基于正反向模拟的板料成形毛坯精确设计

介绍了一种用于冲压毛坯设计的新方法——基于正、反向模拟的毛坯外形设计技术,即先用全量法进行反向模拟,快速得出近似的坯料,再用增量法进行正向模拟修正毛坯的外轮廓,从而得到比较精确的坯料尺寸。并结合这种方法解决了实际生产中的一些问题。     

基于数值模拟和人工神经网络技术的汽车覆盖件坯料设计优化

阐述了运用数值模拟和人工神经网络技术相结合的方法进行汽车覆盖件坯料设计的思路,试验研究的结果表明：采用设计优化切实可行,具有良好的实际应用效果。     

汽车覆盖件翻边成形切边线优化设计及算例研究

主要研究了汽车覆盖件翻边成形工艺的切边线优化设计,提出了一种基于误差修正的预示翻边切边线的迭代算法,基于LS-DYNA的仿真模拟,根据模拟结果轮廓与目标轮廓间的形状误差来不断优化毛坯形状,对于复杂的汽车覆盖件翻边零件,一至两次的迭代优化后即可得到精确的切边线形状。在程序中实现了LS-DYNA求解器的自动调用,大大提高了切边线的优化效率。最后通过2个汽车覆盖件翻边成形的算例研究证明了该方法的有效性,为汽车覆盖件拉深模和切边模同步开发提供了切实可行的技术手段。     

镁合金筒形件正反向快速气压胀形实验研究

采用两种不同轮廓的反向预成形模具以1.5mm厚的AZ31轧制镁合金板材为坯料进行了筒形件的快速气压胀形实验,结果表明预成形模具型腔轮廓曲率半径过小(r=5)时,反向胀形时间可达到120s。当反向胀形变形量较大时,在较高的气压下成形预成形件内表面会产生一些垂直于板料轧制方向的拉裂痕。筒形件单向和正反向气压胀形实验结果表明,在400℃温度下胀形300s可以成形出高径比(高度/直径)为0.37的完好筒形件,筒形件壁厚介于0.44和1.40mm之间,最薄处位于底部拐角处。     

筒形件强力旋压三维刚塑性有限元模拟中几个关键问题的研究

本文对筒形件强旋三维刚塑性有限元模拟中的关键技术问题进行了研究。精确计算了旋轮和坯料的接触轮廓, 建立了有限元网格离散模型, 给出了旋轮与坯料接触区空间约束及速度边界条件的处理方法。文中对筒形件反旋模拟的结果表明, 所提出的处理方法是可靠的。     

筒形件强力旋压三维刚塑性有限元中几个关键问题的研究

本文对筒形件强旋三维刚塑性有限元模拟中的关键技术问题进行了研究。精确计算了旋转和坯料的接触轮廓,建立了有限元网络格离散模型,给出了旋轮与坯料接触区空间约束及速度边界条件的处理方法,文中对筒形件反旋模拟的结果表明,所提出的处理方法是可靠的。     

6082铝合金散热器折叠缺陷预测及精锻工艺优化

"折叠"是铝合金精锻件的常见缺陷。利用Deform-3D软件对汽车用6082铝合金散热器精锻成形过程进行模拟,结合成形过程中金属的流动规律及应力应变分布,分析了铝合金精锻过程中折叠缺陷产生的原因。结果表明:模具设计不合理、坯料轮廓选择不当、压下量过大、润滑不均匀等,均可造成金属流动不均匀,以及局部金属充满饱满后回流造成折叠缺陷。通过优化工艺参数、坯料轮廓及模具结构,模拟和实验均获得了无缺陷的6082铝合金散热器精锻件。     

铝合金侧围拉延工艺分析与优化

针对铝合金汽车覆盖件拉延成形时易出现开裂、起皱等问题,以某品牌汽车铝合金侧围为例,对制件的工艺性进行了分析,设计了工艺补充面,并进行了初始模拟与分析。主要研究了门洞开裂的优化方案,提出了内圈拉延筋锁紧、优化坯料线R角、降低冲压速度3种方案,研究了其对门洞开裂的影响。模拟结果表明:锁紧内圈拉延筋,门洞处切向撕裂现象缓解,但板件内部出现开裂,此方案不可行;门洞开裂与坯料线R角有很大关系,钝化坯料线R角能有效解决门洞开裂问题;通过降低冲压速度,能对门洞应力集中区域起到辅助优化的作用。实际制件与仿真结果基本一致,对同类产品具有很好的参考意义。     

数值模拟技术在汽车覆盖件成形中的应用

金属薄板成形的数值模拟技术在汽车覆盖件生产及其模具设计制造中起着十分重要的作用。数值模拟技术的广泛应用可以帮助模具设计人员显著地减少模具开发时间、试模周期和费用。为此，详细介绍了应用Dynaform软件模拟覆盖件成形过程的一般步骤，并以某汽车覆盖件的拉深为例，对其成形过程进行了数值仿真。通过对模具零件的运动、板料的成形，以及板料厚度的变化，应力应变分布，成形极限预测等结果的分析，进一步弄清了板料形状，压料筋布置以及压边力大小等工艺参数对汽车覆盖件质量的影响。在案例分析的基础上，针对覆盖件坯料拉深过程中可能出现的起皱现象，给出了相应的拉深工艺优化和模具方案优化。     

基于Dynaform的汽车覆盖件拉延成形仿真研究

基于UG-CAD和Dynaform软件,对某汽车覆盖件的拉延成形过程进行了数值仿真.通过对板料的成形过程的分析和成形极限的预测,弄清了坯料的尺寸和位置、拉延筋的布置和深度等工艺参数对汽车覆盖件成形质量的影响.在典型实例分析的基础上,针对覆盖件坯料拉深过程中的成形质量问题,给出了相应的拉深工艺优化方案.     

新型的治疗阿尔茨海默氏症药物(1-二甲基磷酰基-2,2,2-三氯)-乙基-1-醇烟酸醋对体外神经细胞的作用

目的: 观察本实验室合成的一种治疗阿尔茨海默氏症(AD)的药物(1-二甲基磷酰基-2, 2, 2 -三氯)-乙基^-1-醇烟酸醋(NMF),对体外培养的皮层神经细胞活性的影响以及对海人藻酸(KA)所致的神经损伤的保护作用。方法: 采用体外培养皮层神经元的方法,解剖分离 15 d胚胎小鼠皮层神经细胞, 接种于 96孔板,48 h 后加药并培养 72 h,以 MIT 法 观察 NMF 对小鼠皮层神经细胞活性的影响;同时将接种于 24 孔板的细胞预先给予 NMF,d 3 时加或不加KA处理后,以台盼蓝染色鉴别并计数死、活细胞,可得出细胞的存活率。结果: NMF 明显促进胎鼠皮层神经元活性,其中 NMF1、0. 1、10nmol·L^-1促进神经元活性增殖率分别高达 34.7%、37.4%、36. 7%, NMF 明显促进正常胎鼠皮层神经元存活卒,与对照组比较,10nmol·L^-1 NMF 对皮层神经元的存活率分别提高 39.3%、73.5%。 NMF能显著 对抗 KA 所致的神经元损伤,与 KA 损伤组相比, NMF0.1、10、10nmol·L^-1对损伤皮层神经元的保护率分别为 77.30%、80.10%、84.15%。结论: NMF 明 显促进胎鼠皮层神经元的洁性、提高正常皮层神经元,的存活卒,并能有效地保护KA所致的神经元损伤,提示 NMF 是一种很有潜力的治疗 AD 的药物。     

Three-Dimensional Growth of Coherent Ferrite in Austenite: A Molecular Dynamics Study

Coherent second phase often exhibits anisotropic morphology with specifi c orientations with respect to both the second and the matrix phases. As a key feature of microstructure, the morphology of the coherent particles is essential for understanding the second-phase strengthening eff ect in various industrial alloys. This letter reports anisotropic growth of coherent ferrite from austenite matrix in pure iron based on molecular dynamics simulation. We found that the ferrite grain tends to grow into an elongated plate-like shape, independent of its initial confi guration. The fi nal shape of the ferrite is closely related to the misfi t between the two phases, with the longest direction and the broad facet of the plate being, respectively, consistent with the best matching direction and the best matching plane calculated via the Burgers vector content(BVC) method. The strain energy calculation in the framework of Eshelby's inclusion theory verifi es that the simulated orientation of the coherent ferrite is energetically favorable. It is anticipated that the BVC method will be applicable in analysis of anisotropic growth and morphology of coherent second phase in other phase transformation systems.     

Effect of Short-Time Aging on the Pitting Corrosion Behavior of a Novel Lean Duplex Stainless Steel 2002

The effect of short-time aging in the temperature range between 400 and 1000 °C on the pitting corrosion behavior and mechanical property of a novel lean duplex stainless steel(LDSS) 2002 was investigated through the potentiostatic critical pitting temperature(CPT) tests and the Charpy impact tests. Both the pitting corrosion resistance and the toughness of aged specimens degraded due to the precipitation of detrimental secondary phases and the most significant reduction of CPT and impact energy emerged at 650 °C concurrently. The CPT of LDSS 2002 specimen aged at 650 °C decreased by 28 °C, and the impact energy dropped from 69 to 29 J/cm~2 compared with the solution-annealed sample. Transmission electron microscopy characterization showed that the main precipitates in LDSS 2002 were Cr_2N and M_(23)C_6 along the ferrite–austenite grain boundaries.     

INTRODUCTION TO PATENTS

The invention provides a method of making a mold which can reduce SOx generation rate while preventing decrease in hardening rate in the case of using sulfuric acid for a hardener composition. The method has a mixture step in which fire-resistant particles, a hardener composition and a binder composition are mixed to obtain a composition for a mold. The hardener composition contains sulfuric acid. In the mixture step, sodium carbonate is added. A molar ratio of the sulfuric acid to the sodium carbonate is 0.5 or more and 4.0 or less.     

China Foundry Week 2014

China Foundry Week, hosted by the Foundry Institution of Chinese Mechanical Engineering Society （FICMES） each year, is a large academic event in China. It is one of the ten high-impact activities sponsored by the Chinese Mechanical Engineering Society.     

17th Conference of Hydrodynamic and Electromechanical Control Engineering Call for papers

正1.Contents In order to promote the academic exchanges and technical communication of the research in the field of fluid power transmission and control,fluid control engineering specialized committee of the Chinese Society of Theoretical and Applied Mechanics will hold the 17th Conference of Hydrodynamic and Electromechanical Control Engineering on July 27-29,2014 in Tibet,Lhasa city.     

Information for Contributors

正The Transactions of Nonferrous Metals Society of China,founded in 1991 and sponsored by The Nonferrous Metals Society of China,is published monthly now and mainly contains reports of original research which reflect the new progresses in the field of nonferrous metals science and technology,including mineral processing,extraction metallurgy,metallic materials and heat treatments,metal working,physical metallurgy,powder metallurgy,with the emphasis     

Preface

<正>We are pleased to present this Special Issue of Transactions of Nonferrous Metals Society of China containing selected papers from the First Asian Conference on Aluminum Alloys(ACAA-2013),held in Beijing,China,13–17 October 2013.This conference has been initiated,with approval of     

Information for Contributors

The Transactions of Nonferrous Metals Society of China, founded in 1991 and sponsored by The Nonferrous Metals Society of China, is published monthly now and mainly contains reports of original research which reflect the new progresses in the field of nonferrous metals science and technology, including mineral processing, extraction metallurgy, metallic materials and heat treatments, metal working, physical metallurgy, powder metallurgy, with the emphasis on fundamental science. It is the unique preeminent publication in English for scientists, engineers, under/post-graduates on the field of nonferrous metals industry. This journal is covered by many famous abstract/index systems and databases such as SCI Expanded, Ei Compendex Plus, 1NSPEC, CA, METADEX, AJ and JICST.     

Rheology Feature of Simple Metal Melt

The rheology feature of Sb, Bi melt and alloys was studied using coaxial cylinder high-temperature viscometer. The results showed that the curve of torsion-rotational speed for Sb melt presents a linear relation in all measured temperature ranges, whereas for the Bi melt, the curve presents obvious non-Newtonian feature within the low temperature range and at relative high shear stress. The rheology feature of Sb80Bi20 and Sb20Bi80 alloy melts was well correlated with that of Sb and Bi, respectively. It is considered that the rheology behavior of Sb melt plays a crucial role in Sb80Bi20 alloy and that of Bi melt plays a crucial role in Sb20Bi80 alloy.