动车组座椅弹性支撑粘接接头设计

对动车组座椅弹性支撑的粘接接头进行了设计,采用Bigwood法测算出胶层在接头边缘部位承受的极限载荷,通过试验对两种备选胶粘剂老化前后的强度进行了测试并计算其特征参数。研究结果表明:粘接面长度、宽度值至少应大于96 mm时,可以避免应力集中;极限载荷约为5.6 MPa;胶粘剂A特征参数为-3.25 MPa,胶粘剂B为7.75 MPa,胶粘剂B可满足接头要求。     

聚氨酯胶粘剂在电力机车前窗玻璃粘接密封中的应用

简述了单组分聚氨酯胶粘剂在电力机车前窗玻璃粘接密封中应用的意义以及前窗玻璃连接形式,同时详细说明了前窗玻璃粘接密封的工艺方法和施胶过程中的技巧。     

新型单组分弹性环氧胶粘剂

介绍了一种潜伏性的中温固化环氧胶粘剂,该胶固化后具有一定的弹性,良好的粘接性能和耐湿热老化性,贮存期在常温(25℃)约三个月。文中还将此胶的性能与日本进口的同类胶粘剂做了对比。     

聚氨酯胶粘剂在地铁车辆侧窗粘接中的应用

介绍了单组分聚氨酯胶粘剂的粘接技术、原理、特点及其在地铁车辆装备过程中的应用。以地铁车辆侧窗玻璃粘接为例,简述了聚氨酯胶粘剂的粘接工艺和质量管控。     

CRH3型动车组侧窗的粘接结构设计

根据CRH3型高速动车组侧窗的结构,设计了侧窗粘接接头的形式及粘接密封结构;根据胶粘剂厂商提供的数据及粘接工艺,分析设计了侧窗粘接厚度和接缝宽度。研究结果表明:侧窗粘接接头应选择搭接接头,粘接厚度的理论设计值为5～10mm,接缝宽度的理论设计值为10～17mm;将动车组侧窗的受力情况进行模型化,通过理论计算,并引入衰减因子和安全因子,可推算出侧窗粘接用聚氨酯(PU)弹性胶粘剂的剪切强度需超过0.54MPa,而目前国内外PU结构胶的剪切强度均超过此数值。     

湿面粘接理论

本文叙述了粘接面上水的状态，水影响胶接强度的机理和湿面粘接理论．介绍了按照湿面粘接理论设计的环氧树脂胶粘剂和甲基丙烯酸酯类胶粘剂对混凝有水表面的胶接强度分别提高31％和1．6－2．2倍．     

粘接自行车架用的新型胶粘剂

日本桥石自行车公司研制成功一种新型胶粘剂,这种胶粘剂可用来粘接诸如铝、碳、硼、非晶体物质和晶须等新材料。与此同时,该公司还开发成功使用这种新型胶粘剂的新的粘接方法。这样,该公司就可以批量生产用新型轻质材料制造的自行车架了。上述新型胶粘剂是一种高性能改性丙烯酸酯胶,它具有优异的粘接强度。用这种胶粘     

CRH3高速动车组前风挡玻璃粘接安全系数评估

对匀速前进、紧急制动、露天会车及单列车过隧道4种工况时的高速动车组风挡玻璃粘接胶层进行应力分析,综合评估了风挡玻璃的粘接安全系数。研究结果表明:当露天会车时,风挡玻璃最低的粘接安全系数(2.88)仍满足BS EN 12663—2010标准中对极限破坏安全系数(>1.5)的要求,故使用弹性胶粘剂粘接高速动车组风挡玻璃是安全可靠的。     

耐高温热固化胶粘剂问世

由北京航空材料研究院研制出一种耐高温热固化胶粘剂。该研究采用向硅橡中加入乙烯基三特丁基过氧化硅　和金属氧化物等混合配成胶粘剂,这种方法可提高胶粘剂的粘接强度和耐热性能,解决了硅橡胶和金属的粘接技术　困难。粘接件在室温下的粘接扯离强度达2 5MPa ,在30 0℃达0 83～1 4 5MPa,最高使用温度可达35 0℃,该胶的研　制成功,拓宽了硅橡胶及其胶粘剂的应用范围。耐高温热固化胶粘剂问世     

耐高温热固化硅橡胶胶粘剂

北京航空材料研究院研制出一种耐高温热固化橡胶胶粘剂。该研究采用向硅橡胶中加入乙烯基三特丁基过氧化硅烷和金属氧化物等混合配成胶粘剂 ,这种方法可提高胶粘剂的粘接强度和耐热性能 ,解决了硅橡胶和金属的粘接技术困难 ,粘接件在室温下的粘接扯离强度达 2 .5MPa以上 ,在30 0℃下的粘接扯离强度达 0 .83～ 1.4 5MPa ,最高使用温度可达 35 0℃。该胶的研制成功 ,拓宽了硅橡胶及其胶粘剂的应用范围。耐高温热固化硅橡胶胶粘剂     

Breaking of window glass close to fire,II: Circular panes

A heat-conduction equation with linearized radiation cooling boundary conditions is used to calculate the thermal field in a circular window pane heated by thermal radiation (fire) but screened on narrow strips along edges built into the frame. This temperature field is used to calculate a quasi-static thermal stress field in the pane in the first-order planar thermal stresses build up at the edges in a narrow strip of a few times the pane thickness. As the radius of the pane grows the edge stresses quickly approach those of the linear strip pane. The round window does not differ much from the strip window in the geometrical region of practical utility in windows. The results also indicate, without explicit calculations, that in rectangular windows the stresses do not concentrate in the corner regions. As the final result of the theoretical work it seems plausible to use simple, general relationships obtained for the strip window as well for all geometries deviating from linear to evaluate approximately the danger of thermal breakage of a pane.     

Adhesive Failure of Model Acrylic Pressure Sensitive Adhesives

An axisymmetric adhesion apparatus was used to characterize the adhesive and viscoelastic properties of acrylic block copolymer layers that behave as model pressure sensitive adhesives. The mechanisms of deformation were summarized and related to the structure and linear viscoelastic response of each model adhesive. In cases where the area between the adhesive layer and adhering surface remained circular and shrunk uniformly during detachment, the adhesive failure criterion can be quantified and compared to predictions from linear elastic fracture mechanics. The nature of adhesive failure can not be reconciled with these traditional, low-strain approaches, but is consistent with models of large strain elasticity, provided that the finite thickness of the adhesive layer is taken into account. A dimensionless ratio involving the adhesive strength, elastic modulus and adhesive layer thickness can be used to define the regime in which the adhesive failure criterion can be quantified with linear elastic fracture mechanics.     

Adhesive Failure of Model Acrylic Pressure Sensitive Adhesives

An axisymmetric adhesion apparatus was used to characterize the adhesive and viscoelastic properties of acrylic block copolymer layers that behave as model pressure sensitive adhesives. The mechanisms of deformation were summarized and related to the structure and linear viscoelastic response of each model adhesive. In cases where the area between the adhesive layer and adhering surface remained circular and shrunk uniformly during detachment, the adhesive failure criterion can be quantified and compared to predictions from linear elastic fracture mechanics. The nature of adhesive failure can not be reconciled with these traditional, low-strain approaches, but is consistent with models of large strain elasticity, provided that the finite thickness of the adhesive layer is taken into account. A dimensionless ratio involving the adhesive strength, elastic modulus and adhesive layer thickness can be used to define the regime in which the adhesive failure criterion can be quantified with linear elastic fracture mechanics.     

有机硅纳米杂化改性环氧胶的研制和应用

通过溶胶-凝胶法制备了纳米有机硅溶胶。用透射电镜和红外光谱表征和分析了纳米粒子的形态和粒径,粒径为30－70nm。制备了用活性稀释剂糠醛和丙酮及有机硅纳米杂化改性的环氧胶。研究了胶液的初始黏度、渗透性、力学强度、弹性模量、粘接性、表面疏水性和防腐蚀性能。实验结果表明,环氧树脂含量、有机硅溶胶、硅烷偶联剂等对改性环氧胶的这些性能有显著影响,改性环氧胶双组分混合液的初始黏度可低至1.1mPa·s,渗透性强,固结体抗压强度高达40．8－81．5MPa,弹性模量为1．3－2．1×10^3MPa,剪切粘接强度5．1－11．9MPa,防水抗渗性及防腐蚀耐候性良好,可应用于灌浆防水加固补强、工业地坪涂料和防腐蚀涂料等多种用途。     

Measurement of nanoindentation properties of polymers considering adhesion effects between AFM sharp indenter and material

Abstract

Nanomechanical properties of polymer samples were calculated using an adhesive contact model appropriate for AFM indentation problems. A series of Polydimethylsiloxane (PDMS) samples were indented by the sharp indenter in the air by using an AFM, and dozens of the force–displacement curves of each sample were obtained. An adhesive contact model suitable for sharp indentation with adhesion was established based on the same assumptions of the JKR model which is only suitable for spherical indentation at small penetration depth. Differences between sharp indentation problems with and without adhesion were discussed, and the limitations of the traditional adhesion model were given. The elastic modulus was obtained by fitting experimental force–displacement curves with theoretical ones, and results were compared to those macroscopic values in literature. The adhesion energy between the indenter and the sample surface was accurately calculated using the adhesion model based on the calculated elastic modulus. The influence of the indenter tip angle on the calculation results of the elastic modulus was also discussed theoretically. In this study, the mechanical properties of polymer samples were calculated at the nanoscale considering the adhesion effect.     

Thermal Fluctuations Limit the Adhesive Strength of Compliant Solids

For compliant solids, the stress required to separate an interface (its adhesive strength) appears to be much lower than that calculated by computing intersurface interactions. We explore the hypothesis that the adhesive strength is limited in value by thermal fluctuations. In a simple model of an interface, molecules bridging the two surfaces are represented by linear entropic springs. Asymptotic and numerical analyses are carried out to evaluate the adhesive strength and effective work of adhesion. For stiff materials, adhesive strength is found to be equal to the intrinsic strength—the maximum value of intersurface stress computed ignoring fluctuations. For compliant materials, adhesive strength is significantly reduced and is on the order of the elastic modulus. The effective work of adhesion agrees with the intrinsic work of adhesion for stiff materials and can decay slowly with increasing compliance.     

Thermal Fluctuations Limit the Adhesive Strength of Compliant Solids

For compliant solids, the stress required to separate an interface (its adhesive strength) appears to be much lower than that calculated by computing intersurface interactions. We explore the hypothesis that the adhesive strength is limited in value by thermal fluctuations. In a simple model of an interface, molecules bridging the two surfaces are represented by linear entropic springs. Asymptotic and numerical analyses are carried out to evaluate the adhesive strength and effective work of adhesion. For stiff materials, adhesive strength is found to be equal to the intrinsic strength—the maximum value of intersurface stress computed ignoring fluctuations. For compliant materials, adhesive strength is significantly reduced and is on the order of the elastic modulus. The effective work of adhesion agrees with the intrinsic work of adhesion for stiff materials and can decay slowly with increasing compliance.     

室温固化丙烯酸结构胶的研究

为了满足快速粘接的需要,采用甲基丙烯酸环氧酯和烯类单体制备了一种室温快速固化的结构胶。研究了复合稳定剂对胶体稳定性的影响。测试了粘接时间对粘接强度的影响。结果表明：复合稳定剂用量在0．02％以上时,胶体能稳定贮存一年以上;粘接强度在固化初期明显增长,12h达到最高强度的90％以上;胶体无气味,使用方便,固化速度快,强度增长快,粘接强度高。该结构胶能满足快速粘接、特别适合动荷载情况下快速粘接的使用要求,具有良好的市场前景。     

弹性环氧建筑结构胶粘剂的研究

采用酸碱催化剂催化合成糠叉丙酮改性环氧树脂 ,改性后的环氧树脂经胺固化后都具有良好的应力 应变关系 ,碱法抗压强度达 72 .4MPa ,拉伸强度 16 .5MPa,剪切强度 13.8MPa ,压缩弹性模量 1.40× 10 3MPa和超过 7.0MPa的拉伸粘接强度 ;酸法抗压强度可达 86 .2MPa ,压缩弹性模量为 9.2 3× 10 2 MPa。酸催化合成的糠叉丙酮改性环氧树脂具有储存时间长、反应易控制及成本较低的优点。