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| A new multi-step approach considering bending effects and its application in the stretch bending of rectangular tubes |
| Received:July 27, 2009 Revised:June 13, 2010 |
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| DOI：10.7511/jslx20116021 |
| KeyWord:multi-step approach bending effects BST element the penalty method stretch bending of rectangular tube |
| Author | Institution |
| 傅立军 |
上海交通大学塑性成形工程系, 上海 |
| 董湘怀 |
上海交通大学塑性成形工程系, 上海 |
| 王鹏 |
上海交通大学塑性成形工程系, 上海 |
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| Abstract: |
| 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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