覆盖件拉延模工艺补充及压料面的参数化设计新方法

针对基于有限元法的板料成形数值模拟技术已广泛应用于汽车覆盖件制造行业的状况,对快速、自动化的有限元网格建模方法提出迫切要求的现状提出一种新的汽车覆盖件模具冲压工艺设计思路与方法,使用离散三角面片模型,在CAE的前处理软件中进行参数化的工艺补充面和压料面设计,方便进行修改。在完成工艺设计的同时,可自动生成整套模具的网格模型,供有限元仿真分析使用。提供参数化的真实拉深筋的模型建模手段,能够精确模拟拉深筋的形状和拉延过程中拉深筋的力学行为。完成了相关软件STLMesher的开发,大量的算例证明该方法具有较高的精度和较强的工程实用性。     

汽车覆盖件冲压成形仿真研究进展

汽车覆盖件冲压成形仿真技术的发展,突破了原有汽车冲压件模具及工艺设计的设计方法,对保证工件质量、减少材料消耗、缩短产品开发周期、降低制造成本具有重要意义.概述了目前汽车覆盖件冲压成形仿真所涉及到的热点领域,如摩擦与接触、回弹分析、模具系统和工艺参数、材料屈服模型和板料形状设计,讨论了这些领域的研究进展和进一步研究的发展方向.     

基于Dynaform的汽车覆盖件冲压成形仿真的研究

介绍了汽车覆盖件冲压成形仿真的研究背景,详细论述了板料冲压成形数值模拟的理论和主要步骤.在Dynaform中对汽车行李箱门板进行了冲压成形过程的仿真,证明了仿真设计方法具有实用性,通过反复模拟,找出了合理的工艺参数,有利于优化冲压成形的过程及其结果.     

应用模糊分析法汽车覆盖件加工过程参数优化

汽车车身覆盖件用冷轧钢板的成形性能与材料内部结构、力学性能等指标密切相关，当工艺技术参数相关稳定时，成形结果很大程度决定于自身的性能。根据汽车覆盖件的特点和使用要求，对钢板成形性能指标进行分析，采用模糊层次分析法来求取各评价指标值的权重，并且使用模糊综合评价获得材料的成形性能决策参数，作为汽车用钢新产品开发和性能评价的基本依据。利用DYNAFORM建立冲压仿真模型，对覆盖件加工过程进行仿真分析，获取合理的试验工艺参数。在此基础上，基于网格应变分析技术，进行胀形试验，对选取的汽车覆盖件冲压时工艺参数进行验证。结果可知：参数优化结果表明，当板料与凸模、压边圈、凹模的摩擦系数设置为0.025、0.125、0.125，压边力为120kN时，材料的成形结果较为理想；试验测试与仿真分析结果误差控制在3%以内，且临界区域保持一致，表明分析方法和结果的可靠性，为此类设计研究提供参考。     

汽车覆盖件冲压成形仿真的应用与研究

介绍了汽车覆盖件冲压成形仿真的研究背景,详细论述了板料冲压成形数值模拟的理论和流程.在Dynaform中对汽车右侧壁上外板进行了冲压成形过程的仿真,通过对仿真结果进行分析,提出了改进工艺参数的措施,有利于优化冲压成形的过程和结果.     

基于正交试验的汽车覆盖件冲压工艺参数优化

将正交试验设计方法与冲压数值模拟相结合,综合评估了冲压过程中的压边力、摩擦系数、模具间隙和冲压速度等对汽车覆盖件冲压成形质量的影响,并确定优选的工艺参数组合.以汽车翼子板为例,建立了冲压件和模具的计算机辅助工程模型.运用正交试验方法进行仿真计算方案的设计,通过对仿真数据的方差等分析,找到了最优的工艺参数组合.所得结论对冲压工艺的设计具有指导意义.     

灰色关联分析法在覆盖件成形优化中的应用

由于汽车覆盖件塑性变形过程复杂,容易产生多种质量缺陷,最优成形工艺参数难以确定。现将正交试验设计方法、灰色关联分析法与冲压数值仿真相结合,针对拉延工艺参数进行优化设计,借助板料成形仿真软件Pam Stamp对某汽车翼子板拉延过程数值仿真。通过仿真数据分别计算单目标函数关联度系数,多目标函数关联度和自变量对理想质量目标平均关联度,从而全面衡量压边力、摩擦因子及拉延筋几何尺寸对翼子板拉延成形质量影响,确定最优拉延工艺参数组合,为汽车覆盖件成形工艺参数设计提供理论依据。     

基于NSGA-Ⅱ算法的汽车后背门内板拉延成形质量控制与预测

为避免汽车覆盖件冲压时出现起皱、开裂等成形缺陷,提出基于带精英策略的非排序遗传算法（NSGA-Ⅱ）对冲压成形工艺参数进行优化,实现对冲压成形质量的控制与预测。以某型汽车后背门内板作为研究对象,以压边力、摩擦系数、冲压速度和模具间隙作为试验因素,拉延变形时的最大增厚率和最大减薄率作为质量控制目标。应用拉丁超立方抽样方法并结合CAE分析技术建立试验样本,构建冲压工艺参数同成形质量控制目标之间的响应面模型,基于NSGA-Ⅱ算法在构建的响应面模型内计算获得了满足成形质量的一组最优工艺参数组合,同时给出了成形质量的预测值。实际冲压试模结果证明了文章所提方法的有效性,为汽车覆盖件的冲压成形质量控制与预测提供了一套可借鉴的方法。     

基于Autoform的轿车引擎盖板冲压成形仿真的研究

介绍了轿车引擎盖零件冲压成形仿真的研究背景,详细论述了板料冲压成形数值模拟的理论和主要步骤.以典型轿车引擎覆盖件为研究对象,以三维成形分析软件Autoform为平台,研究了板科与凸模、凹模的摩擦、压边力、拉深筋等因素对成形性能的影响.通过Autoform的成形仿真预测板料成形过程中减薄、拉裂、起皱等缺陷,分析产生缺陷的原因,进而优化板料成形工艺参数.     

基于Dynaform的汽车覆盖件拉延模具设计

以板料成形非线性有限元分析软件Dynaform为平台,介绍汽车覆盖件拉延模具型面设计过程,对某种汽车引擎盖冲压成形过程进行数值模拟,根据模拟结果进行成形性分析,为优化工艺参数和模具结构提供强有力的工具.     

真实拉延筋参数化建模及其在薄板冲压仿真中的应用

提出一种参数化的拉延筋网格模型建模方法,在自主开发的有限元前处理软件中,建立了具有真实几何尺寸的半圆形、三角形拉延筋和拉深槛的网格模型,并提供了灵活的拉延筋布置手段。提出一种改进的全四边形网格加密方法,对成形过程中将会流过拉延筋区域的板料网格,以及可能与模具上曲率变化大的区域相接触的板料网格进行加密操作,以满足网格的适应性要求。提出一系列的网格拓扑清理模版,对加密后的网格进行拓扑清理操作,有效地提高了板料网格的质量。大量的算例证明所提出方法具有较高的精度和较强的工程实用性。     

基于CAE技术的汽车覆盖件拉延模具设计

介绍了在CAE技术基础上进行的汽车覆盖件模具设计过程,利用板料成形有限元分析软件Autoform实现了模具压料面、工艺补充面以及拉伸筋设计和覆盖件成形过程模拟。实现了在有限元软件内部进行模具的参数化设计,既缩短了模具设计时间,又提高了模具设计可靠性。     

Analysis of drawbead process by static-explicit finite element method

The problem analyzed here is a sheet metal forming process which requires a drawbead. The drawbead provides the sheet metal enough tension to be deformed plastically along the punch face and consequently, ensures a proper shape of final products by fixing the sheet to the die. Therefore, the optimum design of drawbead is indispensable in obtaining the desired formability. A static-explicit Finite element analysis is carried out to provide a perspective tool for designing the drawbead. The finite element formulation is constructed from static equilibrium equation and takes into account the boundary condition that involves a proper contact condition. The deformation behavior of sheet material is formulated by the elastic-plastic constitutive equation. The finite element formulation has been solved based on an existing method that is called the static-explicit method. The main features of the static-explicit method are first that there is no convergence problem. Second, the problem of contact and friction is easily solved by application of very small time interval. During the analysis of drawbead processes, the strain distribution and the drawing force on drawbead can be analyzed. And the effects of bead shape and number of beads on sheet forming processes were investigated. The results of the static explicit analysis of drawbead processes show no convergence problem and comparatively accurate results even though severe high geometric and contact-friction nonlinearity. Moreover, the computational results of a static-explicit finite element analysis can supply very valuable information for designing the drawbead process in which the defects of final sheet product can be removed.     

基于有限元逆算法的拉深筋工艺设计和优化

汽车覆盖件拉深成形中，一般通过设置适当的拉深筋控制成形过程中的板料塑性流动规律来提高覆盖件成形质量。针对覆盖件工艺设计需求，提出一种基于有限元逆算法的拉深筋工艺优化算法。该算法以灵敏度优化方法为基础，考虑了板料的成形度、破裂和起皱等成形缺陷。在板料成形模拟FASTAMP系统中，开发了拉深筋优化模块，并以实际覆盖件为例，验证了该算法能快速准确地模拟等效拉深筋力的布置情况以及优化板料的成形性。     

Optimization of sheet metal forming processes by the use of space mapping based metamodeling method

In this study, an adaptive space mapping technique based on response of objective was suggested for solving practical engineering problems. Response surface methodology was engaged in approximation of objective and constraint functions based on coarser model. The fine simulation model is not only used for correction of the coarser simulation model and validation of final solution but also for applied construction of space mapping expression. Finally, genetic algorithm (GA) was used to optimize updated metamodel according to coarse model. The proposed method combines the space mapping technology based on response of coarse model and modification of design of experiment. It guarantees that metamodel based coarser model is stepwise updated in the right searching direction. For demonstrating practicability of developed method, it was applied for optimization of geometric parameters of addendum surface, blank holder force and drawbead restraining force in sheet forming problems. It was confirmed that the corresponding problem can be optimized successfully in remarkably short computing time by proposed optimization method.     

基于响应面法的复杂件回弹有限元模拟优化设计

由于单元多、复杂件的回弹很难预测和控制。基于应变增加降低回弹理论,采用变拉延筋阻力方法,对复杂覆盖件的回弹进行了控制研究。拉延筋阻力的预测,采用二维平面应变有限元法。考虑到拉延筋设计的困难,提出了基于数据挖掘,进行拉延筋反向设计的思想。采用响应面方法对拉延筋阻力进行了优化设计,提出采用未充分变形区的面积作为目标函数,通过响应面模型拟合得到了一个优化的阻力。采用该阻力进行模拟,发现成型件中未充分变形区得到消除,模拟发现回弹大大降低,达到设计要求。     

等效拉延筋模型及其在板料成形数值模拟中的应用

讨论等效拉延筋的建模方法、常用模型及其在板料成形数值模拟中的应用情况,并指出研究中仍存在的问题及今后的发展方向。     

Sectional finite element analysis of forming processes for aluminum-alloy sheet metals

The sectional finite element analysis of the forming processes for the aluminum-alloy sheet metal known to be planar anisotropic was performed. The two-dimensional rigid-viscoplastic FEM formulation based on the bending augmented membrane theory as well as the anisotropic yield criteria was introduced. For modeling the anomalous behavior of aluminum-alloy sheet metals, Barlat's strain rate potential and Hill's (Journal of the Mechanics and Physics of Solids 1990;38:405–17) non-quadratic yield theory with an isotropic hardening rule were employed. Furthermore, a new method to determine anisotropic coefficients of Barlat's strain rate potential was proposed. For evaluating bending effects in the forming process of aluminum-alloy sheet metals, the bending equivalent forces were calculated in terms of the changes in the interior angle at a node between two linear finite elements and were augmented to the membrane stretch forces. In order to verify the validity of sectional finite element formulation based on the bending augmented membrane theory, the plane strain stretch/draw forming processes of a square cup test were simulated and simulation results are compared with experimental measurements. Friction coefficient was obtained from drawbead friction test. The properties of selected material were obtained from uniaxial tensile tests. Simulation shows good agreement with measurements. For the application of the sectional finite element formulation introduced in this research, the drawing process of a rear seat back upper bracket of passenger cars is simulated assuming plane strain condition. The thinning distribution of the simulation agreed well with that of the measurement, so that the sectional analysis is acceptable in the design and analysis of aluminum-alloy sheet stamping dies.     

汽车覆盖件冲压成形仿真的研究及其工程应用

拉延是板料冲压成NAFORM建立有限元冲压仿真系统,对板料拉延成形过程进行了研究.结果表明,坯料形状、压边力大小和拉延筋布置是影响板料拉延成形的关键因素;典型仿真范例验证了研究结果的可靠性,并从成形极限图(FLD)上进行了工艺方案的改进.     

基于Dynaform对拉延筋在板材拉深中的应用研究

板材冲压工艺应用十分广泛,如何提高板材在拉深工艺中的成形质量,是从事冲压的技术人员和研究人员一直关注的热点问题。在板材拉深成形控制中设置拉延筋是既经济灵活又广泛运用的方法。在参考国内外资料的基础上,应用CAE中的专用分析软件Dynaform分别模拟了有拉延筋和无拉延筋存在的板材拉深成形过程,并对各自的数值模拟的结果进行对比分析,得出了拉延筋可以更有效地提高拉延件的成形质量的结论。