温度变化对复合材料双面搭接接头拉伸强度的影响分析

介绍了复合材料三种连接方式之一——胶接。对双面搭接接头进行了有限元建模,在不同的高温环境下进行拉伸试验,运用相关的失效准则,分析判断复合材料胶接接头的破坏形式,确定温度对破坏形式的影响。通过试验,验证了分析的正确性,对复合材料胶接接头的强度校核及设计改进有重要的指导作用。     

复合材料快速连接抗拉接头受力性能研究

分析了复合材料轻质桥梁中的快速连接接头的受力,提出了一种大拉力接头的构造,完成了一批接头的拉伸试验和桥跨模型试验,证实了接头具有足够的承载能力,并依据破坏模式建议了接头的改进构造。还采用有限元软件对桥跨模型试验中的接头进行了分析,其破坏模式和破坏承载力与试验吻合。     

聚乙烯管材热熔对接接头性能的研究

通过使用两种不同聚乙烯(PE)原料制成的管材热熔对接接头试样进行(5±1)mm/min、(50±1)mm/min恒定速度拉伸试验,阐述了PE管材热熔对接接头的性能低于管材本体;利用对PE管材热熔对接接头试样加热的方法,以及对热熔对接接头试样焊缝四周切口后进行的(5±1)mm/min恒定速度拉伸试验,判定PE管材热熔对接接头的性能,这种方法与其它破坏性试验的统计结果相一致;并介绍了国外对PE管材热熔对接接头质量的评价方法。     

焊接电流对Q235钢焊接接头残余应力的影响

对12 mm厚Q235试板进行手工电弧焊试验研究。采用3种不同焊接电流参数对3组试板进行焊接,以研究不同焊接电流下焊接接头所产生的残余应力。3组试板均采用双面焊。分别对正面填充焊和盖面层焊采用155 A、165 A、175 A三种焊接电流。焊完后采用残余应力测试方法对焊接接头进行分析。研究结果表明,Q235钢在175 A电流下焊接接头残余应力比165 A电流下大,155 A电流下最小。随着焊接电流的增大,焊接残余应力升高。     

平流层飞艇碳纤维复合材料刚性骨架的管件连接方法研究

碳纤维复合材料凭借优良的力学性能在浮空器领域具有很好的应用前景。根据某平流层飞艇项目的工程需求,本文对飞艇刚性骨架的碳纤维管件结构件连接问题开展了初步研究。基于对目前碳纤维复合材料管件连接方法现状的调查,对法兰接头连接、卡槽接头连接和榫卯接头连接三种简易连接方法进行了轴向拉伸试验研究及适用性分析。在此基础上,提出了一种使用螺纹套管接头的连接方法,并通过试验和有限元软件模拟,验证了该方法可以满足飞艇工程设计的抗拉能力指标要求和作为平流层飞艇刚性结构件的构造要求,并具有安装/拆装便捷等优点,解决了平流层飞艇项目的工程需求。     

柔性复合材料改造城市燃气管道性能研究

在西气东输中采用柔性复合材料改造城市原有煤气管道接头来输送天然气是一种经济、实用的方法.本文介绍了一种高性能的聚氨酯-涤纶布-铝箔复合材料内衬的煤气管道接头密封连接结构,还介绍了"诺迪霸工艺",并按有关试验标准,对管道接头密封结构进行了气密性、耐气压、抗弯曲、抗剥离强度及人工加速老化等试验.试验结果证明,这种结构形式和施工工艺性能优良、安全可靠,能够满足天然气输送.     

除氧器复合钢板的对接焊接工艺

分析了用于制造除氧器的不锈钢复合板的焊接工艺.对SA516Gr70+SA240TP304不锈钢复合板采用新的SAW加FCAW焊接工艺,并将其与原SAW加SMAW焊接工艺进行对比.对由这两种焊接工艺得到的焊接接头试样进行金相组织和力学性能试验.试验结果表明,新焊接工艺可获得性能良好的对接接头,焊接接头各个截面上微观组织结...     

埋弧焊焊接速度对Cr-Mo-V钢焊接接头性能的影响

采取5种不同焊接速度对临氢高压设备用Cr-Mo-V钢埋弧焊焊接接头性能的影响进行试验,结果表明焊接速度控制在24~27m/h时焊缝成形和接头性能良好。     

三维编织复合材料胶接接头力学性能试验研究

为了比较三维编织复合材料阶梯型和嵌套式搭接接头的胶接修复效果,对搭接长度相同的两种接头进行了拉伸和弯曲力学性能研究。通过实验得到两种接头及完好试件的载荷-位移曲线,对比了修补后的试件强度与完好试件的强度,得到了接头试件的修复效率,并分析和总结了拉伸与弯曲试验试件的损伤过程及损伤形貌。实验结果显示:阶梯型胶接接头拉伸载荷作用下的修复率为37.75%,弯曲载荷作用下的修复率为66.25%;嵌套式胶接接头拉伸载荷作用下的修复率为18.97%,弯曲载荷作用下的修复率为21.44%。对比试验结果得出阶梯型胶接接头力学性能较好。     

夹层结构榫卯T型接头弯曲破坏机理试验研究

本文针对复合材料蜂窝夹层结构榫卯胶接T型接头,进行了弯曲破坏模式和承载能力的试验研究。试验研究了不同榫头宽度、不同榫头数量的五种T型接头试验件,绘制了弯矩-位移曲线图。弯曲试验结果表明:T型接头试验件的破坏包括榫肩区域的胶接面拉伸破坏和榫头区域上面板胶接面剪切破坏或面板拉断。在加载过程中榫肩区域首先发生脱黏,榫头区域承担大部分载荷,最后榫头区域上面板与底板脱黏或面板被拉断。参数研究结果表明:对于复合材料蜂窝夹层结构榫卯胶接T型接头,增加榫头宽度和榫头数量能显著增加T型接头的弯曲刚度,对提高T型接头的弯曲承载能力也有重要贡献。     

真空和电子束钎焊1Cr18Ni9Ti实验研究

采用三种钎料对1C r18N i9T i不锈钢进行真空和电子束钎焊,分析了钎焊接头力学性能。结果表明:纯铜、BПP-1、BN i-2钎料电子束钎焊接头的抗剪切强度均高于其真空钎焊接头的抗剪切强度值。不论是电子束钎焊还是真空钎焊,三种钎料中纯铜钎料钎焊接头力学性能最好。     

真空和电子束钎焊1Cr18NigTi实验研究

采用三种钎料对1Crl8Ni9Ti不锈钢进行真空和电子束钎焊，分析了钎焊接头力学性能。结果表明：纯铜、BHP-1、BNi-2钎料电子束钎焊接头的抗剪切强度均高于其真空钎焊接头的抗剪切强度值。不论是电子束钎焊还是真空钎焊．三种钎料中纯铜钎料钎焊接头力学性能最好。     

折曲胶接接头应力分布的数值分析

运用有限元法研究了偏轴、同轴和折曲型等三种单搭接胶接接头的工作应力分布规律。结果表明:与其他两种接头相比,折曲型单搭接胶接接头可有效降低搭接区端部的剥离应力和剪切应力峰值;在数值分析所用参数及条件下,I型折曲接头的剥离应力降幅超过了75%,其他峰值应力的降幅也超过了45%～50%,并且应力分布趋于均匀;I型折曲接头使出现应力峰值的位置从搭接区的端部转移至中部,从而显著提高了接头的承载能力,是一种优于普通同轴接头的胶接接头形式;对于受剪切载荷作用的接头而言,采用II型折曲接头更为合理,可进一步提高接头承受剪切载荷的能力。     

An investigation of fatigue failure prediction of adhesively bonded metal/metal joints

A fracture mechanics-based model for fatigue failure prediction of adhesive joints has been applied in this work. The model is based on the integration of the kinetic law of evolution of defects originated at stress concentrations within the joint. Final failure can be either brittle (fracture toughness-driven) or ductile (tensile/shear strength-driven) depending on the adhesive. The model has been validated against experiments conducted on single-lap shear joints bonded with a structural adhesive. Three different kinds of adhesives, namely a modified methacrylate, a one-part epoxy and a two-part epoxy supplied by Henkel, have been considered and three different overlap lengths have been tested. Fracture toughness and fatigue crack growth properties of the adhesives have been determined with mode I tests. The number of cycles to failure has been successfully predicted in several cases. It is interesting to notice that in the case of joints loaded at the same average shear stress, the shorter the joint, the longer the duration. This fact is also captured by the model.     

乙烯球罐用9％Ni钢焊接接头低温JFAC研究

分析了９％Ｎｉ钢母材及３类焊接接头的低温失效评定曲线，分别基于弹塑性有限元和ＥＰＲＩ方法建立了ＪＦＡＣ线，并与Ｒ６第３版的通用曲线比较，得出了乙烯球罐缺陷安全评定可以采用通用曲线的结论。     

AGING CHARACTERIZATION OF ADVANCED POLYMER SYSTEMS

Aging of three advanced polymer systems used as adhesives in the aerospace industry is characterized by Fourier transform infrared spectroscopy (FTIR) with attenuated total reflectance (ATR-FTIR), dynamic mechanical analysis (DMA), thermogravimetric analysis (TGA), and X-ray photoelectron spectroscopy (XPS).Since significant changes in mechanical properties were observed for AF191, FM®73, and FM®5 bonded joints, the purpose of this work was to identify whether there is any chemical and physical degradation for the adhesives used in these joints. Each of the adhesives has been evaluated after exposing to Hot/Wet and Hot/Dry environments for 5000 h. They were also thermally cycled in conditions that represent subsonic and supersonic cruise. Hot/wet exposures demonstrated a greater amount of possible degradation than hot/dry or thermally cycled exposures. The hot/wet aging condition resulted in more pronounced O-H, C-H, and N-H infrared absorptions, reduced glass transition temperature of adhesives, and reduced tensile and fracture properties of corresponding bonded systems. Overall, these adhesives were chemically very stable under the environments to which they were exposed, even though some of the joints showed reduced fracture toughness due to the exposure. Additional work is needed to understand the mechanism causing the change in joint properties when exposed to these environments.     

几种工程塑料摩擦磨损性能的分析与比较

对聚甲醛，尼龙1010和聚四氟乙烯三种工程塑料的摩擦磨损性能进行了测试，分析和比较了它们不同截荷及不同对磨时间的摩擦磨损性能。     

CFRP旋刨刀具钻孔的可行性实验研究

CFRP是典型的难加工材料,特别是钻削直径d≥8 mm的孔。探究性设计了一种新型钻削CFRP的旋刨刀具,基于对旋刨刀刀具、麻花钻、套料钻进行的钻削实验,在不同的主轴转速和进给速度下,得到三种刀具轴向力的大小,然后利用MATLAB分别拟合出三种刀具的经验公式,并分析对比不同的转速和进给速度下轴向力对三种刀具的影响。结果表明旋刨刀刀具对CFRP制孔效果更优。     

Failure analysis of 2D C/SiC composite z-pinned/bonded hybrid single-lap joints

Z-pinned/bonded hybrid joints are widely used in the 2D C/SiC composite structures, whose mechanical behavior and failure mechanisms are directly related with the structure integrity. The hybrid joints for 2D C/SiC composite structures are formed by depositing SiC into the gap of z-pinned joints. To evaluate the SiC bonding effect, the tensile experiments for two kinds of z-pinned joints with and without bonded layer were conducted. It was proved that the failure modes of the pin were the tensile and shear failure, and the bonded layer was the interlaminar shear failure of the substrate plate instead of the shear failure of SiC bonded layer due to the smaller interlaminar shear strength. The bonded zone states of specimens were also examined, which were reproduced in the shell-fastener numerical model with surface-based cohesive behavior. Combining with shear strength theory, a numerical model is developed to study the failure processes of the hybrid joints. The SiC bonded zone areas can also greatly influence the failure response of the hybrid joints. The large SiC bonded layer zone can improve the shear strength of the joints. The failure of the joints is determined by the SiC bonded layer when the SiC bonded zone is large enough. This study can be helpful to evaluate and design the SiC bonded zone states of the hybrid joints in the engineering application.     

三种色母粒注射装置特点分析

对三种色母粒注射装置:K-Tron-Soder 公司 LWF 型失重喂料器、国产小螺杆给料机以及Colortronic 公司计量、混合装置的应用及特点进行了分析比较.提出选用注色器及消化吸收Colotronic 技术的建议.