Abstract
In this paper, we present a method to create draw-beads for improving the strength of sheet metal structures. We define a mechanically natural creation law such that local curvatures are created in proportion to the amount of local stresses in the perpendicular direction of the principal stress direction for resisting distributed bending moments. The local curvature is created by self-equilibrium bending moment. Owing to the law, the draw-beads are created without any artificial operations such as basis vectors. The thickness is assumed to be constant and the volume is constrained to a specified value. By repeating the stress analysis and the bead creation analysis alternately, the maximum stress is reduced, while creating the draw-beads. Orthogonal material property is defined only in the bead creation analysis. A threshold value is introduced to avoid a meaningless disturbance of the shape, and its effect is investigated. The validity of this numerical method to create the draw-beads for improving the strength of sheet metal structures is verified through some examples.
