金属塑性变形过程的刚(粘)塑性有限元数值模拟

介绍有限元法在塑性加工领域的研究进展和数值模拟的程序实现及关键技术;论述了刚(粘)塑性有限元法的主要思想和处理方法.基于前期的本构模型,得出了刚(粘)塑性有限元法的求解列式.并对有限元数值模拟的发展前景作了预测.     

大型立辊轧机辗边行为模拟

本文应用刚－粘塑性有限元法成功地模拟了Ａｌ５０５６和铅两种材料的辗边过程，着重分析了工艺参数对辗边力能参数的影响，得出一些重要结论。计算结果与试验结果吻合较好。     

材料各向异性对板料拉延成形的影响

文章用刚塑性有限元法,开发了一个二维数值模拟程序系统,以厚向异性、平面异性为条件,对圆筒件拉延成形中的法兰变形区进行了数值模拟,给出了法兰变形区的金属流动规律。     

钨丝拉拔过程刚塑性有限元法与热分析耦合的数值计算

摘自清华大学机械工程系研究生张新泉的博士学位论文,导师:王祖唐,金其坚 本文用刚塑性有限元法和热分析建立钨丝拉拔过程速度场与温度场的计算模型,论述了耦合计算的原理、公式和方法。利用耦合热分析的刚塑性有限元法,综合考察了拉丝工艺中主要工艺因素的影响,使计算机数值模拟更接近实际生产情况。通过速度场和温度场的耦合数值计算,获得了钨丝拉拔加工过     

刚粘塑性有限元——边界元耦合方法在模拟板材热（连）轧过程中的应用

介绍了一种用计算机模拟板材热（连）轧过程的新方法。该方法是用刚粘塑性有限元法分析轧件的塑性变形，用边界元法分析轧辊的弹性变形，考虑到轧件塑性变形与轧辊弹性变形之间的相互影响，通过在轧件与轧辊接触面上建立力的平衡方程来实现耦合，从而更精确地模拟出板材热（连）轧的轧制过程。     

铝型材宽展挤压过程的数值模拟及模具结构优化

采用刚粘塑性有限元法,在Deform-3D有限元商业软件上成功实现了导流宽展铝型材挤压过程的三维数值模拟,获得了挤压过程中材料的流动规律、应力场、应变场和温度场的分布,以及模具出口处金属流速的分布情况。通过数值模拟发现型材出口流速不均匀,造成端面不齐,对此提出了模具修改方案,通过调节模具工作带的长度,实现了型材挤压出口流速均匀的目的,从而保障了型材的产品质量。模拟结果为模具的优化设计及工艺参数的选取提供了理论依据。     

四辊组合孔型（圆—方）轧制金属流动规律的刚塑性准平面应变有限元数值...

建立和推导了刚塑性准平面应变有限元能量泛函式，编制了相应计算程序，模拟了四辊组合孔型（圆－方）轧制时的金属流动，得到了变形区内不同横断面内的网格变化规律和金属流动规律。应用表明，刚塑性准平面应变有限元法是一种较好的适用于微机的三维变形模拟方法。     

铜材接触线扩展挤压成形的三维有限元数值模拟

根据有限变形刚粘塑性有限元理论,基于DEFORM-3D软件平台,对接触线在模腔中扩展挤压成形过程进行了三维有限元数值模拟,获得了扩展挤压成形过程的应力场、应变场、温度场和速度场分布,并揭示了金属流动规律,从而为模具设计提供理论依据。     

ZK60合金多道次ECAP晶粒组织模拟和实验分析

采用刚粘塑性有限元软件对ZK60合金四道次等通道转角挤压(ECAP)过程进行数值模拟。对一至四道次ECAP试样进行晶粒组织模拟,观察晶粒细化程度的分布和变化规律。通过多道次ECAP实验,利用金相显微观察试样头部和尾部的晶粒尺寸的变化以及动态再结晶形成机理。对比有限元数值模拟与实验组织分析结果,探索利用有限元模拟与实验分析相结合的方法,研究镁合金ECAP成形过程的晶粒组织变化规律。     

正向、反向挤压变形均匀性的定量分析

本文以铝棒材为研究对象,在参考了相关文献的基础上,建立了考虑塑性功、摩擦生热、对流换热和热传导等多种边界条件的热-力耦合温度场的有限元模型。使用MSC-Superform有限元分析软件,选用刚塑性有限元法和平面轴对称单元,通过对2A11铝棒材反向挤压和正向挤压的数值模拟,结合影响挤压效果的各种因素,尝试对铝棒材正、反向挤压的变形均匀性进行定量的分析。     

Rapid Finite Element Analysis of Bulk Metal Forming Process Based on Deformation Theory

 The one-step finite element method (FEM), based on plastic deformation theory, has been widely used to simulate sheet metal forming processes, but its application in bulk metal forming simulation has been seldom investigated, because of the complexity involved. In this paper, a bulk metal forming process is analyzed by using a rapid finite element simulation method based on deformation theory. The material is assumed to be rigid-plastic, strain hardening. The constitutive relationship between stress and total strain is adopted, whereas the incompressible condition is enforced by penalty function. The geometrical non-linearity in large plastic deformation is taken into consideration. Furthermore, the force boundary condition is treated by a simplified equivalent approach, considering the contact history. Based on constraint variational principle, the deformation finite element method is proposed. The one-step forward simulation of axisymmetric upsetting process is performed by this method. The results are compared with those obtained by the traditional incremental FEM to verify the feasibility of the proposed method.     

FEM Simulation of Large Diameter Pipe Bending Using Local Heating

 With the aid of elastic plastic large deformation finite element method (FEM), an elastic plastic and coupling thermo mechanical model was built to calculate the bending process of the bent pipe, combining with local heating or cooling of the bent pipe. Based on the FEM simulation, the metal deformation during the bending process was analyzed in detail. The thinning and thickening ratio of the pipe wall thickness, the ovality of the cross section of the pipe and the spring back angle, etc, are presented.     

"狗骨"材平轧的三维刚塑性有限元分析

用全三维刚塑性有限元法分析了２Ｓ－Ａｌ板坯立轧和随后平轧的稳定轧制过程。侧重分析了仅消除“狗骨”形状的随后平轧过程,并对不同立辊孔型侧壁斜度条件产轧轧制力、轧制力矩以及平轧后的断面形状进行了比较,所得计算结果与献〖１〗的实验结果吻合较好。     

推动模型在棒线材轧制过程模拟中的应用

基于三维热一机耦合有限元分析方法建立了刚性体推动模型，模拟棒线材多道次连轧过程。刚性体推动模型与常规有限元模型的比较结果说明刚性体推动模型可以在获得相同的精度前提下，显著地提高运算效率。将所建立的有限元模型应用于304不锈钢粗轧过程的数值模拟，得到了轧件6道次连轧过程的温度场、应变场和轧件的变形过程，并比较了各道次的轧制力模拟结果和轧机许用轧制力。温度场的模拟结果与测量结果的比较证明了模型的可靠性。     

无缝钢管定减径过程的有限元模拟

利用非线性有限元分析软件MSC．Marc对无缝钢管连轧工艺中的定减径过程进行了有限元模拟,分析了变形过程中金属的流动、管子的变形以及轧制力的变化等规律,得到了定减径过程中应力与变形的分布与变化以及各个轧制道次和最终成品管的结构形状,并通过实验的结果验证了所建立的钢管定减径过程有限元分析模型的正确性。研究的结果为生产实际提供了有益的依据。     

Prediction of Velocity and Deformation Fields During Multipass Plate Hot Rolling by Novel Mixed Analytical-Numerical Method

 An integrated mathematical model is proposed to predict the velocity field and strain distribution during multi-pass plate hot rolling. This model is a part of the mixed analytical-numerical method (ANM) aiming at prediction of deformation variables, temperature and microstructure evolution for plate hot rolling. First a velocity field with undetermined coefficients is developed according to the principle of volume constancy and characteristics of metal flow during rolling, and then it is solved by minimizing the total energy consumption rate. Meanwhile a thermal model coupling with the plastic deformation is exploited through series function solution to determine temperature distribution and calculate the flow stress. After that, strain rate field is calculated through geometric equations and strain field is derived by means of difference method. This model is employed in simulation of an industrial seven-pass plate hot rolling process. The velocity field result and strain field result are in good agreement with that from FEM simulation. Furthermore, the rolling force and temperature agree well with the measured ones. The comparisons verify the validity of the presented method. The calculation of temperature, strain and strain rate are helpful in predicting microstructure. Above all, the greatest advantage of the presented method is the high efficiency, it only takes 12 s to simulate a seven-pass schedule, so it is more efficient than other numerical methods such as FEM.     

数值模拟在极限规格H型钢工艺优化中的应用

针对HW150mm×150mm极限规格H型钢产品偏心问题,采用有限元方法对粗轧阶段孔型系统进行三维热力耦合数值模拟。基于模拟结果分析金属流动、塑性应变及温度变化,以此为基础,根据变形特点及各孔型轧件尺寸分析偏心产生的原因,优化孔型并进行验证,最后进行现场实践,排除缺陷。结果表明,有限元模拟有助于分析轧制过程中的金属成形,尤其对于型钢轧制过程中的变形规律及缺陷分析具有较高的参考价值和指导意义。     

平面应变压缩金属流变规律及影响因素分析

 平面应变热模拟技术是塑性加工领域广泛应用的一种实验室模拟技术,现被广泛应用于测量金属的变形抗力以及金属的流动状态,是热轧过程模拟的最好的方法。为了全面研究平面应变技术,采用理论分析、数值模拟以及物理模拟的方法,系统分析了刚端、摩擦、试样尺寸以及对中性对平面应变过程中的应力状态以及金属流动的影响。研究结果显示各因素对金属流动以及实验结果的准确性有较大影响。