固化工艺对胶接接头冲击性能的影响

研究了固化温度、时间等固化工艺参数对结构钢／环氧胶接接头冲击韧度的影响。结果表明,固化温度从60℃增加到120℃时,冲击韧度值变化显著：当固化时间为1h时,结构钢胶接接头的冲击韧度先随固化温度的提高而有所上升,在90℃时达到最大值,其后随温升而降低;当固化时间为2h时,随固化温度提高冲击韧度出现两个峰值。研究还发现,在研究所采取的工艺条件下,被粘物的待胶接表面经粗细不同的砂纸打磨处理后,冲击性能有一定差异,粗砂纸打磨引起接头冲击韧度实验结果的离散度增大。     

结构胶胶接接头耐久性的研究进展

结构胶是胶黏剂中具有高强度、耐高温、高耐久特性的一类胶黏剂的总称,主要用于部件中承受载荷的胶接连接。胶接接头的耐久性能是结构胶应用中的一个重要指标。主要从影响胶接接头耐久性的内在因素和外在因素以及实验室研究方法对结构胶胶接接头耐久性的研究进展进行综述。     

结构胶胶接接头在混合连接工艺中的应用研究进展

混合连接工艺包括两种或两种以上连接技术的结合,如焊接、铆接和胶接。结构胶粘剂是混合连接工艺中不可缺少的一部分,它们为连接提供了优异的连接强度、耐久性和灵活性,并已越来越多地被应用于汽车、航空航天、电子和其他行业。综述了结构胶胶接接头在混合连接工艺中的应用。     

胶层厚度及固化工艺对湿态剥离强度的影响

讨论了影响金属胶接接头剥离强度的主要因素，采用作者研制的简易测试装置测定了钢制试样的剥离强度，并分析了胶层厚度及固化工艺参数对湿态剥离强度的影响。     

力和介质共同作用对环氧胶接接头老化行为的影响

为了考察外加载荷和介质共同作用对环氧胶接接头老化寿命的影响,在常温条件下将环氧胶接接头浸泡在不同介质中,然后固定在拉力机上分别施加500N、1000N、2000N的外加载荷,研究了环氧胶接接头在不同大小载荷和不同介质作用下的老化寿命变化规律.结果表明,所施外加载荷越大其寿命越短;在相同载荷作用下,铝合金环氧接头在介质中的失效时间顺序为:5%氯化钠溶液＜水,而对于钛合金环氧接头在介质中的失效时间顺序为:10%HCl＜10%H2SO4＜10%NaOH(wt).     

金属胶接工艺设计专家系统

介绍了用Turbo—PROLOG说明性语言写成的金属胶接接头工艺设计专家系统。本系统对钢、铝及其合金、铜及其合金、不锈钢、钛及其合金、铸铁等同种或异种金属胶接接头的工艺设计，胶粘剂选择、胶接工艺参数的确定均可自动完成．     

金属胶接接头的内应力及其消除

对引起金属胶接接头内应力的因素进行了分析，指出胶粘剂的受拘束收缩及受热时胶层内的塑性压缩应变发生是导致接头中出现拉伸内应力的主要原因。文中提出了消除或减轻金属胶接接头拉伸内应力的有效工艺措施。     

膨胀机缸体胶接接头设计及工艺

用合理的接头设计,适宜的胶接工艺及性能优良的胶粘剂,对制氧设备的膨胀机缸体裂缝进行了胶接尝试。经过半年多的运行考核,证明满足了设备运转要求。     

SY-24中温固化胶接体系

介绍了航空结构胶接用SY－24中温固化胶接体系的全面胶接性能,该胶接体系的研究及在航空结构件上的使用概况。可以看出,这类经过改性的环氧树脂单组份胶粘剂适于大面积的金属结构(包括铝蜂窝夹芯结构)胶接,其工程性能是优良的,并有可能在更为广泛的领域发挥其作用。     

Effect of carriers on the performance of aluminum alloy joints bonded with a structural film adhesive

The effect of polyester and nylon carriers on the durability of metal joints bonded with the modified epoxide adhesive BSL 312 has been examined. Joints have been exposed to air at 50°C and 100 percent RH for periods of up to 10,000 h. Some joints were under tensile stress and this seems to have no effect on durability. Carriers cause a slight lowering of the strength of dry joints, but they appear to have negligible effect on joint durability. An analysis of water distribution in exposed joints implies that the rate of strength loss is dependent upon the rate at which water enters joints by diffusion.     

一种建筑结构胶用环氧固化剂的研制

选用了甲基环戊二胺为主要原料进行曼尼希改性,探讨了甲基环戊二胺曼尼希改性中原料物质的量比、温度、含水率等因素对产品性能的影响。对改性环氧固化剂进行了分析测试和配制的建筑结构胶的力学性能测试。测试结果表明,甲基环戊二胺曼尼希改性的产品是一种理想的结构胶用环氧固化剂。     

Selected aspects of epoxy adhesive compositions curing process

The paper focuses on selected parameters of curing process – temperature and time. The tests aimed at evaluating the impact of short-term thermal recuring on 1050A and 2017A aluminium alloy sheet adhesive joints strength. Joints were formed with two different adhesives, the main component of which was in both cases epoxy resin Epidian 53 and two different cure agents – poliamineamide C (PAC) and triethylenetetraamine (PF) curing agents. Curing conditions – first curing time, recuring time and recuring temperature – were modified for each of the four tests conducted. For the sake of comparative analysis, adhesive joints were subjected to a single-stage cure cycle at ambient temperature. A two-stage cure cycle of both Epidian 53 compositions at 80?°C for 1 and 2?h produces a material of different mechanical properties than the same material which submits a single-stage cure cycle at ambient temperature, as well as at 60?°C for 30?min. Simultaneously, Epidian 53/PF/100:50 composition proves to produce higher joint strength after recuring than Epidian 53/PAC/100:80; the strength of a joint formed with the former composition increases up to 50% when compared with joints subjected to a single-stage cure cycle. Moreover, tests show that recuring of the adhesive joint formed with both compositions at 60?°C for 30?min does not have a considerable influence on either 1050A or 2017A aluminium adhesive joint strength.     

流变仪在环氧结构胶黏剂工艺性能评价中的应用

通过剪切应力扫描、时间扫描和角频率扫描3种不同的流变方法,研究了2种环氧结构胶的流变性能。结果表明:环氧结构胶的黏弹性能与其最终使用性能密切相关;通过采用流变仪测试环氧结构胶的屈服应力、固化速率和低频下的黏弹性能,可快速评估环氧结构胶的抗垂挂性能、可操作时间和储存稳定性能。     

Principles and practices of adhesive bonded structural joints and repairs

Adhesive bonding has been used for a number of decades for construction of aircraft components. Light weight sandwich construction and structural bonded joints form a major proportion of modern aircraft. Bonded patches are also used for repair of sandwich panels, cracks in metallic structure or reinforcement of deficient structures. The in-service durability of bonded structures and repairs has varied dramatically, with some structures and repairs providing life-of-type service and others failing in a very short time, leading to a poor acceptance by aircraft operators of adhesive bonded structures and repairs. A corresponding reluctance has occurred amongst manufacturers and repair authorities to accept the superior performance of adhesive bonding which has been demonstrated in laboratory and field trials over a number of decades. The variability of bonded joints can occasionally be traced to deficient bonded joint design, but usually the deficiency lies in a lack of understanding of the adhesive bonding processes. If some basic principles are applied (and preferably embodied in some form of design and processing standard for airworthiness certification) reliable adhesive bonded structures and repairs would achieve a significantly superior performance over conventional mechanically fastened systems. This paper details basic principles required for the production of strong, durable adhesive bonds.     

Modeling of cohesive failure processes in structural adhesive bonded joints

This paper presents an approach to predicting the strength of joints bonded by structural adhesives using a finite element method. The material properties of a commercial structural adhesive and the strength of single-lap joints and scarf joints of aluminum bonded by this adhesive were experimentally measured to provide input for and comparison with the finite element model. Criteria based on maximum strain and stress were used to characterize the cohesive failure within the adhesive and adherend failure observed in this study. In addition to its simplicity, the approach described in this paper is capable of analyzing the entire deformation and failure process of adhesive joints in which different fracture modes may dominate and both adhesive and adherends may undergo inelastic deformation. It was shown that the finite element predictions of the joint strength generally agreed well with the experimental measurements.     

Long endurance fatigue performance of bonded structural joints

Resin bonded joints are being used for a variety of applications in highway bridges. Such uses involve operation under different combinations of dead and live loading plus weathering. This paper is concerned with the fatigue performance of steel-to-steel lap joints for endurances of up to 10⁸ cycles. The effects on fatigue performance of curing temperature and operating temperature have been examined and work in progress to investigate effects of weathering is described. Special attention is given to performances at long endurances and low stresses relevant to traffic loading during service.     

Effect of carriers on the performance of aluminium alloy joints bonded with an epoxide-polyamide adhesive

The introduction of a carrier fabric into an epoxide nylon adhesive lowered the initial shear strengths of lap joints, the effect being more severe with a close knitted carrier. The close knitted carrier led to a large additional decrease in joint strength after exposure to warm humid conditions. Stressing at 20% of the dry lap shear strength sometimes led to complete failure of the joints; this effect was much more marked in the presence of the close knitted carrier. Freeze-thaw cycling after exposure to water did not cause further reduction in joint strength. Drying unsupported adhesive joints after exposure to high humidity resulted in recovery to 80% of the initial dry strength. The total amount of water in a lap joint, calculated from the diffusion coefficient, was found to be linearly related to joint strength.     

Comparison study of dicyandiamide-cured epoxy bonded steel joints and polyamidoamine-cured epoxy bonded steel joints

There are instances where efficiency and safety may be compromised as a result of deteriorating fluid transport systems. Thus, it is worth evaluating other methods that can repair the damage for a temporary period without shutting down the operation. The objective was to evaluate the durability of an epoxy-bonded steel in aqueous environments that would represent such a repair. EPON^® 828 was chosen as the epoxy resin, and dicyandiamide and polyamidoamine were two types of curing agents evaluated in this study. The epoxy-bonded steel joints were exposed in either distilled water or 3.4% NaCl solution for various times. The mechanical strength of the bonded joints was evaluated using a three-point flexure test. The interfacial shear strength of unaged samples ranged from 0.93 to 0.32 MPa. It was found that the interfacial shear strength decreased with aging time for both epoxy-bonded systems. Scanning electron microscopy (SEM), optical microscopy, and X-ray photoelectron spectroscopy (XPS) were used to determine the locus of failure of the bonded joints. It was concluded that failure occurred cohesively within the oxide layer if oxides were present on the substrate surface prior to the bonding procedure.     

Fatigue damage evaluation of adhesively bonded butt joints with a rubber-modified epoxy adhesive

A damage evolution of adhesively bonded butt joints with a rubber-modified adhesive has been investigated under cyclic loading. An isotropic continuum damage model coupled with a kinetic law of damage evolution was applied to the butt joint. To solve the kinetic law, analytic and numerical methods were tried: the former solution was derived with some simplifications and the latter one was derived rigorously without simplications. On comparing the analytic solutions with the numerical ones, it was confirmed that differences in the two solutions were small. Furthermore, the estimated S-N curves based on the analytic equation agreed well with experimental data.