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滚压包边是一种复杂的多工步单点连续加载工艺过程,在产品早期开发阶段就需要对滚压包边工艺进行可行性设计,依赖经验和试错的方法已无法满足滚压包边技术的要求。从单元模型、加载方法等方面深入研究滚压包边仿真分析建模关键技术,以指导产品和工艺设计。研究表明:采用最小尺寸为0.5 mm的壳单元,既能提高计算效率,也能保证数值模拟精度;考虑到计算的效率,数值模拟研究均采用了厚向7个积分点的4节点减积分壳单元S4R;可以采用摩擦系数为0的滚轮滑动模拟滚动;对零件轮廓尺寸变动量进行数值模拟时,可以不考虑翻边变形所产生的材料强化,模拟材料断裂时不能忽略翻边所产生的预应变。 相似文献
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板料冲压成形中坯料优化设计方法研究 总被引:2,自引:0,他引:2
较为系统地介绍了冲压件坯料的优化设计方法,并比较分析了其各自的优缺点。相比于其他方法,一步模拟方法效率高、适应面广、功能较强,可以在产品的设计之初提供较为丰富的信息。因此,对其作了较为详细的论述。实例证明,一步模拟法可用于板料成形工艺方案的快速评价及参数优化。 相似文献
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时间步长对淬火过程温度场和组织场模拟精度的影响 总被引:2,自引:1,他引:1
淬火过程是一个温度、相变、应力应变相互影响的高度非线性过程,在用有限元方法计算温度场和组织场时,极易造成数据振荡现象.本文针对淬火过程温度场的特点,为了尽量提高温度场和组织的计算精度,使用集中热容矩阵、网格细化和自适应时间步长的方法,编写了淬火过程有限元模拟程序,并提出了一种控制模拟时间步长的方法--基于最大和最小温差的自适应步长,该方法是用前一步模拟得到的温度场与当前步模拟所得的温度场的差值控制模拟时间步长.用编写的程序对轴对称零件进行有限元模拟,从模拟结果的对比中可以看出,基于最大和最小温差的自适应步长方法不但可以避免数据振荡和提高模拟精度,而且可缩短计算模拟的时间. 相似文献
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轿车变速箱轴类件多工位冷精锻工艺及模具研究 总被引:1,自引:0,他引:1
轿车变速箱轴类件种类繁多,但其外形结构特点较为单一,其主要特征为细而长且多台阶.详细分析了该类锻件采用多工位冷精锻工艺方案的可行性.多工位冷精锻能顺利成形锻件,该工艺具有产品质量高、材料利用率高和生产效率高等优点,适合大批量生产.以输入轴为例,基于减径挤压工艺知识,制定了输入轴的五工位冷精锻工步图,计算并确定了工艺参数,研究了工步之间工艺参数的匹配关系;提出了多工位冷精锻模具设计原则和方法,设计了输入轴五工位冷精锻模;采用塑性成形模拟软件DEFORM-2D对输入轴各工步成形过程进行了模拟分析,验证了该工艺方案的可行性. 相似文献
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磁控溅射技术制备的薄膜膜层均匀,内部无气孔,密度高,与衬底的附着性良好,薄膜质量高,被广泛应用于科学研究和工业生产中,且适合应用计算机模拟来研究溅射过程和溅射结果,这样既可以检验模拟的准确性,又可以对实验现象的内在意义进行挖掘,为后续实验提供参考信息。在介绍磁控溅射薄膜生长常用模拟方法原理的基础上,详细讨论了第一性原理(First-principles calculations)、分子动力学(Molecular dynamics,MD)和蒙特卡洛(Monte Carlo,MC)等3种方法的适用条件和模拟结果,从3种方法适合解决的问题、相互之间的区别等方面,对国内外最新的研究进展进行总结与分析。发现3种方法在精确度和计算量上依次递减,在可模拟的时间和空间尺度上依次递增,在模拟对象上,第一性原理方法由于其高度的精确性被广泛应用于对薄膜本身的性质或对粒子间的运动等方面,且模拟结果可以是具体数值,从而对实验进行更加精确的预测和指导,分子动力学方法多用于模拟薄膜生长过程和原子间行为等方面,蒙特卡洛方法相较于前两者,用途更加广泛,可模拟的对象除了薄膜本身,也可以对电磁场等进行模拟。最后,对磁控溅射薄膜生长模拟未来的研究方向进行了展望。 相似文献
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R. Padmanabhan M.C. Oliveira A.J. Baptista J.L. Alves L.F. Menezes 《Journal of Materials Processing Technology》2009,209(5):2402-2411
Deep drawing is a forming process controlled by a number of parameters. The initial blank shape is one of the most important process parameter that has a direct impact on the quality of the finished part. This paper describes a new method to determine the optimal blank shape for a formed part using the deformation behaviour predicted by finite element simulations and salient features of NURBS surfaces. The proposed optimization method involves an initial blank shape, which is iteratively trimmed according to the deep drawing simulations results, to achieve the final optimal blank shape. The deep drawing simulations were carried out using DD3IMP, an implicit in-house finite element code. Parametric NURBS surfaces are used to optimize the initial blank shape based on the deformation behaviour predicted by numerical simulation. The proposed method can determine the optimal blank shape for any part within a few iterations. 相似文献
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复杂汽车结构件多工位级进模具有工位多、结构复杂、工位关联性强的特点,其冲裁工位刃口线受成形工位的影响,刃口线的预测精度低。基于此,提出一种基于应变路径的精确刃口线优化方法。采用有限元逆算法对零件分步展开,获得板料的初始轮廓线;基于真实压力机参数、精细化模面和真实工艺参数,对条料进行全工序精细化数值模拟。将板料初始网格的边界节点基于B样曲线拟合,提取成形前后边界节点的应变及其路径。以设计零件的产品边界为目标,建立精确刃口线优化的目标函数,通过调整B样条曲线,对轮廓线进行迭代优化。实例表明,该优化方法可有效提高复杂多工位级进模刃口线优化的精度和效率。 相似文献
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Guoqun Zhao Ed Wright Ramana V. Grandhi 《International Journal of Machine Tools and Manufacture》1995,35(9)
This paper presents a preform design method which employs an alternative boundary node release criterion in the finite element simulation of backward deformation of forging processes. The method makes use of the shape complexity factor which provides an effective measure of forging difficulty. The objective is to release die contacting nodes in a sequence which will minimize the geometric complexity throughout the backward deformation simulation. This is done by calculating the effect of releasing each of a select group of boundary element nodes at each finite element solution step. The particular detached node which results in the minimum shape complexity factor will be released for the current step. This process continues for each backward step until the last few nodes remain in contact. This design method is demonstrated through the simulated forging of an integrated blade and rotor turbine disk blank. A preform shape developed by this method is compared with an empirically designed preform. Performance parameters for comparison include die fill, flash volume, effective strain variance, frictional power and die load. Comparing the results of the forward simulations indicates improved performance of the preform design using FEM based backward deformation method over that of the empirical design. 相似文献
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A modified membrane finite element with a proper formulation for planar anisotropic materials is introduced to correctly enhance the flexural rigidity not only within an element but among elements. The strain energy term in the formulation is decomposed into the membrane energy term for mean stretching and the bending energy term for pure bending. This procedure needs careful evaluation for the orientation of the anisotropic axes. The formulation is then combined with an effective algorithm to deal with the contact between the material and the dies. Distribution of the blank holding force is calculated in each step according to the thickness in the flange region. The calculation employs a special relation between the thickness and the blank holding force. The simulation examples demonstrate the validity and versatility of the computer code by showing the earing phenomenon in circular cup drawing and the variation of the blank holding force in rectangular cup drawing. The results shows that the thickness variation in the flange region redistributes the blank holding force during the deformation. The present algorithm can predict more precise contour lines in the flange region and a more precise shape and strain distribution. 相似文献
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1 INTRODUCTIONDuringautoproductdevelopmentprocess ,manystructurecomponents/partsandbodypanelsaresheetmetalpartsthatarefabricatedthroughstampingpro cesses.Theeffectivestampingtoolanddiedevelop mentcancertainlyspeedupthevehicleproductdevel opment processandshortenthetimetomarket.Whileamongthestampingtechniques ,thedrawingprocessisthemostimportant processthatshapesmostofthegeometricfeaturesexcludingtheholesandflanges .Duringthesheetmetalpartdrawingprocessdesign ,it scriticaltoselect/determi… 相似文献