鸟嘴节点桁架在水泥厂封闭皮带输送栈桥中的应用研究

鸟嘴节点桁架是一种新型钢桁架设计，桁架中鸟嘴节点力学性能表现优越，有利于实现抗震设计中“强节点弱构件”的设计原则。通过本文研究，鸟嘴节点桁架对比传统型钢桁架，自重有所减轻，桁架整体受力性能得以提升，桁架承载能力和抗震能力得到提高。在实际设计应用中，桁架腹杆可使用相同外径的方钢管，并采用铆钉方式将压型钢板与腹杆直接连接，能够充分发挥压型钢板的蒙皮效应，使得桁架各项杆件计算应力比、桁架挠度等设计指标均明显低于结构设计规范容许值。     

基于遗传算法的桁架形状优化及最小质量设计

在工程结构的优化设计中,应用遗传算法的基本原理,研究了离散设计变量全局寻优等传统优化方法难于解决的特殊问题。以平面桁架梁作为解析例,选取桁架的节点坐标和杆件的截面特征为设计参数,模拟遗传操作过程中的生物进化机制,对桁架的构成和形状的优化问题进行了解析。得到桁架在不同情况下的形状优化解,并使桁架质量趋于最小。研究结果验证了遗传算法在桁架的形状最优化和最小质量设计中应用的可行性。     

轻量化复合材料桁架桥承载性能试验研究

轻量化复合材料桁架桥是以碳/玻混杂纤维增强复合材料(FRP)与铝合金为原材料的,为武警部队研发、通行重型荷载的应急桥装备。为了验证桥梁的承载性能,对30 m跨轻量化复合材料桁架桥进行了静载与动载试验。结果表明:轻量化后的应急桥在静动载作用下,结构处于线弹性状态,杆件应力与桥梁变形均小于设计允许值,桥梁性能良好,达到了工程应用的设计要求。     

航天器用复合材料桁架结构研究进展

桁架结构凭借其空间可伸展、易组装、整体性好、设计灵活等优点,在各类航天器中得到了广泛的应用。由于航天器对结构质量、尺寸稳定性、阻尼性能等具有较高要求,更倾向于采用先进复合材料制造桁架结构。本文详细介绍了复合材料桁架结构的制造工艺和在国内外航天器中的应用情况,探讨了复合材料桁架结构工程化应用中存在的问题,最后展望了复合材料桁架结构的应用前景。     

弧形三角截面碳纤维复合材料桁架结构的研制

复合材料桁架结构具有重量轻、比刚度和比强度高、载荷分布合理的特点。为适应飞艇等浮空器的弧形曲面结构,创新设计了弧形三角截面碳纤维复合材料(CFRP)桁架结构,并对其制备技术进行了研究。桁架弦杆管件采用外模内加压的成型方式,三角腹杆与接头为整体结构、一体化成型,整体单元桁架在专用工装上组装连接。通过本方法制备的单元桁架组件比强度和比刚度大,各项性能满足设计指标要求,具有轻量化和承载性良好的特点。最终通过单元桁架组件的连接组合形成环形或弧形整体复合材料桁架结构件,可实现在飞艇、高空气球等浮空器桁架结构上的应用。     

树脂基复合材料在雷达结构中的应用

本文介绍了树脂基复合材料的性能和成型工艺特点及其结构件的设计方法；阐述了树脂基复合材料在雷达结构中的应用；分析了目前树脂基复合材料在雷达结构中应用存在的问题，并给出了一些建议。     

有机纤维增强水泥基复合材料研究进展

目前有机纤维作为增强体被用于水泥基复合材料成为研究的热点。阐述了有机纤维对水泥基复合材料性能影响的研究进展。首先,介绍了不同种类有机纤维的性能,阐述了不同有机纤维对水泥基复合材料性能的影响,并分析了增强增韧机理。其次,分析了有机纤维性能对水泥基复合材料性能的影响。最后,对今后的进一步研究提出了建议。     

钢管桁架结构相贯节点设计分析和实验研究

武汉·中国光谷广场轻钢屋盖采用了柱顶树状支撑的三角形钢管桁架及单层椭圆旋转壳,本文介绍了双K型钢管相贯节点设计情况,并分析了桁架节点设计计算假定对结构计算的影响;对无间隙相贯管节点中不可见相贯线是否必须进行焊接进行了分析,并介绍了足尺节点试验研究的情况。其经验可供类似工程参考。     

电子基板用玻璃/陶瓷复合材料的低温共烧与性能

玻璃/陶瓷低温共烧复合材料具有高导热性、快速电子信号传输性能、热膨胀系数与硅匹配、力学性能良好等优点,被广泛应用作电子基板材料。本文简要阐述了玻璃/陶瓷复合材料的烧结机理和影响因素,综述了主要的制备方法,指出了烧结过程中可能存在的关键问题,并讨论了玻璃/陶瓷复合材料的性能调控方法。最后,展望了玻璃/陶瓷复合材料在电子信息领域的发展方向和应用前景。     

天然纤维增强聚乳酸性能的研究进展

综述了天然纤维增强聚乳酸性能的最新研究进展,重点阐述了天然纤维对聚乳酸力学性能、结晶性能、耐热性能、吸水性能、降解性能、阻燃性能的影响,并对此类复合材料的应用前景提出展望。指出天然纤维增强聚乳酸复合材料在纺织、汽车、飞机和其它领域的研发和应用成为可能,应将优化加工工艺、增塑增容改性作为研究重点,最终实现该复合材料的高效和多产。     

暗肋夹芯式轻骨料混凝土外墙板热工性能研究

为解决现有建筑能耗中由墙体引起的热损失问题,本文提出一种暗肋夹芯式复合轻质保温墙板,并围绕该种新型墙板的热工性能开展研究。首先分别测试轻骨料混凝土、聚苯颗粒混凝土的热工参数,研究内外叶及芯层不同厚度组合、内置钢筋网及平面桁架对复合墙板热工性能的影响。然后将试验结果与理论分析结果进行对比,验证理论分析模型的可靠性,为复合保温墙板的热工设计提供基础研究支撑。对比常规预制混凝土外墙板,新型复合墙板表现出良好的热工性能。     

A detailed experimental parametric analysis of bolted and hybrid bolted/bonded composite joints

Hybrid bolted/bonded joints may have the advantages of both mechanical and adhesively bonded joints or disadvantages, which depends entirely on reasonable design. The design of the hybrid bolted/bonded joint is a complex issue, which is related to the material properties of the connected parts and adhesive layer, the number and size of the bolt, and the geometrical characteristics of the joint. Furthermore, the secondary bending in the single-lap joint and the bypass load in the multirow bolted joint to increase the complexity of the problems. Therefore, detailed tests and adequate data are essential to do further research on the mechanical behaviors of bolted and hybrid bolted/bonded composite joints, especially for the joints of bismaleimide resin composite. An experimental parametric study was carried out to reveal the effect mechanisms of different configurations on the mechanical properties of bismaleimide resin composite joints in this study. Single-lap bolted and hybrid bolted/bonded composite joints were focused on and their mechanical behaviors were discussed. According to the investigation of experimental analysis, some useful conclusions have been deduced, which are helpful for the design of bolted and hybrid bolted/bonded composite joints.     

Effect of insulation on the fire behaviour of steel floor trusses

This paper describes a study into the fire behaviour of open‐web steel trusses supporting concrete floor slabs, exposed to a range of realistic design fires. This study is intended to give some insight into the possible structural behaviour of the floor trusses in the World Trade Center (WTC) towers. The analysis was carried out using a non‐linear finite element program SAFIR. The trusses were analysed with and without protective insulation for several different fires, each with three types of connections; pinned at both ends, simply supported, and simply supported with an axial spring. This paper shows that the likely failure mode of the floor truss depends on the connection strength, and emphasizes the importance of ensuring that the insulation remains intact. Unlike the actual event in the WTC with multiple floors exposed to fire, this analysis only considers a single floor, hence the results from this analysis do not confirm the actual behaviour of the buildings while they collapsed. Copyright © 2004 John Wiley & Sons, Ltd.     

复合材料/金属胶接结构研究进展及发展趋势

胶接连接应用日渐广泛,特别是在汽车和航空航天等结构领域。首先分析了复合材料/金属胶接连接方式的特点,重点介绍了接头中的次弯曲效应、异质材料间刚度与热膨胀系数的不匹配特性以及载荷传递特性。然后总结了提高胶接接头强度的研究进展,主要包括增大胶接长度和宽度、选择胶黏剂、表面处理、增加胶瘤和被粘合物形状的设计等方面。最后对胶接接头的发展趋势进行了展望。     

基于柔性模辅助RTM技术的整体推力结构的分析与设计

本文介绍了柔性模辅助RTM(FMARTM)技术的基本原理。基于FMARTM成型技术,设计了一种整体复合材料推力结构。该结构解决了支架式推力结构的复合材料推力管与法兰边连接的难题,同时也克服了锥形壳式推力结构通风散热性能差和不便于管路设计连接的缺点。利用有限元方法对该结构的铺层方式进行了优化,采用优化铺层方式的整体推力结构的垂直压缩率和偏心率都小于1%,表明推力结构的设计是可靠的。     

Torque Transmission Capabilities of Bonded Polygonal Lap Joints for Carbon Fiber Epoxy Composites

Although carbon fiber epoxy composite materials have excellent properties for structures, the joint in composite materials often reduces the efficiency of the composite structure because the joint is often the weakest area in the composite structure.

In this paper, the effects of the adhesive thickness and the adherend surface roughness on the static and fatigue strengths of adhesively-bonded tubular polygonal lap joints have been investigated by experimental methods. The dependencies of the static and fatigue strengths on the stacking sequences of the composite adherends were observed.

From the experimental investigations, it was found that the fatigue strength of the circular adhesively-bounded joints was quite dependent on the surface roughness of the adherends and that polygonal adhesively-bonded joints had better fatigue strength characteristics than circular adhesively-bonded joints.     

Fast joining of composite pipes using UV curing FRP composites

In this paper, twelve butt-weld composite pipe joints were prepared. Among them, six were prepared using ultraviolet (UV) curing fiber reinforced plastics (FRPs) and six were prepared using ambient environment curing FRPs as controls. Filament wound composite pipes were used. Each section of pipe was 304.8 mm long with a 101.6 mm inner diameter. The wet lay-up technique was used to prepare the test samples. The curing time for the UV curing samples was 40 minutes, while the curing time was 24 hours for the control samples. Both internal pressure tests and four-point bending tests were conducted on the prepared samples. The test results show that the UV curing FRP wrapped composite pipe joints achieved nearly the same bending strength as the control samples. However, the internal pressure rating achieved by the UV curing FRP coupled joints was lower than that achieved by the control samples. A finite element analysis was conducted to understand the mechanism for the lowered internal pressure rating. Based on the test and the finite element analysis results, the UV curing FRP can be used in joining composite truss structures and composite frame structures. Suggestions were made to increase the internal pressure rating of UV curing FRP coupled composite pipes. Polym. Compos. 25:298–306, 2004. © 2004 Society of Plastics Engineers.     

Torque Transmission Capabilities of Bonded Polygonal Lap Joints for Carbon Fiber Epoxy Composites

Although carbon fiber epoxy composite materials have excellent properties for structures, the joint in composite materials often reduces the efficiency of the composite structure because the joint is often the weakest area in the composite structure.

In this paper, the effects of the adhesive thickness and the adherend surface roughness on the static and fatigue strengths of adhesively-bonded tubular polygonal lap joints have been investigated by experimental methods. The dependencies of the static and fatigue strengths on the stacking sequences of the composite adherends were observed.

From the experimental investigations, it was found that the fatigue strength of the circular adhesively-bounded joints was quite dependent on the surface roughness of the adherends and that polygonal adhesively-bonded joints had better fatigue strength characteristics than circular adhesively-bonded joints.     

Computational design of structured chemical products

In chemical product design, the aim is to formulate a product with desired performance. Ingredients and internal product structure are two key drivers of product performance with direct impact on the mechanical, electrical, and thermal properties. Thus, there is a keen interest in elucidating the dependence of product performance on ingredients, structure, and the manufacturing process to form the structure. Design of product structure, particularly microstructure, is an intrinsically complex problem that involves different phases of different physicochemical properties, mass fraction, morphology, size distribution, and interconnectivity. Recently, computational methods have emerged that assist systematic microstructure quantification and prediction. The objective of this paper is to review these computational methods and to show how these methods as well as other developments in product design can work seamlessly in a proposed performance, ingredients, structure, and manufacturing process framework for the design of structured chemical products. It begins with the desired target properties and key ingredients. This is followed by computation for microstructure and then selection of processing steps to realize this microstructure. The framework is illustrated with the design of nanodielectric and die attach adhesive products.     

An Experimental Study of the Static Torque Capacity of the Adhesively-Bonded Tubular Single Lap Joint

With the wide application of fiber-reinforced composite materials in aircraft, space structures and robot arms, the design and manufacture of composite joints have become a very important research area because they are often the weakest areas in composite structures. In this study, the effects of the adhesive thickness and tensile thermal residual stress on the torque capacity of tubular single lap joints were studied. The torque capacities of the adhesive joints were experimentally determined and found to be inversely proportional to the adhesive thickness. In order to match the experimental results to the theoretical analyses, the elastic-perfectly plastic material properties of the adhesive were used in the closed form solution. Also, the tensile thermal residual stresses of the joints were calculated by the finite element method and it was found that the thermal residual stresses could play an important role in the torque capacity when the adhesive thickness was large.