薄板成形切边回弹模拟的切边算法

为保证薄板多工步冲压成形切边回弹有限元数值模拟精度,提出了一种基于切边单元自适应模板的切边算法.首先进行三维切边线与零件网格的求交计算,生成有序截面线;然后进行单元取舍判断;最后沿截面线路径逐个单元调用自适应模板执行切边操作.算法避免了边界锯齿、对称约束和边界缝隙等缺点,并实现了多条切边线对加密网格进行一步切边,提高了切边效率.将算法集成到冲压成形分析软件KMAS系统切边回弹模块,通过对NUMISHEET 2005提供的国际标准考题--某汽车底板横梁拉延件的切边数值模拟,验证了算法的适用性和可靠性.

Trimming Algorithm in Trimming Springback Simulation of Thin Sheet Forming

In order to assure the accuracy of trimming springback of multi-step forming by finite element method, a trimming algorithm based on self-adaptive template of trimmed elements was proposed. In this algorithm, the intersection calculation between 3 D trimming lines and mesh of part was executed at first. Then the accepting and rejecting judgement of elements was achieved. Finally, the method of trimming element by element along the path of the section lines was used in trimming operation. Therefore, the problems of boundary serration, axial symmetry and boundary gap have been totally avoided, and multi-trimming on refined mesh was achieved to improve the efficiency of trimming operation. The present algorithm has been integrated into the independently developed KMAS forming analysis system. By using the numerical simulation on automotive underbody cross member which was provided by benchmark test of NUMISHEET 2005, the applicability and reliability of introduced algorithm were verified.