板材超塑性胀形过程的数值仿真

板料超塑性胀形成形是一种全新的金属成形工艺.用Pare-Stamp2G板料成形数值模拟软件对一个实际成形件的超塑性胀形过程进行了数值仿真,分析了超塑性胀形成形变形过程中成形件的应力、应变、摩擦和厚度分布,研究了超塑性胀形过程中金属变形规律和工艺参数对成形过程的影响.结果表明,Pam-Stamp 2G板料成形数值模拟软件是超塑性胀形成形工艺应用到实践中的有效分析工具.     

板材超塑性拉延过程的数值模拟

板料超塑性成形是一种全新的成形方法。用刚塑性有限元法对Zn-22Al合金U形拉延过程进行了数值模拟，分析了变形过程中工件的应力、应变、摩擦和厚度分布，揭示了成形过程中金属的性变形规律，为成形工艺设计提供了有效的分析工具。     

板料电磁成形顺序耦合三维有限元仿真

电磁成形有限元模拟涉及多场耦合作用,其中结构场与电磁场之间的不同耦合方法对模拟结果影响显著。与松散耦合方法相比,顺序耦合方法考虑了板料变形对电磁场的影响,从而能够更精确的描述电磁成形过程。以ANSYS仿真软件为平台,建立板料电磁成形的顺序耦合三维有限元模型。通过不同耦合方法的模拟结果与实验结果对比表明,采用顺序耦合模型得到的板料变形与实验接近,而采用松散耦合模型得到的板料变形明显大于实验值。由此可见,顺序耦合模型是适合于电磁成形模拟的可靠模型。采用顺序耦合模型研究发现,放电电流的加载时间对板料电磁成形中板料变形的影响显著。当取放电时间为电流曲线的1.5个周期时,模拟结果与实验数据吻合最好。综合考虑计算效率与精度,板料电磁成形中放电电流的加载时间取1.5个周期为宜。     

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。     

电磁微成形技术研究进展

随着塑性微成形特征尺寸进一步缩小，材料种类不断扩大，单纯依靠模具施加载荷的方法已经越来越难以制备出满足尺寸精度和使用性能要求的微型三维构件，亟需探索新的塑性微成形新原理、新方法和新工艺。电磁微成形技术是一种利用载流导体在磁场中受到洛伦兹力而变形的高应变速率成形方法，能够有效克服微成形过程中成形性能下降、尺寸精度难以保障等问题，具有拓展塑性微成形应用领域的巨大潜力。首先从电磁成形技术的原理与特点出发，介绍了电磁成形过程中高应变速率效应对材料性能的特殊作用，然后综合分析了微成形过程中尺度效应对材料力学行为和成形性能的影响规律及相关机制，详细评述了电磁微成形技术在金属超薄板冲压以及金属表面微纳结构压印中的优势与不足，最后总结并提出了电磁微成形技术在理论和工艺方面所面临的机遇与挑战。     

辊压成形板材表面微结构数值模拟研究

微结构辊压成形技术是耦合了传统的辊压技术与微挤压成形技术的一种新型成形技术,该技术将所需微结构复制到辊表面,然后将辊上的微结构再复印到板材表面。通过有限元对板材微结构辊压成形过程进行数值模拟,对成形阶段及温度在90,120和150℃等条件下对成形力的影响进行分析,结果表明:整个辊压阶段,板料发生剧烈塑性变形的范围只集中在板料表层,应变的最大值总是分布在凹槽的底面,板料中间至底部几乎没有应变;同时随着温度升高,稳定成形阶段的载荷值呈降低趋势。通过实验进行了验证,给出了实验结果的局部测量值。     

金属体积成形过程中温度场的分析

以耦合的方式来处理体积成形过程中塑性变形和温度场之间的相互影响和相互作用 ,开发了一套能进行热力耦合分析的刚塑性 /刚粘塑性有限元模拟软件HFORGE2D ,并利用该软件对镦粗过程和模锻过程进行了数值模拟 ,揭示了成形过程中塑性变形和温度场之间的内在联系     

LY12半球形件拉深成形过程的动力显式有限元模拟

基于连续介质力学及有限变形理论，建立了用于三维板料成形过程模拟的有限元模型，开发了动力显式算法的板料成形过程模拟的有限元分析程序DESSFORMM3D。最后，用笔者新开发的动力显式弹粘塑性有限元程序对不同压边情况下半球形件的拉深过程进行分析，并把数值结果与实验结果进行对比，验证了软件的计算结果。     

UOE焊管成形三维有限元模拟

建立了UOE焊管成形过程的三维有限元模型,模拟具有大变形和复杂接触的成形过程,分析板料各个成形段的回弹,获得了不同成形段板料的变形构形、等效塑性应变分布以及成形载荷的变化。研究结果可为UOE工艺设计以及评估成形机组制管能力提供指导。     

锥形件电磁成形数值模拟及试验研究

采用半耦合法对锥形件电磁成形过程进行数值模拟。应用ANSYS/LS-DANA软件对平板线圈磁场进行计算,求得作用在板坯上的磁压力,应用eta/DYNAFORM软件对锥形件成形过程进行模拟,在此基础上分析了坯料直径对成形质量的影响,进行不同直径坯料的锥形件电磁成形试验,验证了有限元模拟方法用于锥形件电磁成形分析的有效性。     

Research on continuous multi-point forming method for rotary surface

In order to realize high efficient and flexible manufacturing for 3-D surface, continuous multi-point forming (CMPF) is researched. Firstly, principle of CMPF is described, and its characteristics are analyzed by comparing with the conventional spinning methods. Secondly, FEA model of CMPF for disc-shape surface is established, forming load is analyzed theoretically, equivalent stress and plastic strain distributions of disc-shape surface are analyzed. Thirdly, wrinkling is analyzed through simulation results. Fourthly, forming process of tube-shape surface is studied. Finally, CMPF equipment is developed, and experiments are carried out. Results indicate: For disc-shape surface, equivalent stress in regions of center fixture and flexible roller exceeds yield stress; the maximum plastic strain is generated in center region; plastic strain in region of flexible roller takes the second place; shell elements in wrinkling region generate tangent direction compress deformation. For tube-shape surface, maximum value of equivalent stress appears in region of flexible roller; plastic strain field presents annular distribution, its maximum value appears in marginal region. Measure results of curvature radius of disc-shape surface and tube-shape surface almost accord with simulation results. Simulation results of stress field, strain field and wrinkling almost accord with practical situation.     

Determination of Flow Curves at High Strain Rates using the Electromagnetic Forming Process and an Iterative Finite Element Simulation Scheme

The knowledge of reliable material parameters is an essential requirement for the numerical analysis and planning of forming processes, especially when using high speed forming processes in industry. Therefore, a method was developed and implemented to determine the relationship between yield stress, plastic strain, and strain rate of aluminium alloys at very high strain rates of up to 10,000 s-1 by using the electromagnetic forming process (EMF) of tubular specimens. To determine the associated flow curves, an inverse engineering strategy combining an online measurement technique and multi-physical coupled finite element simulations is used. The results are discussed with regard to the anisotropic behaviour of specific aluminium alloys.     

Experimental Observations of Quasi-Static-Dynamic Formability in Biaxially Strained AA5052-O

To establish the efficacy of electromagnetically assisted sheet metal stamping (EMAS), a series of combined hydraulic bulging and electromagnetic forming (EMF) experiments are presented to evaluate the biaxial quasi-static-dynamic formability of an aluminum alloy (AA5052-O) sheet material. Data on formability are plotted in principal strain space and show an enhanced biaxial formability beyond the corresponding experimental results from conventional forming limit diagram. The plastic strains produced by the combined process are a little larger than or at least similar with those obtained in the fully dynamic EMF process. In addition, the biaxial forming limits of aluminum sheets undergoing both very low and high quasi-static prestraining are almost similar in quasi-static-dynamic bulging process. Limit formability seems to depend largely on the high-velocity loading condition as dictated by EMF. It appears that in quasi-static-dynamic forming, quasi-static loading is not of primary importance to the material’s formability. Based on these observations, one may be able to develop forming operations that take advantage of this formability improvement of quasi-static-dynamic deformation. Also, this could enable the use of a quasi-static preform fairly close to the quasi-static material limits for the design of an EMAS process.     

液压油箱成型机设计及工艺参数控制

针对现有围板成型方式的不足,提出一种伸缩式的支撑方式,极大地提高了工作效率。基于金属塑性成型理论,根据板料成型过程中的塑性条件和板料卸载原理,推导出塑性成型弯曲回弹规律。基于材料力学小变形叠加原理,进行折弯辊挠度推导,应用Workbench仿真设计,得到折弯辊最小挠度尺寸。通过以上计算与仿真得出的围板成型工艺参数,保证了产品质量。     

Rapid design of corner restraining force in deep drawn rectangular parts

With the development of finite element method and computer technology, the complete modeling of the forming of a 3D sheet metal part is becoming realistic. However, an accurate 3D simulation is usually too time-consuming to be used in the early stage of design. One solution is to model the straight side of a 3D part as a plane strain problem and the corner section as an axisymmetric problem. Unfortunately, the axisymmetric solution often over-predicts the severity of the deformation at the corner and leads to a very conservative design. In this study, a modified axisymmetric model with a center offset is proposed to predict tearing failure in the corner sections of 3D parts. The proposed offset is found to be a function of the center strains, failure height, and tooling/process parameters, including tooling geometry, material properties, friction coefficient, and restraining force provided by the binder. Finite element analyses of both 3D and 2D axisymmetric models for square and rectangular cup forming are utilized to verify the proposed concept and to define the function. Excellent predictions of the failure heights are obtained. The proposed model enables engineers to rapidly specify the right amount of the restraining force in the corner section based on the desired center strains and forming depth. A detailed design algorithm is provided.     

椭球底零件侧孔翻孔模设计及有限元分析

介绍了某椭球底零件侧孔翻孔的成形工艺,基于工艺计算以及生产经验设计了模具结构,通过PAM-STAMP 2G软件的成形仿真,预测了板料成形过程中不同区域的变形趋势、等效应力以及等效塑性应变分布,为实际生产提供了理论基础及进一步优化板料成形工艺参数和改进模具结构提供了参考。     

采用有限元法设计电磁成形的非均匀线圈(英文)

电磁成形是一种使用脉冲电磁力快速成形的工艺。线圈是电磁成形系统中的一个重要组成部分,需要根据实际应用情况来设计。均匀螺旋线圈通常用在金属板材零件成形中。然而,对于这类非均匀线圈,工件中心部位的电磁力弱,从而导致变形不充分并且还有其它问题出现,如滞留气泡。因此,提出一个设计非均匀线圈的概念,以便电磁力的分布更均匀。采用有限元法对提出的非均匀线圈与传统的均匀螺旋线圈就电磁力的分布、磁场和电流密度进行比较。结果表明,非均匀线圈的电磁力分布更均匀。还计算了线圈的感应强度并进行了比较。     

高强度双相钢DP800成形件碰撞性能仿真分析

针对双相钢板DP800,在完成U型梁冲压成形及回弹仿真分析的基础上,建立了闭口帽型梁的碰撞分析模型。采用映射的方法完成冲压成形件U型梁的厚度、应力、应变向碰撞结构件的结果传递。在考虑成形、回弹及应变率等多种因素的影响下,对帽型梁的碰撞过程进行了多工况仿真分析。研究结果表明,成形后的材料厚度变化、残余应力、加工硬化以及应变率,对碰撞过程将产生直接的影响。研究结果为提高汽车碰撞仿真分析的精度提供了参考。     

塑性成形过程摩擦测试的研究进展

摩擦是影响金属塑性成形及其过程有限元模拟的重要因素 ,因此有必要对其测试方法进行研究。本文介绍塑性成形过程摩擦测试研究方法和测试技术的研究现状与进展 ,并对模拟试验法和直接测量法各自的特点进行了分析。作者设计出一种新型的探针传感器 ,开发出了铝合金板料温成形过程摩擦在线检测系统 ,并对铝合金板(5 182 )圆筒形件温成形过程进行了摩擦测试。