸,延伸至加载点垂直面时,以平行于桩长方向继续扩展,最后形成贯通面;按等效圆形截面法计算PRC-G桩的开裂剪力是符合设计要求的,且偏于保守。

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。

玻璃纤维/环氧树脂复合材料燃烧特性研究

采用锥形量热仪、垂直水平燃烧试验仪、极限氧指数测试仪等手段研究玻璃纤维/环氧树脂复合材料在不同火灾环境下的燃烧特性。结果表明:随热辐射强度的增加,实验样品的平均点燃时间逐渐缩短,热释放速率和热释放速率峰值均增大,峰值出现时间提前,燃烧后残余率降低。由于玻璃纤维的抑制作用,复合材料总体质量损失幅度较小。实验样品在水平燃烧试验中未能点燃,在垂直燃烧试验中,平均烧焦长度48.3mm,移去火源后的平均焰燃时间为11.8s。氧指数试验显示,温度升高200℃后,其值降为室温氧指数的74.9%,表明在高温环境下复合材料更易被点燃。玻璃纤维的存在能够抑制环氧树脂的热解和燃烧。

GFRP拉结件预制混凝土夹心保温外墙板的数值模拟和组合性能分析

为研究玻璃纤维增强树脂(glass fiber reinforced polymer,GFRP)拉结件预制混凝土夹心保温外墙板的组合性能,文章利用ABAQUS有限元软件建立预制混凝土夹心保温外墙板的三维有限元模型,对其进行非线性数值模拟;在验证有限元模型准确性的基础上,通过变参数分析方法,研究拉结件的数量和外叶板的厚度对预制混凝土夹心保温外墙板组合性能的影响。结果表明:随着拉结件数量增加,承载力组合度逐渐增加,刚度组合度先增加后降低,但始终不小于初始值;随着外叶板厚度增加,其承载力组合度逐渐增加并趋于定值,刚度组合度先减少后增加,但始终不大于初始值;拉结件数量和外叶板厚度的增加均能在非线性阶段提高预制混凝土夹心保温外墙板的刚度,相比而言,外叶板厚度的增加更能提高墙板的刚度。研究结果可为GFRP拉结件三明治墙板的设计提供参考。

玻璃纤维/环氧树脂复合材料热解特性研究

采用热重-差热分析仪研究玻璃纤维/环氧树脂复合材料在空气及氮气氛围下不同升温速率的热解特性规律。结果表明,在空气气氛下,热解分为两个阶段;氮气气氛下,热解只存在一个热分解阶段,与空气气氛相比热解初始分解温度较高,热解温度范围变窄,失重速率明显变大。在两种气氛下,玻璃纤维均不参与热解。随着升温速率的增加,热解反应各阶段的起始温度、终止温度、最大失重速率温度均向高温方向移动,热解温度范围大小都基本保持不变。氮气气氛下使用Kissinger法、FWO法和Starink法计算出玻璃纤维环氧树脂的平均表观活化能分别为106.42、123.09和119.48kJ/mol。复合材料活化能随转化率的增加而升高,表观活化能保持在一定数值范围内且数值相近,热解反应比较稳定,具有较低A值,表明其具有较强的热稳定性。

玻纤增强环氧树脂力学与耐老化性能研究

采用偶联剂KH560对短切玻璃纤维(玻纤)进行改性,并以改性短切玻纤作为增强材料制备得到玻纤/环氧树脂复合材料。随着玻纤质量分数的增加,材料的拉伸、弯曲和冲击强度均呈现先增大后减小的趋势。当玻纤填充质量分数为10%时,材料的力学增强、增韧效果达到最佳。SEM表征表明玻纤与树脂基体界面结合良好,可以有效传递树脂与玻纤间的应力,且玻纤的介入也可有效阻挡裂纹的扩展,起到增强、增韧作用。然而当玻纤质量分数过高时,由于材料的分散性变差,其力学性能下降。复合材料经短时间的紫外老化后,因紫外光氧作用颜色发生很大变化,然而由于玻纤具有很好的化学稳定性,可以延缓紫外氧化损伤进一步深入到材料内部,材料的外观颜色变化开始放缓。在水分作用下,树脂也会发生一定的水解。这些破坏使材料的力学性能随着老化时间的延长不断降低。上述研究可为后续开发用于替代金属电力金具的性能更优越的玻纤增强环氧树脂提供理论基础。

γ辐照作用下GFRP电绝缘性能及其微观结构机理研究

玻璃纤维增强塑料(GFRP)作为一种具有良好电绝缘性能、热绝缘性能和力学性能的复合材料,在高能物理和核物理实验中被用来制作支撑设备,而高能物理和核物理实验中往往会产生一定剂量的γ或中子辐照,进而改变GFRP的性能。为保证GFRP支撑设备在辐照条件下的安全运行,有必要对辐照前后GFRP的电绝缘性能进行研究。本研究通过导电性能测试仪、扫描电子显微镜、红外光谱和X射线光电子能谱研究了γ辐照前后GFRP电绝缘性能的变化规律,并从微观结构上揭示了引起材料电绝缘性能变迁的机理。结果表明:GFRP平均电阻率与辐照剂量之间具有明显的线性关系,在经20 kGy、100 kGy和200 kGy的γ辐照后,其平均电阻率由辐照前的8.16×10^12Ω·m分别提高到15.88×10^12Ω·m、23.13×10^12Ω·m和43.15×10^12Ω·m,辐照使GFRP的平均电阻率升高,电绝缘性增强。通过对GFRP微观结构进行研究,发现辐照后玻璃纤维表面出现裂纹,环氧树脂呈现碎片化趋势且有孔洞出现,二者之间的界面遭到破坏,分子键发生断裂,GFRP发生了氧化老化,这些均为GFRP电绝缘性能增强的重要原因。GFRP材料可以满足高能物理和核物理辐照环境下的高电绝缘性要求。

Axial compressive behavior of GFRP‑timber‑reinforced concrete composite columns

本文提出了一种由外层玻璃纤维增强复合材料(GFRP)布、内部填充泡桐木芯和钢筋混凝土组成的组合柱(GTRC柱)。对13个GTRC柱试件进行了轴心受压试验,研究了不同木芯直径、长细比和GFRP层数/铺层角度对其力学性能的影响规律。结果表明,随着木芯直径的增加,组合柱的延性和耗能能力分别增加了52.6%和21.6%,而极限承载力和初始刚度略有下降。另外,GFRP布显著提高了其极限受压承载能力、刚度、延性和能量耗散能力,分别提高了212.1%、26.6%、64.3%和3820%。此外,考虑到木芯直径的影响,提出了极限受压承载力调整系数。最后,基于力平衡原理和叠加原理,建立了GTRC柱极限承载力理论分析模型,得到了其承载力计算公式。

Thermally Conductive and Insulating Epoxy Composites by Synchronously Incorporating Si-sol Functionalized Glass Fibers and Boron Nitride Fillers

Glass fibers(GFs)/epoxy laminated composites always present weak interlaminar shear strength(ILSS)and low cross-plane thermal conductivity coefficient(λ⊥).In this work,silica-sol,synthesized from tetraethyl orthosilicate(TEOS)and KH-560 via sol-gel method,was employed to functionalize the surface of GFs(Si-GFs).Together with a spherical boron nitride(BNN-30),the thermally conductive BNN-30/Si-GFs/epoxy laminated composites were then fabricated.Results demonstrate that Si-sol is beneficial to the improvement of mechanical properties for epoxy laminated composites(especially for ILSS).The BNN-30/Si-GFs/epoxy laminated composites with 15 wt%BNN-30 fillers display the optimal comprehensive properties.In-planeλ(λ//)andλ⊥reach the maximum of 2.37 and 1.07 W.m-1.K-1,146.9%and 132.6%higher than those of SiGFs/epoxy laminated composites(λ//=0.96 W.m-1.K-1 andλ⊥=0.46 W.m-1K-1),respectively,and also about 10.8 and 4.9 times those of pure epoxy resin(λ//=λ⊥,0.22 W.m-1.K-1).And the heat-resistance index(THRI),dielectric constant(ε),dielectric loss(tanδ),breakdown strength(E0),surface resistivity(ρs)as well as volume resistivity(ρv)are 197.3℃,4.95,0.0046,22.3 kV.mm-1,1.8×1014Ω,and 2.1×1014Ω.cm,respectively.

GFRP-微珠泡沫组合柱抗车辆撞击仿真与优化设计

近年来,国内外桥梁碰撞事故频繁发生,对桥墩造成破坏甚至导致桥梁垮塌,造成人员伤亡及经济损失。本文以玻璃纤维增强复合材料(GFRP)-混凝土组合柱为参照柱,在满足GFRP-微珠泡沫组合柱吸能不小于参照柱的条件下,对其进行精细化模拟及优化设计。结果表明:优化后的GFRP-微珠泡沫组合柱不仅具有与GFRP-混凝土组合柱同样的吸能能力,还可以大幅削减冲击力峰值,提高冲击持续时间和比吸能,降低对撞击车船和人身的损害,达到轻质高强、吸能能力强的效果。