电网调度操作票系统中数据库的开发和实现

在电网调度操作票自动生成与管理系统中,数据库系统具有十分重要的作用。文章研究操作票系统与SCADA(实时监控)系统和DMIS(调度信息管理系统)间的数据共享和集成方案,实现智能操作票系统与SCADA系统的实时数据共享、与DMIS的集成,完成操作票的网络发布功能。同时,该数据库的设计还考虑了良好的用户可维护性和易扩充性,并且易于实现历史票的存储和管理功能。基于该数据库系统的电网调度操作票自动生成与管理系统目前已在福建省电网投入使用。应用表明,该系统具有很强的实用性。     

An Approach to Modelling the Forming Process of Sheet Metal-Polymer Composites

Polymer Injection Forming (PIF) and Polymer Injection-Compression Forming (PICF) are new manufacturing technologies for sheet metal-polymer macro-composites, which result from the combination of injection moulding and sheet metal forming. In these processes, a metal blank is formed inside an injection mould by using the pressure of the molten polymer that, after cooling, permanently bonds to the metal sheet creating a fully finished product in only one production step. This paper presents a calibrated multi-physics numerical model of the processes that proves to be suitable to investigate the mutual metal-polymer interactions and to provide a reliable tool in designing the process as well as its control.     

Finite element analysis of the effects of martensitic phase transformation in TRIP steel sheet forming

This paper aims at investigating the effects of the martensitic phase transformation on the formability of unstable austenitic steel sheets. To this end, the constitutive model developed by Iwamoto and Tsuta (International Journal of Plasticity 2002;18:1583–606) has been implemented in the user's material subroutine of the finite element code Abaqus/Explicit. The different contributions of the martensitic transformation to the overall plastic behaviour are analysed with the aim of assessing their influence in sheet-metal forming. The effects of transformation strains, and of the stress-state dependence of the kinetics of phase transformation are critically discussed in the case of the cup drawing test. The simulation results are also compared with experimental cup tests from the literature.     

虚拟板材冲压皱曲特性试验

利用非线性有限元软件系统的数值模拟运算功能，对冲压板材皱曲特性试验（YBT）的试样、夹具和载荷进行数字化虚拟，并对试验过程和试验结果进行运算和讨论。     

Tensile Test of very thin Sheet Metal and Determination of Flow Stress Considering the Scaling Effect

The reduction in size of mechanical parts is becoming more and more important in metal forming processes. This trend towards miniaturization leads to new requirements regarding the material and the product. The main object of this research is the so-called scaling effect which can occur during the forming process of very thin sheet metals. The goal is to determine and investigate variables which considerably influence the scaling effect. The optimisation of such forming processes needs a more comprehensive use of simulation and finite element analysis. The conventional model used for large and thick sheet specimens is not sufficient yet. Existing research reports on this topic show that among other things the thickness and the grain size of the material influence the scaling effect. Thus it is important to consider these material characteristics in the determination of the flow stress curve. In this paper the flow stress curve is investigated on a micro scale of up to 10μm specimen thickness considering different sheet thicknesses and widths.     

板料成形模具设计仿真系统

数值模拟技术为工程师解决复杂的板料成形模具设计问题提供了强有力的分析工具．与ＣＡＤ／ＣＡＭ软件相比，同样作为计算机辅助手段的ＣＡＥ软件却没有得到广泛的重视和应用。本文分析了产生这种状况的一些原因，并从程应用的角度提供了一些思路，指出ＣＡＤ／ＣＡＭ集成化的研究方向，以及将通用大型系统化整为零，编写专业软件的策略。     

机油盘冲压过程截面的有限元模拟与实验验证

板料冲压过程的模具设计是一个费时费力的过程。采用有限元可以降低设计费用 ,缩短设计周期。本文采用有限元软件 MARC基于拉格朗日的弹塑性本构方程建立了一个有限元模型来分析机油盘的成形过程。模拟中考虑板料的厚向异性 ,接触面间的摩擦约束采用库仑摩擦模型。模具看作刚体 ,板料作为变形体。模拟和实验结果的比较表明模拟的壁厚变薄分布与测量结果吻合得很好 ,因而理论模拟的结果可用于真实情况的预测     

Pneumatic Bulging of Magnesium AZ 31 Sheet Metals at Elevated Temperatures

This paper deals with forming magnesium sheet metal components like auto body parts by pneumatic bulging. Furthermore, this paper deals with the evaluation of true stress-true strain curves as well as with forming limit curves determined by pneumatic bulging at temperatures up to 350°C. It can be shown that magnesium AZ31 is quite good formable at temperatures in the range of 250°C to 350°C.Outgoing from these fundamental investigations, an auto body sheet metal component was formed by pneumatic bulging at a temperature of about 300°C.Furthermore, the strains over the component were measured with an automated grid analysis. This analysis shows a nearly equal distribution of the strains over the component.     

Determination of forming limit diagrams - a new analysis method for characterization of materials' formability

This paper introduces a new analysis method for characterization of materials' formability independent of individual expertise. Therefore forming limit diagrams (FLDs) are determined using the Nakazima method. Investigations on the influence of the analysis method and the failure criterion in detail will be presented. The new analysis method avoids misinterpretation of the forming limits of any material and the FLD. The forming behavior of materials has to be recorded with a frequency up to 20 Hz, in order to detect the forming limits within a sequence of pictures from onset of necking to failure by cracking.     

A systematic method of adaptive joint design considering different assembly sequence in sheet metal product

In sheet metal assembly, not only the component variations and tool errors, but also the component structure (joint type) and assembly process (assembly sequence) affect the final dimensional quality. In this paper, a systematic method for adaptive joint design considering different assembly sequence is proposed to meet the in-process dimensional adjustability of KCs (key characteristics). First, the adaptive characteristic of the sheet metal joint is depicted. Then, the mathematical model in order for concurrently optimizing both joint type and different assembly sequence is presented. How to evaluate the combination of joint type and assembly sequence is carried out according to two conditions: (1) for single KC, and (2) for multiple KCs. The KC confliction is considered to ensure the important KCs. Genetic algorithm is used to resolve the optimization of joint design. An example is chosen to demonstrate our method finally, and various joint designs are acquired according to different assembly sequences by this means. The proposed methods make it possible for us to improve the dimensional quality of product in the design stage.