| 傅立军,董湘怀,王鹏.一种可考虑弯曲效应的多步法及其在矩形管拉弯成形中的应用[J].计算力学学报,2011,28(6):938~942 |
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| 一种可考虑弯曲效应的多步法及其在矩形管拉弯成形中的应用 |
| A new multi-step approach considering bending effects and its application in the stretch bending of rectangular tubes |
| 投稿时间：2009-07-27 修订日期：2010-06-13 |
| DOI：10.7511/jslx20116021 |
| 中文关键词: 多步法 弯曲效应 BST壳单元 罚函数法 矩形管拉弯 |
| 英文关键词:multi-step approach bending effects BST element the penalty method stretch bending of rectangular tube |
| 基金项目:国家自然科学基金(50575143)资助项目. |
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| 摘要点击次数: 2054 |
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| 中文摘要: |
| 多步法可以考虑变形历史,也顺应了多工步成形的需要,在板料成形的数值模拟中有着良好的应用前景。但传统的多步法主要是基于膜单元的,没有能够准确地考虑成形中的弯曲效应,不适合模拟弯曲变形占主导的成形过程,如型材的拉弯成形。为此,本文将无转动自由度的BST壳单元引入,通过单元片内四个相邻单元,方便地计算出相邻构型的曲率,并通过每步内的塑性势增量取极值,采用罚函数法处理接触,推导建立了新的多步法公式。基于此公式,开发了多步法有限元程序,在6个大计算步内快速完成了矩形管拉弯成形分析,特别考察了其截面畸变和回弹问题,所得到的模拟结果与增量分析和试验结果基本上一致。 |
| 英文摘要: |
| Multi-step approach can take the deformation history into account, adapts to multi-stage forming and has a good application prospect in the simulation of sheet metal forming. But traditional multi-step approaches are mostly based on the membrane element without considering bending effects exactly, not suited to the bending-dominated process, such as the stretch bending of profiles etc. Therefore the rotation-free BST element is introduced here to describe deformation, in which the curvatures are computed by a patch of four adjacent elements. Then using the principle of extremum work and the BST element, a new multi-step formulation is presented, in which the penalty method is adopted to treat the contact between the workpiece and bending tools. Based on the formulation, a program has been developed and utilized to simulate the process for stretch bending of rectangular tubes within six large steps, including pre-stretch and bending, with special attentions paid on the cross sectional distortions and springback problems. The numerical results basically agree with those of incremental analysis and experiments. |
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