NUMERICAL OPTIMIZATION OF SHEET METAL FORMING PROCESSUSING NEW FRACTURE CRITERION

摘要

A numerical optimization system for sheet metal forming process has been developed based on a combination of response-surface-based optimization strategy with finite element simulation. The most important feature of the optimization system is introduction of a new fracture criterion to predict fracture limit under non-proportional deformation. In addition, a sheet-edge fracture criterion is also introduced to predict fracture limit under stretch-flanging deformation. The numerical optimization system is developed using the fracture criteria as accurate fracture constraints to avoid sheet breakage. The developed optimization system is applied to the optimum blank design for a square-cup deep drawing process of perforated blank. The optimum blank design, which minimizes the amount of material and avoids the sheet fracture, is obtained successfully. The effect of definition of fracture constraints on optimization calculation is also discussed.