复杂汽车覆盖件冲压仿真中的若干问题

介绍了复杂汽车覆盖件冲压仿真中的经验，结合中支柱外盖板的冲压仿真过程，阐述了利用eta/DYNAFORM软件进行复杂汽车覆盖件冲压仿真设计中需要注意的一些问题及解决的办法。     

The Size Effects on Process Design of Micro Deep Drawing

This paper suggested to reformulate cylindrical deep drawing parameters with dimensionless form. A diagram, in which a feasible zone is drawn to bound both the maximal allowable tension and compression stress during the deep drawing process, was established. Since it is presented in a dimensionless form, it may be applied for both conventional and micro deep drawing. Cylindrical cup deep drawing was taken as an example to show the dimensionless process design method. In addition, the size effects should be taken into account. Two kinds of size effects on micro deep drawing were investigated, which can be explained by surface layer model and strain gradient model. Numerical simulations were carried out to compare the strain distribution with or without consideration of size effect.     

3D Numerical simulation of non-isothermal resin transfer molding filling process using unstructured tetrahedron mesh

We present a numerical formulation for resin flow based on the concept of quasi-steady state situation at the flow front. To be fit for complicated product shapes, we use the four-node unstructured tetrahedron mesh based on which the numerical formulation of temperature and degree of cure is developed. The validity of our method is established in the case where flexible meshes are used. The results show that the numerical procedure, tested on known data, provides numerically valid and reasonably accurate predictions.     

Investigation on Two Electrically-Assisted Forming Processes of AZ31B Magnesium Alloy Sheets

Two new types of electrically-assisted forming(EAF) processes of AZ31B magnesium alloy sheets,i.e., electrically-assisted blanking(EAB) and electrically-assisted sheet upset-extruding(EASUE), are proposed in this paper. During EAB, pulsed current(PC) decreases blanking load and improves blanked surface quality,and higher frequency has a more effective improvement; when the frequency reaches 600 Hz, the whole punched hole fracture is improved to smooth zone. Moreover, EAB does not influence the microstructure and does not induce obvious annealing, and this process is advantageous to the materials that cannot change microstructure.During EASUE, PC can reduce extrusion load and enhance extrusion height, and higher frequency also has a more effective improvement. Both processes indicate that introducing PC can effectively improve the part quality and have an application prospection.     

用添加剂提高铅酸蓄电池性能之研讨

在不改变铅酸蓄电池结构，参数和使用条件的情况下，应用添加剂可以大幅度提高铅酸蓄电池经济技术指标，对普遍存在的寿命短，比能量小，内阻损耗大，自放电严重问题有所改善。     

Experimental exploration of electrical pulse-assisted roller hemming of AZ31B magnesium alloy sheet

The purpose of this research is to explore the feasibility of roller hemming of AZ31B magnesium alloy sheet. During the test, a special experimental setup considering the current flow and insulation was designed and employed. For the sake of simplicity, the flat surface-straight edge hemming style was selected. Electrical pulses were introduced in the pre-hemming and final hemming processes. The results show that when hemming at 448 K with hemming speed of 30 mm/min, AZ31B magnesium alloy sheet was successfully hemmed with excellent perceived quality. No recoil/warp defect, cracking or springback was observed. Electrical pulses induced dynamic recrystallized grains were observed along the grain boundaries in the severely deformed area, which is of great importance to the improvement of the ductility of the material. The hardness was slightly increased after hemming with electrical pulses, and this fact could improve the friction resistance performance of the hemmed part.     

如何提高列车铅酸蓄电池的使用寿命

在不改变铅酸蓄电池结构技术参数和使用条件下，应用添加剂可以大幅度提高铅蓄电池经济技术指标，改善普遍存在的寿命短，比能量小，内阻损耗大，自放电严重问题，以达到增效延寿目的。本文介绍了该领域进展的状况和郑州车辆段的试验与研讨结果。     

铁路地理信息系统中决策支持子系统的研究

针对目前中国铁路信息化建设的现状,分析了目前地理信息系统(RGIS)建设中有关决策支持的误区与盲点,提出了一种基于数据仓库和数据挖掘的RGIS决策支持子系统(DSS)的体系结构,并对其数据平台与网络结构作了进一步探讨.