共查询到19条相似文献,搜索用时 46 毫秒
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介绍了板材成形数值模拟技术的研究和应用在国内外发展的概况,并从基本算法、单元模型和网格划分、材料模型、接触摩擦、起皱问题、破裂问题和回弹计算等方面介绍了弹塑性有限元的基本原理、关键技术和主要难点,结合在工厂实际生产中的使用情况和存在的问题,展望了板材数值模拟技术今后的发展方向. 相似文献
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为了提高大幅面板材成形的模拟精度,在板材折弯平面应变假设条件下,推导出基于Hill各向异性屈服准则的弹塑性本构方程.借助ABAQUS有限元软件本构模块用户子程序接口,通过编程将上述推导的应力-应变本构关系显示表达式嵌入ABAQUS分析平台.以超长大开口半椭圆形工件成形为例,建立了大幅面钢板渐进折弯的三维弹塑性有限元模型,并数值模拟了多道次渐进折弯成形及回弹全过程.模拟效果和工程应用结果表明,与传统的基于平面应力假设的本构关系模型相比,采用平面应变假设的本构关系模型的模拟结果更接近实验值. 相似文献
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目的揭示铝合金板材磁脉冲辅助弯曲成形对回弹的影响机理。方法基于两种磁脉冲辅助成形方案,采用数值模拟软件LS-DYNA,建立磁脉冲辅助U形弯曲的有限元模型。结果与准静态成形相比,磁脉冲辅助U形弯曲成形能减小板料圆角区的残余应力,方案Ⅰ板料圆角区等效塑性应变大于方案Ⅱ板料圆角区的等效塑性应变;电磁体积力能有效减小回弹,且放电能量越大,回弹角越小;磁脉冲辅助U形弯曲成形能减小板料的弹性应变能。结论相同放电电压下,方案Ⅰ的回弹控制效果好于方案Ⅱ的回弹控制效果。磁脉冲辅助U形弯曲减小回弹的主要原因是板料圆角区残余应力的减小和弹性应变能的降低。 相似文献
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目的 研究软模成形过程中塑性应变比r值对双极板成形深度及壁厚的影响,探究不同工艺参数对双极板尺寸的影响规律。方法 通过单向拉伸实验得到纯钛极薄带的力学性能参数,然后采用橡胶软模成形方法制备纯钛燃料电池双极板,利用光学显微镜对制备的双极板尺寸及壁厚进行测量并深入分析。结果 TD取向的r值最大为2.56,沿该方向成形时,纯钛极薄带在载荷为300 kN、软模硬度为77HA条件下得到的双极板深度最大,为0.293 mm;同时,其壁厚减薄较小,在减薄最严重的位置壁厚减薄率仅为13.52%。结论 较大的载荷与适宜的软模硬度能得到较好的双极板深度,对双极板周期无影响;双极板深度、壁厚与r值有关,r值越大,纯钛极薄带抵抗壁厚减薄的能力越强,成形深度越大。 相似文献
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板料渐进成形数值模拟与实验研究 总被引:1,自引:0,他引:1
为提高渐进成形的成形效率和成形质量,了解板料渐进成形的变形规律及工艺参数对成形的影响,采用有限元方法对板料渐进成形过程进行了数值模拟研究,分析了斜壁盒形件渐进成形过程应力分布和厚度变化趋势,通过对不同进给量和不同成形路径进行数值模拟,分析了工艺参数对成形的影响.结果表明,斜壁盒形件最大应力和最大厚度减薄发生在底面拐角处;成形过程中工具头运动轨迹应尽量采用走螺旋线的方式,可以提高成形件的成形能力和成形质量.渐进成形实验表明,数值模拟结果与实验结果基本吻合. 相似文献
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多点成形中压痕的数值模拟及极限成形力的分析 总被引:4,自引:0,他引:4
压痕是多点成形中特有的成形缺陷之一,对压痕形成过程进行模拟时,采用实体单元比壳单元计算更准确.但是板料较薄时,采用实体单元划分的有限元很多,计算时间极长.为获得最佳的计算效率及模拟结果,对不同材料和不同厚度的球面和马鞍面样件进行了对比的数值模拟.结果表明,当板厚与板宽的比值小于0.015时,采用壳单元模拟压痕也能得到比较准确的结果,而当比值大于0.015时,则应采用实体单元.在此基础上,对不同板厚、不同曲率半径下的马鞍面和球面件出现压痕时的极限成形力进行分析,得到了厚向压应变为1%和5%的压痕对应的成形力极限图. 相似文献
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Using neural network to predict punch radius based on the results of air-bending experiments of sheet metal is a high efficiency work in spite of little error. A three-layer back propagation neural network (BPNN) is developed to best fit this discrete engineering problem involving many parameters of air-bending forming. A genetic algorithm (GA) is used to optimize the weights of neural network for minimizing the error between the predictive punch radius and the experimental one. Then, with the predicted punch radius and other geometrical parameters of a tool, 2D and 3D ABAQUS finite-element models (FEM) are established, respectively. The original forming process of multiple-step incremental air-bending of sheet metal, obtained from geometric planning for semiellipse-shaped workpiece, is simulated using the FEM. This process is further adjusted with simulation-optimization results, because of existing large errors in the workpiece simulated with the original forming process. Finally, a semiellipse-shaped workpiece, with average errors of +0.61/−0.62 mm, is manufactured with the optimized adjustment process. The experimental results show that the punch design method is feasible with the prediction model of GA-BPNN, and the means of optimizing process with FEM simulation is effective. It can be taken as a new approach for punch and process design of multiple-step incremental air-bending forming of sheet metal. 相似文献
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针对板件初始毛坯形状计算以及正交异性板的快速有限元分析问题,依据拉深件的UG模型,导出了零件的三角网格数据,并采用几何映射方法得到了用于快速有限元分析的拉深件初始展开毛坯.在此基础上,基于理想变形假设以及Hill’48正交异性屈服准则,给出了用于拉深件成形过程快速分析的一步法数学公式和有限元表达,并在Unigraphics系统中进行了有限元分析的后置处理.此外,对TC1钛板筒型拉深件毛坯初始形状进行了优化,并对成形中拉深件厚向应变分布进行了分析,得到了满意结果. 相似文献
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Jae‐Jun Lee Gyung‐Jin Park 《International journal for numerical methods in engineering》2011,85(2):247-268
In the sheet metal forming process, forming the final desired shape is difficult to obtain due to wrinkling, tearing, failure of material, etc. Various conditions of the forming process should be controlled for the desired shape. These conditions are the velocity of the punch, the friction factor, the blank holding force, the initial shape of the blank and others. Many researchers have conducted studies to predetermine the initial blank shape. The structural optimization technique is one of them. Non‐linear response structural optimization is required because non‐linearities are involved in the analysis of the metal forming process. When the conventional method is utilized, the cost is extremely high due to repeated non‐linear analysis for function and sensitivity calculation. In this paper, the equivalent static loads (ESLs) method is used to determine the blank shape which leads to the final desired shape and reduced wrinkling. The ESLs method is a structural optimization method where non‐linear dynamic loads are transformed into ESLs, and these ESLs are utilized as external loads in linear response optimization. The design is updated in linear response optimization. Non‐linear analysis is performed with the updated design and the process proceeds in a cyclic manner. An optimization formulation is defined for the examples, the formulated problems are solved to verify the proposed method and the results are discussed. Non‐linear analysis is performed using the commercial software LS‐DYNA, NASTRAN is used for calculating the ESLs and linear response optimization, and an interface program for LS‐DYNA and NASTRAN is developed. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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基于FEA的板料成形工艺优化及评价函数研究 总被引:1,自引:0,他引:1
基于有限元和优化方法的板料成形工艺优化设计技术已经成为新的研究热点,建立合理的评价标准以形成目标函数,从而用于评价冲压件的成形性是其关键技术之一.提出局部成形性、整体成形性和综合成形性评价函数.基于试验设计法,结合方盒形件拉深以及发动机罩外板成形,验证了本文提出的评价函数具有良好的可靠性和易用性. 相似文献