Stiffening of cambered sheet metal designs: numeric bead optimization by a coupled algorithm considering nonlinear forming limits

微珠用于拉深钣金件，以增加零件的刚度。这样就可以减少金属薄板的厚度，从而减轻重量。珠子的类型和位置的样式指南是存在的，它们经常被应用。然而，通过数值优化可以实现更高的刚度效果。现有的弹珠优化算法在计算次数与加筋效果的关系上存在不足。这些算法也没有充分考虑到制造过程以及钣金零件的几何形状。在本研究项目中，将开发一种优化方法，该方法结合了两种不同优化策略的优点，并进一步考虑了拔罐的制造过程和额外的深拉伸珠。采用基于成本效益最优准则的方法确定焊头路径，采用基于灵敏度的优化方法检测焊头轮廓参数。这种两种不同优化策略的组合还允许在合理的计算成本下考虑最大成形性。所要开发的优化算法考虑了由拉深和镦粗组成的两步制造过程。在这两个制造步骤的成形性是一个限制因素。考虑到非线性应变路径，可接受的几何形状和工艺参数将在数值和实验测试中确定。这些将被整合到优化算法中。此外，该算法还根据深拉几何的弧度考虑了珠子对刚度的影响。并将通过仿真和实验进行验证。

Beads are used in deep drawn sheet metal parts for increasing the part stiffness. Thus reductions of sheet metal thickness and consequently weight reduction can be reached. Style guides for types and positions of beads exist, which are often applied. However, higher stiffness effects can be realized using numeric optimization. Existing algorithms for the optimization of beads have disadvantages concerning the relationship between computing times and stiffening effect. Manufacturing processes as well as the geometry of the sheet metal part are also not taken into account sufficiently by these algorithms.Within this research project, an optimization method will be developed which combines the advantages of two different optimization strategies and furthermore considers the manufacturing process of cupping with an additional deep drawing of beads. The bead paths will be determined with a cost-efficient optimality criteria-based (OC) method, the bead profile parameters will be detected by a sensitivity-based optimization method. This combination of two different optimization strategies also allows the consideration of the maximum formability under justifiable computational costs.The optimization algorithm to be developed considers the two-stepped manufacturing process consisting of deep drawing and beading. The formability in both manufacturing steps represents a limiting factor. Considering nonlinear strain paths, acceptable geometry and process parameters will be determined in numerical and experimental tests. These will be integrated in the optimization algorithm. Furthermore the algorithm considers the effect of beads on the stiffness according to the camber of the deep drawn geometry. This will also be verified using simulation and experiment.