汽车覆盖件冲压成形仿真有限元方程及其解法

通过对汽车覆盖件冲压成形仿真有限元方程及其算法的研究，认为动力显式解法更适合于冲压成形仿真。     

机车前围板蒙皮冲压成形模具设计及数值模拟

分析机车前围板蒙皮成形工艺,设计冲压成形模具,利用DYNAFROM有限元软件模拟仿真机车前围板蒙皮冲压成形过程,证明有限元法具有实用性.利用数值模拟结果,验证冲压模具凹型面、凸型面空间复杂曲面尺寸、定位等设计可行性,为实际生产中的模具设计、工艺参数的制定提供参考,减少试模次数,降低生产成本.     

基于SA-RBF神经网络的冲压成形拉延筋优化

为提高神经网络预测精度,利用模拟退火算法对基于k-均值聚类的RBF(radical basis function)神经网络进行了结构优化.首先,以NUMISHEET 02翼子板冲压成形为研究对象,以6条等效拉延筋力作为输入变量,基于Spearman相关分析和拉丁超立方抽样抽取相关性系数较小的数据作为SA-RBF(simulated annealing-RBF)神经网络的训练样本;其次,将训练样本进行Dynaform数值仿真,以起皱缺陷和拉裂缺陷建立的成形质量评价函数为目标函数,通过SA-RBF神经网络建立等效拉延筋力与目标函数间的非线性映射关系;再次,利用NSGA-II算法对其进行求解得到Pareto最前沿,通过灰色关联分析理论确定最佳拉延筋力;第三,利用优化的拉延筋力对翼子板成形进行数值仿真分析,成形极限图结果表明,优化后的成形件起皱显著减少,而且塑性变形更加均匀,提高了成形质量.     

铁路罐车封头冲压成形研究

为保证某型铁路罐车封头冷冲压成形质量,设计了具有圆形拉延筋、矩形拉延筋和不设置拉延筋3种结构形式的拉延模具型面;使用有限元方法,对3种模具结构形式下封头的冲压成形过程进行模拟分析,对比了封头起皱趋势、 成形回弹和料厚变化等模拟结果,并根据仿真结果选择合理的模具结构形式进行了试验.研究结果表明:采用矩形拉延筋进行封头冲压成形,能更有效的避免封头出现起皱、鼓包等成形缺陷,而且成形后回弹量较小;矩形拉延筋模具冲压试验所得封头无成形缺陷,测得封头最小料厚为9.6 mm,最大料厚为10.5 mm,与模拟结果基本一致;采用矩形拉延筋模具进行该型封头冷冲压成形是有效的.      

汽车碰撞CAE技术中几个尚未解决的问题

综述了汽车碰撞及汽车覆盖件冲压成形CAE技术研究概况，介绍了常用CAE软件的基本情况，从汽车覆盖件冲压成形CAE技术的角度出发，提出了汽车碰撞CAE技术中存在的几个没有解决好的问题，包括壳单元的畸变、复杂模型中单元积分的阶、材料的开裂准则及冲压成形过程对材料性能的影响等问题。这已经影响了汽车碰撞CAE的应用，希望这些问题能够早日得到解决。     

基于RBF神经网络模型的板料成形变压边力优化

为了解决变压边力优化过程中RBF(radial basis function )神经网络隐层节点训练难的问题,利用人工智能算法的优越性,建立了基于人工免疫算法的RBF神经网络,并将其用于非线性函数的逼近中.结合分块压边圈与改变压边力控制技术,通过Dynaform软件进行数值模拟获得成形数据,建立了变压边力与成形质量之间的RBF神经网络近似模型.利用人工免疫智能算法对该近似模型进行优化,获得最优压边力参数.将该方法应用于S形梁冲压成形中,与优化前的结果进行比较,采用优化后最优变压边力可以抑制起皱,最大起皱量减少了89.53%.      

金属板件冲压过程的数值模拟

本文介绍以大时间增量方法求解金属板件冲压成形数值模拟的原理及实施方式。讨论了与之相关具有接触和摩擦几何非线性问题的描述方法，并给出二维问题的算例。     

板料轴对称成形应力分析中平衡方程的修正

指出了权威金属塑性成形理论专著中给出的板料轴对称冲压成形过程应力分析之平衡方程的不足,并导出了这些方程的修正式,为精确分析金属板料轴对称冲压成形工序的应力应变提供了理论依据．     

高强钢热冲压温度场数值模拟及关联度分析

以平板件为研究对象,基于Abaqus对热冲压成形过程中的板料及模具温度场进行数值模拟研究。基于正交试验的关联度分析,计算出了工艺参数对成形件最大温差、凸凹模最高温度影响趋势的量化值。结果表明:成形件温度分布呈梯度分布,高温区在成形件心部,次边缘及边缘区域温度依次递减;而模具温度分布与板料相反。淬火时间对成形件最大温差、凸凹模温度影响趋势的量化值为0.5874、0.7555、0.7602,板料初始温度对成形件最大温差、凸凹模温度影响趋势的量化值为0.5781、0.7268、0.7339,保压压力对成形件最大温差、凸凹模温度影响趋势的量化值为0.5105、0.6791、0.6828。根据量化值得到淬火时间对成形件最大温差、凸凹模温度的影响最显著,其次是板料初始温度及保压压力。为选取与优化热冲压工艺参数提供了参考。     

电感测长法研究

分析金属材料冲压造形中出现“颈缩”现象的原因,是降低废品率,提高产品质量的重要课题。为适应锻压生产工艺的需要,目前已有了金属表面印图机(由大连铁道学院研制,并已于1986年通过鉴定),可在冲压成形前的金属板材上印制网格,但如何在它冲压成形后,再对这些网格的变形进行定量分析,找出产生废品的原因以便改进产品冲压工艺和提高产品成形率,则目前尚缺乏相应的测试方法和仪器.     

Sensitivity Analysis of Effect Related with Material Process and Assembly Variations to Loads Deformation and Stress on HSS Stamping Die

During stamping process, the material properties, process design parameters and production environments inevitably have variation and noisy factors, which possibly affect the sheet metal formability and the deformation of the die structure.After gaining a success in applying sheet metal forming numerical simulation analysis to get the forming loads during stamping process, a methodology of die structure analysis based on sheet metal forming simulation was proposed and validated by experiments.Based on these results, the effect related with initial blank thickness, blank holder force, blank positioning error and die alignment error variations to a DP600 hyperbolic bottomed cup drawing die's forming loads(especially unbalanced loads), and deformation and stress was studied numerically.The influence level of these variations to the die's forming loads, deformation and stress was disclosed.The findings can guide die design, die tryout and process control for high-strength steel(HSS) stamping with increased forming load and decreased sheet metal formability.     

金属焊接毛坯冲压成形残余应力的试验研究

论述了焊接，冲夺加工中残余应力的产生过程，测试了金属焊接毛坯冲压成形的残余应力，并对试验结果进行了分析。     

FEM Analysis of Tube Preforming and Hydroforming Process for an Automotive Part

The tube hydroforming technology is used today in the mass production of lightweight components for the automotive industries due to its advantages over conventional stamping methods. A typical tube hydroforming process is usually a multiple forming operation process. The tube preforming and hydroforming process of an automobile subframe were analyzed by finite element method (FEM), and a parametric study was also carried out to obtain the effect of the forming parameters such as the die closing, the internal pressure and the axial feeding. The simulation results were also compared with industrial products in respect to the thickness distribution of some typical and key cross-sections. The study indicates that the internal pressure and the axial feeding should be set correctly and the multiple forming operations of tube hydroforming process can be simulated well by using the explicit code Ls-Dyna.     

An Approach to Determine Tool Speed for Cylindrical Part Drawing

In order to evaluate inertial effect on sheet deformation in the simulation of stamping processes by dynamic explicit FEM, an analytic model is established for analyzing cylindrical cup drawing process. The main factors governing the extent of inertial effect on sheet deformation pattern are investigated by energy method, and the approach to the selection of reasonable tool speed for dynamic analysis of stamping processes is proposed. The effectiveness of the present approach is further demonstrated and justified by the numerical result herewith provided.     

基于移动网格技术的微型客车会车外流场仿真研究

本文采用计算流体力学CFD软件,对微型面包车与大型客车相会进行了会车多工况仿真计算,给出了处于会车特征位置的小车侧面压力值及压力场分布图,为我国实现汽车外形自主研发提供方法借鉴。     

Application of Decision Tree Algorithm in Stamping Process

Introduction Learning is the main symbol of human intelli-gence and the basic means to acquire the knowl-edge. Machine learning can extract the rules hid-den in data through analyzing the relations amongobjects, which is also computational theory to in-vestigate learning. Nowadays, various methodsare adopted in machine learning field, such as deci-sion tree, Bayesian classification, neural network,genetic algorithm and rough set[1]. Many machinelearning methods have been used as the convenien…     

A reconfigurable stamping die and its stamping process

A reconfigurable flexible poles die was developed. The die can be used to implement the process of “the multi-point pressing and forming sheet”. Sheet metal is restricted by the elastic pressing forces putting on the upper and lower surfaces of sheet in stamping process. The method is an effective way to enhance the buckling critical stresses and reduce wrinkling of sheet. The results of tests indicate that the die can achieve “one die brings multi-purpose” and suppress the wrinkle of sheet. The process of the multi-point pressing and forming sheet provides a practical and effective way for the curved sheet metal forming.     

货车冲压件CAPP系统的研究

针对货车板材冲压件,就开发其CAPP系统进行了研究。以成组技术的基本原理为依据,提出了零件描述和工艺过程生成的新方法,其主要特点是:计算机辅助编码,运用专家知识库进行决策判断,检索与创成相结合。系统采用模块化的设计方法,做到了系统的柔性化。系统采用了汉字DBASE数据库和MS-PASCAL语言,适用于IBM-PC机及其兼容机。