A model for process-based crash simulation

Manufacturing of a bumper system from aluminium extrusions often involves series of forming operations performed in the soft W-temper condition, and then artificially age-hardening of the components to the material's peak hardness T6 condition. It is probable that proper finite element (FE) modelling of the crash performance of the resulting systems must rely upon a geometry obtained from an FE model following the process route, i.e., including simulation of all major forming operations. The forming operations also result in an inhomogeneous evolution of some internal variables (among others the effective plastic strain) within the shaped components. Results from tensile tests reveal that plastic straining in W-temper leads to a significant change of the T6 work-hardening curves. In addition, the tests show that the plastic pre-deformation causes a reduction of the elongation of the T6 specimens. In the present work, these process effects have been included in a user-defined elastoplastic constitutive model in LS-DYNA incorporating a state-of-the-art anisotropic yield criterion, the associated flow rule and a non-linear isotropic work hardening rule as well as some ductile fracture criteria. A first demonstration and assessment of the modelling methodology is shown by ‘through-process analysis’ of two uniaxial tensile test series. The industrial use and relevance of the modelling technique is subsequently demonstrated by a case study on an industrial bumper beam system.     

喷气纺纱喷嘴安装位置对成纱强力的影响

研究了喷气纺纱喷嘴安装位置有关参数及解捻管槽数对成纱强力的影响规律。试验结果表明：一级喷嘴与前钳口间距存在临界值，当间距为11mm时成纱强力最高；当两级喷嘴间距为4mm时，成纱强力较高且波最小；异纱钩与二级喷嘴的最佳 间距为88mm，该距离过大过小成纱强力均有降低；随着解捻管槽数的增加，成纱强力提高，实际生是中可选 用四槽。     

金属的复合成形技术及其发展

引入了“复合成形技术”的概念，并对其现状及发展进行了阐述。如现代的科学越来越相互交叉、渗透，出现许多边缘学科、交叉学科一样，材料成形技术也逐渐突破原有铸、锻、焊等技术相互独立的格局，相互融合、渗透，“复合成形技术”的产生是技术发展的必然结果。这种技术的复合已经不仅限于材料“成形”的范围，也延伸到材料制备技术与成形技术的融合。可以说，“复合成形技术”是成形技术领域的一种创新，是将两种或两种以上的传统成形技术在时问、空间或物态上进行集约化组合而形成的一种全新概念的技术，有广阔的技术发展和应用空间。     

A review of the development of creep age forming: Experimentation, modelling and applications

About twenty years ago, the process of Creep Age Forming (CAF) was invented, and since then has been developed for the manufacture of heat treatable aluminium alloy panel components particularly, it has been successfully used for aircraft wing panels. Significant research work has been carried out in recent years and process applications have been expanded. This paper contains a review of recent research and development of this novel forming process. It covers process applications in the aircraft industry and scientific research, including the development of forming tools, experimental studies, materials and process modelling and springback prediction. Some potential future applications and challenges for deeper understanding of this novel process are also discussed.     

筋板类构件成形技术研究进展

筋板类构件因结构复杂,给加工带来许多困难。介绍了筋板类构件的应用概况,综述了其国内外成形技术发展现状。     

MIMO技术及在3G中的应用

介绍MIMO技术的定义和历史,从空间复用、传输分集技术、波束成型等方面对MIMO技术进行说明,并对MIMO在3G(HSPA+)中的应用做了简单的描述。     

QQ-06浆料在特细号纱上浆中的应用

为减少PVA用量、提高特细号高密品种的浆纱质量,设计了以变性淀粉、丙烯酸类浆料和QQ-06浆料为主的配方.对应用QQ-06浆料前后纯棉品种和涤棉混纺品种的上浆效果、织造效果进行了测试对比,结果表明:应用QQ-06浆料后,浆料粘度稳定,浆轴疵点得到控制,织机效率提高10个百分点.     

控制低比例纯涤纶色纺纱外观质量的体会

色纺纱织物具有色泽自然，层次清晰的特殊风格，但色纺纱在纺制过程中容易出现色差、色条等外观疵点，为提高色纺纱外观质量，应从以下几方面着手：合理选配工艺流程，加强色纤维管理，合理使用回花并控制短片段色比不匀，在络筒工序采用上蜡处理的方法改善成纱毛羽，加强操作管理及现场检查，通过采取以上措施，有效改善了色纺纱的外观质量。     

棉涤交织弹力织物的生产要点

探讨棉涤交织弹力织物的设计思路及生产要点。介绍了产品设计思路和织物经纬纱质量指标;鉴于织物组织循环较大,给出了织物的纹板图;介绍了穿综方法和经纬纱循环;采用分批整经;优选浆料配方和浆纱工艺;采用GA747-200型剑杆织机,优选进剑时间;后整理中,定形温度控制在180℃~200℃,时间控制在1min~2min。通过采取一系列技术措施,保证了织物质量,达到了预期效果。认为:生产中应针对经纬纱特点和织物组织优选工艺参数,以保证顺利生产。     

新型细纱牵仲器材及其使用效果（下）

阐述国内新研制开发的细纱牵伸器材的技术性能及其使用效果。介绍了细纱罗拉的质量要求和维护要求，指出应用新型优质的无害机械波罗拉有利于降低成纱条干不匀；介绍了SE6819-SG型细纱双滑道上罗拉轴承的结构和性能特点，双滑道上罗拉轴承前后排钢球采用相同结构，受力均匀，运转稳定；介绍了丁腈胶辊、丁腈胶圈新产品，环保型胶辊涂料、高效能胶辊胶圈专用清洁剂的技术特点和使用效果，胶辊制作与纺纱工艺配置要求；介绍了聚氨酯胶辊性能特点和初步使用效果；介绍了尼龙弹性钳口上销、T形下销、下胶圈轴承式节能张力辊、V形牵伸后牵伸区压力棒装置的纺纱效果。实践表明，优选新型细纱牵伸器材，合理配置纺纱工艺，有利于成纱质量的稳定提高。