针对板料回弹控制问题,提出了一种基于多目标优化的综合评判回弹的方法,建立了以等效应力偏差来表征并考虑高斯积分点位置影响的目标函数和以等效塑性应变表征的目标函数;运用试验设计技术、响应面法和多目标遗传算法,结合LS-DYNA关键字文件建立了基于回弹控制的成形工艺参数的集成优化模型,并分析了变压边力和拉延筋力对回弹的影响.结果表明：先小后大的变压边方式可以保证产品产生较大的塑性变形,后期较大的压边力还能使厚度方向的应力偏差减少,从而显著抑制回弹;而根据产品形状分段设置拉延筋,并分别施加合适的拉延筋力对于抑制回弹也有一定的效果;优化后回弹由1.952 50mm减少到0.674 51mm,证实了模型的多目标函数能够综合评判回弹.

In order to control the springback in the forming process of sheet metal,a synthetical method to evaluate the springback is proposed based on multi-objective opitmization.In this method,two objective functions are established,one of which considers both the equivalent stress deviation and the coordinates of Gaussain integration point,and the other considers the equivalent plastic strain.Then,an integrated optimization model based on the springback control is put forward by combining the design of experiment,the response surface method and the multi-objective genetic algorithm with LS-DYNA keyword file.Moreover,the influences of variable blank holder force（VBHF） and drawbead restraining force on the springback are analyzed.The results show that（1） when the VBHF takes its value first small and then great,large plastic deformation can be achieved,and larger blank holder force in the later stage may lead to small equivalent stress deviation in the thickness direction,thus significantly inhibiting the springback;（2） a reasonable configuration of drawbeads adapting to the product shape and appropriate drawbead restraining forces also have some effects on the springback reduction;and（3） the amount of springback decreases from 1.95250mm to 0.67451mm after the optimization,which means that the proposed multi-objective functions are effective in evaluating the springback.