截齿锻件冷锻成形工艺分析

根据截齿锻件的形状特点,制定其冷锻成形工艺方案,即制坯、预成形与终锻成形。采用镦粗预成形时,易发生局部失稳现象,无法获得合格的截齿锻件。针对该问题,提出正挤预成形的改进工艺方案,并进行三维有限元模拟,模拟结果表明改进方案合理可行。在此基础上,设计出截齿锻件模具实现了截齿锻件的批量生产。     

基于MSP430FE425的单相多功能电能表设计

介绍了小型分布式电源并网模型及其电能计量特点。针对传统机械式、电子式电能表精度低、损耗大等缺点,设计了一款以MSP430FE425微处理器为核心的高精度单相智能电表。介绍了智能电表的硬件设计和主程序流程图。所设计电能表不仅能够精确计量电量参数,还可实现双向通信、预付费、需量计量、数据存储、防窃电和报警等功能。试验结果表明,该智能电表具有较高的计量精度,能够满足分布式电源并网对双向电能计量的功能需求,具有良好的发展应用前景。     

应用于平面EMI滤波器集成LC元件寄生电容的提取

为有效预估和分析平面EMI滤波器的高频特性,必须考虑平面电感的寄生电容对滤波器高频性能的影响.本文分别建立了应用于平面EMI滤波器集成LC元件的2D和3D有限元静电场模型来计算各匝间的寄生电容,由此得到PCB导线组成的多匝平面绕组的集总参数模型,进一步得到平面绕组的等效并联电容.讨论了介电常数对匝间电容的影响,并分析了...     

可重构柔性模具蒙皮拉形有限元等效模型

等效模型是模拟计算精度和现实计算能力矛盾的产物。从实际生产工艺出发,在PAM-STAMP2G中构建贴近实际生产过程的可重构柔性模具蒙皮拉形有限元模型。鉴于该有限元模型模拟效率低的缺陷,从可重构柔性模面和弹性垫层描述两方面进行简化,引入5种等效模型。分析结果表明,光滑连续模面包覆垫层有限元模型,能够在保证模拟精度的前提下获得较好的模拟效果。在此基础上,提出连续模面单层实体单元包覆垫层等效模型,当弹性垫层厚度小于30mm时,它和连续模面多层实体单元包覆垫层等效模型有相同的模拟效果。     

Fe modelling of CFRP-concrete interface subjected to cyclic temperature,humidity and mechanical stress

Modelling of environmental effects on the bond surface between FRP composites and concrete is crucial for the purpose of life prediction of strengthened members. The service performance of composite systems depends on the degree of chemical and physical aging of the system. Physical aging is a reversible process which is related mainly to temperature fluctuations. Chemical aging is the permanent molecular level degradation of fibres, resin or interfaces due to long-term exposure to the environment. The resulting strength reduction and the system behaviour due to aging are important in evaluating the strengthening of civil engineering infrastructure. In this paper, a finite element model is developed to predict the interface properties after long-term exposure to the cyclic temperature and the constant humidity. Effects of sustained loading are also taken into account. The predicted strength, cracks pattern, failure mode and strain variation along the bond line agree well with test results.     

Analytical behaviour of concrete-filled double skin steel tubular (CFDST) stub columns

This paper reports a finite element analysis of the compressive behaviour of CFDST stub columns with SHS (square hollow section) or CHS (circular hollow section) outer tube and CHS inner tube. A set of test data reported by different researchers were used to verify the FE modelling. Typical curves of average stress versus longitudinal strain, stress distributions of concrete, interaction of concrete and steel tubes, as well as effects of hollow ratio on the behaviour of CFDST stub columns, were presented. The influences of important parameters that determine sectional capacities of the composite columns were investigated.