In this paper, a method to create draw-beads, or embossed ribs for improving the rigidity or the strength of thin plate structures is presented. Draw-beads are self-created based on a natural creation law without any artificial operations such as the combination of shape basis vectors. By the creation law local initial curvatures are applied to all finite elements in proportion to the amount of local index in the perpendicular direction of the principal stress direction for resisting local bending moments. Orthogonal material property is used to apply the local curvatures. As the local index, we use the strain energy density in the rigidity design, and the maximum principal stress in the strength design. The thickness is assumed to be constant and the volume is constrained to a specified value. By repeating the stress analysis to evaluate the local index and the shape variation analysis to create the draw beads alternately, the compliance or the maximum stress is reduced. The validity of this numerical method to create the draw-beads for improving the rigidity or the strength of thin plate structures is verified through examples.
