Structural topology optimization of a stamping die made from high-strength steel sheet metal based on load mapping

Even though high-strength steel is a favourable material because of its high strength and good formability, this material poses new challenges on the structure of stamping dies owing to potential damages of the die during production. Stamping dies are conventionally produced according to design manuals and standard manufacturing guidelines, where a high safety factor is specified to ensure that the stamping die is heavy and thick. A structural topology optimization method for a stamping die is presented in this study based on finite element simulations of the sheet metal stamping process. The finite element model of the stamping die is first established. Next, the boundary forces acting on the sheet metal are obtained from simulations and these forces are applied to the punch surface by means of load mapping during topology optimization. These forces are equivalent to the interaction between the blank and die. The objective function is to maximize the static stiffness under multi-conditions, which is defined by using the compromise programming approach. The analytic hierarchy process method is used to determine the weight ratio of the body stiffness in various load conditions and conduct topology optimization of the comprehensive objective function. The results show that the weight of the optimal punch is reduced while its performance is improved. More importantly, the reconstructed punch can be manufactured practically.