Automated bead design considering production constraints

For design of stiff and lightweight sheet metal parts different construction methods are practicable. One important is weight neutral stiffness increasing using beads. Mostly empiric guidelines are used for designing bead structures until now. Alternatively rudiment simulation based methods for optimizing bead structures exist. But they do not consider production constraints such as formability or forming history. Users have to interpret optimizing results and have to transfer them into forming tools. Thus stiffness properties can be easily changed in a wrong way. Within the framework of a research project funded by the Deutsche Forschungsgemeinschaft a new method for automated design of bead structures considering production constraints, defined as ManuBeadOpt (Manufacturing based Bead Optimization), is developed. The methods substantial goal is linking forming simulation (based on inverse approach) and bead optimization to generate iteratively an optimal production-oriented bead structure. Therefore a forming tool based on the Nakazima-experiment for determining forming limit curves has been developed where punch is scaled on 400 mm diameter. Depending on this punch diameter a selected preformed area on pole of test pieces will be used for bead punching. Thereby specific strain allocations are possible, which accordingly affect the final test piece geometry. Afterwards the beaded area will be blanked and tested concerning stiffness behavior depending on bending, torsion and shear load cases. So relations between forming history, bead geometry, bead depth, stiffness, tool parameters, etc. will be identified. This knowledge is integrated in ManuBeadOpt for automatic evaluation of manufacturing. Tool, experimental and simulation results as well as the optimization method ManuBeadOpt will be shown.