Optimization methods for the tube hydroforming process applied to advanced high-strength steels with experimental verification

In this paper, an optimization method linked with the finite element method is presented for developing forming parameters of the tube hydroforming (THF) process for several advanced high-strength steel (AHSS) materials. The goal of this research was to maximize formability by identifying the optimal internal hydraulic pressure and end-feed rate, while satisfying the failure limits defined by the forming limit diagram (FLD). The optimization software HEEDS was used in combination with the nonlinear structural finite element code LS-DYNA to carry out the investigation. The pressure and feed profiles identified through the automated optimization procedures were obtained with accuracy and with no trial-and-error experiments. Experimental validation of the optimized profiles by hydroforming multiple tubes made from different materials was then performed successfully.