对轮旋压过程的刚塑性有限元分析

提出了一种新的成形工艺－－对轮施压。并用刚塑性有限元进行了分析,得到了变形区的塑性流动场、速度场;以及旋轮的进给速度、减薄率对变形的影响。这对研究对轮施压新工艺,正确选择工艺参数具重要的理论意义。     

内径滚压连接三维有限元分析

通过对成形过程中关键问题的合理处理,建立了钛合金导管内径滚压连接成形,利用ABAQUS/Dynamic Explicit算法进行模拟计算,真实地反映了物理试验中各组件的运动情况;探讨导管材料塑性变形特点、成形后位移场分布,以及导管与管套之间接触力随时间的变化规律,从而掌握了滚压连接成形特点,模拟结果与试验吻合较好。综合分析得出,导管材料嵌入管套凹槽形成拉脱阻力和导管与管套之间存在残余接触压力,是连接成形的机理。     

Rigid-plastic and elastic-plastic finite element analysis on the clinching joint process of thin metal sheets

This article describes the joining of thin metal sheets by a single stroke clinching process. Elastic-plastic and rigid-plastic finite element analysis were applied by employing Coulomb friction and constant shear friction in order to investigate the behavior of the clinch joint formation process. Four process variables, such as die diameter, die depth, groove width, and groove corner radius were selected to investigate the parametric effect on the clinch joint. The strength of clinch joints were evaluated by examining the separation strengths, such as peel strength and tensile shear strength, respectively. A failure diagram was constructed that summarizes the analysis results. The simulation results showed that die diameter and depth were the most decisive parameters for controlling the quality of the clinch joint, while the bottom’s thickness was the most important evaluation parameter to determine the separation strengths.     

Void closure prediction in cold rolling using finite element analysis and neural network

Cold rolling is used to eliminate void defects in cast materials thus improving the material performance during service. A comprehensive procedure is developed using finite element analysis and neural network to predict the degree of void closure. A three-dimensional nonlinear dynamic finite element model was used to study the mechanism of void deformation. Experiments were conducted to investigate void closure during the cold flat rolling process. Experimental results are compared to the three-dimensional finite element predictions to validate the model. The void reduction predictions from finite element analysis are in good agreement with experimental findings. Plastic strain, principal stress distribution around the void and void reduction ratio are presented for various case studies. As finite element simulation is time-consuming, a back-propagation neural network model is also developed to predict void closure behavior. Based on the correlation analysis, the reduction in sheet thickness, the dimension of the void and the size of the rollers were selected as the inputs for the neural network. The neural network model was trained based on results obtained from finite element analysis for various simulation cases. The trained neural network model provides an accurate and efficient procedure to predict void closure behavior in cold rolling.     

滚动体具有局部缺陷滚动轴承的动力学分析

在同时考虑缺陷宽度、深度以及载荷区等因素的情况下,根据滚动体上单一点蚀缺陷滚过内外圈时,接触副接触变形量的变化所引起的弹性接触力的变化,建立了滚动体产生单一局部故障的滚动轴承的动力学模型.通过仿真证实了当滚动体具有单一局部缺陷时,滚动轴承振动信号的低频成分为保持架的旋转频率、滚动体的自转频率及其倍频、以及信号调制形成的边频这一结论论;并通过实验进一步证实了所建立模型和仿真结果的有效性.     

变形参数对半固态轧制影响规律的有限元模拟

建立了半固态材料刚 -粘塑性分析模型 ,以高温钢铁材料为研究对象 ,用MARC软件模拟分析了半固态轧制时 ,轧辊辊缝、轧辊转速等变形参数和浆料初始温度对应力场、速度场的影响 ;结合有限元模拟结果 ,进行了半固态实际轧制试验。实际轧制试验表明 ,轧辊辊缝、轧辊转速和浆料初始温度对半固态轧制试验的影响规律基本与有限元模拟一致 ,其中浆料初始流入速度和温度控制是保证半固态轧制过程顺利进行的关键     

有限元分析在冲压模具设计中的应用

通过建立有限元模型，运用成形缺陷模拟和虚拟修模，解决由于不规则的形状而导致塑性流动的不均匀性所产生的拉裂和起皱，并运用在有限元分析过程中得到的工艺参考参数，如板料应力应变分布、厚度分布、成形力和压边力变化曲线等，缩短冲压模具设计周期。     

剪切机机架应力变形的有限元分析

采用 ANSYS有限元软件的结构分析模块对剪切机机架进行了三维应力变形分析 ,找出了其薄弱环节 ;并对机架应力进行实际测试 ,经比较 ,有限元分析与测试结果相吻合     

重轨全万能轧制显式动力学有限元分析

基于ANSYS/LS-DYNA非线性显式有限元软件,以60 kg·m~(-1)重轨为研究对象,采用三维弹塑性热力耦合的有限元方法模拟了重轨在万能轧机组中的变形过程,有效的解决了轧制咬入难、网格畸变最大等难题.分析了典型道次的应力、应变分布和轧制力的变化情况,结果表明:刚咬入时轧件所受的纵向压力和横向压力均为压应力,应变与塑性变形的程度有关,轧制力与速度呈负相关关系.     

环件轧制过程的显式有限元模拟分析

用于金属成形模拟的有限元方程的求解方法 ,主要有隐式和显式积分两种方法。对于复杂的三维变形分析 ,如环件轧制 ,隐式方法需要很长的运行时间。而利用显式方法 ,可以达到很好的效果。本文利用Abaqus /Ex plicit通用有限元程序对径向环轧进行了模拟。     

采用热弹塑性有限元方法预测低碳钢钢管焊接变形

用有限元分析软件ABAQUS Code开发了用于模拟焊接温度场、焊接残余应力和焊接变形的热弹塑性有限元计算方法.通过建立三维有限元模型,预测了低碳钢钢管多层焊接时的温度场和焊接变形,并通过试验验证了所提出计算方法的精度和有效性.结果表明,在多层焊接条件下,采用有限元方法计算得到的焊接变形与试验结果十分吻合.     

板带轧制过程的三维耦合有限元分析

对板带轧制过程进行严密的三维分析是研究轧制参数对轧后板带尺寸、板形和机械性能的影响 ,从而实施有效控制的基础。本文简要回顾了板带轧制过程三维数值模拟的研究进展 ,提出了一个分析板带轧制过程的耦合有限元模型 ,其中 ,轧件塑性变形采用刚塑性有限元法计算 ,辊系弹性变形采用弹性有限元法计算。计算实践表明 ,该模型具有良好的精度和较高的效率。     

Review on finite element analysis of welding deformation and residual stress

Welding deformation and residual stress have negative influence on assembly accuracy and service performance. Thermal elastic plastic (TEP) and inherent strain finite element analysis (FEA) methods were used to study this challenge. Basic principle of these two methods was first introduced. The influence of welding process, constraints, solid phase transformation and multi-pass welding on deformation and residual stress was discussed, and computation accuracy and efficiency were summarised. Loading method of inherent strain in inherent strain FEA was analysed, interface element was introduced to simulate effects of the gap on deformation in assembly welding especially for large structures. The future work, including accurately multiscale TEP model, efficiently transient prediction method of large structures, and flexible evaluation software, was planned.     

Study of workability limits of porous materials under different upsetting conditions by compressible rigid plastic finite element method

Workability limits must be considered when designing powder metallurgy (PM) forging processes. This research successfully applied the general upsetting experiment method to the deformation of porous materials. Based on the plastic theory of porous materials, the compressible rigid plastic finite element method is used to simulate the deformation processes of cold upsetting of disks and rings for porous metal materials with a full account of contact friction boundary conditions, the height-to-diameter ratio, the initial relative density, and the die and workpiece geometry. Furthermore, a successful analysis of the cold forging process results in the prediction of the stress, the strain, and the density field. By coupling with the ductile fracture criterion, which is a strain-based criterion obtained by Lee and Kuhn, possible defects leading to material failure have been checked. This research reveals that larger height to diameter and a lesser friction factor can delay the local strain locus to intersect with the Lee and Kuhn’s fracture line and restrain formation of the surface crack. Meanwhile, it reveals that the initial relative density has only a very small influence on the strain to fracture in compression, and it shows the forming behavior of the ring and disk with the curved die. According to Lee and Kuhn’s results, the calculated results agree well with the experimental results.     

有限元模拟技术在板带钢轧制中的应用

介绍了板带钢轧制过程中常用的有限元模拟方法的类型,及其近年来在揭示轧制力能参数、温度场、板形控制及板带轧制新技术和新工艺开发中的一些应用实例,并指出其存在的问题和发展前景。     

双金属复合带材轧制过程有限元模拟

采用刚塑性有限元法,以实验结果为依据,以大型有限元软件ANSYS为分析工具,对双金属复合带材轧制过程进行计算机数值模拟,分析了双金属复合带材同步或异步轧制过程中,轧辊和轧件的应力,应变分布和轧件的塑性流动变形情况以及轧制力和力矩,以动画的方式模拟轧制过程,给出了一种预测轧制结构,减少实验时间和费用的有效方法。     

Simulation of vertical-horizontal rolling process during width reduction by full three-dimensional rigid-plastic finite element method

Vertical-horizontal (V-H) rolling is an important process during width reduction in the roughing stand of hot strip mill. A simulation of steady-state V-H rolling was carried out by the full three-dimensional rigid-plastic finite element method (3D RPFEM). To consider the shear work rate and cope with a singular point, an extremely thin array of elements was attached before the entry of the roll. The slab shape, the spread, the separating force, and the rolling torque calculated were in good agreement with the experimental values.     

Y25型转向架侧梁焊接变形热弹塑性有限元分析

针对低合金结构钢材料的特点,采用热循环曲线法对Y25型转向架侧梁的焊接变形进行仿真计算,该方法不考虑相变的影响,研究装夹部位对焊接变形的影响。结果表明:约束位置对焊接变形的影响较大,不同约束位置下的平均角变形变化高达63.47%;在能进行正常施工的条件下,采用优化的夹持位置能有效地减小焊接变形量。因此,在制定焊接工艺时应把夹具约束的位置作为重点影响因素考虑。     

板料成形中有限元模拟技术的应用

使用传统的靠经验和反复修模试模的方法研发模具，不仅难以掌握板料成形的真实过程，而且会造成人、财、物、时的浪费。将有限元技术引入冲压成形模拟中是解决这一问题行之有效的方法，对板料冲压成形模拟进行了讨论，并重点介绍了Dynaform软件的应用。     

AZ31镁合金交叉轧制塑性应变有限元模拟分析

镁合金板材的各向异性会受板材塑性应变的影响.采用交叉轧制工艺研究了镁合金板材上任一点塑性应变的变化规律.应用Deform-3D 软件,通过改变压下制度,对AZ31镁合金交叉轧制过程中的塑性应变进行了有限元模拟.研究结果表明,等道次等压下量时交叉轧制的各道次塑性应变量的差值比单向轧制的要小,说明交叉轧制工艺能够减小镁合金板材的各向异性.