Optimization of press bend forming path of aircraft integral panel

In order to design the press bend forming path of aircraft integral panels,a novel optimization method was proposed, which integrates FEM equivalent model based on previous study,the artificial neural network response surface,and the genetic algorithm.First,a multi-step press bend forming FEM equivalent model was established,with which the FEM experiments designed with Taguchi method were performed.Then,the BP neural network response surface was developed with the sample data from the FEM experiments.Furthe...     

双曲率飞机整体壁板压弯成形有限元建模(英文)

为了建立压弯成形工艺的有限元模型,提出一种特殊的模拟过程和一种基于压弯线坐标的上下模边界条件计算方法。实现了双曲率飞机整体壁板七道次压弯成形工艺的模拟并且可以较好地模拟真实的生产过程,本建模方法可用于此复杂成形工艺的研究。分析了应力和应变分布,揭示了成形工艺的变形机理。通过进行定量的比较,得知七道次压弯成形的成形精度和表面质量较好。     

FEM modelling for press bend forming of doubly curved integrally stiffened aircraft panel

In order to establish an FEM model for aircraft integral panel press bend forming process, a special simulation procedure and a calculation method for the punch and die boundary condition based on the bending line coordinates were proposed. The simulation of a seven-step press bend forming process of doubly curved integrally stiffened aircraft panels was realized, and it could well simulate the real fabrication process, so that it could assist in studying this complicated forming process. Stress and strain distributions were analyzed, which reveals the deformation mechanics of this process. With quantitative comparisons, it can be concluded that forming quality of the seven step press bend forming is quite good, considering both the forming precision and the surface quality.     

火车车轮预成形过程的有限元分析

本文通过大变形弹塑性有限元热力耦合的方法 ,模拟计算了火车车轮预成形过程。分析了摩擦状态对车轮锻压变形过程的影响。进一步证实了成形坯在变形过程中存在分流面的理论。得到了车轮预成形过程各工步等效应变分布     

圆角结构对新型金属桥塞密封件液压成形性能的影响

针对新型金属桥塞密封件的成形工艺开展研究,探究圆角结构对密封件液压成形性的影响。采用有限元模拟(MSC.Marc软件)和实验相结合的方法,选取零件的形状和中间薄壁弧形段壁厚作为调控对象。通过比较不同圆角半径对零件等效塑性应变分布和大小以及对液压成形力的影响作用,得出合理的圆角结构尺寸。结果表明,随着圆角半径增大,零件中间弧形薄壁段等效塑性应变更加均匀,数值也逐渐减小,液压成形力逐渐增大。模拟和实验结果基本一致,圆角半径为2.5 mm时,对密封件的成形效果最佳,圆角部位不仅未开裂,且外形尺寸满足要求,因此,利用液压成形工艺加工该类金属桥塞密封件可行且高效。     

整体壁板压弯成形中的筋条失稳预测(英文)

为实现对整体壁板压弯成形中筋条失稳的预测,基于能量法、弹塑性力学和数值解析提出压弯成形过程中筋条临界失稳载荷的求解方法。在设计的压弯模具上进行压弯失稳试验。结果表明,基于本文提出的方法所得的理论临界失稳载荷与试验结果吻合较好。采用本文所提出的方法可以对铝合金高筋整体壁板压弯成形中的筋条失稳问题进行合理地预测。     

有限元模拟在后轴支架锻造设计中的应用

针对汽车后轴支架,进行锻造过程三维有限元模拟和工艺、模具设计。采用刚粘塑性有限元模拟技术,得到锻件内部应力场、应变场等参数,分析了这些参数对锻件塑性变形的影响。在此基础上,对此类锻件传统的锻造工艺进行了改进,将预锻工序由开式模锻改进为封闭飞边闭式模锻。同时,模具设计重点从预成形设计考虑,给出了合理的制坯模具设计。在40MN热模锻压力机上进行了试验,试验表明,模拟结果和实际成形过程吻合良好。     

伺服成形技术及其若干发展动向

伺服压力机是近年来塑性成形领域最重大的创新之一,将伺服压力机以及基于伺服压力机的成形工艺统称为伺服成形技术.简要介绍了伺服成形技术的特点和目前的应用情况,重点论述了该技术当前的若干发展新动向,包括伺服压力机设计方法的研究、新型功能部件和储能技术开发、滑块运动路径设计与优化、伺服成形机理及成形过程的数值模拟、智能制造中的...     

J55钢级中直径厚壁HFW套管成型过程的有限元仿真

通过有限元仿真软件模拟出J55钢级中直径厚壁Φ508 mmx16.13 mm HFW套管的排辊成型过程,从成型结果和各部分的等效塑性应变两个方面研究了板带的变形情况,分析了排辊成型生产中直径厚壁HFW套管的可靠性.模拟结果显示,板带总体成型良好,各成型段的变形也满足生产需要,但板带端部在精成型后有部分变形不规则,存在变...     

Sheet metal forming limit prediction based on plastic deformation energy

For sheet metals, the endurance to fracture under different strain paths may be different. Based on plastic deformation energy, the sheet metal forming limit is calculated, and the relationship model between maximum allowable integral value of the general plastic work criterion and the strain path is built. In addition, the strain-hardening exponent, anisotropy coefficient and the initial thickness of the material are also taken into account to consider their effects on forming limit. In order to simplify the process of parameter determination, only uniaxial tension test is used to calculate the material property parameters and necessary limit strain, and the expression of the criterion is determined finally. Then the limit strains under other strain paths between uniaxial tension to equi-biaxial tension are predicted by the criterion combined with numerical simulation of the forming process. The criterion is also applied to limit strain prediction under bilinear strain path.     

EXPERIMENTS AND SIMULATIONS OF A NEW DEVELOPED FORMING TECHNOLOGY-SHEAR-EXTRUSION PROCESS OF COMPONENTS WITH BRANCHES

1. IntroductionAs one of special forging processes, extrusion technique has been widely used in formingcomplex-shape componepts in industry. With the research for metal extrusion process tillsprocess has been classified into many categories such as forward extrusion, backward extrusion, cup-bar extrusion, upsetting-extrusion, radial extrusion, and lateral extrusion etc.according to the direction between punch and metal flo.[1--3]. Among those categories,upsetting-extrusion and radial extrusion…     

汽车离合器减震轴套精锻成形数值模拟与分析

简述了汽车离合器减震轴套的几种典型成形工艺。基于Deform3D通用有限元软件,应用三维刚粘塑性有限元显式算法对预减震轴套精锻成形过程进行了模拟分析,得出了变形中材料的流动状态和等效塑性应变分布规律。根据有限元模拟分析结果对减震轴套精锻成形工艺参数、模具结构进行了优化设计,并进行了预减震轴套精锻成形工艺试验。试验验证了有限元模拟分析结果,并精锻成形出合格的汽车预减震轴套产品。     

圆柱体平板间镦粗的热力分析

金属塑性成形是一种典型的热力耦合过程 ,本文在推导塑性成形过程中温度场控制方程的基础上 ,探讨了成形过程中的势力耦合效应。运用有限元方法 ,对弹塑性圆柱体平板间镦粗过程中温度场和等效应变场的变化规律进行了数值模拟 ,讨论了成形速度和坯料初始温度对成形过程的影响。     

基于全量理论的金属体积成形多步数值模拟

运用一种基于全量理论的多步有限元方法计算分析了金属体积成形过程.该方法针对刚塑性不可压缩材料,在静力平衡条件下以约束变分原理通过最小化近似塑性势能进行有限元求解.多步模拟在各中间构形的虚拟滑动约束下沿变形路径进行分步迭代计算,考虑了接触和变形历史,能够快速模拟较复杂的体积成形问题.运用该方法对几个典型金属体积成形过程进行了正向一步和多步数值模拟,将计算结果与增量有限元法计算结果进行了比较.结果表明:在计算金属体积成形过程中,基于全量理论的多步有限元模拟能够在大大缩短计算时间的同时获得与增量法计算结果相比偏差小于10%的计算结果.     

板材单点渐进成形工艺数值模拟与成形缺陷研究

工具头运动轨迹的动态加载是建立板材渐进成形有限元模型的难题。首先基于DYNAFORM建立基本的有限元模型,而后直接提取数控代码中工具头的位移坐标信息并添加至关键字文件,从而实现任意复杂运动曲线的加载;数控代码规划的加工轨迹存在起刀区域集中和加工方向单一的问题,容易造成破裂和失稳缺陷。起刀区域塑性变形大,累积效应使该区域板材严重减薄,采用均布策略,并保证均布后相邻起刀点的空间距离大于塑性变形区的最大半径可避免此缺陷。同时,运用顺逆相间的加工方式避免了单一方向加工方式存在的材料堆积引起的形状失稳和棱纹缺陷。     

基于UG的汽车覆盖件冲压CAPP/CAE集成系统的研究

对UG环境下汽车覆盖件冲压CAPP/CAE集成系统进行了研究,重点探讨了有限元网格的生成、数据模型转换以及后置处理相关技术.通过自行编制的模型转换程序,实现了有限元模型在CAD系统和CAE系统间的方便快捷的相互转换.应用实例表明,该系统可以进行快速的优化设计和成形性模拟,解决汽车覆盖件自适应工艺设计的优化问题,提高工艺设计的效率和质量.     

复合管拉拔过程的计算机仿真

采用弹塑性大变形有限元法建立了复合管的拉拔模型,并对整个拉拔过程进行了仿真。研究各种工艺参数对复合管拉拔拔制力的影响,计算结果与实验数据十分吻合。     

矩形管多点压弯成形截面畸变的数值分析

基于有限元分析软件ABAQUS,建立了矩形管多点压弯成形三维有限元模型,对比分析了矩形管整体压弯和多点压弯的截面畸变,研究了矩形管多点压弯成形时摩擦系数、管壁厚度、弯曲半径对截面畸变的影响。结果表明:矩形管多点压弯的截面畸变量略大于矩形管整体压弯的截面畸变量,且最大畸变率小于10%;摩擦系数对截面畸变影响较小;管壁越厚,截面畸变越小;弯曲半径越大,截面畸变越小。成形实验验证了矩形管多点压弯成形的可行性。     

响应面法在大锻件微观组织质量控制中的应用

以某T型截面大锻件分段多道次成形工艺为研究对象,引入数学统计工具-响应面法(RSM)对该分段、不连续变形下的组织均匀性控制问题进行了研究。将工艺条件-道次进行参数表征,采用有限元方法 (FEM)和响应面法相结合,建立了以改善锻件微观组织质量为评价目标,以坯料温度、压力机速度、上模斜角角度和道次表征量为设计变量的二阶响应模型。研究了设计变量与评价目标之间的作用规律,通过Matlab软件得到了最优锻造工艺和工艺参数组合,即采用3道次成形工艺,坯料温度为440℃,压力机速度为8 mm·s-1,上模斜角角度为160°。采用优化结果进行大锻件的生产试制验证,金像分析显示所成形锻件内部组织均匀,表明了应用RSM和FEM可以有效地对分段多道次成形工艺下的锻件组织均匀性进行控制。     

Characteristics of tee tube forming deformation zone using plastic pressure-building medium

An unconventional forming process using plastic pressure-building medium is presented to manufacture tee tube. A special experimental device was designed and built, and a three-dimensional rigid-plastic FEM code was developed to simulate the forming process. On the basis of the results of FEM simulation and experimental research, the plastic deformation of tee tube is divided into five different zones, which reveals the characteristics of metal deformation during the unconventional forming processes.