Optimal preform die design through controlling deformation uniformity in metal forging

A finite element based sensitivity analysis method for the preform die shape design in metal forging is developed. The optimization goal is to obtain more uniform deformation within the final forging by controlling the deformation uniformity. The objective function expressed by the effective strain is constructed. The sensitivity equations of the objective function, elemental volume, elemental effective strain rate and the elemental strain rate with respect to the design variables are constituted. The preform die shapes of an H-shaped forging process in axisymmetric deformation are designed by using this method. The numerical tests show that more uniform deformed final forging can be obtained by use of the optimized preform die shape than by the non-optimized case.