Collapse of composite-repaired cylinders with internal metal loss subjected to external hydrostatic pressure

The present study investigates the collapse performance of composite-repaired cylinders with internal metal loss subjected to external pressure. Three groups of intact, thinned, and repaired cylinders were designed, analytically verified, fabricated, geometrically measured, externally tested, and numerically modeled. Each group had three nominally identical cylinders to ensure the repeatability of experiments. The cylinders had the same end closure, effective length, total length, external radius, and intact thickness for an equivalent comparison. The thinned cylinder was considered as the intact cylinder with internal metal loss, whereas the repaired cylinder was considered as the thinned cylinder with composite reinforcement. The results indicated that the external loading capacity of cylinders with internal metal loss could be fully restored and even enhanced by composite reinforcement. Composite-repaired cylinders are much less sensitive to initial geometrical imperfections than intact cylinders.     

Automated manufacture of optimised shape-adaptive composite hydrofoils with curvilinear fibre paths for improved bend-twist performance

Composite marine propellers improve hydrodynamic efficiency by inducing bend-twist coupling and allowing for passive pitch changes. One critical limitation, however, is the extent to which a composite propeller blade can deform and cause a pitch change without incurring structural failure. Recent numerical studies showed that curvilinear tows could improve the structural response of a composite blade by lowering its deflection or stress and strain required to induce a pitch change, but no experimental validation has been carried out before. The current study, thus, presents the manufacture of composite sandwich hydrofoils made with steered tows using automated fibre placement and validates the curvilinear tow benefits. Two hydrofoils were optimised with straight and curved fibre path layups, respectively and were manufactured for mechanical testing. The manufacturing complications arising from steering curvilinear tows in a three-dimensional convex mould are also discussed in the paper. The study found that significant tow buckling occurred near the tool cavity edge due to excessive steering radius during manufacture. The follow-up structural cantilevered tests showed that the experimental results were consistent with the FE predictions despite the presence of some manufacturing defects. The experiment agreed that the hydrofoil manufactured with curved tows achieved a similar tip twist but a significant reduction in deflection and critical principal strains compared to the hydrofoil made with straight tows. The use of a foam core reduced the overall weight of the sandwich hydrofoils by about 25% compared to that of a fully-carbon composite hydrofoil, and the numerical analysis showed that the core shear failure induced by transverse shear stresses was unlikely to occur.     

可在线涂装的“碳纤维/钢”复合结构汽车B柱分总成的研发

为提高汽车安全性和轻量化水平,开发了一种可在线涂装的“碳纤维/钢”复合结构B柱分总成,该分总成包括钢制B柱加强板和碳纤维增强复合材料(CFRP)B柱中部支撑板,采用结构胶粘接而成。研究了真空袋压与热压罐成型工艺对CFRP层压板涂装前后性能的影响,并对“碳纤维/钢”的粘接强度、B柱分总成的刚度和强度等力学性能进行了研究,结果表明,复合结构B柱分总成在涂装前后的性能均优于传统钢制总成,CFRP中部支撑板减重64.1%。     

无伸缩缝桥梁合成梁式结点的受力性能和试验研究

提出一种受力性能介于整体式和半整体式桥台无伸缩缝桥梁之间的新型的结点构造方式--合成梁式的结点构造.通过有限元通用程序ANSYS建立该结点的有限元模型,研究在最不利荷载情况下的结点受力性能及结点参数对受力性能的影响,并进行了结点模型试验.研究表明,合成梁式的结点可用于无伸缩缝桥梁设计;在满足设计承载力的情况下,桥台的高度和长度宜取小值;桩存在一个合适的相对刚度,当桩相对刚度超过这个值时,对合成梁式的结点受力几乎没有影响.     

汽车用聚醚醚酮复合材料研究

聚醚醚酮工程塑料具有优异的综合性能，在汽车工业中已显示出代替金属和其它高性能材料的优势。针对聚醚醚酮改性的纤维增强复合材料、无机填充复合材料、有机共混复合材料的摩擦性能进行了研究，以满足汽车工业持续发展对工程塑料提出的高性能、低成本的要求，扩大其在汽车工程领域的应用范围。     

汽车悬架用空气弹簧的非线性有限元分析

讨论了空气弹簧的材料、几何、接触、载荷等非线性力学特征，提出了运用非线性有限元法对空气弹簧进行结构分析的思路，并对某型汽车空气弹簧进行了充气变形与刚度特性分析，刚度特性的有限元分析结果与试验结果吻合较好。     

基于无机复合材料的排气管路保温性能研究

重型商用车后处理系统排气管路的保温性能对整车排放性性能有着重要的影响,减小排气管路沿程热损失,提高后处理器内部反应温度和污染物转化效率,是整车实现排放性能升级的重要途径.应用新型无机复合材料包覆排气管路,降低排气管路的热损失,提高后处理器内部化学反应温度,能够有效提升后处理器内部载体的转化能力.在不同的环境温度条件下,...     

HGM-D型高摩合成闸瓦在肯尼亚蒙内铁路的运用

介绍了肯尼亚蒙内铁路概况及线路特点,HGM-D型高摩合成闸瓦性能参数以及在蒙内铁路C70E、X70、NX70型货车上运用验证情况.验证表明HGM-D型高摩合成闸瓦有效降低车轮和闸瓦磨耗量以及闸瓦金属镶嵌物,提高了车辆运行品质和制动效能.     

复合式中墙连拱隧道设计施工分析

文章以云南思小高速公路麻地河隧道为例,对复合式中墙连拱隧道设计和施工的重点、难点进行了分析,指出了依据监控量测结果进行动态设计、优化设计与信息化施工的重要性,并对复合式中墙连拱隧道的施工工序和施工技术提出了建议。     

复合地层中盾构滚刀磨损原因分析及对策

通过系统地总结和分析约40台次混合式盾构机在复合地层中掘进近100 km的滚刀磨损情况,对滚刀磨损做了定性分类,并根据滚刀磨损的影响因素,提出滚刀磨损的对策,以期指导今后复合地层施工中盾构机刀盘刀具选择、配置及盾构掘进。