板料成形反向模拟法提高应力计算精度的策略

A Strategy to Improve Stress Calculation in Inverse Analysis Method of Sheet Metal Forming

针对目前板料成形反向模拟法无法准确预测成形零件应力分布的缺点,采用一种DKT壳单元,可以描述内外层应力分布的差异而导致的弯曲力矩.根据反向模拟法求解的特点,提出一种快速搜索流经模具圆角的单元的方法.引入一种简化的纯弯曲梁的弯矩计算思想,对流经模具圆角的单元进行弯矩修正.在NUMISHEET’93盒形件拉深的标准考题中,通过与增量模拟软件Dynaform的比较,验证了采用DKT壳单元和进行弯矩的修正可以更好地描述变形历史,获得更为真实的应力分布.

Inverse analysis method of sheet metal forming has the shortcoming of not being able to predict stress distribution precisely. A DKT shell element is implemented to describe the bending moment caused by the difference of stress distribution between inner and outer layer. A fast and reliable searching scheme is used to find elements passing by die entrance radius during the deformation process. The theory of pure bending of beams is used to modify the bending moments for elements passing by die entrance radius. The NUMISHEET＇93 square box drawing benchmark demonstrates that these improvements can significantly enhance the prediction of stress distribution by comparison with the incremental theory based software Dynaform.