Stiffened panel as a kind of thin-walled component is widely used in aircraft. A novel stiffened panel manufacturing method has been proposed that the plate is bent into designed shape first with multi-point forming method and then milled into integral panel. However, in the bending process, springback is a great issue. In this paper, an analytical method is proposed to predict the springback of the double-curved bent plate in multi-point forming process. The method takes advantage of the loading force, which is obtained by the stress in the thickness direction, and the arrangement of the punches to calculate the bending moment in the forming process. Through Bezier surface blending method, the profile after springback was constructed. Moreover, the strain and stress variation through thickness during loading and unloading process were also analyzed. And the finite element simulation and bending experiment were conducted to make verification. The results show that the method proposed can effectively predict the springback of the double-curved bent plate in multi-point forming.

中文翻译：

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一种基于多点成形法的双曲板弯曲回弹预测方法

加筋板作为一种薄壁构件，广泛应用于飞机。提出了一种新的加筋板制造方法，即先用多点成型方法将板弯曲成设计形状，然后铣削成整体板。然而，在弯曲过程中，回弹是一个很大的问题。本文提出了一种预测双曲弯板在多点成形过程中回弹的解析方法。该方法利用由厚度方向的应力得到的加载力和冲头的排列来计算成形过程中的弯矩。通过贝塞尔曲面混合方法构建回弹后的轮廓。而且，还分析了加载和卸载过程中随厚度变化的应变和应力变化。并进行了有限元仿真和弯曲实验进行验证。结果表明，所提出的方法可以有效地预测双曲弯板在多点成形中的回弹量。